linux-stable.git/arch/x86/kernel/cpu/amd.c, branch linux-3.12.y

x86: kvm: use alternatives for VMCALL vs. VMMCALL if kernel text is read-only

2014-12-03T11:07:27+00:00

commit c1118b3602c2329671ad5ec8bdf8e374323d6343 upstream.

On x86_64, kernel text mappings are mapped read-only with CONFIG_DEBUG_RODATA.
In that case, KVM will fail to patch VMCALL instructions to VMMCALL
as required on AMD processors.

The failure mode is currently a divide-by-zero exception, which obviously
is a KVM bug that has to be fixed.  However, picking the right instruction
between VMCALL and VMMCALL will be faster and will help if you cannot upgrade
the hypervisor.

Reported-by: Chris Webb 
Tested-by: Chris Webb 
Cc: Thomas Gleixner 
Cc: Ingo Molnar 
Cc: "H. Peter Anvin" 
Cc: x86@kernel.org
Acked-by: Borislav Petkov 
Signed-off-by: Paolo Bonzini 
Signed-off-by: Chris J Arges 
Signed-off-by: Jiri Slaby

x86, cpu, amd: Add workaround for family 16h, erratum 793

2014-02-06T19:22:22+00:00

commit 3b56496865f9f7d9bcb2f93b44c63f274f08e3b6 upstream.

This adds the workaround for erratum 793 as a precaution in case not
every BIOS implements it.  This addresses CVE-2013-6885.

Erratum text:

[Revision Guide for AMD Family 16h Models 00h-0Fh Processors,
document 51810 Rev. 3.04 November 2013]

793 Specific Combination of Writes to Write Combined Memory Types and
Locked Instructions May Cause Core Hang

Description

Under a highly specific and detailed set of internal timing
conditions, a locked instruction may trigger a timing sequence whereby
the write to a write combined memory type is not flushed, causing the
locked instruction to stall indefinitely.

Potential Effect on System

Processor core hang.

Suggested Workaround

BIOS should set MSR
C001_1020[15] = 1b.

Fix Planned

No fix planned

[ hpa: updated description, fixed typo in MSR name ]

Signed-off-by: Borislav Petkov 
Link: http://lkml.kernel.org/r/20140114230711.GS29865@pd.tnic
Tested-by: Aravind Gopalakrishnan 
Signed-off-by: H. Peter Anvin 
Signed-off-by: Greg Kroah-Hartman

Merge branch 'x86-asmlinkage-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

2013-09-04T15:42:44+00:00

Pull x86/asmlinkage changes from Ingo Molnar:
 "As a preparation for Andi Kleen's LTO patchset (link time
  optimizations using GCC's -flto which build time optimization has
  steadily increased in quality over the past few years and might
  eventually be usable for the kernel too) this tree includes a handful
  of preparatory patches that make function calling convention
  annotations consistent again:

   - Mark every function without arguments (or 64bit only) that is used
     by assembly code with asmlinkage()

   - Mark every function with parameters or variables that is used by
     assembly code as __visible.

  For the vanilla kernel this has documentation, consistency and
  debuggability advantages, for the time being"

* 'x86-asmlinkage-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/asmlinkage: Fix warning in xen asmlinkage change
  x86, asmlinkage, vdso: Mark vdso variables __visible
  x86, asmlinkage, power: Make various symbols used by the suspend asm code visible
  x86, asmlinkage: Make dump_stack visible
  x86, asmlinkage: Make 64bit checksum functions visible
  x86, asmlinkage, paravirt: Add __visible/asmlinkage to xen paravirt ops
  x86, asmlinkage, apm: Make APM data structure used from assembler visible
  x86, asmlinkage: Make syscall tables visible
  x86, asmlinkage: Make several variables used from assembler/linker script visible
  x86, asmlinkage: Make kprobes code visible and fix assembler code
  x86, asmlinkage: Make various syscalls asmlinkage
  x86, asmlinkage: Make 32bit/64bit __switch_to visible
  x86, asmlinkage: Make _*_start_kernel visible
  x86, asmlinkage: Make all interrupt handlers asmlinkage / __visible
  x86, asmlinkage: Change dotraplinkage into __visible on 32bit
  x86: Fix sys_call_table type in asm/syscall.h

x86, microcode, AMD: Make cpu_has_amd_erratum() use the correct struct cpuinfo_x86

2013-08-12T16:25:00+00:00

cpu_has_amd_erratum() is buggy, because it uses the per-cpu cpu_info
before it is filled by smp_store_boot_cpu_info() / smp_store_cpu_info().

If early microcode loading is enabled its collect_cpu_info_amd_early()
will fill ->x86 and so the fallback to boot_cpu_data is not used. But
->x86_vendor was not filled and is still X86_VENDOR_INTEL resulting in
no errata fixes getting applied and my system hangs on boot.

Using cpu_info in cpu_has_amd_erratum() is wrong anyway: its only
caller init_amd() will have a struct cpuinfo_x86 as parameter and the
set_cpu_bug() that is controlled by cpu_has_amd_erratum() also only uses
that struct.

So pass the struct cpuinfo_x86 from init_amd() to cpu_has_amd_erratum()
and the broken fallback can be dropped.

[ Boris: Drop WARN_ON() since we're called only from init_amd() ]

Signed-off-by: Torsten Kaiser 
Signed-off-by: Borislav Petkov

x86, asmlinkage: Make several variables used from assembler/linker script visible

2013-08-06T21:20:13+00:00

Plus one function, load_gs_index().

Signed-off-by: Andi Kleen 
Link: http://lkml.kernel.org/r/1375740170-7446-10-git-send-email-andi@firstfloor.org
Signed-off-by: H. Peter Anvin

x86: delete __cpuinit usage from all x86 files

2013-07-14T23:36:56+00:00

The __cpuinit type of throwaway sections might have made sense
some time ago when RAM was more constrained, but now the savings
do not offset the cost and complications.  For example, the fix in
commit 5e427ec2d0 ("x86: Fix bit corruption at CPU resume time")
is a good example of the nasty type of bugs that can be created
with improper use of the various __init prefixes.

After a discussion on LKML[1] it was decided that cpuinit should go
the way of devinit and be phased out.  Once all the users are gone,
we can then finally remove the macros themselves from linux/init.h.

Note that some harmless section mismatch warnings may result, since
notify_cpu_starting() and cpu_up() are arch independent (kernel/cpu.c)
are flagged as __cpuinit  -- so if we remove the __cpuinit from
arch specific callers, we will also get section mismatch warnings.
As an intermediate step, we intend to turn the linux/init.h cpuinit
content into no-ops as early as possible, since that will get rid
of these warnings.  In any case, they are temporary and harmless.

This removes all the arch/x86 uses of the __cpuinit macros from
all C files.  x86 only had the one __CPUINIT used in assembly files,
and it wasn't paired off with a .previous or a __FINIT, so we can
delete it directly w/o any corresponding additional change there.

[1] https://lkml.org/lkml/2013/5/20/589

Cc: Thomas Gleixner 
Cc: Ingo Molnar 
Cc: "H. Peter Anvin" 
Cc: x86@kernel.org
Acked-by: Ingo Molnar 
Acked-by: Thomas Gleixner 
Acked-by: H. Peter Anvin 
Signed-off-by: Paul Gortmaker

mm/x86: prepare for removing num_physpages and simplify mem_init()

2013-07-03T23:07:38+00:00

Prepare for removing num_physpages and simplify mem_init().

Signed-off-by: Jiang Liu 
Cc: Thomas Gleixner 
Cc: Ingo Molnar 
Cc: "H. Peter Anvin" 
Cc: Andreas Herrmann 
Cc: Tang Chen 
Cc: Wen Congyang 
Cc: Jianguo Wu 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

x86, CPU, AMD: Drop useless label

2013-04-16T09:50:51+00:00

All we want to do is return from this function so stop jumping around
like a flea for no good reason.

Signed-off-by: Borislav Petkov 
Link: http://lkml.kernel.org/r/1365436666-9837-5-git-send-email-bp@alien8.de
Signed-off-by: H. Peter Anvin

x86, AMD: Correct {rd,wr}msr_amd_safe warnings

2013-04-16T09:50:51+00:00

The idea with those routines is to slowly phase them out and not call
them on anything else besides K8. They even have a check for that which,
when called too early, fails. Let me explain:

It gets the cpuinfo_x86 pointer from the per_cpu array and when this
happens for cpu0, before its boot_cpu_data has been copied back to the
per_cpu array in smp_store_boot_cpu_info(), we get an empty struct and
thus the check fails.

Use boot_cpu_data directly instead.

Signed-off-by: Borislav Petkov 
Link: http://lkml.kernel.org/r/1365436666-9837-4-git-send-email-bp@alien8.de
Signed-off-by: H. Peter Anvin

x86, cpu: Convert AMD Erratum 400

2013-04-02T17:12:55+00:00

Convert AMD erratum 400 to the bug infrastructure. Then, retract all
exports for modules since they're not needed now and make the AMD
erratum checking machinery local to amd.c. Use forward declarations to
avoid shuffling too much code around needlessly.

Signed-off-by: Borislav Petkov 
Link: http://lkml.kernel.org/r/1363788448-31325-7-git-send-email-bp@alien8.de
Signed-off-by: H. Peter Anvin