dummy/linux-stable-mirror
1
0
Fork 1
mirror of https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ synced 2025-04-19 20:58:31 +09:00
Code Issues Packages Projects Releases Wiki Activity

x86/cpu/amd: Fix workaround for erratum 1054

Browse Source 
Erratum 1054 affects AMD Zen processors that are a part of Family 17h
Models 00-2Fh and the workaround is to not set HWCR[IRPerfEn]. However,
when X86_FEATURE_ZEN1 was introduced, the condition to detect unaffected
processors was incorrectly changed in a way that the IRPerfEn bit gets
set only for unaffected Zen 1 processors.

Ensure that HWCR[IRPerfEn] is set for all unaffected processors. This
includes a subset of Zen 1 (Family 17h Models 30h and above) and all
later processors. Also clear X86_FEATURE_IRPERF on affected processors
so that the IRPerfCount register is not used by other entities like the
MSR PMU driver.

Fixes: 232afb557835 ("x86/CPU/AMD: Add X86_FEATURE_ZEN1")
Signed-off-by: Sandipan Das <sandipan.das@amd.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Borislav Petkov <bp@alien8.de>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/caa057a9d6f8ad579e2f1abaa71efbd5bd4eaf6d.1744956467.git.sandipan.das@amd.com
This commit is contained in:
Sandipan Das 2025-04-18 11:49:40 +05:30 committed by Ingo Molnar
parent d466304c43
commit 263e55949d
1 changed files with 12 additions and 7 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

19
arch/x86/kernel/cpu/amd.c
View File

@ -869,6 +869,16 @@ static void init_amd_zen1(struct cpuinfo_x86 *c)
pr_notice_once("AMD Zen1 DIV0 bug detected. Disable SMT for full protection.\n");
setup_force_cpu_bug(X86_BUG_DIV0);
/*
* Turn off the Instructions Retired free counter on machines that are
* susceptible to erratum #1054 "Instructions Retired Performance
* Counter May Be Inaccurate".
*/
if (c->x86_model < 0x30) {
msr_clear_bit(MSR_K7_HWCR, MSR_K7_HWCR_IRPERF_EN_BIT);
clear_cpu_cap(c, X86_FEATURE_IRPERF);
}
}
static bool cpu_has_zenbleed_microcode(void)
@ -1052,13 +1062,8 @@ static void init_amd(struct cpuinfo_x86 *c)
if (!cpu_feature_enabled(X86_FEATURE_XENPV))
set_cpu_bug(c, X86_BUG_SYSRET_SS_ATTRS);
/*
* Turn on the Instructions Retired free counter on machines not
* susceptible to erratum #1054 "Instructions Retired Performance
* Counter May Be Inaccurate".
*/
if (cpu_has(c, X86_FEATURE_IRPERF) &&
(boot_cpu_has(X86_FEATURE_ZEN1) && c->x86_model > 0x2f))
/* Enable the Instructions Retired free counter */
if (cpu_has(c, X86_FEATURE_IRPERF))
msr_set_bit(MSR_K7_HWCR, MSR_K7_HWCR_IRPERF_EN_BIT);
check_null_seg_clears_base(c);