On 1/24/22 17:52, Sean Christopherson wrote:
On Mon, Jan 24, 2022, Vitaly Kuznetsov wrote:
Paolo Bonzini <pbonzini@xxxxxxxxxx> writes:
+ if (memcmp(e2, vcpu->arch.cpuid_entries, nent * sizeof(*e2)))
+ return -EINVAL;
Hmm, not sure about that due to the padding in struct kvm_cpuid_entry2.
It might break userspace that isn't too careful about zeroing it.
Given that we already are fully committed to potentially breaking userspace by
disallowing KVM_SET_CPUID{2} after KVM_RUN, we might as well get greedy.
Hmm, I thought this series was because we were _not_ fully committed. :)
FWIW, QEMU zeroes the whole thing before setting individual CPUID
entries. Legacy KVM_SET_CPUID call is also not afffected as it copies
entries to a newly allocated "struct kvm_cpuid_entry2[]" and explicitly
zeroes padding.
Do we need to at least add a check for ".flags"?
Yes.
Yes, we do. Alternatively, we can replace memdup with a copy in the
style of KVM_CPUID.
Paolo
