Messages in this thread Patch in this message | | | From | "Huang, Kai" <> | Subject | Re: [PATCH v2 1/8] KVM: VMX: Open code writing vCPU's PAT in VMX's MSR handler | Date | Fri, 12 May 2023 10:18:35 +0000 |
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On Thu, 2023-05-11 at 16:33 -0700, Sean Christopherson wrote: > From: Wenyao Hai <haiwenyao@uniontech.com> > > Open code setting "vcpu->arch.pat" in vmx_set_msr() instead of bouncing > through kvm_set_msr_common() to get to the same code in kvm_mtrr_set_msr(). > This aligns VMX with SVM, avoids hiding a very simple operation behind a > relatively complicated function call (finding the PAT MSR case in > kvm_set_msr_common() is non-trivial), and most importantly, makes it clear > that not unwinding the VMCS updates if kvm_set_msr_common() isn't a bug > (because kvm_set_msr_common() can never fail for PAT). > > Opportunistically set vcpu->arch.pat before updating the VMCS info so that > a future patch can move the common bits (back) into kvm_set_msr_common() > without a functional change. > > Note, MSR_IA32_CR_PAT is 0x277, and is very subtly handled by > > case 0x200 ... MSR_IA32_MC0_CTL2 - 1: > > in kvm_set_msr_common(). > > Cc: Kai Huang <kai.huang@intel.com> > Signed-off-by: Wenyao Hai <haiwenyao@uniontech.com> > [sean: massage changelog, hoist setting vcpu->arch.pat up] > Signed-off-by: Sean Christopherson <seanjc@google.com>
Reviewed-by: Kai Huang <kai.huang@intel.com>
> --- > arch/x86/kvm/vmx/vmx.c | 8 +++----- > 1 file changed, 3 insertions(+), 5 deletions(-) > > diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c > index 44fb619803b8..33b8625d3541 100644 > --- a/arch/x86/kvm/vmx/vmx.c > +++ b/arch/x86/kvm/vmx/vmx.c > @@ -2290,16 +2290,14 @@ static int vmx_set_msr(struct kvm_vcpu *vcpu, struct msr_data *msr_info) > if (!kvm_pat_valid(data)) > return 1; > > + vcpu->arch.pat = data; > + > if (is_guest_mode(vcpu) && > get_vmcs12(vcpu)->vm_exit_controls & VM_EXIT_SAVE_IA32_PAT) > get_vmcs12(vcpu)->guest_ia32_pat = data; > > - if (vmcs_config.vmentry_ctrl & VM_ENTRY_LOAD_IA32_PAT) { > + if (vmcs_config.vmentry_ctrl & VM_ENTRY_LOAD_IA32_PAT) > vmcs_write64(GUEST_IA32_PAT, data); > - vcpu->arch.pat = data; > - break; > - } > - ret = kvm_set_msr_common(vcpu, msr_info); > break; > case MSR_IA32_MCG_EXT_CTL: > if ((!msr_info->host_initiated && > -- > 2.40.1.606.ga4b1b128d6-goog >
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