<feed xmlns='http://www.w3.org/2005/Atom'>
<title>linux.git/arch/powerpc/include, branch v5.4-rc2</title>
<subtitle>Linux kernel source tree</subtitle>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/'/>
<entry>
<title>Merge tag 'libnvdimm-fixes-5.4-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/nvdimm/nvdimm</title>
<updated>2019-09-29T17:33:41+00:00</updated>
<author>
<name>Linus Torvalds</name>
<email>torvalds@linux-foundation.org</email>
</author>
<published>2019-09-29T17:33:41+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=a3c0e7b1fe1fc62bba5f591c4bc404eea96823b8'/>
<id>a3c0e7b1fe1fc62bba5f591c4bc404eea96823b8</id>
<content type='text'>
More libnvdimm updates from Dan Williams:

 - Complete the reworks to interoperate with powerpc dynamic huge page
   sizes

 - Fix a crash due to missed accounting for the powerpc 'struct
   page'-memmap mapping granularity

 - Fix badblock initialization for volatile (DRAM emulated) pmem ranges

 - Stop triggering request_key() notifications to userspace when
   NVDIMM-security is disabled / not present

 - Miscellaneous small fixups

* tag 'libnvdimm-fixes-5.4-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/nvdimm/nvdimm:
  libnvdimm/region: Enable MAP_SYNC for volatile regions
  libnvdimm: prevent nvdimm from requesting key when security is disabled
  libnvdimm/region: Initialize bad block for volatile namespaces
  libnvdimm/nfit_test: Fix acpi_handle redefinition
  libnvdimm/altmap: Track namespace boundaries in altmap
  libnvdimm: Fix endian conversion issues 
  libnvdimm/dax: Pick the right alignment default when creating dax devices
  powerpc/book3s64: Export has_transparent_hugepage() related functions.
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
More libnvdimm updates from Dan Williams:

 - Complete the reworks to interoperate with powerpc dynamic huge page
   sizes

 - Fix a crash due to missed accounting for the powerpc 'struct
   page'-memmap mapping granularity

 - Fix badblock initialization for volatile (DRAM emulated) pmem ranges

 - Stop triggering request_key() notifications to userspace when
   NVDIMM-security is disabled / not present

 - Miscellaneous small fixups

* tag 'libnvdimm-fixes-5.4-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/nvdimm/nvdimm:
  libnvdimm/region: Enable MAP_SYNC for volatile regions
  libnvdimm: prevent nvdimm from requesting key when security is disabled
  libnvdimm/region: Initialize bad block for volatile namespaces
  libnvdimm/nfit_test: Fix acpi_handle redefinition
  libnvdimm/altmap: Track namespace boundaries in altmap
  libnvdimm: Fix endian conversion issues 
  libnvdimm/dax: Pick the right alignment default when creating dax devices
  powerpc/book3s64: Export has_transparent_hugepage() related functions.
</pre>
</div>
</content>
</entry>
<entry>
<title>Merge tag 'powerpc-5.4-2' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux</title>
<updated>2019-09-28T20:43:00+00:00</updated>
<author>
<name>Linus Torvalds</name>
<email>torvalds@linux-foundation.org</email>
</author>
<published>2019-09-28T20:43:00+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=a2953204b576ea3ba4afd07b917811d50fc49778'/>
<id>a2953204b576ea3ba4afd07b917811d50fc49778</id>
<content type='text'>
Pull powerpc fixes from Michael Ellerman:
 "An assortment of fixes that were either missed by me, or didn't arrive
  quite in time for the first v5.4 pull.

   - Most notable is a fix for an issue with tlbie (broadcast TLB
     invalidation) on Power9, when using the Radix MMU. The tlbie can
     race with an mtpid (move to PID register, essentially MMU context
     switch) on another thread of the core, which can cause stores to
     continue to go to a page after it's unmapped.

   - A fix in our KVM code to add a missing barrier, the lack of which
     has been observed to cause missed IPIs and subsequently stuck CPUs
     in the host.

   - A change to the way we initialise PCR (Processor Compatibility
     Register) to make it forward compatible with future CPUs.

   - On some older PowerVM systems our H_BLOCK_REMOVE support could
     oops, fix it to detect such systems and fallback to the old
     invalidation method.

   - A fix for an oops seen on some machines when using KASAN on 32-bit.

   - A handful of other minor fixes, and two new selftests.

  Thanks to: Alistair Popple, Aneesh Kumar K.V, Christophe Leroy,
  Gustavo Romero, Joel Stanley, Jordan Niethe, Laurent Dufour, Michael
  Roth, Oliver O'Halloran"

* tag 'powerpc-5.4-2' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux:
  powerpc/eeh: Fix eeh eeh_debugfs_break_device() with SRIOV devices
  powerpc/nvdimm: use H_SCM_QUERY hcall on H_OVERLAP error
  powerpc/nvdimm: Use HCALL error as the return value
  selftests/powerpc: Add test case for tlbie vs mtpidr ordering issue
  powerpc/mm: Fixup tlbie vs mtpidr/mtlpidr ordering issue on POWER9
  powerpc/book3s64/radix: Rename CPU_FTR_P9_TLBIE_BUG feature flag
  powerpc/book3s64/mm: Don't do tlbie fixup for some hardware revisions
  powerpc/pseries: Call H_BLOCK_REMOVE when supported
  powerpc/pseries: Read TLB Block Invalidate Characteristics
  KVM: PPC: Book3S HV: use smp_mb() when setting/clearing host_ipi flag
  powerpc/mm: Fix an Oops in kasan_mmu_init()
  powerpc/mm: Add a helper to select PAGE_KERNEL_RO or PAGE_READONLY
  powerpc/64s: Set reserved PCR bits
  powerpc: Fix definition of PCR bits to work with old binutils
  powerpc/book3s64/radix: Remove WARN_ON in destroy_context()
  powerpc/tm: Add tm-poison test
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Pull powerpc fixes from Michael Ellerman:
 "An assortment of fixes that were either missed by me, or didn't arrive
  quite in time for the first v5.4 pull.

   - Most notable is a fix for an issue with tlbie (broadcast TLB
     invalidation) on Power9, when using the Radix MMU. The tlbie can
     race with an mtpid (move to PID register, essentially MMU context
     switch) on another thread of the core, which can cause stores to
     continue to go to a page after it's unmapped.

   - A fix in our KVM code to add a missing barrier, the lack of which
     has been observed to cause missed IPIs and subsequently stuck CPUs
     in the host.

   - A change to the way we initialise PCR (Processor Compatibility
     Register) to make it forward compatible with future CPUs.

   - On some older PowerVM systems our H_BLOCK_REMOVE support could
     oops, fix it to detect such systems and fallback to the old
     invalidation method.

   - A fix for an oops seen on some machines when using KASAN on 32-bit.

   - A handful of other minor fixes, and two new selftests.

  Thanks to: Alistair Popple, Aneesh Kumar K.V, Christophe Leroy,
  Gustavo Romero, Joel Stanley, Jordan Niethe, Laurent Dufour, Michael
  Roth, Oliver O'Halloran"

* tag 'powerpc-5.4-2' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux:
  powerpc/eeh: Fix eeh eeh_debugfs_break_device() with SRIOV devices
  powerpc/nvdimm: use H_SCM_QUERY hcall on H_OVERLAP error
  powerpc/nvdimm: Use HCALL error as the return value
  selftests/powerpc: Add test case for tlbie vs mtpidr ordering issue
  powerpc/mm: Fixup tlbie vs mtpidr/mtlpidr ordering issue on POWER9
  powerpc/book3s64/radix: Rename CPU_FTR_P9_TLBIE_BUG feature flag
  powerpc/book3s64/mm: Don't do tlbie fixup for some hardware revisions
  powerpc/pseries: Call H_BLOCK_REMOVE when supported
  powerpc/pseries: Read TLB Block Invalidate Characteristics
  KVM: PPC: Book3S HV: use smp_mb() when setting/clearing host_ipi flag
  powerpc/mm: Fix an Oops in kasan_mmu_init()
  powerpc/mm: Add a helper to select PAGE_KERNEL_RO or PAGE_READONLY
  powerpc/64s: Set reserved PCR bits
  powerpc: Fix definition of PCR bits to work with old binutils
  powerpc/book3s64/radix: Remove WARN_ON in destroy_context()
  powerpc/tm: Add tm-poison test
</pre>
</div>
</content>
</entry>
<entry>
<title>Merge branch 'akpm' (patches from Andrew)</title>
<updated>2019-09-24T23:10:23+00:00</updated>
<author>
<name>Linus Torvalds</name>
<email>torvalds@linux-foundation.org</email>
</author>
<published>2019-09-24T23:10:23+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=9c9fa97a8edbc3668dfc7a25de516e80c146e86f'/>
<id>9c9fa97a8edbc3668dfc7a25de516e80c146e86f</id>
<content type='text'>
Merge updates from Andrew Morton:

 - a few hot fixes

 - ocfs2 updates

 - almost all of -mm (slab-generic, slab, slub, kmemleak, kasan,
   cleanups, debug, pagecache, memcg, gup, pagemap, memory-hotplug,
   sparsemem, vmalloc, initialization, z3fold, compaction, mempolicy,
   oom-kill, hugetlb, migration, thp, mmap, madvise, shmem, zswap,
   zsmalloc)

* emailed patches from Andrew Morton &lt;akpm@linux-foundation.org&gt;: (132 commits)
  mm/zsmalloc.c: fix a -Wunused-function warning
  zswap: do not map same object twice
  zswap: use movable memory if zpool support allocate movable memory
  zpool: add malloc_support_movable to zpool_driver
  shmem: fix obsolete comment in shmem_getpage_gfp()
  mm/madvise: reduce code duplication in error handling paths
  mm: mmap: increase sockets maximum memory size pgoff for 32bits
  mm/mmap.c: refine find_vma_prev() with rb_last()
  riscv: make mmap allocation top-down by default
  mips: use generic mmap top-down layout and brk randomization
  mips: replace arch specific way to determine 32bit task with generic version
  mips: adjust brk randomization offset to fit generic version
  mips: use STACK_TOP when computing mmap base address
  mips: properly account for stack randomization and stack guard gap
  arm: use generic mmap top-down layout and brk randomization
  arm: use STACK_TOP when computing mmap base address
  arm: properly account for stack randomization and stack guard gap
  arm64, mm: make randomization selected by generic topdown mmap layout
  arm64, mm: move generic mmap layout functions to mm
  arm64: consider stack randomization for mmap base only when necessary
  ...
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Merge updates from Andrew Morton:

 - a few hot fixes

 - ocfs2 updates

 - almost all of -mm (slab-generic, slab, slub, kmemleak, kasan,
   cleanups, debug, pagecache, memcg, gup, pagemap, memory-hotplug,
   sparsemem, vmalloc, initialization, z3fold, compaction, mempolicy,
   oom-kill, hugetlb, migration, thp, mmap, madvise, shmem, zswap,
   zsmalloc)

* emailed patches from Andrew Morton &lt;akpm@linux-foundation.org&gt;: (132 commits)
  mm/zsmalloc.c: fix a -Wunused-function warning
  zswap: do not map same object twice
  zswap: use movable memory if zpool support allocate movable memory
  zpool: add malloc_support_movable to zpool_driver
  shmem: fix obsolete comment in shmem_getpage_gfp()
  mm/madvise: reduce code duplication in error handling paths
  mm: mmap: increase sockets maximum memory size pgoff for 32bits
  mm/mmap.c: refine find_vma_prev() with rb_last()
  riscv: make mmap allocation top-down by default
  mips: use generic mmap top-down layout and brk randomization
  mips: replace arch specific way to determine 32bit task with generic version
  mips: adjust brk randomization offset to fit generic version
  mips: use STACK_TOP when computing mmap base address
  mips: properly account for stack randomization and stack guard gap
  arm: use generic mmap top-down layout and brk randomization
  arm: use STACK_TOP when computing mmap base address
  arm: properly account for stack randomization and stack guard gap
  arm64, mm: make randomization selected by generic topdown mmap layout
  arm64, mm: move generic mmap layout functions to mm
  arm64: consider stack randomization for mmap base only when necessary
  ...
</pre>
</div>
</content>
</entry>
<entry>
<title>mm: consolidate pgtable_cache_init() and pgd_cache_init()</title>
<updated>2019-09-24T22:54:09+00:00</updated>
<author>
<name>Mike Rapoport</name>
<email>rppt@linux.ibm.com</email>
</author>
<published>2019-09-23T22:35:31+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=782de70c42930baae55234f3df0dc90774924447'/>
<id>782de70c42930baae55234f3df0dc90774924447</id>
<content type='text'>
Both pgtable_cache_init() and pgd_cache_init() are used to initialize kmem
cache for page table allocations on several architectures that do not use
PAGE_SIZE tables for one or more levels of the page table hierarchy.

Most architectures do not implement these functions and use __weak default
NOP implementation of pgd_cache_init().  Since there is no such default
for pgtable_cache_init(), its empty stub is duplicated among most
architectures.

Rename the definitions of pgd_cache_init() to pgtable_cache_init() and
drop empty stubs of pgtable_cache_init().

Link: http://lkml.kernel.org/r/1566457046-22637-1-git-send-email-rppt@linux.ibm.com
Signed-off-by: Mike Rapoport &lt;rppt@linux.ibm.com&gt;
Acked-by: Will Deacon &lt;will@kernel.org&gt;		[arm64]
Acked-by: Thomas Gleixner &lt;tglx@linutronix.de&gt;	[x86]
Cc: Catalin Marinas &lt;catalin.marinas@arm.com&gt;
Cc: Ingo Molnar &lt;mingo@redhat.com&gt;
Cc: Borislav Petkov &lt;bp@alien8.de&gt;
Cc: Matthew Wilcox &lt;willy@infradead.org&gt;
Signed-off-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
Signed-off-by: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Both pgtable_cache_init() and pgd_cache_init() are used to initialize kmem
cache for page table allocations on several architectures that do not use
PAGE_SIZE tables for one or more levels of the page table hierarchy.

Most architectures do not implement these functions and use __weak default
NOP implementation of pgd_cache_init().  Since there is no such default
for pgtable_cache_init(), its empty stub is duplicated among most
architectures.

Rename the definitions of pgd_cache_init() to pgtable_cache_init() and
drop empty stubs of pgtable_cache_init().

Link: http://lkml.kernel.org/r/1566457046-22637-1-git-send-email-rppt@linux.ibm.com
Signed-off-by: Mike Rapoport &lt;rppt@linux.ibm.com&gt;
Acked-by: Will Deacon &lt;will@kernel.org&gt;		[arm64]
Acked-by: Thomas Gleixner &lt;tglx@linutronix.de&gt;	[x86]
Cc: Catalin Marinas &lt;catalin.marinas@arm.com&gt;
Cc: Ingo Molnar &lt;mingo@redhat.com&gt;
Cc: Borislav Petkov &lt;bp@alien8.de&gt;
Cc: Matthew Wilcox &lt;willy@infradead.org&gt;
Signed-off-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
Signed-off-by: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>mm: remove quicklist page table caches</title>
<updated>2019-09-24T22:54:09+00:00</updated>
<author>
<name>Nicholas Piggin</name>
<email>npiggin@gmail.com</email>
</author>
<published>2019-09-23T22:35:19+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=13224794cb0832caa403ad583d8605202cabc6bc'/>
<id>13224794cb0832caa403ad583d8605202cabc6bc</id>
<content type='text'>
Patch series "mm: remove quicklist page table caches".

A while ago Nicholas proposed to remove quicklist page table caches [1].

I've rebased his patch on the curren upstream and switched ia64 and sh to
use generic versions of PTE allocation.

[1] https://lore.kernel.org/linux-mm/20190711030339.20892-1-npiggin@gmail.com

This patch (of 3):

Remove page table allocator "quicklists".  These have been around for a
long time, but have not got much traction in the last decade and are only
used on ia64 and sh architectures.

The numbers in the initial commit look interesting but probably don't
apply anymore.  If anybody wants to resurrect this it's in the git
history, but it's unhelpful to have this code and divergent allocator
behaviour for minor archs.

Also it might be better to instead make more general improvements to page
allocator if this is still so slow.

Link: http://lkml.kernel.org/r/1565250728-21721-2-git-send-email-rppt@linux.ibm.com
Signed-off-by: Nicholas Piggin &lt;npiggin@gmail.com&gt;
Signed-off-by: Mike Rapoport &lt;rppt@linux.ibm.com&gt;
Cc: Tony Luck &lt;tony.luck@intel.com&gt;
Cc: Yoshinori Sato &lt;ysato@users.sourceforge.jp&gt;
Signed-off-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
Signed-off-by: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Patch series "mm: remove quicklist page table caches".

A while ago Nicholas proposed to remove quicklist page table caches [1].

I've rebased his patch on the curren upstream and switched ia64 and sh to
use generic versions of PTE allocation.

[1] https://lore.kernel.org/linux-mm/20190711030339.20892-1-npiggin@gmail.com

This patch (of 3):

Remove page table allocator "quicklists".  These have been around for a
long time, but have not got much traction in the last decade and are only
used on ia64 and sh architectures.

The numbers in the initial commit look interesting but probably don't
apply anymore.  If anybody wants to resurrect this it's in the git
history, but it's unhelpful to have this code and divergent allocator
behaviour for minor archs.

Also it might be better to instead make more general improvements to page
allocator if this is still so slow.

Link: http://lkml.kernel.org/r/1565250728-21721-2-git-send-email-rppt@linux.ibm.com
Signed-off-by: Nicholas Piggin &lt;npiggin@gmail.com&gt;
Signed-off-by: Mike Rapoport &lt;rppt@linux.ibm.com&gt;
Cc: Tony Luck &lt;tony.luck@intel.com&gt;
Cc: Yoshinori Sato &lt;ysato@users.sourceforge.jp&gt;
Signed-off-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
Signed-off-by: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>powerpc/book3s64: Export has_transparent_hugepage() related functions.</title>
<updated>2019-09-24T17:22:29+00:00</updated>
<author>
<name>Aneesh Kumar K.V</name>
<email>aneesh.kumar@linux.ibm.com</email>
</author>
<published>2019-09-24T04:24:40+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=a6f197f889ce0a5fd583674d9fa39259f5c8f72f'/>
<id>a6f197f889ce0a5fd583674d9fa39259f5c8f72f</id>
<content type='text'>
In later patch, we want to use hash_transparent_hugepage() in a kernel module.
Export two related functions.

Acked-by: Michael Ellerman &lt;mpe@ellerman.id.au&gt;
Signed-off-by: Aneesh Kumar K.V &lt;aneesh.kumar@linux.ibm.com&gt;
Link: https://lore.kernel.org/r/20190924042440.27946-1-aneesh.kumar@linux.ibm.com
Signed-off-by: Dan Williams &lt;dan.j.williams@intel.com&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
In later patch, we want to use hash_transparent_hugepage() in a kernel module.
Export two related functions.

Acked-by: Michael Ellerman &lt;mpe@ellerman.id.au&gt;
Signed-off-by: Aneesh Kumar K.V &lt;aneesh.kumar@linux.ibm.com&gt;
Link: https://lore.kernel.org/r/20190924042440.27946-1-aneesh.kumar@linux.ibm.com
Signed-off-by: Dan Williams &lt;dan.j.williams@intel.com&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>powerpc/mm: Fixup tlbie vs mtpidr/mtlpidr ordering issue on POWER9</title>
<updated>2019-09-24T10:58:55+00:00</updated>
<author>
<name>Aneesh Kumar K.V</name>
<email>aneesh.kumar@linux.ibm.com</email>
</author>
<published>2019-09-24T03:52:53+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=047e6575aec71d75b765c22111820c4776cd1c43'/>
<id>047e6575aec71d75b765c22111820c4776cd1c43</id>
<content type='text'>
On POWER9, under some circumstances, a broadcast TLB invalidation will
fail to invalidate the ERAT cache on some threads when there are
parallel mtpidr/mtlpidr happening on other threads of the same core.
This can cause stores to continue to go to a page after it's unmapped.

The workaround is to force an ERAT flush using PID=0 or LPID=0 tlbie
flush. This additional TLB flush will cause the ERAT cache
invalidation. Since we are using PID=0 or LPID=0, we don't get
filtered out by the TLB snoop filtering logic.

We need to still follow this up with another tlbie to take care of
store vs tlbie ordering issue explained in commit:
a5d4b5891c2f ("powerpc/mm: Fixup tlbie vs store ordering issue on
POWER9"). The presence of ERAT cache implies we can still get new
stores and they may miss store queue marking flush.

Cc: stable@vger.kernel.org
Signed-off-by: Aneesh Kumar K.V &lt;aneesh.kumar@linux.ibm.com&gt;
Signed-off-by: Michael Ellerman &lt;mpe@ellerman.id.au&gt;
Link: https://lore.kernel.org/r/20190924035254.24612-3-aneesh.kumar@linux.ibm.com
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
On POWER9, under some circumstances, a broadcast TLB invalidation will
fail to invalidate the ERAT cache on some threads when there are
parallel mtpidr/mtlpidr happening on other threads of the same core.
This can cause stores to continue to go to a page after it's unmapped.

The workaround is to force an ERAT flush using PID=0 or LPID=0 tlbie
flush. This additional TLB flush will cause the ERAT cache
invalidation. Since we are using PID=0 or LPID=0, we don't get
filtered out by the TLB snoop filtering logic.

We need to still follow this up with another tlbie to take care of
store vs tlbie ordering issue explained in commit:
a5d4b5891c2f ("powerpc/mm: Fixup tlbie vs store ordering issue on
POWER9"). The presence of ERAT cache implies we can still get new
stores and they may miss store queue marking flush.

Cc: stable@vger.kernel.org
Signed-off-by: Aneesh Kumar K.V &lt;aneesh.kumar@linux.ibm.com&gt;
Signed-off-by: Michael Ellerman &lt;mpe@ellerman.id.au&gt;
Link: https://lore.kernel.org/r/20190924035254.24612-3-aneesh.kumar@linux.ibm.com
</pre>
</div>
</content>
</entry>
<entry>
<title>powerpc/book3s64/radix: Rename CPU_FTR_P9_TLBIE_BUG feature flag</title>
<updated>2019-09-24T10:58:47+00:00</updated>
<author>
<name>Aneesh Kumar K.V</name>
<email>aneesh.kumar@linux.ibm.com</email>
</author>
<published>2019-09-24T03:52:52+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=09ce98cacd51fcd0fa0af2f79d1e1d3192f4cbb0'/>
<id>09ce98cacd51fcd0fa0af2f79d1e1d3192f4cbb0</id>
<content type='text'>
Rename the #define to indicate this is related to store vs tlbie
ordering issue. In the next patch, we will be adding another feature
flag that is used to handles ERAT flush vs tlbie ordering issue.

Fixes: a5d4b5891c2f ("powerpc/mm: Fixup tlbie vs store ordering issue on POWER9")
Cc: stable@vger.kernel.org # v4.16+
Signed-off-by: Aneesh Kumar K.V &lt;aneesh.kumar@linux.ibm.com&gt;
Signed-off-by: Michael Ellerman &lt;mpe@ellerman.id.au&gt;
Link: https://lore.kernel.org/r/20190924035254.24612-2-aneesh.kumar@linux.ibm.com
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Rename the #define to indicate this is related to store vs tlbie
ordering issue. In the next patch, we will be adding another feature
flag that is used to handles ERAT flush vs tlbie ordering issue.

Fixes: a5d4b5891c2f ("powerpc/mm: Fixup tlbie vs store ordering issue on POWER9")
Cc: stable@vger.kernel.org # v4.16+
Signed-off-by: Aneesh Kumar K.V &lt;aneesh.kumar@linux.ibm.com&gt;
Signed-off-by: Michael Ellerman &lt;mpe@ellerman.id.au&gt;
Link: https://lore.kernel.org/r/20190924035254.24612-2-aneesh.kumar@linux.ibm.com
</pre>
</div>
</content>
</entry>
<entry>
<title>KVM: PPC: Book3S HV: use smp_mb() when setting/clearing host_ipi flag</title>
<updated>2019-09-24T02:46:26+00:00</updated>
<author>
<name>Michael Roth</name>
<email>mdroth@linux.vnet.ibm.com</email>
</author>
<published>2019-09-11T22:31:55+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=3a83f677a6eeff65751b29e3648d7c69c3be83f3'/>
<id>3a83f677a6eeff65751b29e3648d7c69c3be83f3</id>
<content type='text'>
On a 2-socket Power9 system with 32 cores/128 threads (SMT4) and 1TB
of memory running the following guest configs:

  guest A:
    - 224GB of memory
    - 56 VCPUs (sockets=1,cores=28,threads=2), where:
      VCPUs 0-1 are pinned to CPUs 0-3,
      VCPUs 2-3 are pinned to CPUs 4-7,
      ...
      VCPUs 54-55 are pinned to CPUs 108-111

  guest B:
    - 4GB of memory
    - 4 VCPUs (sockets=1,cores=4,threads=1)

with the following workloads (with KSM and THP enabled in all):

  guest A:
    stress --cpu 40 --io 20 --vm 20 --vm-bytes 512M

  guest B:
    stress --cpu 4 --io 4 --vm 4 --vm-bytes 512M

  host:
    stress --cpu 4 --io 4 --vm 2 --vm-bytes 256M

the below soft-lockup traces were observed after an hour or so and
persisted until the host was reset (this was found to be reliably
reproducible for this configuration, for kernels 4.15, 4.18, 5.0,
and 5.3-rc5):

  [ 1253.183290] rcu: INFO: rcu_sched self-detected stall on CPU
  [ 1253.183319] rcu:     124-....: (5250 ticks this GP) idle=10a/1/0x4000000000000002 softirq=5408/5408 fqs=1941
  [ 1256.287426] watchdog: BUG: soft lockup - CPU#105 stuck for 23s! [CPU 52/KVM:19709]
  [ 1264.075773] watchdog: BUG: soft lockup - CPU#24 stuck for 23s! [worker:19913]
  [ 1264.079769] watchdog: BUG: soft lockup - CPU#31 stuck for 23s! [worker:20331]
  [ 1264.095770] watchdog: BUG: soft lockup - CPU#45 stuck for 23s! [worker:20338]
  [ 1264.131773] watchdog: BUG: soft lockup - CPU#64 stuck for 23s! [avocado:19525]
  [ 1280.408480] watchdog: BUG: soft lockup - CPU#124 stuck for 22s! [ksmd:791]
  [ 1316.198012] rcu: INFO: rcu_sched self-detected stall on CPU
  [ 1316.198032] rcu:     124-....: (21003 ticks this GP) idle=10a/1/0x4000000000000002 softirq=5408/5408 fqs=8243
  [ 1340.411024] watchdog: BUG: soft lockup - CPU#124 stuck for 22s! [ksmd:791]
  [ 1379.212609] rcu: INFO: rcu_sched self-detected stall on CPU
  [ 1379.212629] rcu:     124-....: (36756 ticks this GP) idle=10a/1/0x4000000000000002 softirq=5408/5408 fqs=14714
  [ 1404.413615] watchdog: BUG: soft lockup - CPU#124 stuck for 22s! [ksmd:791]
  [ 1442.227095] rcu: INFO: rcu_sched self-detected stall on CPU
  [ 1442.227115] rcu:     124-....: (52509 ticks this GP) idle=10a/1/0x4000000000000002 softirq=5408/5408 fqs=21403
  [ 1455.111787] INFO: task worker:19907 blocked for more than 120 seconds.
  [ 1455.111822]       Tainted: G             L    5.3.0-rc5-mdr-vanilla+ #1
  [ 1455.111833] "echo 0 &gt; /proc/sys/kernel/hung_task_timeout_secs" disables this message.
  [ 1455.111884] INFO: task worker:19908 blocked for more than 120 seconds.
  [ 1455.111905]       Tainted: G             L    5.3.0-rc5-mdr-vanilla+ #1
  [ 1455.111925] "echo 0 &gt; /proc/sys/kernel/hung_task_timeout_secs" disables this message.
  [ 1455.111966] INFO: task worker:20328 blocked for more than 120 seconds.
  [ 1455.111986]       Tainted: G             L    5.3.0-rc5-mdr-vanilla+ #1
  [ 1455.111998] "echo 0 &gt; /proc/sys/kernel/hung_task_timeout_secs" disables this message.
  [ 1455.112048] INFO: task worker:20330 blocked for more than 120 seconds.
  [ 1455.112068]       Tainted: G             L    5.3.0-rc5-mdr-vanilla+ #1
  [ 1455.112097] "echo 0 &gt; /proc/sys/kernel/hung_task_timeout_secs" disables this message.
  [ 1455.112138] INFO: task worker:20332 blocked for more than 120 seconds.
  [ 1455.112159]       Tainted: G             L    5.3.0-rc5-mdr-vanilla+ #1
  [ 1455.112179] "echo 0 &gt; /proc/sys/kernel/hung_task_timeout_secs" disables this message.
  [ 1455.112210] INFO: task worker:20333 blocked for more than 120 seconds.
  [ 1455.112231]       Tainted: G             L    5.3.0-rc5-mdr-vanilla+ #1
  [ 1455.112242] "echo 0 &gt; /proc/sys/kernel/hung_task_timeout_secs" disables this message.
  [ 1455.112282] INFO: task worker:20335 blocked for more than 120 seconds.
  [ 1455.112303]       Tainted: G             L    5.3.0-rc5-mdr-vanilla+ #1
  [ 1455.112332] "echo 0 &gt; /proc/sys/kernel/hung_task_timeout_secs" disables this message.
  [ 1455.112372] INFO: task worker:20336 blocked for more than 120 seconds.
  [ 1455.112392]       Tainted: G             L    5.3.0-rc5-mdr-vanilla+ #1

CPUs 45, 24, and 124 are stuck on spin locks, likely held by
CPUs 105 and 31.

CPUs 105 and 31 are stuck in smp_call_function_many(), waiting on
target CPU 42. For instance:

  # CPU 105 registers (via xmon)
  R00 = c00000000020b20c   R16 = 00007d1bcd800000
  R01 = c00000363eaa7970   R17 = 0000000000000001
  R02 = c0000000019b3a00   R18 = 000000000000006b
  R03 = 000000000000002a   R19 = 00007d537d7aecf0
  R04 = 000000000000002a   R20 = 60000000000000e0
  R05 = 000000000000002a   R21 = 0801000000000080
  R06 = c0002073fb0caa08   R22 = 0000000000000d60
  R07 = c0000000019ddd78   R23 = 0000000000000001
  R08 = 000000000000002a   R24 = c00000000147a700
  R09 = 0000000000000001   R25 = c0002073fb0ca908
  R10 = c000008ffeb4e660   R26 = 0000000000000000
  R11 = c0002073fb0ca900   R27 = c0000000019e2464
  R12 = c000000000050790   R28 = c0000000000812b0
  R13 = c000207fff623e00   R29 = c0002073fb0ca808
  R14 = 00007d1bbee00000   R30 = c0002073fb0ca800
  R15 = 00007d1bcd600000   R31 = 0000000000000800
  pc  = c00000000020b260 smp_call_function_many+0x3d0/0x460
  cfar= c00000000020b270 smp_call_function_many+0x3e0/0x460
  lr  = c00000000020b20c smp_call_function_many+0x37c/0x460
  msr = 900000010288b033   cr  = 44024824
  ctr = c000000000050790   xer = 0000000000000000   trap =  100

CPU 42 is running normally, doing VCPU work:

  # CPU 42 stack trace (via xmon)
  [link register   ] c00800001be17188 kvmppc_book3s_radix_page_fault+0x90/0x2b0 [kvm_hv]
  [c000008ed3343820] c000008ed3343850 (unreliable)
  [c000008ed33438d0] c00800001be11b6c kvmppc_book3s_hv_page_fault+0x264/0xe30 [kvm_hv]
  [c000008ed33439d0] c00800001be0d7b4 kvmppc_vcpu_run_hv+0x8dc/0xb50 [kvm_hv]
  [c000008ed3343ae0] c00800001c10891c kvmppc_vcpu_run+0x34/0x48 [kvm]
  [c000008ed3343b00] c00800001c10475c kvm_arch_vcpu_ioctl_run+0x244/0x420 [kvm]
  [c000008ed3343b90] c00800001c0f5a78 kvm_vcpu_ioctl+0x470/0x7c8 [kvm]
  [c000008ed3343d00] c000000000475450 do_vfs_ioctl+0xe0/0xc70
  [c000008ed3343db0] c0000000004760e4 ksys_ioctl+0x104/0x120
  [c000008ed3343e00] c000000000476128 sys_ioctl+0x28/0x80
  [c000008ed3343e20] c00000000000b388 system_call+0x5c/0x70
  --- Exception: c00 (System Call) at 00007d545cfd7694
  SP (7d53ff7edf50) is in userspace

It was subsequently found that ipi_message[PPC_MSG_CALL_FUNCTION]
was set for CPU 42 by at least 1 of the CPUs waiting in
smp_call_function_many(), but somehow the corresponding
call_single_queue entries were never processed by CPU 42, causing the
callers to spin in csd_lock_wait() indefinitely.

Nick Piggin suggested something similar to the following sequence as
a possible explanation (interleaving of CALL_FUNCTION/RESCHEDULE
IPI messages seems to be most common, but any mix of CALL_FUNCTION and
!CALL_FUNCTION messages could trigger it):

    CPU
      X: smp_muxed_ipi_set_message():
      X:   smp_mb()
      X:   message[RESCHEDULE] = 1
      X: doorbell_global_ipi(42):
      X:   kvmppc_set_host_ipi(42, 1)
      X:   ppc_msgsnd_sync()/smp_mb()
      X:   ppc_msgsnd() -&gt; 42
     42: doorbell_exception(): // from CPU X
     42:   ppc_msgsync()
    105: smp_muxed_ipi_set_message():
    105:   smb_mb()
         // STORE DEFERRED DUE TO RE-ORDERING
  --105:   message[CALL_FUNCTION] = 1
  | 105: doorbell_global_ipi(42):
  | 105:   kvmppc_set_host_ipi(42, 1)
  |  42:   kvmppc_set_host_ipi(42, 0)
  |  42: smp_ipi_demux_relaxed()
  |  42: // returns to executing guest
  |      // RE-ORDERED STORE COMPLETES
  -&gt;105:   message[CALL_FUNCTION] = 1
    105:   ppc_msgsnd_sync()/smp_mb()
    105:   ppc_msgsnd() -&gt; 42
     42: local_paca-&gt;kvm_hstate.host_ipi == 0 // IPI ignored
    105: // hangs waiting on 42 to process messages/call_single_queue

This can be prevented with an smp_mb() at the beginning of
kvmppc_set_host_ipi(), such that stores to message[&lt;type&gt;] (or other
state indicated by the host_ipi flag) are ordered vs. the store to
to host_ipi.

However, doing so might still allow for the following scenario (not
yet observed):

    CPU
      X: smp_muxed_ipi_set_message():
      X:   smp_mb()
      X:   message[RESCHEDULE] = 1
      X: doorbell_global_ipi(42):
      X:   kvmppc_set_host_ipi(42, 1)
      X:   ppc_msgsnd_sync()/smp_mb()
      X:   ppc_msgsnd() -&gt; 42
     42: doorbell_exception(): // from CPU X
     42:   ppc_msgsync()
         // STORE DEFERRED DUE TO RE-ORDERING
  -- 42:   kvmppc_set_host_ipi(42, 0)
  |  42: smp_ipi_demux_relaxed()
  | 105: smp_muxed_ipi_set_message():
  | 105:   smb_mb()
  | 105:   message[CALL_FUNCTION] = 1
  | 105: doorbell_global_ipi(42):
  | 105:   kvmppc_set_host_ipi(42, 1)
  |      // RE-ORDERED STORE COMPLETES
  -&gt; 42:   kvmppc_set_host_ipi(42, 0)
     42: // returns to executing guest
    105:   ppc_msgsnd_sync()/smp_mb()
    105:   ppc_msgsnd() -&gt; 42
     42: local_paca-&gt;kvm_hstate.host_ipi == 0 // IPI ignored
    105: // hangs waiting on 42 to process messages/call_single_queue

Fixing this scenario would require an smp_mb() *after* clearing
host_ipi flag in kvmppc_set_host_ipi() to order the store vs.
subsequent processing of IPI messages.

To handle both cases, this patch splits kvmppc_set_host_ipi() into
separate set/clear functions, where we execute smp_mb() prior to
setting host_ipi flag, and after clearing host_ipi flag. These
functions pair with each other to synchronize the sender and receiver
sides.

With that change in place the above workload ran for 20 hours without
triggering any lock-ups.

Fixes: 755563bc79c7 ("powerpc/powernv: Fixes for hypervisor doorbell handling") # v4.0
Signed-off-by: Michael Roth &lt;mdroth@linux.vnet.ibm.com&gt;
Acked-by: Paul Mackerras &lt;paulus@ozlabs.org&gt;
Signed-off-by: Michael Ellerman &lt;mpe@ellerman.id.au&gt;
Link: https://lore.kernel.org/r/20190911223155.16045-1-mdroth@linux.vnet.ibm.com
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
On a 2-socket Power9 system with 32 cores/128 threads (SMT4) and 1TB
of memory running the following guest configs:

  guest A:
    - 224GB of memory
    - 56 VCPUs (sockets=1,cores=28,threads=2), where:
      VCPUs 0-1 are pinned to CPUs 0-3,
      VCPUs 2-3 are pinned to CPUs 4-7,
      ...
      VCPUs 54-55 are pinned to CPUs 108-111

  guest B:
    - 4GB of memory
    - 4 VCPUs (sockets=1,cores=4,threads=1)

with the following workloads (with KSM and THP enabled in all):

  guest A:
    stress --cpu 40 --io 20 --vm 20 --vm-bytes 512M

  guest B:
    stress --cpu 4 --io 4 --vm 4 --vm-bytes 512M

  host:
    stress --cpu 4 --io 4 --vm 2 --vm-bytes 256M

the below soft-lockup traces were observed after an hour or so and
persisted until the host was reset (this was found to be reliably
reproducible for this configuration, for kernels 4.15, 4.18, 5.0,
and 5.3-rc5):

  [ 1253.183290] rcu: INFO: rcu_sched self-detected stall on CPU
  [ 1253.183319] rcu:     124-....: (5250 ticks this GP) idle=10a/1/0x4000000000000002 softirq=5408/5408 fqs=1941
  [ 1256.287426] watchdog: BUG: soft lockup - CPU#105 stuck for 23s! [CPU 52/KVM:19709]
  [ 1264.075773] watchdog: BUG: soft lockup - CPU#24 stuck for 23s! [worker:19913]
  [ 1264.079769] watchdog: BUG: soft lockup - CPU#31 stuck for 23s! [worker:20331]
  [ 1264.095770] watchdog: BUG: soft lockup - CPU#45 stuck for 23s! [worker:20338]
  [ 1264.131773] watchdog: BUG: soft lockup - CPU#64 stuck for 23s! [avocado:19525]
  [ 1280.408480] watchdog: BUG: soft lockup - CPU#124 stuck for 22s! [ksmd:791]
  [ 1316.198012] rcu: INFO: rcu_sched self-detected stall on CPU
  [ 1316.198032] rcu:     124-....: (21003 ticks this GP) idle=10a/1/0x4000000000000002 softirq=5408/5408 fqs=8243
  [ 1340.411024] watchdog: BUG: soft lockup - CPU#124 stuck for 22s! [ksmd:791]
  [ 1379.212609] rcu: INFO: rcu_sched self-detected stall on CPU
  [ 1379.212629] rcu:     124-....: (36756 ticks this GP) idle=10a/1/0x4000000000000002 softirq=5408/5408 fqs=14714
  [ 1404.413615] watchdog: BUG: soft lockup - CPU#124 stuck for 22s! [ksmd:791]
  [ 1442.227095] rcu: INFO: rcu_sched self-detected stall on CPU
  [ 1442.227115] rcu:     124-....: (52509 ticks this GP) idle=10a/1/0x4000000000000002 softirq=5408/5408 fqs=21403
  [ 1455.111787] INFO: task worker:19907 blocked for more than 120 seconds.
  [ 1455.111822]       Tainted: G             L    5.3.0-rc5-mdr-vanilla+ #1
  [ 1455.111833] "echo 0 &gt; /proc/sys/kernel/hung_task_timeout_secs" disables this message.
  [ 1455.111884] INFO: task worker:19908 blocked for more than 120 seconds.
  [ 1455.111905]       Tainted: G             L    5.3.0-rc5-mdr-vanilla+ #1
  [ 1455.111925] "echo 0 &gt; /proc/sys/kernel/hung_task_timeout_secs" disables this message.
  [ 1455.111966] INFO: task worker:20328 blocked for more than 120 seconds.
  [ 1455.111986]       Tainted: G             L    5.3.0-rc5-mdr-vanilla+ #1
  [ 1455.111998] "echo 0 &gt; /proc/sys/kernel/hung_task_timeout_secs" disables this message.
  [ 1455.112048] INFO: task worker:20330 blocked for more than 120 seconds.
  [ 1455.112068]       Tainted: G             L    5.3.0-rc5-mdr-vanilla+ #1
  [ 1455.112097] "echo 0 &gt; /proc/sys/kernel/hung_task_timeout_secs" disables this message.
  [ 1455.112138] INFO: task worker:20332 blocked for more than 120 seconds.
  [ 1455.112159]       Tainted: G             L    5.3.0-rc5-mdr-vanilla+ #1
  [ 1455.112179] "echo 0 &gt; /proc/sys/kernel/hung_task_timeout_secs" disables this message.
  [ 1455.112210] INFO: task worker:20333 blocked for more than 120 seconds.
  [ 1455.112231]       Tainted: G             L    5.3.0-rc5-mdr-vanilla+ #1
  [ 1455.112242] "echo 0 &gt; /proc/sys/kernel/hung_task_timeout_secs" disables this message.
  [ 1455.112282] INFO: task worker:20335 blocked for more than 120 seconds.
  [ 1455.112303]       Tainted: G             L    5.3.0-rc5-mdr-vanilla+ #1
  [ 1455.112332] "echo 0 &gt; /proc/sys/kernel/hung_task_timeout_secs" disables this message.
  [ 1455.112372] INFO: task worker:20336 blocked for more than 120 seconds.
  [ 1455.112392]       Tainted: G             L    5.3.0-rc5-mdr-vanilla+ #1

CPUs 45, 24, and 124 are stuck on spin locks, likely held by
CPUs 105 and 31.

CPUs 105 and 31 are stuck in smp_call_function_many(), waiting on
target CPU 42. For instance:

  # CPU 105 registers (via xmon)
  R00 = c00000000020b20c   R16 = 00007d1bcd800000
  R01 = c00000363eaa7970   R17 = 0000000000000001
  R02 = c0000000019b3a00   R18 = 000000000000006b
  R03 = 000000000000002a   R19 = 00007d537d7aecf0
  R04 = 000000000000002a   R20 = 60000000000000e0
  R05 = 000000000000002a   R21 = 0801000000000080
  R06 = c0002073fb0caa08   R22 = 0000000000000d60
  R07 = c0000000019ddd78   R23 = 0000000000000001
  R08 = 000000000000002a   R24 = c00000000147a700
  R09 = 0000000000000001   R25 = c0002073fb0ca908
  R10 = c000008ffeb4e660   R26 = 0000000000000000
  R11 = c0002073fb0ca900   R27 = c0000000019e2464
  R12 = c000000000050790   R28 = c0000000000812b0
  R13 = c000207fff623e00   R29 = c0002073fb0ca808
  R14 = 00007d1bbee00000   R30 = c0002073fb0ca800
  R15 = 00007d1bcd600000   R31 = 0000000000000800
  pc  = c00000000020b260 smp_call_function_many+0x3d0/0x460
  cfar= c00000000020b270 smp_call_function_many+0x3e0/0x460
  lr  = c00000000020b20c smp_call_function_many+0x37c/0x460
  msr = 900000010288b033   cr  = 44024824
  ctr = c000000000050790   xer = 0000000000000000   trap =  100

CPU 42 is running normally, doing VCPU work:

  # CPU 42 stack trace (via xmon)
  [link register   ] c00800001be17188 kvmppc_book3s_radix_page_fault+0x90/0x2b0 [kvm_hv]
  [c000008ed3343820] c000008ed3343850 (unreliable)
  [c000008ed33438d0] c00800001be11b6c kvmppc_book3s_hv_page_fault+0x264/0xe30 [kvm_hv]
  [c000008ed33439d0] c00800001be0d7b4 kvmppc_vcpu_run_hv+0x8dc/0xb50 [kvm_hv]
  [c000008ed3343ae0] c00800001c10891c kvmppc_vcpu_run+0x34/0x48 [kvm]
  [c000008ed3343b00] c00800001c10475c kvm_arch_vcpu_ioctl_run+0x244/0x420 [kvm]
  [c000008ed3343b90] c00800001c0f5a78 kvm_vcpu_ioctl+0x470/0x7c8 [kvm]
  [c000008ed3343d00] c000000000475450 do_vfs_ioctl+0xe0/0xc70
  [c000008ed3343db0] c0000000004760e4 ksys_ioctl+0x104/0x120
  [c000008ed3343e00] c000000000476128 sys_ioctl+0x28/0x80
  [c000008ed3343e20] c00000000000b388 system_call+0x5c/0x70
  --- Exception: c00 (System Call) at 00007d545cfd7694
  SP (7d53ff7edf50) is in userspace

It was subsequently found that ipi_message[PPC_MSG_CALL_FUNCTION]
was set for CPU 42 by at least 1 of the CPUs waiting in
smp_call_function_many(), but somehow the corresponding
call_single_queue entries were never processed by CPU 42, causing the
callers to spin in csd_lock_wait() indefinitely.

Nick Piggin suggested something similar to the following sequence as
a possible explanation (interleaving of CALL_FUNCTION/RESCHEDULE
IPI messages seems to be most common, but any mix of CALL_FUNCTION and
!CALL_FUNCTION messages could trigger it):

    CPU
      X: smp_muxed_ipi_set_message():
      X:   smp_mb()
      X:   message[RESCHEDULE] = 1
      X: doorbell_global_ipi(42):
      X:   kvmppc_set_host_ipi(42, 1)
      X:   ppc_msgsnd_sync()/smp_mb()
      X:   ppc_msgsnd() -&gt; 42
     42: doorbell_exception(): // from CPU X
     42:   ppc_msgsync()
    105: smp_muxed_ipi_set_message():
    105:   smb_mb()
         // STORE DEFERRED DUE TO RE-ORDERING
  --105:   message[CALL_FUNCTION] = 1
  | 105: doorbell_global_ipi(42):
  | 105:   kvmppc_set_host_ipi(42, 1)
  |  42:   kvmppc_set_host_ipi(42, 0)
  |  42: smp_ipi_demux_relaxed()
  |  42: // returns to executing guest
  |      // RE-ORDERED STORE COMPLETES
  -&gt;105:   message[CALL_FUNCTION] = 1
    105:   ppc_msgsnd_sync()/smp_mb()
    105:   ppc_msgsnd() -&gt; 42
     42: local_paca-&gt;kvm_hstate.host_ipi == 0 // IPI ignored
    105: // hangs waiting on 42 to process messages/call_single_queue

This can be prevented with an smp_mb() at the beginning of
kvmppc_set_host_ipi(), such that stores to message[&lt;type&gt;] (or other
state indicated by the host_ipi flag) are ordered vs. the store to
to host_ipi.

However, doing so might still allow for the following scenario (not
yet observed):

    CPU
      X: smp_muxed_ipi_set_message():
      X:   smp_mb()
      X:   message[RESCHEDULE] = 1
      X: doorbell_global_ipi(42):
      X:   kvmppc_set_host_ipi(42, 1)
      X:   ppc_msgsnd_sync()/smp_mb()
      X:   ppc_msgsnd() -&gt; 42
     42: doorbell_exception(): // from CPU X
     42:   ppc_msgsync()
         // STORE DEFERRED DUE TO RE-ORDERING
  -- 42:   kvmppc_set_host_ipi(42, 0)
  |  42: smp_ipi_demux_relaxed()
  | 105: smp_muxed_ipi_set_message():
  | 105:   smb_mb()
  | 105:   message[CALL_FUNCTION] = 1
  | 105: doorbell_global_ipi(42):
  | 105:   kvmppc_set_host_ipi(42, 1)
  |      // RE-ORDERED STORE COMPLETES
  -&gt; 42:   kvmppc_set_host_ipi(42, 0)
     42: // returns to executing guest
    105:   ppc_msgsnd_sync()/smp_mb()
    105:   ppc_msgsnd() -&gt; 42
     42: local_paca-&gt;kvm_hstate.host_ipi == 0 // IPI ignored
    105: // hangs waiting on 42 to process messages/call_single_queue

Fixing this scenario would require an smp_mb() *after* clearing
host_ipi flag in kvmppc_set_host_ipi() to order the store vs.
subsequent processing of IPI messages.

To handle both cases, this patch splits kvmppc_set_host_ipi() into
separate set/clear functions, where we execute smp_mb() prior to
setting host_ipi flag, and after clearing host_ipi flag. These
functions pair with each other to synchronize the sender and receiver
sides.

With that change in place the above workload ran for 20 hours without
triggering any lock-ups.

Fixes: 755563bc79c7 ("powerpc/powernv: Fixes for hypervisor doorbell handling") # v4.0
Signed-off-by: Michael Roth &lt;mdroth@linux.vnet.ibm.com&gt;
Acked-by: Paul Mackerras &lt;paulus@ozlabs.org&gt;
Signed-off-by: Michael Ellerman &lt;mpe@ellerman.id.au&gt;
Link: https://lore.kernel.org/r/20190911223155.16045-1-mdroth@linux.vnet.ibm.com
</pre>
</div>
</content>
</entry>
<entry>
<title>Merge tag 'pci-v5.4-changes' of git://git.kernel.org/pub/scm/linux/kernel/git/helgaas/pci</title>
<updated>2019-09-24T02:16:01+00:00</updated>
<author>
<name>Linus Torvalds</name>
<email>torvalds@linux-foundation.org</email>
</author>
<published>2019-09-24T02:16:01+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=299d14d4c31aff3b37a03894e012edf8421676ee'/>
<id>299d14d4c31aff3b37a03894e012edf8421676ee</id>
<content type='text'>
Pull PCI updates from Bjorn Helgaas:
 "Enumeration:

   - Consolidate _HPP/_HPX stuff in pci-acpi.c and simplify it
     (Krzysztof Wilczynski)

   - Fix incorrect PCIe device types and remove dev-&gt;has_secondary_link
     to simplify code that deals with upstream/downstream ports (Mika
     Westerberg)

   - After suspend, restore Resizable BAR size bits correctly for 1MB
     BARs (Sumit Saxena)

   - Enable PCI_MSI_IRQ_DOMAIN support for RISC-V (Wesley Terpstra)

  Virtualization:

   - Add ACS quirks for iProc PAXB (Abhinav Ratna), Amazon Annapurna
     Labs (Ali Saidi)

   - Move sysfs SR-IOV functions to iov.c (Kelsey Skunberg)

   - Remove group write permissions from sysfs sriov_numvfs,
     sriov_drivers_autoprobe (Kelsey Skunberg)

  Hotplug:

   - Simplify pciehp indicator control (Denis Efremov)

  Peer-to-peer DMA:

   - Allow P2P DMA between root ports for whitelisted bridges (Logan
     Gunthorpe)

   - Whitelist some Intel host bridges for P2P DMA (Logan Gunthorpe)

   - DMA map P2P DMA requests that traverse host bridge (Logan
     Gunthorpe)

  Amazon Annapurna Labs host bridge driver:

   - Add DT binding and controller driver (Jonathan Chocron)

  Hyper-V host bridge driver:

   - Fix hv_pci_dev-&gt;pci_slot use-after-free (Dexuan Cui)

   - Fix PCI domain number collisions (Haiyang Zhang)

   - Use instance ID bytes 4 &amp; 5 as PCI domain numbers (Haiyang Zhang)

   - Fix build errors on non-SYSFS config (Randy Dunlap)

  i.MX6 host bridge driver:

   - Limit DBI register length (Stefan Agner)

  Intel VMD host bridge driver:

   - Fix config addressing issues (Jon Derrick)

  Layerscape host bridge driver:

   - Add bar_fixed_64bit property to endpoint driver (Xiaowei Bao)

   - Add CONFIG_PCI_LAYERSCAPE_EP to build EP/RC drivers separately
     (Xiaowei Bao)

  Mediatek host bridge driver:

   - Add MT7629 controller support (Jianjun Wang)

  Mobiveil host bridge driver:

   - Fix CPU base address setup (Hou Zhiqiang)

   - Make "num-lanes" property optional (Hou Zhiqiang)

  Tegra host bridge driver:

   - Fix OF node reference leak (Nishka Dasgupta)

   - Disable MSI for root ports to work around design problem (Vidya
     Sagar)

   - Add Tegra194 DT binding and controller support (Vidya Sagar)

   - Add support for sideband pins and slot regulators (Vidya Sagar)

   - Add PIPE2UPHY support (Vidya Sagar)

  Misc:

   - Remove unused pci_block_cfg_access() et al (Kelsey Skunberg)

   - Unexport pci_bus_get(), etc (Kelsey Skunberg)

   - Hide PM, VC, link speed, ATS, ECRC, PTM constants and interfaces in
     the PCI core (Kelsey Skunberg)

   - Clean up sysfs DEVICE_ATTR() usage (Kelsey Skunberg)

   - Mark expected switch fall-through (Gustavo A. R. Silva)

   - Propagate errors for optional regulators and PHYs (Thierry Reding)

   - Fix kernel command line resource_alignment parameter issues (Logan
     Gunthorpe)"

* tag 'pci-v5.4-changes' of git://git.kernel.org/pub/scm/linux/kernel/git/helgaas/pci: (112 commits)
  PCI: Add pci_irq_vector() and other stubs when !CONFIG_PCI
  arm64: tegra: Add PCIe slot supply information in p2972-0000 platform
  arm64: tegra: Add configuration for PCIe C5 sideband signals
  PCI: tegra: Add support to enable slot regulators
  PCI: tegra: Add support to configure sideband pins
  PCI: vmd: Fix shadow offsets to reflect spec changes
  PCI: vmd: Fix config addressing when using bus offsets
  PCI: dwc: Add validation that PCIe core is set to correct mode
  PCI: dwc: al: Add Amazon Annapurna Labs PCIe controller driver
  dt-bindings: PCI: Add Amazon's Annapurna Labs PCIe host bridge binding
  PCI: Add quirk to disable MSI-X support for Amazon's Annapurna Labs Root Port
  PCI/VPD: Prevent VPD access for Amazon's Annapurna Labs Root Port
  PCI: Add ACS quirk for Amazon Annapurna Labs root ports
  PCI: Add Amazon's Annapurna Labs vendor ID
  MAINTAINERS: Add PCI native host/endpoint controllers designated reviewer
  PCI: hv: Use bytes 4 and 5 from instance ID as the PCI domain numbers
  dt-bindings: PCI: tegra: Add PCIe slot supplies regulator entries
  dt-bindings: PCI: tegra: Add sideband pins configuration entries
  PCI: tegra: Add Tegra194 PCIe support
  PCI: Get rid of dev-&gt;has_secondary_link flag
  ...
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Pull PCI updates from Bjorn Helgaas:
 "Enumeration:

   - Consolidate _HPP/_HPX stuff in pci-acpi.c and simplify it
     (Krzysztof Wilczynski)

   - Fix incorrect PCIe device types and remove dev-&gt;has_secondary_link
     to simplify code that deals with upstream/downstream ports (Mika
     Westerberg)

   - After suspend, restore Resizable BAR size bits correctly for 1MB
     BARs (Sumit Saxena)

   - Enable PCI_MSI_IRQ_DOMAIN support for RISC-V (Wesley Terpstra)

  Virtualization:

   - Add ACS quirks for iProc PAXB (Abhinav Ratna), Amazon Annapurna
     Labs (Ali Saidi)

   - Move sysfs SR-IOV functions to iov.c (Kelsey Skunberg)

   - Remove group write permissions from sysfs sriov_numvfs,
     sriov_drivers_autoprobe (Kelsey Skunberg)

  Hotplug:

   - Simplify pciehp indicator control (Denis Efremov)

  Peer-to-peer DMA:

   - Allow P2P DMA between root ports for whitelisted bridges (Logan
     Gunthorpe)

   - Whitelist some Intel host bridges for P2P DMA (Logan Gunthorpe)

   - DMA map P2P DMA requests that traverse host bridge (Logan
     Gunthorpe)

  Amazon Annapurna Labs host bridge driver:

   - Add DT binding and controller driver (Jonathan Chocron)

  Hyper-V host bridge driver:

   - Fix hv_pci_dev-&gt;pci_slot use-after-free (Dexuan Cui)

   - Fix PCI domain number collisions (Haiyang Zhang)

   - Use instance ID bytes 4 &amp; 5 as PCI domain numbers (Haiyang Zhang)

   - Fix build errors on non-SYSFS config (Randy Dunlap)

  i.MX6 host bridge driver:

   - Limit DBI register length (Stefan Agner)

  Intel VMD host bridge driver:

   - Fix config addressing issues (Jon Derrick)

  Layerscape host bridge driver:

   - Add bar_fixed_64bit property to endpoint driver (Xiaowei Bao)

   - Add CONFIG_PCI_LAYERSCAPE_EP to build EP/RC drivers separately
     (Xiaowei Bao)

  Mediatek host bridge driver:

   - Add MT7629 controller support (Jianjun Wang)

  Mobiveil host bridge driver:

   - Fix CPU base address setup (Hou Zhiqiang)

   - Make "num-lanes" property optional (Hou Zhiqiang)

  Tegra host bridge driver:

   - Fix OF node reference leak (Nishka Dasgupta)

   - Disable MSI for root ports to work around design problem (Vidya
     Sagar)

   - Add Tegra194 DT binding and controller support (Vidya Sagar)

   - Add support for sideband pins and slot regulators (Vidya Sagar)

   - Add PIPE2UPHY support (Vidya Sagar)

  Misc:

   - Remove unused pci_block_cfg_access() et al (Kelsey Skunberg)

   - Unexport pci_bus_get(), etc (Kelsey Skunberg)

   - Hide PM, VC, link speed, ATS, ECRC, PTM constants and interfaces in
     the PCI core (Kelsey Skunberg)

   - Clean up sysfs DEVICE_ATTR() usage (Kelsey Skunberg)

   - Mark expected switch fall-through (Gustavo A. R. Silva)

   - Propagate errors for optional regulators and PHYs (Thierry Reding)

   - Fix kernel command line resource_alignment parameter issues (Logan
     Gunthorpe)"

* tag 'pci-v5.4-changes' of git://git.kernel.org/pub/scm/linux/kernel/git/helgaas/pci: (112 commits)
  PCI: Add pci_irq_vector() and other stubs when !CONFIG_PCI
  arm64: tegra: Add PCIe slot supply information in p2972-0000 platform
  arm64: tegra: Add configuration for PCIe C5 sideband signals
  PCI: tegra: Add support to enable slot regulators
  PCI: tegra: Add support to configure sideband pins
  PCI: vmd: Fix shadow offsets to reflect spec changes
  PCI: vmd: Fix config addressing when using bus offsets
  PCI: dwc: Add validation that PCIe core is set to correct mode
  PCI: dwc: al: Add Amazon Annapurna Labs PCIe controller driver
  dt-bindings: PCI: Add Amazon's Annapurna Labs PCIe host bridge binding
  PCI: Add quirk to disable MSI-X support for Amazon's Annapurna Labs Root Port
  PCI/VPD: Prevent VPD access for Amazon's Annapurna Labs Root Port
  PCI: Add ACS quirk for Amazon Annapurna Labs root ports
  PCI: Add Amazon's Annapurna Labs vendor ID
  MAINTAINERS: Add PCI native host/endpoint controllers designated reviewer
  PCI: hv: Use bytes 4 and 5 from instance ID as the PCI domain numbers
  dt-bindings: PCI: tegra: Add PCIe slot supplies regulator entries
  dt-bindings: PCI: tegra: Add sideband pins configuration entries
  PCI: tegra: Add Tegra194 PCIe support
  PCI: Get rid of dev-&gt;has_secondary_link flag
  ...
</pre>
</div>
</content>
</entry>
</feed>
