<feed xmlns='http://www.w3.org/2005/Atom'>
<title>linux.git/arch/x86/kernel/cpu/mce, branch v6.10</title>
<subtitle>Linux kernel source tree</subtitle>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/'/>
<entry>
<title>Merge tag 'ras_core_for_v6.10_rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip</title>
<updated>2024-05-14T15:39:42+00:00</updated>
<author>
<name>Linus Torvalds</name>
<email>torvalds@linux-foundation.org</email>
</author>
<published>2024-05-14T15:39:42+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=b4864f6565ab57d6418ec469330e320f77eeee95'/>
<id>b4864f6565ab57d6418ec469330e320f77eeee95</id>
<content type='text'>
Pull RAS update from Borislav Petkov:

 - Change the fixed-size buffer for MCE records to a dynamically sized
   one based on the number of CPUs present in the system

* tag 'ras_core_for_v6.10_rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/mce: Dynamically size space for machine check records
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Pull RAS update from Borislav Petkov:

 - Change the fixed-size buffer for MCE records to a dynamically sized
   one based on the number of CPUs present in the system

* tag 'ras_core_for_v6.10_rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/mce: Dynamically size space for machine check records
</pre>
</div>
</content>
</entry>
<entry>
<title>Merge tag 'x86-cpu-2024-05-13' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip</title>
<updated>2024-05-14T01:44:44+00:00</updated>
<author>
<name>Linus Torvalds</name>
<email>torvalds@linux-foundation.org</email>
</author>
<published>2024-05-14T01:44:44+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=ecd83bcbed7ad657c80b784eaced84e097e63de7'/>
<id>ecd83bcbed7ad657c80b784eaced84e097e63de7</id>
<content type='text'>
Pull x86 cpu updates from Ingo Molnar:

 - Rework the x86 CPU vendor/family/model code: introduce the 'VFM'
   value that is an 8+8+8 bit concatenation of the vendor/family/model
   value, and add macros that work on VFM values. This simplifies the
   addition of new Intel models &amp; families, and simplifies existing
   enumeration &amp; quirk code.

 - Add support for the AMD 0x80000026 leaf, to better parse topology
   information

 - Optimize the NUMA allocation layout of more per-CPU data structures

 - Improve the workaround for AMD erratum 1386

 - Clear TME from /proc/cpuinfo as well, when disabled by the firmware

 - Improve x86 self-tests

 - Extend the mce_record tracepoint with the ::ppin and ::microcode fields

 - Implement recovery for MCE errors in TDX/SEAM non-root mode

 - Misc cleanups and fixes

* tag 'x86-cpu-2024-05-13' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (34 commits)
  x86/mm: Switch to new Intel CPU model defines
  x86/tsc_msr: Switch to new Intel CPU model defines
  x86/tsc: Switch to new Intel CPU model defines
  x86/cpu: Switch to new Intel CPU model defines
  x86/resctrl: Switch to new Intel CPU model defines
  x86/microcode/intel: Switch to new Intel CPU model defines
  x86/mce: Switch to new Intel CPU model defines
  x86/cpu: Switch to new Intel CPU model defines
  x86/cpu/intel_epb: Switch to new Intel CPU model defines
  x86/aperfmperf: Switch to new Intel CPU model defines
  x86/apic: Switch to new Intel CPU model defines
  perf/x86/msr: Switch to new Intel CPU model defines
  perf/x86/intel/uncore: Switch to new Intel CPU model defines
  perf/x86/intel/pt: Switch to new Intel CPU model defines
  perf/x86/lbr: Switch to new Intel CPU model defines
  perf/x86/intel/cstate: Switch to new Intel CPU model defines
  x86/bugs: Switch to new Intel CPU model defines
  x86/bugs: Switch to new Intel CPU model defines
  x86/cpu/vfm: Update arch/x86/include/asm/intel-family.h
  x86/cpu/vfm: Add new macros to work with (vendor/family/model) values
  ...
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Pull x86 cpu updates from Ingo Molnar:

 - Rework the x86 CPU vendor/family/model code: introduce the 'VFM'
   value that is an 8+8+8 bit concatenation of the vendor/family/model
   value, and add macros that work on VFM values. This simplifies the
   addition of new Intel models &amp; families, and simplifies existing
   enumeration &amp; quirk code.

 - Add support for the AMD 0x80000026 leaf, to better parse topology
   information

 - Optimize the NUMA allocation layout of more per-CPU data structures

 - Improve the workaround for AMD erratum 1386

 - Clear TME from /proc/cpuinfo as well, when disabled by the firmware

 - Improve x86 self-tests

 - Extend the mce_record tracepoint with the ::ppin and ::microcode fields

 - Implement recovery for MCE errors in TDX/SEAM non-root mode

 - Misc cleanups and fixes

* tag 'x86-cpu-2024-05-13' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (34 commits)
  x86/mm: Switch to new Intel CPU model defines
  x86/tsc_msr: Switch to new Intel CPU model defines
  x86/tsc: Switch to new Intel CPU model defines
  x86/cpu: Switch to new Intel CPU model defines
  x86/resctrl: Switch to new Intel CPU model defines
  x86/microcode/intel: Switch to new Intel CPU model defines
  x86/mce: Switch to new Intel CPU model defines
  x86/cpu: Switch to new Intel CPU model defines
  x86/cpu/intel_epb: Switch to new Intel CPU model defines
  x86/aperfmperf: Switch to new Intel CPU model defines
  x86/apic: Switch to new Intel CPU model defines
  perf/x86/msr: Switch to new Intel CPU model defines
  perf/x86/intel/uncore: Switch to new Intel CPU model defines
  perf/x86/intel/pt: Switch to new Intel CPU model defines
  perf/x86/lbr: Switch to new Intel CPU model defines
  perf/x86/intel/cstate: Switch to new Intel CPU model defines
  x86/bugs: Switch to new Intel CPU model defines
  x86/bugs: Switch to new Intel CPU model defines
  x86/cpu/vfm: Update arch/x86/include/asm/intel-family.h
  x86/cpu/vfm: Add new macros to work with (vendor/family/model) values
  ...
</pre>
</div>
</content>
</entry>
<entry>
<title>Merge tag 'x86-cleanups-2024-05-13' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip</title>
<updated>2024-05-14T01:21:24+00:00</updated>
<author>
<name>Linus Torvalds</name>
<email>torvalds@linux-foundation.org</email>
</author>
<published>2024-05-14T01:21:24+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=c4273a66921219803b70491469c8d248909cd185'/>
<id>c4273a66921219803b70491469c8d248909cd185</id>
<content type='text'>
Pull x86 cleanups from Ingo Molnar:

 - Fix function prototypes to address clang function type cast
   warnings in the math-emu code

 - Reorder definitions in &lt;asm/msr-index.h&gt;

 - Remove unused code

 - Fix typos

 - Simplify #include sections

* tag 'x86-cleanups-2024-05-13' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/pci/ce4100: Remove unused 'struct sim_reg_op'
  x86/msr: Move ARCH_CAP_XAPIC_DISABLE bit definition to its rightful place
  x86/math-emu: Fix function cast warnings
  x86/extable: Remove unused fixup type EX_TYPE_COPY
  x86/rtc: Remove unused intel-mid.h
  x86/32: Remove unused IA32_STACK_TOP and two externs
  x86/head: Simplify relative include path to xen-head.S
  x86/fred: Fix typo in Kconfig description
  x86/syscall/compat: Remove ia32_unistd.h
  x86/syscall/compat: Remove unused macro __SYSCALL_ia32_NR
  x86/virt/tdx: Remove duplicate include
  x86/xen: Remove duplicate #include
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Pull x86 cleanups from Ingo Molnar:

 - Fix function prototypes to address clang function type cast
   warnings in the math-emu code

 - Reorder definitions in &lt;asm/msr-index.h&gt;

 - Remove unused code

 - Fix typos

 - Simplify #include sections

* tag 'x86-cleanups-2024-05-13' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/pci/ce4100: Remove unused 'struct sim_reg_op'
  x86/msr: Move ARCH_CAP_XAPIC_DISABLE bit definition to its rightful place
  x86/math-emu: Fix function cast warnings
  x86/extable: Remove unused fixup type EX_TYPE_COPY
  x86/rtc: Remove unused intel-mid.h
  x86/32: Remove unused IA32_STACK_TOP and two externs
  x86/head: Simplify relative include path to xen-head.S
  x86/fred: Fix typo in Kconfig description
  x86/syscall/compat: Remove ia32_unistd.h
  x86/syscall/compat: Remove unused macro __SYSCALL_ia32_NR
  x86/virt/tdx: Remove duplicate include
  x86/xen: Remove duplicate #include
</pre>
</div>
</content>
</entry>
<entry>
<title>x86/mce: Switch to new Intel CPU model defines</title>
<updated>2024-04-29T08:31:23+00:00</updated>
<author>
<name>Tony Luck</name>
<email>tony.luck@intel.com</email>
</author>
<published>2024-04-24T18:15:11+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=4a5f2dd162fd68f588784eb9b0a927e3b328736d'/>
<id>4a5f2dd162fd68f588784eb9b0a927e3b328736d</id>
<content type='text'>
New CPU #defines encode vendor and family as well as model.

  [ bp: Squash *three* mce patches into one, fold in fix:
    https://lore.kernel.org/r/20240429022051.63360-1-tony.luck@intel.com ]

Signed-off-by: Tony Luck &lt;tony.luck@intel.com&gt;
Signed-off-by: Dave Hansen &lt;dave.hansen@linux.intel.com&gt;
Signed-off-by: Borislav Petkov (AMD) &lt;bp@alien8.de&gt;
Link: https://lore.kernel.org/all/20240424181511.41772-1-tony.luck%40intel.com
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
New CPU #defines encode vendor and family as well as model.

  [ bp: Squash *three* mce patches into one, fold in fix:
    https://lore.kernel.org/r/20240429022051.63360-1-tony.luck@intel.com ]

Signed-off-by: Tony Luck &lt;tony.luck@intel.com&gt;
Signed-off-by: Dave Hansen &lt;dave.hansen@linux.intel.com&gt;
Signed-off-by: Borislav Petkov (AMD) &lt;bp@alien8.de&gt;
Link: https://lore.kernel.org/all/20240424181511.41772-1-tony.luck%40intel.com
</pre>
</div>
</content>
</entry>
<entry>
<title>x86/mce: Implement recovery for errors in TDX/SEAM non-root mode</title>
<updated>2024-04-09T07:30:36+00:00</updated>
<author>
<name>Tony Luck</name>
<email>tony.luck@intel.com</email>
</author>
<published>2024-04-08T18:09:44+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=7911f145de5fecbee1d67f27f73bec12f0fbc472'/>
<id>7911f145de5fecbee1d67f27f73bec12f0fbc472</id>
<content type='text'>
Machine check SMIs (MSMI) signaled during SEAM operation (typically
inside TDX guests), on a system with Intel eMCA enabled, might eventually
be reported to the kernel #MC handler with the saved RIP on the stack
pointing to the instruction in kernel code after the SEAMCALL instruction
that entered the SEAM operation. Linux currently says that is a fatal
error and shuts down.

There is a new bit in IA32_MCG_STATUS that, when set to 1, indicates
that the machine check didn't originally occur at that saved RIP, but
during SEAM non-root operation.

Add new entries to the severity table to detect this for both data load
and instruction fetch that set the severity to "AR" (action required).

Increase the width of the mcgmask/mcgres fields in "struct severity"
from unsigned char to unsigned short since the new bit is in position 12.

Action required for these errors is just mark the page as poisoned and
return from the machine check handler.

HW ABI notes:
=============

The SEAM_NR bit in IA32_MCG_STATUS hasn't yet made it into the Intel
Software Developers' Manual. But it is described in section 16.5.2
of "Intel(R) Trust Domain Extensions (Intel(R) TDX) Module Base
Architecture Specification" downloadable from:

  https://cdrdv2.intel.com/v1/dl/getContent/733575

Backport notes:
===============

Little value in backporting this patch to stable or LTS kernels as
this is only relevant with support for TDX, which I assume won't be
backported. But for anyone taking this to v6.1 or older, you also
need commit:

  a51cbd0d86d3 ("x86/mce: Use severity table to handle uncorrected errors in kernel")

Signed-off-by: Tony Luck &lt;tony.luck@intel.com&gt;
Signed-off-by: Ingo Molnar &lt;mingo@kernel.org&gt;
Link: https://lore.kernel.org/r/20240408180944.44638-1-tony.luck@intel.com
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Machine check SMIs (MSMI) signaled during SEAM operation (typically
inside TDX guests), on a system with Intel eMCA enabled, might eventually
be reported to the kernel #MC handler with the saved RIP on the stack
pointing to the instruction in kernel code after the SEAMCALL instruction
that entered the SEAM operation. Linux currently says that is a fatal
error and shuts down.

There is a new bit in IA32_MCG_STATUS that, when set to 1, indicates
that the machine check didn't originally occur at that saved RIP, but
during SEAM non-root operation.

Add new entries to the severity table to detect this for both data load
and instruction fetch that set the severity to "AR" (action required).

Increase the width of the mcgmask/mcgres fields in "struct severity"
from unsigned char to unsigned short since the new bit is in position 12.

Action required for these errors is just mark the page as poisoned and
return from the machine check handler.

HW ABI notes:
=============

The SEAM_NR bit in IA32_MCG_STATUS hasn't yet made it into the Intel
Software Developers' Manual. But it is described in section 16.5.2
of "Intel(R) Trust Domain Extensions (Intel(R) TDX) Module Base
Architecture Specification" downloadable from:

  https://cdrdv2.intel.com/v1/dl/getContent/733575

Backport notes:
===============

Little value in backporting this patch to stable or LTS kernels as
this is only relevant with support for TDX, which I assume won't be
backported. But for anyone taking this to v6.1 or older, you also
need commit:

  a51cbd0d86d3 ("x86/mce: Use severity table to handle uncorrected errors in kernel")

Signed-off-by: Tony Luck &lt;tony.luck@intel.com&gt;
Signed-off-by: Ingo Molnar &lt;mingo@kernel.org&gt;
Link: https://lore.kernel.org/r/20240408180944.44638-1-tony.luck@intel.com
</pre>
</div>
</content>
</entry>
<entry>
<title>x86/mce: Make sure to grab mce_sysfs_mutex in set_bank()</title>
<updated>2024-04-04T15:25:15+00:00</updated>
<author>
<name>Borislav Petkov (AMD)</name>
<email>bp@alien8.de</email>
</author>
<published>2024-03-13T13:48:27+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=3ddf944b32f88741c303f0b21459dbb3872b8bc5'/>
<id>3ddf944b32f88741c303f0b21459dbb3872b8bc5</id>
<content type='text'>
Modifying a MCA bank's MCA_CTL bits which control which error types to
be reported is done over

  /sys/devices/system/machinecheck/
  ├── machinecheck0
  │   ├── bank0
  │   ├── bank1
  │   ├── bank10
  │   ├── bank11
  ...

sysfs nodes by writing the new bit mask of events to enable.

When the write is accepted, the kernel deletes all current timers and
reinits all banks.

Doing that in parallel can lead to initializing a timer which is already
armed and in the timer wheel, i.e., in use already:

  ODEBUG: init active (active state 0) object: ffff888063a28000 object
  type: timer_list hint: mce_timer_fn+0x0/0x240 arch/x86/kernel/cpu/mce/core.c:2642
  WARNING: CPU: 0 PID: 8120 at lib/debugobjects.c:514
  debug_print_object+0x1a0/0x2a0 lib/debugobjects.c:514

Fix that by grabbing the sysfs mutex as the rest of the MCA sysfs code
does.

Reported by: Yue Sun &lt;samsun1006219@gmail.com&gt;
Reported by: xingwei lee &lt;xrivendell7@gmail.com&gt;
Signed-off-by: Borislav Petkov (AMD) &lt;bp@alien8.de&gt;
Cc: &lt;stable@kernel.org&gt;
Link: https://lore.kernel.org/r/CAEkJfYNiENwQY8yV1LYJ9LjJs%2Bx_-PqMv98gKig55=2vbzffRw@mail.gmail.com
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Modifying a MCA bank's MCA_CTL bits which control which error types to
be reported is done over

  /sys/devices/system/machinecheck/
  ├── machinecheck0
  │   ├── bank0
  │   ├── bank1
  │   ├── bank10
  │   ├── bank11
  ...

sysfs nodes by writing the new bit mask of events to enable.

When the write is accepted, the kernel deletes all current timers and
reinits all banks.

Doing that in parallel can lead to initializing a timer which is already
armed and in the timer wheel, i.e., in use already:

  ODEBUG: init active (active state 0) object: ffff888063a28000 object
  type: timer_list hint: mce_timer_fn+0x0/0x240 arch/x86/kernel/cpu/mce/core.c:2642
  WARNING: CPU: 0 PID: 8120 at lib/debugobjects.c:514
  debug_print_object+0x1a0/0x2a0 lib/debugobjects.c:514

Fix that by grabbing the sysfs mutex as the rest of the MCA sysfs code
does.

Reported by: Yue Sun &lt;samsun1006219@gmail.com&gt;
Reported by: xingwei lee &lt;xrivendell7@gmail.com&gt;
Signed-off-by: Borislav Petkov (AMD) &lt;bp@alien8.de&gt;
Cc: &lt;stable@kernel.org&gt;
Link: https://lore.kernel.org/r/CAEkJfYNiENwQY8yV1LYJ9LjJs%2Bx_-PqMv98gKig55=2vbzffRw@mail.gmail.com
</pre>
</div>
</content>
</entry>
<entry>
<title>x86/extable: Remove unused fixup type EX_TYPE_COPY</title>
<updated>2024-04-04T15:01:40+00:00</updated>
<author>
<name>Tong Tiangen</name>
<email>tongtiangen@huawei.com</email>
</author>
<published>2024-02-04T08:26:25+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=cb517619f96718a4c3c2534a3124177633f8998d'/>
<id>cb517619f96718a4c3c2534a3124177633f8998d</id>
<content type='text'>
After

  034ff37d3407 ("x86: rewrite '__copy_user_nocache' function")

rewrote __copy_user_nocache() to use EX_TYPE_UACCESS instead of the
EX_TYPE_COPY exception type, there are no more EX_TYPE_COPY users, so
remove it.

  [ bp: Massage commit message. ]

Signed-off-by: Tong Tiangen &lt;tongtiangen@huawei.com&gt;
Signed-off-by: Borislav Petkov (AMD) &lt;bp@alien8.de&gt;
Link: https://lore.kernel.org/r/20240204082627.3892816-2-tongtiangen@huawei.com
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
After

  034ff37d3407 ("x86: rewrite '__copy_user_nocache' function")

rewrote __copy_user_nocache() to use EX_TYPE_UACCESS instead of the
EX_TYPE_COPY exception type, there are no more EX_TYPE_COPY users, so
remove it.

  [ bp: Massage commit message. ]

Signed-off-by: Tong Tiangen &lt;tongtiangen@huawei.com&gt;
Signed-off-by: Borislav Petkov (AMD) &lt;bp@alien8.de&gt;
Link: https://lore.kernel.org/r/20240204082627.3892816-2-tongtiangen@huawei.com
</pre>
</div>
</content>
</entry>
<entry>
<title>x86/mce: Dynamically size space for machine check records</title>
<updated>2024-03-26T11:40:42+00:00</updated>
<author>
<name>Tony Luck</name>
<email>tony.luck@intel.com</email>
</author>
<published>2024-03-07T19:27:04+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=108c6494bdf1dfeaefc0a506e2f471aa92fafdd6'/>
<id>108c6494bdf1dfeaefc0a506e2f471aa92fafdd6</id>
<content type='text'>
Systems with a large number of CPUs may generate a large number of
machine check records when things go seriously wrong. But Linux has
a fixed-size buffer that can only capture a few dozen errors.

Allocate space based on the number of CPUs (with a minimum value based
on the historical fixed buffer that could store 80 records).

  [ bp: Rename local var from tmpp to something more telling: gpool. ]

Signed-off-by: Tony Luck &lt;tony.luck@intel.com&gt;
Signed-off-by: Borislav Petkov (AMD) &lt;bp@alien8.de&gt;
Reviewed-by: Sohil Mehta &lt;sohil.mehta@intel.com&gt;
Reviewed-by: Avadhut Naik &lt;avadhut.naik@amd.com&gt;
Link: https://lore.kernel.org/r/20240307192704.37213-1-tony.luck@intel.com
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Systems with a large number of CPUs may generate a large number of
machine check records when things go seriously wrong. But Linux has
a fixed-size buffer that can only capture a few dozen errors.

Allocate space based on the number of CPUs (with a minimum value based
on the historical fixed buffer that could store 80 records).

  [ bp: Rename local var from tmpp to something more telling: gpool. ]

Signed-off-by: Tony Luck &lt;tony.luck@intel.com&gt;
Signed-off-by: Borislav Petkov (AMD) &lt;bp@alien8.de&gt;
Reviewed-by: Sohil Mehta &lt;sohil.mehta@intel.com&gt;
Reviewed-by: Avadhut Naik &lt;avadhut.naik@amd.com&gt;
Link: https://lore.kernel.org/r/20240307192704.37213-1-tony.luck@intel.com
</pre>
</div>
</content>
</entry>
<entry>
<title>Merge tag 'ras_core_for_v6.9_rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip</title>
<updated>2024-03-12T00:22:57+00:00</updated>
<author>
<name>Linus Torvalds</name>
<email>torvalds@linux-foundation.org</email>
</author>
<published>2024-03-12T00:22:57+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=d8941ce52b708cfd520994e65760a2fa6a646dfb'/>
<id>d8941ce52b708cfd520994e65760a2fa6a646dfb</id>
<content type='text'>
Pull RAS fixlet from Borislav Petkov:

 - Constify yet another static struct bus_type instance now that the
   driver core can handle that

* tag 'ras_core_for_v6.9_rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/mce: Make mce_subsys const
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Pull RAS fixlet from Borislav Petkov:

 - Constify yet another static struct bus_type instance now that the
   driver core can handle that

* tag 'ras_core_for_v6.9_rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/mce: Make mce_subsys const
</pre>
</div>
</content>
</entry>
<entry>
<title>Merge tag 'x86-fred-2024-03-10' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip</title>
<updated>2024-03-11T23:00:17+00:00</updated>
<author>
<name>Linus Torvalds</name>
<email>torvalds@linux-foundation.org</email>
</author>
<published>2024-03-11T23:00:17+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=720c857907530e6cdc86c9bc1102ea6b372fbfb6'/>
<id>720c857907530e6cdc86c9bc1102ea6b372fbfb6</id>
<content type='text'>
Pull x86 FRED support from Thomas Gleixner:
 "Support for x86 Fast Return and Event Delivery (FRED).

  FRED is a replacement for IDT event delivery on x86 and addresses most
  of the technical nightmares which IDT exposes:

   1) Exception cause registers like CR2 need to be manually preserved
      in nested exception scenarios.

   2) Hardware interrupt stack switching is suboptimal for nested
      exceptions as the interrupt stack mechanism rewinds the stack on
      each entry which requires a massive effort in the low level entry
      of #NMI code to handle this.

   3) No hardware distinction between entry from kernel or from user
      which makes establishing kernel context more complex than it needs
      to be especially for unconditionally nestable exceptions like NMI.

   4) NMI nesting caused by IRET unconditionally reenabling NMIs, which
      is a problem when the perf NMI takes a fault when collecting a
      stack trace.

   5) Partial restore of ESP when returning to a 16-bit segment

   6) Limitation of the vector space which can cause vector exhaustion
      on large systems.

   7) Inability to differentiate NMI sources

  FRED addresses these shortcomings by:

   1) An extended exception stack frame which the CPU uses to save
      exception cause registers. This ensures that the meta information
      for each exception is preserved on stack and avoids the extra
      complexity of preserving it in software.

   2) Hardware interrupt stack switching is non-rewinding if a nested
      exception uses the currently interrupt stack.

   3) The entry points for kernel and user context are separate and GS
      BASE handling which is required to establish kernel context for
      per CPU variable access is done in hardware.

   4) NMIs are now nesting protected. They are only reenabled on the
      return from NMI.

   5) FRED guarantees full restore of ESP

   6) FRED does not put a limitation on the vector space by design
      because it uses a central entry points for kernel and user space
      and the CPUstores the entry type (exception, trap, interrupt,
      syscall) on the entry stack along with the vector number. The
      entry code has to demultiplex this information, but this removes
      the vector space restriction.

      The first hardware implementations will still have the current
      restricted vector space because lifting this limitation requires
      further changes to the local APIC.

   7) FRED stores the vector number and meta information on stack which
      allows having more than one NMI vector in future hardware when the
      required local APIC changes are in place.

  The series implements the initial FRED support by:

   - Reworking the existing entry and IDT handling infrastructure to
     accomodate for the alternative entry mechanism.

   - Expanding the stack frame to accomodate for the extra 16 bytes FRED
     requires to store context and meta information

   - Providing FRED specific C entry points for events which have
     information pushed to the extended stack frame, e.g. #PF and #DB.

   - Providing FRED specific C entry points for #NMI and #MCE

   - Implementing the FRED specific ASM entry points and the C code to
     demultiplex the events

   - Providing detection and initialization mechanisms and the necessary
     tweaks in context switching, GS BASE handling etc.

  The FRED integration aims for maximum code reuse vs the existing IDT
  implementation to the extent possible and the deviation in hot paths
  like context switching are handled with alternatives to minimalize the
  impact. The low level entry and exit paths are seperate due to the
  extended stack frame and the hardware based GS BASE swichting and
  therefore have no impact on IDT based systems.

  It has been extensively tested on existing systems and on the FRED
  simulation and as of now there are no outstanding problems"

* tag 'x86-fred-2024-03-10' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (38 commits)
  x86/fred: Fix init_task thread stack pointer initialization
  MAINTAINERS: Add a maintainer entry for FRED
  x86/fred: Fix a build warning with allmodconfig due to 'inline' failing to inline properly
  x86/fred: Invoke FRED initialization code to enable FRED
  x86/fred: Add FRED initialization functions
  x86/syscall: Split IDT syscall setup code into idt_syscall_init()
  KVM: VMX: Call fred_entry_from_kvm() for IRQ/NMI handling
  x86/entry: Add fred_entry_from_kvm() for VMX to handle IRQ/NMI
  x86/entry/calling: Allow PUSH_AND_CLEAR_REGS being used beyond actual entry code
  x86/fred: Fixup fault on ERETU by jumping to fred_entrypoint_user
  x86/fred: Let ret_from_fork_asm() jmp to asm_fred_exit_user when FRED is enabled
  x86/traps: Add sysvec_install() to install a system interrupt handler
  x86/fred: FRED entry/exit and dispatch code
  x86/fred: Add a machine check entry stub for FRED
  x86/fred: Add a NMI entry stub for FRED
  x86/fred: Add a debug fault entry stub for FRED
  x86/idtentry: Incorporate definitions/declarations of the FRED entries
  x86/fred: Make exc_page_fault() work for FRED
  x86/fred: Allow single-step trap and NMI when starting a new task
  x86/fred: No ESPFIX needed when FRED is enabled
  ...
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Pull x86 FRED support from Thomas Gleixner:
 "Support for x86 Fast Return and Event Delivery (FRED).

  FRED is a replacement for IDT event delivery on x86 and addresses most
  of the technical nightmares which IDT exposes:

   1) Exception cause registers like CR2 need to be manually preserved
      in nested exception scenarios.

   2) Hardware interrupt stack switching is suboptimal for nested
      exceptions as the interrupt stack mechanism rewinds the stack on
      each entry which requires a massive effort in the low level entry
      of #NMI code to handle this.

   3) No hardware distinction between entry from kernel or from user
      which makes establishing kernel context more complex than it needs
      to be especially for unconditionally nestable exceptions like NMI.

   4) NMI nesting caused by IRET unconditionally reenabling NMIs, which
      is a problem when the perf NMI takes a fault when collecting a
      stack trace.

   5) Partial restore of ESP when returning to a 16-bit segment

   6) Limitation of the vector space which can cause vector exhaustion
      on large systems.

   7) Inability to differentiate NMI sources

  FRED addresses these shortcomings by:

   1) An extended exception stack frame which the CPU uses to save
      exception cause registers. This ensures that the meta information
      for each exception is preserved on stack and avoids the extra
      complexity of preserving it in software.

   2) Hardware interrupt stack switching is non-rewinding if a nested
      exception uses the currently interrupt stack.

   3) The entry points for kernel and user context are separate and GS
      BASE handling which is required to establish kernel context for
      per CPU variable access is done in hardware.

   4) NMIs are now nesting protected. They are only reenabled on the
      return from NMI.

   5) FRED guarantees full restore of ESP

   6) FRED does not put a limitation on the vector space by design
      because it uses a central entry points for kernel and user space
      and the CPUstores the entry type (exception, trap, interrupt,
      syscall) on the entry stack along with the vector number. The
      entry code has to demultiplex this information, but this removes
      the vector space restriction.

      The first hardware implementations will still have the current
      restricted vector space because lifting this limitation requires
      further changes to the local APIC.

   7) FRED stores the vector number and meta information on stack which
      allows having more than one NMI vector in future hardware when the
      required local APIC changes are in place.

  The series implements the initial FRED support by:

   - Reworking the existing entry and IDT handling infrastructure to
     accomodate for the alternative entry mechanism.

   - Expanding the stack frame to accomodate for the extra 16 bytes FRED
     requires to store context and meta information

   - Providing FRED specific C entry points for events which have
     information pushed to the extended stack frame, e.g. #PF and #DB.

   - Providing FRED specific C entry points for #NMI and #MCE

   - Implementing the FRED specific ASM entry points and the C code to
     demultiplex the events

   - Providing detection and initialization mechanisms and the necessary
     tweaks in context switching, GS BASE handling etc.

  The FRED integration aims for maximum code reuse vs the existing IDT
  implementation to the extent possible and the deviation in hot paths
  like context switching are handled with alternatives to minimalize the
  impact. The low level entry and exit paths are seperate due to the
  extended stack frame and the hardware based GS BASE swichting and
  therefore have no impact on IDT based systems.

  It has been extensively tested on existing systems and on the FRED
  simulation and as of now there are no outstanding problems"

* tag 'x86-fred-2024-03-10' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (38 commits)
  x86/fred: Fix init_task thread stack pointer initialization
  MAINTAINERS: Add a maintainer entry for FRED
  x86/fred: Fix a build warning with allmodconfig due to 'inline' failing to inline properly
  x86/fred: Invoke FRED initialization code to enable FRED
  x86/fred: Add FRED initialization functions
  x86/syscall: Split IDT syscall setup code into idt_syscall_init()
  KVM: VMX: Call fred_entry_from_kvm() for IRQ/NMI handling
  x86/entry: Add fred_entry_from_kvm() for VMX to handle IRQ/NMI
  x86/entry/calling: Allow PUSH_AND_CLEAR_REGS being used beyond actual entry code
  x86/fred: Fixup fault on ERETU by jumping to fred_entrypoint_user
  x86/fred: Let ret_from_fork_asm() jmp to asm_fred_exit_user when FRED is enabled
  x86/traps: Add sysvec_install() to install a system interrupt handler
  x86/fred: FRED entry/exit and dispatch code
  x86/fred: Add a machine check entry stub for FRED
  x86/fred: Add a NMI entry stub for FRED
  x86/fred: Add a debug fault entry stub for FRED
  x86/idtentry: Incorporate definitions/declarations of the FRED entries
  x86/fred: Make exc_page_fault() work for FRED
  x86/fred: Allow single-step trap and NMI when starting a new task
  x86/fred: No ESPFIX needed when FRED is enabled
  ...
</pre>
</div>
</content>
</entry>
</feed>
