linux-stable.git/arch/x86/kernel/cpu/amd.c, branch v6.2

Merge tag 'x86_cpu_for_v6.2' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

2022-12-13T22:56:56+00:00

Pull x86 cpu updates from Borislav Petkov:

 - Split MTRR and PAT init code to accomodate at least Xen PV and TDX
   guests which do not get MTRRs exposed but only PAT. (TDX guests do
   not support the cache disabling dance when setting up MTRRs so they
   fall under the same category)

   This is a cleanup work to remove all the ugly workarounds for such
   guests and init things separately (Juergen Gross)

 - Add two new Intel CPUs to the list of CPUs with "normal" Energy
   Performance Bias, leading to power savings

 - Do not do bus master arbitration in C3 (ARB_DISABLE) on modern
   Centaur CPUs

* tag 'x86_cpu_for_v6.2' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (26 commits)
  x86/mtrr: Make message for disabled MTRRs more descriptive
  x86/pat: Handle TDX guest PAT initialization
  x86/cpuid: Carve out all CPUID functionality
  x86/cpu: Switch to cpu_feature_enabled() for X86_FEATURE_XENPV
  x86/cpu: Remove X86_FEATURE_XENPV usage in setup_cpu_entry_area()
  x86/cpu: Drop 32-bit Xen PV guest code in update_task_stack()
  x86/cpu: Remove unneeded 64-bit dependency in arch_enter_from_user_mode()
  x86/cpufeatures: Add X86_FEATURE_XENPV to disabled-features.h
  x86/acpi/cstate: Optimize ARB_DISABLE on Centaur CPUs
  x86/mtrr: Simplify mtrr_ops initialization
  x86/cacheinfo: Switch cache_ap_init() to hotplug callback
  x86: Decouple PAT and MTRR handling
  x86/mtrr: Add a stop_machine() handler calling only cache_cpu_init()
  x86/mtrr: Let cache_aps_delayed_init replace mtrr_aps_delayed_init
  x86/mtrr: Get rid of __mtrr_enabled bool
  x86/mtrr: Simplify mtrr_bp_init()
  x86/mtrr: Remove set_all callback from struct mtrr_ops
  x86/mtrr: Disentangle MTRR init from PAT init
  x86/mtrr: Move cache control code to cacheinfo.c
  x86/mtrr: Split MTRR-specific handling from cache dis/enabling
  ...

x86/cpu: Switch to cpu_feature_enabled() for X86_FEATURE_XENPV

2022-11-22T15:18:19+00:00

Convert the remaining cases of static_cpu_has(X86_FEATURE_XENPV) and
boot_cpu_has(X86_FEATURE_XENPV) to use cpu_feature_enabled(), allowing
more efficient code in case the kernel is configured without
CONFIG_XEN_PV.

Signed-off-by: Juergen Gross 
Signed-off-by: Borislav Petkov 
Acked-by: Dave Hansen 
Link: https://lore.kernel.org/r/20221104072701.20283-6-jgross@suse.com

x86/cpu: Restore AMD's DE_CFG MSR after resume

2022-11-15T18:15:58+00:00

DE_CFG contains the LFENCE serializing bit, restore it on resume too.
This is relevant to older families due to the way how they do S3.

Unify and correct naming while at it.

Fixes: e4d0e84e4907 ("x86/cpu/AMD: Make LFENCE a serializing instruction")
Reported-by: Andrew Cooper 
Reported-by: Pawan Gupta 
Signed-off-by: Borislav Petkov 
Cc: 
Signed-off-by: Linus Torvalds

treewide: use get_random_u32() when possible

2022-10-11T23:42:58+00:00

The prandom_u32() function has been a deprecated inline wrapper around
get_random_u32() for several releases now, and compiles down to the
exact same code. Replace the deprecated wrapper with a direct call to
the real function. The same also applies to get_random_int(), which is
just a wrapper around get_random_u32(). This was done as a basic find
and replace.

Reviewed-by: Greg Kroah-Hartman 
Reviewed-by: Kees Cook 
Reviewed-by: Yury Norov 
Reviewed-by: Jan Kara  # for ext4
Acked-by: Toke Høiland-Jørgensen  # for sch_cake
Acked-by: Chuck Lever  # for nfsd
Acked-by: Jakub Kicinski 
Acked-by: Mika Westerberg  # for thunderbolt
Acked-by: Darrick J. Wong  # for xfs
Acked-by: Helge Deller  # for parisc
Acked-by: Heiko Carstens  # for s390
Signed-off-by: Jason A. Donenfeld

x86/rdrand: Remove "nordrand" flag in favor of "random.trust_cpu"

2022-07-18T13:04:04+00:00

The decision of whether or not to trust RDRAND is controlled by the
"random.trust_cpu" boot time parameter or the CONFIG_RANDOM_TRUST_CPU
compile time default. The "nordrand" flag was added during the early
days of RDRAND, when there were worries that merely using its values
could compromise the RNG. However, these days, RDRAND values are not
used directly but always go through the RNG's hash function, making
"nordrand" no longer useful.

Rather, the correct switch is "random.trust_cpu", which not only handles
the relevant trust issue directly, but also is general to multiple CPU
types, not just x86.

However, x86 RDRAND does have a history of being occasionally
problematic. Prior, when the kernel would notice something strange, it'd
warn in dmesg and suggest enabling "nordrand". We can improve on that by
making the test a little bit better and then taking the step of
automatically disabling RDRAND if we detect it's problematic.

Also disable RDSEED if the RDRAND test fails.

Cc: x86@kernel.org
Cc: Theodore Ts'o 
Suggested-by: H. Peter Anvin 
Suggested-by: Borislav Petkov 
Acked-by: Borislav Petkov 
Signed-off-by: Jason A. Donenfeld

x86/retbleed: Add fine grained Kconfig knobs

2022-06-29T15:43:41+00:00

Do fine-grained Kconfig for all the various retbleed parts.

NOTE: if your compiler doesn't support return thunks this will
silently 'upgrade' your mitigation to IBPB, you might not like this.

Signed-off-by: Peter Zijlstra (Intel) 
Signed-off-by: Borislav Petkov

x86/cpu/amd: Enumerate BTC_NO

2022-06-27T08:34:01+00:00

BTC_NO indicates that hardware is not susceptible to Branch Type Confusion.

Zen3 CPUs don't suffer BTC.

Hypervisors are expected to synthesise BTC_NO when it is appropriate
given the migration pool, to prevent kernels using heuristics.

  [ bp: Massage. ]

Signed-off-by: Andrew Cooper 
Signed-off-by: Borislav Petkov

x86/cpu/amd: Add Spectral Chicken

2022-06-27T08:34:00+00:00

Zen2 uarchs have an undocumented, unnamed, MSR that contains a chicken
bit for some speculation behaviour. It needs setting.

Note: very belatedly AMD released naming; it's now officially called
      MSR_AMD64_DE_CFG2 and MSR_AMD64_DE_CFG2_SUPPRESS_NOBR_PRED_BIT
      but shall remain the SPECTRAL CHICKEN.

Suggested-by: Andrew Cooper 
Signed-off-by: Peter Zijlstra (Intel) 
Signed-off-by: Borislav Petkov 
Reviewed-by: Josh Poimboeuf 
Signed-off-by: Borislav Petkov

x86/cpu: Clear SME feature flag when not in use

2022-02-16T18:45:53+00:00

Currently, the SME CPU feature flag is reflective of whether the CPU
supports the feature but not whether it has been activated by the
kernel.

Change this around to clear the SME feature flag if the kernel is not
using it so userspace can determine if it is available and in use
from /proc/cpuinfo.

As the feature flag is cleared on systems where SME isn't active, use
CPUID 0x8000001f to confirm SME availability before calling
native_wbinvd().

Signed-off-by: Mario Limonciello 
Signed-off-by: Borislav Petkov 
Acked-by: Tom Lendacky 
Link: https://lore.kernel.org/r/20220216034446.2430634-1-mario.limonciello@amd.com

x86/cpu: Merge Intel and AMD ppin_init() functions

2022-02-01T11:56:23+00:00

The code to decide whether a system supports the PPIN (Protected
Processor Inventory Number) MSR was cloned from the Intel
implementation. Apart from the X86_FEATURE bit and the MSR numbers it is
identical.

Merge the two functions into common x86 code, but use x86_match_cpu()
instead of the switch (c->x86_model) that was used by the old Intel
code.

No functional change.

Signed-off-by: Tony Luck 
Signed-off-by: Borislav Petkov 
Link: https://lore.kernel.org/r/20220131230111.2004669-2-tony.luck@intel.com