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SubjectRe: [PATCH 08/61] KVM: x86: Warn on zero-size save state for valid CPUID 0xD.N sub-leaf
On Fri, Feb 07, 2020 at 04:54:59PM +0100, Vitaly Kuznetsov wrote:
> Sean Christopherson <sean.j.christopherson@intel.com> writes:
>
> > WARN if the save state size for a valid XCR0-managed sub-leaf is zero,
> > which would indicate a KVM or CPU bug. Add a comment to explain why KVM
> > WARNs so the reader doesn't have to tease out the relevant bits from
> > Intel's SDM and KVM's XCR0/XSS code.
> >
> > Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
> > ---
> > arch/x86/kvm/cpuid.c | 13 ++++++++++---
> > 1 file changed, 10 insertions(+), 3 deletions(-)
> >
> > diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
> > index fd9b29aa7abc..424dde41cb5d 100644
> > --- a/arch/x86/kvm/cpuid.c
> > +++ b/arch/x86/kvm/cpuid.c
> > @@ -677,10 +677,17 @@ static inline int __do_cpuid_func(struct kvm_cpuid_entry2 *entry, u32 function,
> > goto out;
> >
> > do_host_cpuid(&entry[i], function, idx);
> > - if (entry[i].eax == 0)
> > - continue;
> > - if (WARN_ON_ONCE(entry[i].ecx & 1))
> > +
> > + /*
> > + * The @supported check above should have filtered out
> > + * invalid sub-leafs as well as sub-leafs managed by
>
> Is it 'sub-leafs' or 'sub-leaves' actually? :-)

Yes. :-D

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