On Wed, 2023-05-03 at 11:28 -0700, Sean Christopherson wrote: > WARN and continue if a write to the PAT MSR reaches kvm_set_msr_common() > now that both VMX and SVM handle PAT writes entirely on their own. Keep > the case statement with a WARN instead of dropping it entirely to document > why KVM's handling of reads and writes isn't symmetrical (reads are still > handled by kvm_get_msr_common(). Why not just merge this patch with the next one? > > Signed-off-by: Sean Christopherson <seanjc@xxxxxxxxxx> > --- > arch/x86/kvm/x86.c | 6 ++++++ > 1 file changed, 6 insertions(+) > > diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c > index 8b356c9d8a81..c36256d00250 100644 > --- a/arch/x86/kvm/x86.c > +++ b/arch/x86/kvm/x86.c > @@ -3701,6 +3701,12 @@ int kvm_set_msr_common(struct kvm_vcpu *vcpu, struct msr_data *msr_info) > } > break; > case MSR_IA32_CR_PAT: > + /* > + * Writes to PAT should be handled by vendor code as both SVM > + * and VMX track the guest's PAT in the VMCB/VMCS. > + */ > + WARN_ON_ONCE(1); > + fallthrough; > case MTRRphysBase_MSR(0) ... MSR_MTRRfix4K_F8000: > case MSR_MTRRdefType: > return kvm_mtrr_set_msr(vcpu, msr, data);
