A problem was introduced with commit f69759be251d ("x86/CPU/AMD: Move Zenbleed check to the Zen2 init function") where a bit in the DE_CFG MSR is getting set after a microcode late load.
The problem seems to be that the microcode late load path calls into amd_check_microcode() and subsequently zen2_zenbleed_check(). Since the patch removes the cpu_has_amd_erratum() check from zen2_zenbleed_check(), this will cause all non-Zen2 CPUs to go through the function and set the bit in the DE_CFG MSR.
Call into the zenbleed fix path on Zen2 CPUs only.
Fixes: f69759be251d ("x86/CPU/AMD: Move Zenbleed check to the Zen2 init function") Cc: stable@vger.kernel.org Acked-by: Borislav Petkov (AMD) bp@alien8.de Signed-off-by: John Allen john.allen@amd.com --- v2: - Clean up commit description --- arch/x86/kernel/cpu/amd.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/arch/x86/kernel/cpu/amd.c b/arch/x86/kernel/cpu/amd.c index 015971adadfc..368344e1394b 100644 --- a/arch/x86/kernel/cpu/amd.c +++ b/arch/x86/kernel/cpu/amd.c @@ -1202,5 +1202,6 @@ void amd_check_microcode(void) if (boot_cpu_data.x86_vendor != X86_VENDOR_AMD) return;
- on_each_cpu(zenbleed_check_cpu, NULL, 1); + if (boot_cpu_has(X86_FEATURE_ZEN2)) + on_each_cpu(zenbleed_check_cpu, NULL, 1); }
The following commit has been merged into the x86/urgent branch of tip:
Commit-ID: ee4d4e8d2c3bec6ee652599ab31991055a72c322 Gitweb: https://git.kernel.org/tip/ee4d4e8d2c3bec6ee652599ab31991055a72c322 Author: John Allen john.allen@amd.com AuthorDate: Mon, 23 Sep 2024 16:44:04 Committer: Borislav Petkov (AMD) bp@alien8.de CommitterDate: Fri, 11 Oct 2024 21:26:45 +02:00
x86/CPU/AMD: Only apply Zenbleed fix for Zen2 during late microcode load
Commit
f69759be251d ("x86/CPU/AMD: Move Zenbleed check to the Zen2 init function")
causes a bit in the DE_CFG MSR to get set erroneously after a microcode late load.
The microcode late load path calls into amd_check_microcode() and subsequently zen2_zenbleed_check(). Since the above commit removes the cpu_has_amd_erratum() call from zen2_zenbleed_check(), this will cause all non-Zen2 CPUs to go through the function and set the bit in the DE_CFG MSR.
Call into the Zenbleed fix path on Zen2 CPUs only.
[ bp: Massage commit message, use cpu_feature_enabled(). ]
Fixes: f69759be251d ("x86/CPU/AMD: Move Zenbleed check to the Zen2 init function") Signed-off-by: John Allen john.allen@amd.com Signed-off-by: Borislav Petkov (AMD) bp@alien8.de Acked-by: Borislav Petkov (AMD) bp@alien8.de Cc: stable@vger.kernel.org Link: https://lore.kernel.org/r/20240923164404.27227-1-john.allen@amd.com --- arch/x86/kernel/cpu/amd.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/arch/x86/kernel/cpu/amd.c b/arch/x86/kernel/cpu/amd.c index 015971a..fab5cae 100644 --- a/arch/x86/kernel/cpu/amd.c +++ b/arch/x86/kernel/cpu/amd.c @@ -1202,5 +1202,6 @@ void amd_check_microcode(void) if (boot_cpu_data.x86_vendor != X86_VENDOR_AMD) return;
- on_each_cpu(zenbleed_check_cpu, NULL, 1); + if (cpu_feature_enabled(X86_FEATURE_ZEN2)) + on_each_cpu(zenbleed_check_cpu, NULL, 1); }
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