diff options
| author | Sean Christopherson <sean.j.christopherson@intel.com> | 2020-03-02 15:56:11 -0800 |
|---|---|---|
| committer | Paolo Bonzini <pbonzini@redhat.com> | 2020-03-16 17:57:59 +0100 |
| commit | 91001d403ad39b9c800a3b805bf48c5b027ecac5 (patch) | |
| tree | bd9fa524c9d4b5b88715be3bd720c34884447085 /arch/x86/kvm/cpuid.c | |
| parent | 1893c9415ae8cad20da863c41bdf308e56a2dd67 (diff) | |
KVM: x86: Warn on zero-size save state for valid CPUID 0xD.N sub-leaf
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.
Reviewed-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'arch/x86/kvm/cpuid.c')
| -rw-r--r-- | arch/x86/kvm/cpuid.c | 13 |
1 files 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 + * 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; |