<feed xmlns='http://www.w3.org/2005/Atom'>
<title>linux.git/arch/powerpc/include/asm/ppc-opcode.h, branch v4.19</title>
<subtitle>Linux kernel source tree</subtitle>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/'/>
<entry>
<title>powerpc: clean the inclusion of stringify.h</title>
<updated>2018-07-30T12:48:17+00:00</updated>
<author>
<name>Christophe Leroy</name>
<email>christophe.leroy@c-s.fr</email>
</author>
<published>2018-07-05T16:24:59+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=5c35a02c545a7bbe77f3a1ae337d9e29beed079b'/>
<id>5c35a02c545a7bbe77f3a1ae337d9e29beed079b</id>
<content type='text'>
Only include linux/stringify.h is files using __stringify()

Signed-off-by: Christophe Leroy &lt;christophe.leroy@c-s.fr&gt;
Signed-off-by: Michael Ellerman &lt;mpe@ellerman.id.au&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Only include linux/stringify.h is files using __stringify()

Signed-off-by: Christophe Leroy &lt;christophe.leroy@c-s.fr&gt;
Signed-off-by: Michael Ellerman &lt;mpe@ellerman.id.au&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>powerpc: move ASM_CONST and stringify_in_c() into asm-const.h</title>
<updated>2018-07-30T12:48:16+00:00</updated>
<author>
<name>Christophe Leroy</name>
<email>christophe.leroy@c-s.fr</email>
</author>
<published>2018-07-05T16:24:57+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=ec0c464cdbf38bf6ddabec8bfa595bd421cab203'/>
<id>ec0c464cdbf38bf6ddabec8bfa595bd421cab203</id>
<content type='text'>
This patch moves ASM_CONST() and stringify_in_c() into
dedicated asm-const.h, then cleans all related inclusions.

Signed-off-by: Christophe Leroy &lt;christophe.leroy@c-s.fr&gt;
[mpe: asm-compat.h should include asm-const.h]
Signed-off-by: Michael Ellerman &lt;mpe@ellerman.id.au&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
This patch moves ASM_CONST() and stringify_in_c() into
dedicated asm-const.h, then cleans all related inclusions.

Signed-off-by: Christophe Leroy &lt;christophe.leroy@c-s.fr&gt;
[mpe: asm-compat.h should include asm-const.h]
Signed-off-by: Michael Ellerman &lt;mpe@ellerman.id.au&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>powerpc: add vcmpequd/vcmpequb ppc instruction macro</title>
<updated>2018-07-24T12:03:20+00:00</updated>
<author>
<name>Simon Guo</name>
<email>wei.guo.simon@gmail.com</email>
</author>
<published>2018-06-07T01:57:52+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=f1ecbaf466be5a7a5c666b41eede6991caff8646'/>
<id>f1ecbaf466be5a7a5c666b41eede6991caff8646</id>
<content type='text'>
Some old tool chains don't know about instructions like vcmpequd.

This patch adds .long macro for vcmpequd and vcmpequb, which is
a preparation to optimize ppc64 memcmp with VMX instructions.

Signed-off-by: Simon Guo &lt;wei.guo.simon@gmail.com&gt;
Signed-off-by: Michael Ellerman &lt;mpe@ellerman.id.au&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Some old tool chains don't know about instructions like vcmpequd.

This patch adds .long macro for vcmpequd and vcmpequb, which is
a preparation to optimize ppc64 memcmp with VMX instructions.

Signed-off-by: Simon Guo &lt;wei.guo.simon@gmail.com&gt;
Signed-off-by: Michael Ellerman &lt;mpe@ellerman.id.au&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>powerpc/mm: Use instruction symbolic names in store_updates_sp()</title>
<updated>2018-05-24T14:08:24+00:00</updated>
<author>
<name>Christophe Leroy</name>
<email>christophe.leroy@c-s.fr</email>
</author>
<published>2018-05-23T07:04:04+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=8a0b1120cb25ccd4480ba4fe3650bc22b0dfadf4'/>
<id>8a0b1120cb25ccd4480ba4fe3650bc22b0dfadf4</id>
<content type='text'>
Use symbolic names defined in asm/ppc-opcode.h
instead of hardcoded values.

Signed-off-by: Christophe Leroy &lt;christophe.leroy@c-s.fr&gt;
Signed-off-by: Michael Ellerman &lt;mpe@ellerman.id.au&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Use symbolic names defined in asm/ppc-opcode.h
instead of hardcoded values.

Signed-off-by: Christophe Leroy &lt;christophe.leroy@c-s.fr&gt;
Signed-off-by: Michael Ellerman &lt;mpe@ellerman.id.au&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>Merge branch 'topic/ppc-kvm' into next</title>
<updated>2018-03-23T21:43:18+00:00</updated>
<author>
<name>Michael Ellerman</name>
<email>mpe@ellerman.id.au</email>
</author>
<published>2018-03-23T21:43:18+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=a26cf1c9fe3c2e3b671b490aeb708ea72fb5ac0a'/>
<id>a26cf1c9fe3c2e3b671b490aeb708ea72fb5ac0a</id>
<content type='text'>
This brings in two series from Paul, one of which touches KVM code and
may need to be merged into the kvm-ppc tree to resolve conflicts.
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
This brings in two series from Paul, one of which touches KVM code and
may need to be merged into the kvm-ppc tree to resolve conflicts.
</pre>
</div>
</content>
</entry>
<entry>
<title>KVM: PPC: Book3S HV: Work around transactional memory bugs in POWER9</title>
<updated>2018-03-23T13:39:13+00:00</updated>
<author>
<name>Paul Mackerras</name>
<email>paulus@ozlabs.org</email>
</author>
<published>2018-03-21T10:32:01+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=4bb3c7a0208fc13ca70598efd109901a7cd45ae7'/>
<id>4bb3c7a0208fc13ca70598efd109901a7cd45ae7</id>
<content type='text'>
POWER9 has hardware bugs relating to transactional memory and thread
reconfiguration (changes to hardware SMT mode).  Specifically, the core
does not have enough storage to store a complete checkpoint of all the
architected state for all four threads.  The DD2.2 version of POWER9
includes hardware modifications designed to allow hypervisor software
to implement workarounds for these problems.  This patch implements
those workarounds in KVM code so that KVM guests see a full, working
transactional memory implementation.

The problems center around the use of TM suspended state, where the
CPU has a checkpointed state but execution is not transactional.  The
workaround is to implement a "fake suspend" state, which looks to the
guest like suspended state but the CPU does not store a checkpoint.
In this state, any instruction that would cause a transition to
transactional state (rfid, rfebb, mtmsrd, tresume) or would use the
checkpointed state (treclaim) causes a "soft patch" interrupt (vector
0x1500) to the hypervisor so that it can be emulated.  The trechkpt
instruction also causes a soft patch interrupt.

On POWER9 DD2.2, we avoid returning to the guest in any state which
would require a checkpoint to be present.  The trechkpt in the guest
entry path which would normally create that checkpoint is replaced by
either a transition to fake suspend state, if the guest is in suspend
state, or a rollback to the pre-transactional state if the guest is in
transactional state.  Fake suspend state is indicated by a flag in the
PACA plus a new bit in the PSSCR.  The new PSSCR bit is write-only and
reads back as 0.

On exit from the guest, if the guest is in fake suspend state, we still
do the treclaim instruction as we would in real suspend state, in order
to get into non-transactional state, but we do not save the resulting
register state since there was no checkpoint.

Emulation of the instructions that cause a softpatch interrupt is
handled in two paths.  If the guest is in real suspend mode, we call
kvmhv_p9_tm_emulation_early() to handle the cases where the guest is
transitioning to transactional state.  This is called before we do the
treclaim in the guest exit path; because we haven't done treclaim, we
can get back to the guest with the transaction still active.  If the
instruction is a case that kvmhv_p9_tm_emulation_early() doesn't
handle, or if the guest is in fake suspend state, then we proceed to
do the complete guest exit path and subsequently call
kvmhv_p9_tm_emulation() in host context with the MMU on.  This handles
all the cases including the cases that generate program interrupts
(illegal instruction or TM Bad Thing) and facility unavailable
interrupts.

The emulation is reasonably straightforward and is mostly concerned
with checking for exception conditions and updating the state of
registers such as MSR and CR0.  The treclaim emulation takes care to
ensure that the TEXASR register gets updated as if it were the guest
treclaim instruction that had done failure recording, not the treclaim
done in hypervisor state in the guest exit path.

With this, the KVM_CAP_PPC_HTM capability returns true (1) even if
transactional memory is not available to host userspace.

Signed-off-by: Paul Mackerras &lt;paulus@ozlabs.org&gt;
Signed-off-by: Michael Ellerman &lt;mpe@ellerman.id.au&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
POWER9 has hardware bugs relating to transactional memory and thread
reconfiguration (changes to hardware SMT mode).  Specifically, the core
does not have enough storage to store a complete checkpoint of all the
architected state for all four threads.  The DD2.2 version of POWER9
includes hardware modifications designed to allow hypervisor software
to implement workarounds for these problems.  This patch implements
those workarounds in KVM code so that KVM guests see a full, working
transactional memory implementation.

The problems center around the use of TM suspended state, where the
CPU has a checkpointed state but execution is not transactional.  The
workaround is to implement a "fake suspend" state, which looks to the
guest like suspended state but the CPU does not store a checkpoint.
In this state, any instruction that would cause a transition to
transactional state (rfid, rfebb, mtmsrd, tresume) or would use the
checkpointed state (treclaim) causes a "soft patch" interrupt (vector
0x1500) to the hypervisor so that it can be emulated.  The trechkpt
instruction also causes a soft patch interrupt.

On POWER9 DD2.2, we avoid returning to the guest in any state which
would require a checkpoint to be present.  The trechkpt in the guest
entry path which would normally create that checkpoint is replaced by
either a transition to fake suspend state, if the guest is in suspend
state, or a rollback to the pre-transactional state if the guest is in
transactional state.  Fake suspend state is indicated by a flag in the
PACA plus a new bit in the PSSCR.  The new PSSCR bit is write-only and
reads back as 0.

On exit from the guest, if the guest is in fake suspend state, we still
do the treclaim instruction as we would in real suspend state, in order
to get into non-transactional state, but we do not save the resulting
register state since there was no checkpoint.

Emulation of the instructions that cause a softpatch interrupt is
handled in two paths.  If the guest is in real suspend mode, we call
kvmhv_p9_tm_emulation_early() to handle the cases where the guest is
transitioning to transactional state.  This is called before we do the
treclaim in the guest exit path; because we haven't done treclaim, we
can get back to the guest with the transaction still active.  If the
instruction is a case that kvmhv_p9_tm_emulation_early() doesn't
handle, or if the guest is in fake suspend state, then we proceed to
do the complete guest exit path and subsequently call
kvmhv_p9_tm_emulation() in host context with the MMU on.  This handles
all the cases including the cases that generate program interrupts
(illegal instruction or TM Bad Thing) and facility unavailable
interrupts.

The emulation is reasonably straightforward and is mostly concerned
with checking for exception conditions and updating the state of
registers such as MSR and CR0.  The treclaim emulation takes care to
ensure that the TEXASR register gets updated as if it were the guest
treclaim instruction that had done failure recording, not the treclaim
done in hypervisor state in the guest exit path.

With this, the KVM_CAP_PPC_HTM capability returns true (1) even if
transactional memory is not available to host userspace.

Signed-off-by: Paul Mackerras &lt;paulus@ozlabs.org&gt;
Signed-off-by: Michael Ellerman &lt;mpe@ellerman.id.au&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>lib/raid6/altivec: Add vpermxor implementation for raid6 Q syndrome</title>
<updated>2018-03-20T05:47:25+00:00</updated>
<author>
<name>Matt Brown</name>
<email>matthew.brown.dev@gmail.com</email>
</author>
<published>2017-08-04T03:42:32+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=751ba79cc552c146595cd439b21c4ff8998c3b69'/>
<id>751ba79cc552c146595cd439b21c4ff8998c3b69</id>
<content type='text'>
This patch uses the vpermxor instruction to optimise the raid6 Q
syndrome. This instruction was made available with POWER8, ISA version
2.07. It allows for both vperm and vxor instructions to be done in a
single instruction. This has been tested for correctness on a ppc64le
vm with a basic RAID6 setup containing 5 drives.

The performance benchmarks are from the raid6test in the
/lib/raid6/test directory. These results are from an IBM Firestone
machine with ppc64le architecture. The benchmark results show a 35%
speed increase over the best existing algorithm for powerpc (altivec).
The raid6test has also been run on a big-endian ppc64 vm to ensure it
also works for big-endian architectures.

Performance benchmarks:
  raid6: altivecx4 gen() 18773 MB/s
  raid6: altivecx8 gen() 19438 MB/s

  raid6: vpermxor4 gen() 25112 MB/s
  raid6: vpermxor8 gen() 26279 MB/s

Signed-off-by: Matt Brown &lt;matthew.brown.dev@gmail.com&gt;
Reviewed-by: Daniel Axtens &lt;dja@axtens.net&gt;
[mpe: Add VPERMXOR macro so we can build with old binutils]
Signed-off-by: Michael Ellerman &lt;mpe@ellerman.id.au&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
This patch uses the vpermxor instruction to optimise the raid6 Q
syndrome. This instruction was made available with POWER8, ISA version
2.07. It allows for both vperm and vxor instructions to be done in a
single instruction. This has been tested for correctness on a ppc64le
vm with a basic RAID6 setup containing 5 drives.

The performance benchmarks are from the raid6test in the
/lib/raid6/test directory. These results are from an IBM Firestone
machine with ppc64le architecture. The benchmark results show a 35%
speed increase over the best existing algorithm for powerpc (altivec).
The raid6test has also been run on a big-endian ppc64 vm to ensure it
also works for big-endian architectures.

Performance benchmarks:
  raid6: altivecx4 gen() 18773 MB/s
  raid6: altivecx8 gen() 19438 MB/s

  raid6: vpermxor4 gen() 25112 MB/s
  raid6: vpermxor8 gen() 26279 MB/s

Signed-off-by: Matt Brown &lt;matthew.brown.dev@gmail.com&gt;
Reviewed-by: Daniel Axtens &lt;dja@axtens.net&gt;
[mpe: Add VPERMXOR macro so we can build with old binutils]
Signed-off-by: Michael Ellerman &lt;mpe@ellerman.id.au&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>Merge tag 'kvm-4.16-1' of git://git.kernel.org/pub/scm/virt/kvm/kvm</title>
<updated>2018-02-10T21:16:35+00:00</updated>
<author>
<name>Linus Torvalds</name>
<email>torvalds@linux-foundation.org</email>
</author>
<published>2018-02-10T21:16:35+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=15303ba5d1cd9b28d03a980456c0978c0ea3b208'/>
<id>15303ba5d1cd9b28d03a980456c0978c0ea3b208</id>
<content type='text'>
Pull KVM updates from Radim Krčmář:
 "ARM:

   - icache invalidation optimizations, improving VM startup time

   - support for forwarded level-triggered interrupts, improving
     performance for timers and passthrough platform devices

   - a small fix for power-management notifiers, and some cosmetic
     changes

  PPC:

   - add MMIO emulation for vector loads and stores

   - allow HPT guests to run on a radix host on POWER9 v2.2 CPUs without
     requiring the complex thread synchronization of older CPU versions

   - improve the handling of escalation interrupts with the XIVE
     interrupt controller

   - support decrement register migration

   - various cleanups and bugfixes.

  s390:

   - Cornelia Huck passed maintainership to Janosch Frank

   - exitless interrupts for emulated devices

   - cleanup of cpuflag handling

   - kvm_stat counter improvements

   - VSIE improvements

   - mm cleanup

  x86:

   - hypervisor part of SEV

   - UMIP, RDPID, and MSR_SMI_COUNT emulation

   - paravirtualized TLB shootdown using the new KVM_VCPU_PREEMPTED bit

   - allow guests to see TOPOEXT, GFNI, VAES, VPCLMULQDQ, and more
     AVX512 features

   - show vcpu id in its anonymous inode name

   - many fixes and cleanups

   - per-VCPU MSR bitmaps (already merged through x86/pti branch)

   - stable KVM clock when nesting on Hyper-V (merged through
     x86/hyperv)"

* tag 'kvm-4.16-1' of git://git.kernel.org/pub/scm/virt/kvm/kvm: (197 commits)
  KVM: PPC: Book3S: Add MMIO emulation for VMX instructions
  KVM: PPC: Book3S HV: Branch inside feature section
  KVM: PPC: Book3S HV: Make HPT resizing work on POWER9
  KVM: PPC: Book3S HV: Fix handling of secondary HPTEG in HPT resizing code
  KVM: PPC: Book3S PR: Fix broken select due to misspelling
  KVM: x86: don't forget vcpu_put() in kvm_arch_vcpu_ioctl_set_sregs()
  KVM: PPC: Book3S PR: Fix svcpu copying with preemption enabled
  KVM: PPC: Book3S HV: Drop locks before reading guest memory
  kvm: x86: remove efer_reload entry in kvm_vcpu_stat
  KVM: x86: AMD Processor Topology Information
  x86/kvm/vmx: do not use vm-exit instruction length for fast MMIO when running nested
  kvm: embed vcpu id to dentry of vcpu anon inode
  kvm: Map PFN-type memory regions as writable (if possible)
  x86/kvm: Make it compile on 32bit and with HYPYERVISOR_GUEST=n
  KVM: arm/arm64: Fixup userspace irqchip static key optimization
  KVM: arm/arm64: Fix userspace_irqchip_in_use counting
  KVM: arm/arm64: Fix incorrect timer_is_pending logic
  MAINTAINERS: update KVM/s390 maintainers
  MAINTAINERS: add Halil as additional vfio-ccw maintainer
  MAINTAINERS: add David as a reviewer for KVM/s390
  ...
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Pull KVM updates from Radim Krčmář:
 "ARM:

   - icache invalidation optimizations, improving VM startup time

   - support for forwarded level-triggered interrupts, improving
     performance for timers and passthrough platform devices

   - a small fix for power-management notifiers, and some cosmetic
     changes

  PPC:

   - add MMIO emulation for vector loads and stores

   - allow HPT guests to run on a radix host on POWER9 v2.2 CPUs without
     requiring the complex thread synchronization of older CPU versions

   - improve the handling of escalation interrupts with the XIVE
     interrupt controller

   - support decrement register migration

   - various cleanups and bugfixes.

  s390:

   - Cornelia Huck passed maintainership to Janosch Frank

   - exitless interrupts for emulated devices

   - cleanup of cpuflag handling

   - kvm_stat counter improvements

   - VSIE improvements

   - mm cleanup

  x86:

   - hypervisor part of SEV

   - UMIP, RDPID, and MSR_SMI_COUNT emulation

   - paravirtualized TLB shootdown using the new KVM_VCPU_PREEMPTED bit

   - allow guests to see TOPOEXT, GFNI, VAES, VPCLMULQDQ, and more
     AVX512 features

   - show vcpu id in its anonymous inode name

   - many fixes and cleanups

   - per-VCPU MSR bitmaps (already merged through x86/pti branch)

   - stable KVM clock when nesting on Hyper-V (merged through
     x86/hyperv)"

* tag 'kvm-4.16-1' of git://git.kernel.org/pub/scm/virt/kvm/kvm: (197 commits)
  KVM: PPC: Book3S: Add MMIO emulation for VMX instructions
  KVM: PPC: Book3S HV: Branch inside feature section
  KVM: PPC: Book3S HV: Make HPT resizing work on POWER9
  KVM: PPC: Book3S HV: Fix handling of secondary HPTEG in HPT resizing code
  KVM: PPC: Book3S PR: Fix broken select due to misspelling
  KVM: x86: don't forget vcpu_put() in kvm_arch_vcpu_ioctl_set_sregs()
  KVM: PPC: Book3S PR: Fix svcpu copying with preemption enabled
  KVM: PPC: Book3S HV: Drop locks before reading guest memory
  kvm: x86: remove efer_reload entry in kvm_vcpu_stat
  KVM: x86: AMD Processor Topology Information
  x86/kvm/vmx: do not use vm-exit instruction length for fast MMIO when running nested
  kvm: embed vcpu id to dentry of vcpu anon inode
  kvm: Map PFN-type memory regions as writable (if possible)
  x86/kvm: Make it compile on 32bit and with HYPYERVISOR_GUEST=n
  KVM: arm/arm64: Fixup userspace irqchip static key optimization
  KVM: arm/arm64: Fix userspace_irqchip_in_use counting
  KVM: arm/arm64: Fix incorrect timer_is_pending logic
  MAINTAINERS: update KVM/s390 maintainers
  MAINTAINERS: add Halil as additional vfio-ccw maintainer
  MAINTAINERS: add David as a reviewer for KVM/s390
  ...
</pre>
</div>
</content>
</entry>
<entry>
<title>KVM: PPC: Book3S: Add MMIO emulation for VMX instructions</title>
<updated>2018-02-09T05:51:51+00:00</updated>
<author>
<name>Jose Ricardo Ziviani</name>
<email>joserz@linux.vnet.ibm.com</email>
</author>
<published>2018-02-03T20:24:26+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=09f984961c137c4b252c368adab7e1c9f035fa59'/>
<id>09f984961c137c4b252c368adab7e1c9f035fa59</id>
<content type='text'>
This patch provides the MMIO load/store vector indexed
X-Form emulation.

Instructions implemented:
lvx: the quadword in storage addressed by the result of EA &amp;
0xffff_ffff_ffff_fff0 is loaded into VRT.

stvx: the contents of VRS are stored into the quadword in storage
addressed by the result of EA &amp; 0xffff_ffff_ffff_fff0.

Reported-by: Gopesh Kumar Chaudhary &lt;gopchaud@in.ibm.com&gt;
Reported-by: Balamuruhan S &lt;bala24@linux.vnet.ibm.com&gt;
Signed-off-by: Jose Ricardo Ziviani &lt;joserz@linux.vnet.ibm.com&gt;
Signed-off-by: Paul Mackerras &lt;paulus@ozlabs.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
This patch provides the MMIO load/store vector indexed
X-Form emulation.

Instructions implemented:
lvx: the quadword in storage addressed by the result of EA &amp;
0xffff_ffff_ffff_fff0 is loaded into VRT.

stvx: the contents of VRS are stored into the quadword in storage
addressed by the result of EA &amp; 0xffff_ffff_ffff_fff0.

Reported-by: Gopesh Kumar Chaudhary &lt;gopchaud@in.ibm.com&gt;
Reported-by: Balamuruhan S &lt;bala24@linux.vnet.ibm.com&gt;
Signed-off-by: Jose Ricardo Ziviani &lt;joserz@linux.vnet.ibm.com&gt;
Signed-off-by: Paul Mackerras &lt;paulus@ozlabs.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>powerpc/8xx: Only perform perf counting when perf is in use.</title>
<updated>2018-01-16T12:47:12+00:00</updated>
<author>
<name>Christophe Leroy</name>
<email>christophe.leroy@c-s.fr</email>
</author>
<published>2018-01-12T12:45:23+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=cd99ddbea250ee79027df6c469f51ad9e5452738'/>
<id>cd99ddbea250ee79027df6c469f51ad9e5452738</id>
<content type='text'>
In TLB miss handlers, updating the perf counter is only useful
when performing a perf analysis. As it has a noticeable overhead,
let's only do it when needed.

In order to do so, the exit of the miss handlers will be patched
when starting/stopping 'perf': the first register restore
instruction of each exit point will be replaced by a jump to
the counting code.

Once this is done, CONFIG_PPC_8xx_PERF_EVENT becomes useless as
this feature doesn't add any overhead.

Signed-off-by: Christophe Leroy &lt;christophe.leroy@c-s.fr&gt;
Signed-off-by: Michael Ellerman &lt;mpe@ellerman.id.au&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
In TLB miss handlers, updating the perf counter is only useful
when performing a perf analysis. As it has a noticeable overhead,
let's only do it when needed.

In order to do so, the exit of the miss handlers will be patched
when starting/stopping 'perf': the first register restore
instruction of each exit point will be replaced by a jump to
the counting code.

Once this is done, CONFIG_PPC_8xx_PERF_EVENT becomes useless as
this feature doesn't add any overhead.

Signed-off-by: Christophe Leroy &lt;christophe.leroy@c-s.fr&gt;
Signed-off-by: Michael Ellerman &lt;mpe@ellerman.id.au&gt;
</pre>
</div>
</content>
</entry>
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