----- Original Message ----- > From: "Borislav Petkov" <b...@alien8.de> > To: "Paolo Bonzini" <pbonz...@redhat.com> > Cc: "Piotr Luc" <piotr....@intel.com>, k...@vger.kernel.org, "he chen" > <he.c...@linux.intel.com>, > linux-kernel@vger.kernel.org, t...@linutronix.de, x...@kernel.org, > h...@zytor.com, mi...@redhat.com, "Luwei Kang" > <luwei.k...@intel.com>, rkrc...@redhat.com > Sent: Saturday, October 29, 2016 2:25:48 PM > Subject: Re: [PATCH] x86/cpuid: expose AVX512_4VNNIW and AVX512_4FMAPS > features to kvm guest > > On Sat, Oct 29, 2016 at 08:21:17AM -0400, Paolo Bonzini wrote: > > Currently none of the bits in CPUID[7,0].edx is ever masked by the host, so > > this would be enough. If we ever need to do some masking, I guess I'll > > practice my puss-in-boots look and submit a patch to add CPUID[7,0] back > > as a separate cpufeature entr. > > I don't understand - why can't it be filtered here if needed? I.e., > > return edx & KVM_CPUID_EDX_7_MASK; > > or so?
Because then it wouldn't be in processor.h. > Btw, we already have a cpuid_edx() helper in arch/x86/include/asm/processor.h Yes, but it doesn't take an ecx. Anyhow this is not an issue for now. It will depend on which other bits are added to CPUID[7,0].edx, but in general it's relatively rare to blacklist bits from cpufeature. Paolo
