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x86/CPU/AMD: Simplify the spectral chicken fix

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msr_set_bit() takes a bit number to set but MSR_ZEN2_SPECTRAL_CHICKEN_BIT
is a bit mask. The usual pattern that code uses is a _BIT-named type
macro instead of a mask.

So convert it to a bit number to reflect that.

Also, msr_set_bit() already does the reading and checking whether the
bit needs to be set so use that instead of a local variable.

Fixup tabbing while at it.

No functional changes.

Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: Nikolay Borisov <nik.borisov@suse.com>
Link: https://patch.msgid.link/20251230110731.28108-1-bp@kernel.org
This commit is contained in:
Borislav Petkov (AMD) 2025-12-30 12:07:31 +01:00
parent c957072d44
commit 736a2dcfda
3 changed files with 6 additions and 12 deletions
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2
arch/x86/include/asm/msr-index.h
View File

@ -795,7 +795,7 @@
/* Zen 2 */ /* Zen 2 */
#define MSR_ZEN2_SPECTRAL_CHICKEN 0xc00110e3 #define MSR_ZEN2_SPECTRAL_CHICKEN 0xc00110e3
#define MSR_ZEN2_SPECTRAL_CHICKEN_BIT BIT_ULL(1) #define MSR_ZEN2_SPECTRAL_CHICKEN_BIT 1
/* Fam 17h MSRs */ /* Fam 17h MSRs */
#define MSR_F17H_IRPERF 0xc00000e9 #define MSR_F17H_IRPERF 0xc00000e9

10
arch/x86/kernel/cpu/amd.c
View File

@ -900,20 +900,14 @@ static void fix_erratum_1386(struct cpuinfo_x86 *c)
void init_spectral_chicken(struct cpuinfo_x86 *c) void init_spectral_chicken(struct cpuinfo_x86 *c)
{ {
#ifdef CONFIG_MITIGATION_UNRET_ENTRY #ifdef CONFIG_MITIGATION_UNRET_ENTRY
u64 value;
/* /*
* On Zen2 we offer this chicken (bit) on the altar of Speculation. * On Zen2 we offer this chicken (bit) on the altar of Speculation.
* *
* This suppresses speculation from the middle of a basic block, i.e. it * This suppresses speculation from the middle of a basic block, i.e. it
* suppresses non-branch predictions. * suppresses non-branch predictions.
*/ */
if (!cpu_has(c, X86_FEATURE_HYPERVISOR)) { if (!cpu_has(c, X86_FEATURE_HYPERVISOR))
if (!rdmsrq_safe(MSR_ZEN2_SPECTRAL_CHICKEN, &value)) { msr_set_bit(MSR_ZEN2_SPECTRAL_CHICKEN, MSR_ZEN2_SPECTRAL_CHICKEN_BIT);
value |= MSR_ZEN2_SPECTRAL_CHICKEN_BIT;
wrmsrq_safe(MSR_ZEN2_SPECTRAL_CHICKEN, value);
}
}
#endif #endif
} }

2
tools/arch/x86/include/asm/msr-index.h
View File

@ -771,7 +771,7 @@
/* Zen 2 */ /* Zen 2 */
#define MSR_ZEN2_SPECTRAL_CHICKEN 0xc00110e3 #define MSR_ZEN2_SPECTRAL_CHICKEN 0xc00110e3
#define MSR_ZEN2_SPECTRAL_CHICKEN_BIT BIT_ULL(1) #define MSR_ZEN2_SPECTRAL_CHICKEN_BIT 1
/* Fam 17h MSRs */ /* Fam 17h MSRs */
#define MSR_F17H_IRPERF 0xc00000e9 #define MSR_F17H_IRPERF 0xc00000e9