[PATCH v9 23/24] x86/cpu/amd: Do not print FW_BUG for Secure TSC

Nikunj A Dadhania
2024-05-31T04:35:27Z

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

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

Secure TSC need not run at P0 frequency, the TSC frequency is set by the
VMM as part of the SNP_LAUNCH_START command. Avoid the check when Secure
TSC is enabled

Signed-off-by: Nikunj A Dadhania <nikunj@amd.com>
Tested-by: Peter Gonda <pgonda@google.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 44df3f11e731..905e57ca324f 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_SECURE_TSC)) {

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