linux-stable.git/arch/x86/kernel/cpu/bugs.c, branch linux-4.1.y Linux kernel stable tree x86/mm: Disable PCID on 32-bit kernels 2018-03-01T00:32:17+00:00 Andy Lutomirski luto@kernel.org 2017-06-29T15:53:19+00:00 3c44d4cab8a2056a235263e3972eaba162986c38 [ Upstream commit cba4671af7550e008f7a7835f06df0763825bf3e ] 32-bit kernels on new hardware will see PCID in CPUID, but PCID can only be used in 64-bit mode. Rather than making all PCID code conditional, just disable the feature on 32-bit builds. Signed-off-by: Andy Lutomirski <luto@kernel.org> Reviewed-by: Nadav Amit <nadav.amit@gmail.com> Reviewed-by: Borislav Petkov <bp@suse.de> Reviewed-by: Thomas Gleixner <tglx@linutronix.de> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Arjan van de Ven <arjan@linux.intel.com> Cc: Borislav Petkov <bp@alien8.de> Cc: Dave Hansen <dave.hansen@intel.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mel Gorman <mgorman@suse.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Rik van Riel <riel@redhat.com> Cc: linux-mm@kvack.org Link: http://lkml.kernel.org/r/2e391769192a4d31b808410c383c6bf0734bc6ea.1498751203.git.luto@kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org> Signed-off-by: Sasha Levin <alexander.levin@microsoft.com> 
[ Upstream commit cba4671af7550e008f7a7835f06df0763825bf3e ]

32-bit kernels on new hardware will see PCID in CPUID, but PCID can
only be used in 64-bit mode.  Rather than making all PCID code
conditional, just disable the feature on 32-bit builds.

Signed-off-by: Andy Lutomirski <luto@kernel.org>
Reviewed-by: Nadav Amit <nadav.amit@gmail.com>
Reviewed-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Arjan van de Ven <arjan@linux.intel.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: linux-mm@kvack.org
Link: http://lkml.kernel.org/r/2e391769192a4d31b808410c383c6bf0734bc6ea.1498751203.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
x86: Get rid of ->hard_math and all the FPU asm fu 2013-06-06T21:32:04+00:00 H. Peter Anvin hpa@zytor.com 2013-04-29T14:04:20+00:00 60e019eb37a8d989031ad47ae9810453536f3127 Reimplement FPU detection code in C and drop old, not-so-recommended detection method in asm. Move all the relevant stuff into i387.c where it conceptually belongs. Finally drop cpuinfo_x86.hard_math. [ hpa: huge thanks to Borislav for taking my original concept patch and productizing it ] [ Boris, note to self: do not use static_cpu_has before alternatives! ] Signed-off-by: H. Peter Anvin <hpa@zytor.com> Link: http://lkml.kernel.org/r/1367244262-29511-2-git-send-email-bp@alien8.de Link: http://lkml.kernel.org/r/1365436666-9837-2-git-send-email-bp@alien8.de Signed-off-by: Borislav Petkov <bp@suse.de> Signed-off-by: H. Peter Anvin <hpa@linux.intel.com> 
Reimplement FPU detection code in C and drop old, not-so-recommended
detection method in asm. Move all the relevant stuff into i387.c where
it conceptually belongs. Finally drop cpuinfo_x86.hard_math.

[ hpa: huge thanks to Borislav for taking my original concept patch
  and productizing it ]

[ Boris, note to self: do not use static_cpu_has before alternatives! ]

Signed-off-by: H. Peter Anvin <hpa@zytor.com>
Link: http://lkml.kernel.org/r/1367244262-29511-2-git-send-email-bp@alien8.de
Link: http://lkml.kernel.org/r/1365436666-9837-2-git-send-email-bp@alien8.de
Signed-off-by: Borislav Petkov <bp@suse.de>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
x86: Fold-in trivial check_config function 2013-04-16T09:50:50+00:00 Borislav Petkov bp@suse.de 2013-04-08T15:57:44+00:00 55a36b65ee7107d6bb557c96fd202c4e90164542 Fold it into its single call site. No functionality change. Signed-off-by: Borislav Petkov <bp@suse.de> Link: http://lkml.kernel.org/r/1365436666-9837-3-git-send-email-bp@alien8.de Signed-off-by: H. Peter Anvin <hpa@zytor.com> 
Fold it into its single call site. No functionality change.

Signed-off-by: Borislav Petkov <bp@suse.de>
Link: http://lkml.kernel.org/r/1365436666-9837-3-git-send-email-bp@alien8.de
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
x86, cpu: Convert FDIV bug detection 2013-04-02T17:12:53+00:00 Borislav Petkov bp@suse.de 2013-03-20T14:07:25+00:00 93a829e8e2c292f1d30155f64803101ca1cb7d3d ... to the new facility. Add a reference to the wikipedia article explaining the FDIV test we're doing here. Signed-off-by: Borislav Petkov <bp@suse.de> Link: http://lkml.kernel.org/r/1363788448-31325-4-git-send-email-bp@alien8.de Signed-off-by: H. Peter Anvin <hpa@zytor.com> 
... to the new facility. Add a reference to the wikipedia article
explaining the FDIV test we're doing here.

Signed-off-by: Borislav Petkov <bp@suse.de>
Link: http://lkml.kernel.org/r/1363788448-31325-4-git-send-email-bp@alien8.de
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
x86 idle: remove 32-bit-only "no-hlt" parameter, hlt_works_ok flag 2013-02-10T08:32:22+00:00 Len Brown len.brown@intel.com 2013-02-10T07:28:46+00:00 27be457000211a6903968dfce06d5f73f051a217 Remove 32-bit x86 a cmdline param "no-hlt", and the cpuinfo_x86.hlt_works_ok that it sets. If a user wants to avoid HLT, then "idle=poll" is much more useful, as it avoids invocation of HLT in idle, while "no-hlt" failed to do so. Indeed, hlt_works_ok was consulted in only 3 places. First, in /proc/cpuinfo where "hlt_bug yes" would be printed if and only if the user booted the system with "no-hlt" -- as there was no other code to set that flag. Second, check_hlt() would not invoke halt() if "no-hlt" were on the cmdline. Third, it was consulted in stop_this_cpu(), which is invoked by native_machine_halt()/reboot_interrupt()/smp_stop_nmi_callback() -- all cases where the machine is being shutdown/reset. The flag was not consulted in the more frequently invoked play_dead()/hlt_play_dead() used in processor offline and suspend. Since Linux-3.0 there has been a run-time notice upon "no-hlt" invocations indicating that it would be removed in 2012. Signed-off-by: Len Brown <len.brown@intel.com> Cc: x86@kernel.org 
Remove 32-bit x86 a cmdline param "no-hlt",
and the cpuinfo_x86.hlt_works_ok that it sets.

If a user wants to avoid HLT, then "idle=poll"
is much more useful, as it avoids invocation of HLT
in idle, while "no-hlt" failed to do so.

Indeed, hlt_works_ok was consulted in only 3 places.

First, in /proc/cpuinfo where "hlt_bug yes"
would be printed if and only if the user booted
the system with "no-hlt" -- as there was no other code
to set that flag.

Second, check_hlt() would not invoke halt() if "no-hlt"
were on the cmdline.

Third, it was consulted in stop_this_cpu(), which is invoked
by native_machine_halt()/reboot_interrupt()/smp_stop_nmi_callback() --
all cases where the machine is being shutdown/reset.
The flag was not consulted in the more frequently invoked
play_dead()/hlt_play_dead() used in processor offline and suspend.

Since Linux-3.0 there has been a run-time notice upon "no-hlt" invocations
indicating that it would be removed in 2012.

Signed-off-by: Len Brown <len.brown@intel.com>
Cc: x86@kernel.org
x86, 386 removal: Remove CONFIG_X86_POPAD_OK 2012-11-29T21:23:03+00:00 H. Peter Anvin hpa@linux.intel.com 2012-11-28T19:50:29+00:00 e3228cf4544355f73437a2b9c6916be9cbafc201 The check_popad() routine tested for a 386-specific bug, and never actually did anything useful with it anyway other than print a message. Signed-off-by: H. Peter Anvin <hpa@linux.intel.com> Link: http://lkml.kernel.org/r/1354132230-21854-8-git-send-email-hpa@linux.intel.com 
The check_popad() routine tested for a 386-specific bug, and never
actually did anything useful with it anyway other than print a
message.

Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
Link: http://lkml.kernel.org/r/1354132230-21854-8-git-send-email-hpa@linux.intel.com
x86, 386 removal: Remove CONFIG_BSWAP 2012-11-29T21:23:02+00:00 H. Peter Anvin hpa@linux.intel.com 2012-11-28T19:50:26+00:00 e5bb8ad862a97a0facc83f3b81731de919fec6ad All 486+ CPUs support BSWAP, so remove the fallback 386 support code. Signed-off-by: H. Peter Anvin <hpa@linux.intel.com> Link: http://lkml.kernel.org/r/1354132230-21854-5-git-send-email-hpa@linux.intel.com 
All 486+ CPUs support BSWAP, so remove the fallback 386 support
code.

Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
Link: http://lkml.kernel.org/r/1354132230-21854-5-git-send-email-hpa@linux.intel.com
x86, fpu: use non-lazy fpu restore for processors supporting xsave 2012-09-18T22:52:11+00:00 Suresh Siddha suresh.b.siddha@intel.com 2012-08-24T21:13:02+00:00 304bceda6a18ae0b0240b8aac9a6bdf8ce2d2469 Fundamental model of the current Linux kernel is to lazily init and restore FPU instead of restoring the task state during context switch. This changes that fundamental lazy model to the non-lazy model for the processors supporting xsave feature. Reasons driving this model change are: i. Newer processors support optimized state save/restore using xsaveopt and xrstor by tracking the INIT state and MODIFIED state during context-switch. This is faster than modifying the cr0.TS bit which has serializing semantics. ii. Newer glibc versions use SSE for some of the optimized copy/clear routines. With certain workloads (like boot, kernel-compilation etc), application completes its work with in the first 5 task switches, thus taking upto 5 #DNA traps with the kernel not getting a chance to apply the above mentioned pre-load heuristic. iii. Some xstate features (like AMD's LWP feature) don't honor the cr0.TS bit and thus will not work correctly in the presence of lazy restore. Non-lazy state restore is needed for enabling such features. Some data on a two socket SNB system: * Saved 20K DNA exceptions during boot on a two socket SNB system. * Saved 50K DNA exceptions during kernel-compilation workload. * Improved throughput of the AVX based checksumming function inside the kernel by ~15% as xsave/xrstor is faster than the serializing clts/stts pair. Also now kernel_fpu_begin/end() relies on the patched alternative instructions. So move check_fpu() which uses the kernel_fpu_begin/end() after alternative_instructions(). Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com> Link: http://lkml.kernel.org/r/1345842782-24175-7-git-send-email-suresh.b.siddha@intel.com Merge 32-bit boot fix from, Link: http://lkml.kernel.org/r/1347300665-6209-4-git-send-email-suresh.b.siddha@intel.com Cc: Jim Kukunas <james.t.kukunas@linux.intel.com> Cc: NeilBrown <neilb@suse.de> Cc: Avi Kivity <avi@redhat.com> Signed-off-by: H. Peter Anvin <hpa@linux.intel.com> 
Fundamental model of the current Linux kernel is to lazily init and
restore FPU instead of restoring the task state during context switch.
This changes that fundamental lazy model to the non-lazy model for
the processors supporting xsave feature.

Reasons driving this model change are:

i. Newer processors support optimized state save/restore using xsaveopt and
xrstor by tracking the INIT state and MODIFIED state during context-switch.
This is faster than modifying the cr0.TS bit which has serializing semantics.

ii. Newer glibc versions use SSE for some of the optimized copy/clear routines.
With certain workloads (like boot, kernel-compilation etc), application
completes its work with in the first 5 task switches, thus taking upto 5 #DNA
traps with the kernel not getting a chance to apply the above mentioned
pre-load heuristic.

iii. Some xstate features (like AMD's LWP feature) don't honor the cr0.TS bit
and thus will not work correctly in the presence of lazy restore. Non-lazy
state restore is needed for enabling such features.

Some data on a two socket SNB system:
 * Saved 20K DNA exceptions during boot on a two socket SNB system.
 * Saved 50K DNA exceptions during kernel-compilation workload.
 * Improved throughput of the AVX based checksumming function inside the
   kernel by ~15% as xsave/xrstor is faster than the serializing clts/stts
   pair.

Also now kernel_fpu_begin/end() relies on the patched
alternative instructions. So move check_fpu() which uses the
kernel_fpu_begin/end() after alternative_instructions().

Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com>
Link: http://lkml.kernel.org/r/1345842782-24175-7-git-send-email-suresh.b.siddha@intel.com
Merge 32-bit boot fix from,
Link: http://lkml.kernel.org/r/1347300665-6209-4-git-send-email-suresh.b.siddha@intel.com
Cc: Jim Kukunas <james.t.kukunas@linux.intel.com>
Cc: NeilBrown <neilb@suse.de>
Cc: Avi Kivity <avi@redhat.com>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
x86/debug: Add KERN_<LEVEL> to bare printks, convert printks to pr_<level> 2012-06-06T07:17:22+00:00 Joe Perches joe@perches.com 2012-05-22T02:50:07+00:00 c767a54ba0657e52e6edaa97cbe0b0a8bf1c1655 Use a more current logging style: - Bare printks should have a KERN_<LEVEL> for consistency's sake - Add pr_fmt where appropriate - Neaten some macro definitions - Convert some Ok output to OK - Use "%s: ", __func__ in pr_fmt for summit - Convert some printks to pr_<level> Message output is not identical in all cases. Signed-off-by: Joe Perches <joe@perches.com> Cc: levinsasha928@gmail.com Link: http://lkml.kernel.org/r/1337655007.24226.10.camel@joe2Laptop [ merged two similar patches, tidied up the changelog ] Signed-off-by: Ingo Molnar <mingo@kernel.org> 
Use a more current logging style:

 - Bare printks should have a KERN_<LEVEL> for consistency's sake
 - Add pr_fmt where appropriate
 - Neaten some macro definitions
 - Convert some Ok output to OK
 - Use "%s: ", __func__ in pr_fmt for summit
 - Convert some printks to pr_<level>

Message output is not identical in all cases.

Signed-off-by: Joe Perches <joe@perches.com>
Cc: levinsasha928@gmail.com
Link: http://lkml.kernel.org/r/1337655007.24226.10.camel@joe2Laptop
[ merged two similar patches, tidied up the changelog ]
Signed-off-by: Ingo Molnar <mingo@kernel.org>
x86-32, fpu: Fix DNA exception during check_fpu() 2011-07-01T00:29:47+00:00 Suresh Siddha suresh.b.siddha@intel.com 2011-07-01T00:19:32+00:00 3e7cf5b00dd5b577b4ee9b2a66e40fb670ef210b Before check_fpu() is called, we have cr0.TS bit set and hence the floating point code to check the FDIV bug was generating a DNA exception. Use kernel_fpu_begin()/kernel_fpu_end() around the floating point code to avoid this unnecessary device not available exception during boot. Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com> Link: http://lkml.kernel.org/r/1309479572.2665.1372.camel@sbsiddha-MOBL3.sc.intel.com Signed-off-by: H. Peter Anvin <hpa@linux.intel.com> 
Before check_fpu() is called, we have cr0.TS bit set and hence the floating
point code to check the FDIV bug was generating a DNA exception.

Use kernel_fpu_begin()/kernel_fpu_end() around the floating point
code to avoid this unnecessary device not available exception during
boot.

Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com>
Link: http://lkml.kernel.org/r/1309479572.2665.1372.camel@sbsiddha-MOBL3.sc.intel.com
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>