| Message ID | 20221205233235.622491-4-kim.phillips@amd.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | x86/cpu, kvm: Support AMD Automatic IBRS | expand |
On Mon, Dec 05, 2022 at 05:32:31PM -0600, Kim Phillips wrote: > It's a part of the CPUID 0x80000021 leaf, and will be grouped > with other feature bits to being propagated via kvm_set_cpu_caps() > instead of open-coding them in __do_cpuid_func(). > > Unlike the other CPUID 0x80000021 EAX feature bits, > X86_FEATURE_LFENCE_RDTSC already had an entry in cpufeatures.h. > > Signed-off-by: Kim Phillips <kim.phillips@amd.com> > --- > arch/x86/kernel/cpu/scattered.c | 1 + > 1 file changed, 1 insertion(+) > > diff --git a/arch/x86/kernel/cpu/scattered.c b/arch/x86/kernel/cpu/scattered.c > index d0734cc19d37..caa03466cd9e 100644 > --- a/arch/x86/kernel/cpu/scattered.c > +++ b/arch/x86/kernel/cpu/scattered.c > @@ -46,6 +46,7 @@ static const struct cpuid_bit cpuid_bits[] = { > { X86_FEATURE_PROC_FEEDBACK, CPUID_EDX, 11, 0x80000007, 0 }, > { X86_FEATURE_MBA, CPUID_EBX, 6, 0x80000008, 0 }, > { X86_FEATURE_NO_NESTED_DATA_BP,CPUID_EAX, 0, 0x80000021, 0 }, > + { X86_FEATURE_LFENCE_RDTSC, CPUID_EAX, 2, 0x80000021, 0 }, Hmm, so this patchset keeps growing and growing with new bits. Perhaps my initial suggestion to make it a scattered one doesn't make a whole lot of sense anymore. /me goes and looks at CPUID_Fn80000021_EAX [Extended Feature 2 EAX] (Core::X86::Cpuid::FeatureExt2Eax) Yah, judging by what's there in that leaf, we are likely to use a lot more bits in the future I think you should go back to https://lore.kernel.org/lkml/20221104213651.141057-2-kim.phillips@amd.com/ But please state in that commit message that the majority of the feature bits in CPUID_Fn80000021_EAX will be used in the kernel and thus a separate leaf makes sense. Thx.
diff --git a/arch/x86/kernel/cpu/scattered.c b/arch/x86/kernel/cpu/scattered.c index d0734cc19d37..caa03466cd9e 100644 --- a/arch/x86/kernel/cpu/scattered.c +++ b/arch/x86/kernel/cpu/scattered.c @@ -46,6 +46,7 @@ static const struct cpuid_bit cpuid_bits[] = { { X86_FEATURE_PROC_FEEDBACK, CPUID_EDX, 11, 0x80000007, 0 }, { X86_FEATURE_MBA, CPUID_EBX, 6, 0x80000008, 0 }, { X86_FEATURE_NO_NESTED_DATA_BP,CPUID_EAX, 0, 0x80000021, 0 }, + { X86_FEATURE_LFENCE_RDTSC, CPUID_EAX, 2, 0x80000021, 0 }, { X86_FEATURE_NULL_SEL_CLR_BASE,CPUID_EAX, 6, 0x80000021, 0 }, { X86_FEATURE_PERFMON_V2, CPUID_EAX, 0, 0x80000022, 0 }, { X86_FEATURE_AMD_LBR_V2, CPUID_EAX, 1, 0x80000022, 0 },
It's a part of the CPUID 0x80000021 leaf, and will be grouped with other feature bits to being propagated via kvm_set_cpu_caps() instead of open-coding them in __do_cpuid_func(). Unlike the other CPUID 0x80000021 EAX feature bits, X86_FEATURE_LFENCE_RDTSC already had an entry in cpufeatures.h. Signed-off-by: Kim Phillips <kim.phillips@amd.com> --- arch/x86/kernel/cpu/scattered.c | 1 + 1 file changed, 1 insertion(+)