Sean Christopherson <sean.j.christopherson@xxxxxxxxx> 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@xxxxxxxxx> > --- > 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? :-) > + * IA32_XSS MSR. Only XCR0-managed sub-leafs should > + * reach this point, and they should have a non-zero > + * save state size. > + */ > + if (WARN_ON_ONCE(!entry[i].eax || (entry[i].ecx & 1))) > continue; > + > entry[i].ecx = 0; > entry[i].edx = 0; > ++*nent; Reviewed-by: Vitaly Kuznetsov <vkuznets@xxxxxxxxxx> -- Vitaly
