On Thu, 2023-05-11 at 16:33 -0700, Sean Christopherson wrote: > Move the common check-and-set handling of PAT MSR writes out of vendor > code and into kvm_set_msr_common(). This aligns writes with reads, which > are already handled in common code, i.e. makes the handling of reads and > writes symmetrical in common code. > > Alternatively, the common handling in kvm_get_msr_common() could be moved > to vendor code, but duplicating code is generally undesirable (even though > the duplicatated code is trivial in this case), and guest writes to PAT > should be rare, i.e. the overhead of the extra function call is a > non-issue in practice. > > Suggested-by: Kai Huang <kai.huang@xxxxxxxxx> > Signed-off-by: Sean Christopherson <seanjc@xxxxxxxxxx> Reviewed-by: Kai Huang <kai.huang@xxxxxxxxx> > --- > arch/x86/kvm/svm/svm.c | 7 ++++--- > arch/x86/kvm/vmx/vmx.c | 7 +++---- > arch/x86/kvm/x86.c | 6 ------ > 3 files changed, 7 insertions(+), 13 deletions(-) > > diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c > index db237ccdc957..61d329760f6c 100644 > --- a/arch/x86/kvm/svm/svm.c > +++ b/arch/x86/kvm/svm/svm.c > @@ -2935,9 +2935,10 @@ static int svm_set_msr(struct kvm_vcpu *vcpu, struct msr_data *msr) > > break; > case MSR_IA32_CR_PAT: > - if (!kvm_pat_valid(data)) > - return 1; > - vcpu->arch.pat = data; > + ret = kvm_set_msr_common(vcpu, msr); > + if (ret) > + break; > + > svm->vmcb01.ptr->save.g_pat = data; > if (is_guest_mode(vcpu)) > nested_vmcb02_compute_g_pat(svm); > diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c > index 33b8625d3541..2d9d155691a7 100644 > --- a/arch/x86/kvm/vmx/vmx.c > +++ b/arch/x86/kvm/vmx/vmx.c > @@ -2287,10 +2287,9 @@ static int vmx_set_msr(struct kvm_vcpu *vcpu, struct msr_data *msr_info) > return 1; > goto find_uret_msr; > case MSR_IA32_CR_PAT: > - if (!kvm_pat_valid(data)) > - return 1; > - > - vcpu->arch.pat = data; > + ret = kvm_set_msr_common(vcpu, msr_info); > + if (ret) > + break; > > if (is_guest_mode(vcpu) && > get_vmcs12(vcpu)->vm_exit_controls & VM_EXIT_SAVE_IA32_PAT) > diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c > index d71cf924cd8f..3759737c0873 100644 > --- a/arch/x86/kvm/x86.c > +++ b/arch/x86/kvm/x86.c > @@ -3701,12 +3701,6 @@ 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); > - > if (!kvm_pat_valid(data)) > return 1; > > -- > 2.40.1.606.ga4b1b128d6-goog >
