On 9/13/2024 11:12 PM, Jim Mattson wrote:
> On Wed, Jul 31, 2024 at 8:16 AM Nikunj A Dadhania <nikunj@xxxxxxx> wrote:
>>
>> 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@xxxxxxx>
>> Tested-by: Peter Gonda <pgonda@xxxxxxxxxx>
>> ---
>> 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 be5889bded49..87b55d2183a0 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)) {
>
> Could we extend this to never complain in a virtual machine? i.e.
Let me get more clarity on the below and your commit[1]
> ...
> - if (cpu_has(c, X86_FEATURE_CONSTANT_TSC)) {
> + if (cpu_has(c, X86_FEATURE_CONSTANT_TSC) &&
> + !cpu_has(c, X86_FEATURE_HYPERVISOR)) {
> ...
Or do this for Family 15h and above ?
Regards
Nikunj
1. https://github.com/torvalds/linux/commit/8b0e00fba934
