On Tue, Nov 09, 2021, Chenyi Qiang wrote: > > On 11/9/2021 1:44 AM, Sean Christopherson wrote: > > Hrm. Ideally this would be open coded in vmx_set_msr(). Long term, the RESET/INIT > > paths should really treat MSR updates as "normal" host_initiated writes instead of > > having to manually handle every MSR. > > > > That would be a bit gross to handle in vmx_vcpu_reset() since it would have to > > create a struct msr_data (because __kvm_set_msr() isn't exposed to vendor code), > > but since vcpu->arch.pkrs is relevant to the MMU I think it makes sense to > > initiate the write from common x86. > > > > E.g. this way there's not out-of-band special code, vmx_vcpu_reset() is kept clean, > > and if/when SVM gains support for PKRS this particular path Just Works. And it would > > be an easy conversion for my pipe dream plan of handling MSRs at RESET/INIT via a > > list of MSRs+values. > > > > diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c > > index ac83d873d65b..55881d13620f 100644 > > --- a/arch/x86/kvm/x86.c > > +++ b/arch/x86/kvm/x86.c > > @@ -11147,6 +11147,9 @@ void kvm_vcpu_reset(struct kvm_vcpu *vcpu, bool init_event) > > kvm_set_rflags(vcpu, X86_EFLAGS_FIXED); > > kvm_rip_write(vcpu, 0xfff0); > > > > + if (kvm_cpu_cap_has(X86_FEATURE_PKS)) > > + __kvm_set_msr(vcpu, MSR_IA32_PKRS, 0, true); > > + > > Got it. In addition, is it necessary to add on-INIT check? like: > > if (kvm_cpu_cap_has(X86_FEATURE_PKS) && !init_event) > __kvm_set_msr(vcpu, MSR_IA32_PKRS, 0, true); > > PKRS should be preserved on INIT, not cleared. The SDM doesn't make this > clear either. Hmm, but your cover letter says: To help patches review, one missing info in SDM is that PKSR will be cleared on Powerup/INIT/RESET, which should be listed in Table 9.1 "IA-32 and Intel 64 Processor States Following Power-up, Reset, or INIT" Which honestly makes me a little happy because I thought I was making stuff up for a minute :-) So which is it?
