| Message ID | 20200201185218.24473-9-sean.j.christopherson@intel.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | KVM: x86: Introduce KVM cpu caps | expand |
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? :-) > + * 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@redhat.com>
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
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 + * 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;
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(-)