On Tue, 2021-01-26 at 07:34 -0800, Dave Hansen wrote: > On 1/26/21 1:30 AM, Kai Huang wrote: > > From: Sean Christopherson <seanjc@xxxxxxxxxx> > > > > Add SGX1 and SGX2 feature flags, via CPUID.0x12.0x0.EAX, as scattered > > features, since adding a new leaf for only two bits would be wasteful. > > As part of virtualizing SGX, KVM will expose the SGX CPUID leafs to its > > guest, and to do so correctly needs to query hardware and kernel support > > for SGX1 and SGX2. > > It's also not _just_ exposing the CPUID leaves. There are some checks > here when KVM is emulating some SGX instructions too, right? I would say trapping instead of emulating, but yes KVM will do more. However those are quite details, and I don't think we should put lots of details here. Or perhaps we can use 'for instance' as brief description: As part of virtualizing SGX, KVM will need to use the two flags, for instance, to expose them to guest. ? > > > diff --git a/arch/x86/include/asm/cpufeatures.h b/arch/x86/include/asm/cpufeatures.h > > index 84b887825f12..18b2d0c8bbbe 100644 > > --- a/arch/x86/include/asm/cpufeatures.h > > +++ b/arch/x86/include/asm/cpufeatures.h > > @@ -292,6 +292,8 @@ > > #define X86_FEATURE_FENCE_SWAPGS_KERNEL (11*32+ 5) /* "" LFENCE in kernel entry SWAPGS path */ > > #define X86_FEATURE_SPLIT_LOCK_DETECT (11*32+ 6) /* #AC for split lock */ > > #define X86_FEATURE_PER_THREAD_MBA (11*32+ 7) /* "" Per-thread Memory Bandwidth Allocation */ > > +#define X86_FEATURE_SGX1 (11*32+ 8) /* Software Guard Extensions sub-feature SGX1 */ > > +#define X86_FEATURE_SGX2 (11*32+ 9) /* Software Guard Extensions sub-feature SGX2 */ > > FWIW, I'm not sure how valuable it is to spell the SGX acronym out three > times. Can't we use those bytes to put something more useful in that > comment? I think we can remove comment for SGX1, since it is basically SGX. For SGX2, how about below? /* SGX Enclave Dynamic Memory Management */
