[PATCH v15 08/13] x86/cpu/amd: Do not print FW_BUG for Secure TSC

Nikunj A Dadhania
2024-12-03T09:01:41Z

When Secure TSC is enabled and TscInvariant (bit 8) in CPUID_8000_0007_edx
is set, the kernel complains with the below firmware bug:

[Firmware Bug]: TSC doesn't count with P0 frequency!

Secure TSC does not need to run at P0 frequency; the TSC frequency is set
by the VMM as part of the SNP_LAUNCH_START command. Skip this check when
Secure TSC is enabled

Signed-off-by: Nikunj A Dadhania <nikunj@amd.com>
Tested-by: Peter Gonda <pgonda@google.com>
Reviewed-by: Tom Lendacky <thomas.lendacky@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 d8408aafeed9..af9dd545f0ec 100644
--- a/arch/x86/kernel/cpu/amd.c
+++ b/arch/x86/kernel/cpu/amd.c
@@ -370,7 +370,8 @@ static void bsp_determine_snp(struct cpuinfo_x86 *c)

static void bsp_init_amd(struct cpuinfo_x86 *c)
{
- if (cpu_has(c, X86_FEATURE_CONSTANT_TSC)) {
+ if (cpu_has(c, X86_FEATURE_CONSTANT_TSC) &&
+ !cc_platform_has(CC_ATTR_GUEST_SNP_SECURE_TSC)) {

if (c->x86 > 0x10 ||
(c->x86 == 0x10 && c->x86_model >= 0x2)) {
--
2.34.1