On Tue, Apr 14, 2020 at 06:23:20PM -0700, Jon Cargille wrote: > From: Eric Northup <digitaleric@xxxxxxxxx> > > Return L2 cache and TLB information to guests. > They could have been set before, but the defaults that KVM returns will be > necessary for usermode that doesn't supply their own CPUID tables. I don't follow the changelog. The code makes sense, but I don't understand the justification. This only affects KVM_GET_SUPPORTED_CPUID, i.e. what's advertised to userspace, it doesn't directly change CPUID emulation in any way. The "They could have been set before" blurb is especially confusing. I assume you want to say something like: Return the host's L2 cache and TLB information for CPUID.0x80000006 instead of zeroing out the entry as part of KVM_GET_SUPPORTED_CPUID. This allows a userspace VMM to feed KVM_GET_SUPPORTED_CPUID's output directly into KVM_SET_CPUID2 (without breaking the guest). > Signed-off-by: Eric Northup <digitaleric@xxxxxxxxxx> > Signed-off-by: Eric Northup <digitaleric@xxxxxxxxx> > Signed-off-by: Jon Cargille <jcargill@xxxxxxxxxx> > Signed-off-by: Jim Mattson <jmattson@xxxxxxxxxx> Jim's tag is unnecessary, unless he was a middleman between Eric and Jon, in which case Jim's tag should also come between Eric's and Jon's. Only one of Eric's signoffs is needed (the one that matches the From: tag, i.e. is the official author). I'm guessing Google would prefer the author to be the @google.com address. > --- > arch/x86/kvm/cpuid.c | 3 +++ > 1 file changed, 3 insertions(+) > > diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c > index b1c469446b072..4a8d67303a42c 100644 > --- a/arch/x86/kvm/cpuid.c > +++ b/arch/x86/kvm/cpuid.c > @@ -734,6 +734,9 @@ static inline int __do_cpuid_func(struct kvm_cpuid_entry2 *entry, u32 function, > entry->ecx &= kvm_cpuid_8000_0001_ecx_x86_features; > cpuid_mask(&entry->ecx, CPUID_8000_0001_ECX); > break; > + case 0x80000006: > + /* L2 cache and TLB: pass through host info. */ > + break; > case 0x80000007: /* Advanced power management */ > /* invariant TSC is CPUID.80000007H:EDX[8] */ > entry->edx &= (1 << 8); > -- > 2.25.1.481.gfbce0eb801-goog >
