On Mon, Jun 13, 2022 at 06:49:17PM +0200, Paolo Bonzini wrote: > On 6/13/22 18:16, Anirudh Rayabharam wrote: > > + if (!kvm_has_tsc_control) > > + msrs->secondary_ctls_high &= ~SECONDARY_EXEC_TSC_SCALING; > > + > > msrs->secondary_ctls_low = 0; > > msrs->secondary_ctls_high &= > > SECONDARY_EXEC_DESC | > > @@ -6667,8 +6670,7 @@ void nested_vmx_setup_ctls_msrs(struct nested_vmx_msrs *msrs, u32 ept_caps) > > SECONDARY_EXEC_RDRAND_EXITING | > > SECONDARY_EXEC_ENABLE_INVPCID | > > SECONDARY_EXEC_RDSEED_EXITING | > > - SECONDARY_EXEC_XSAVES | > > - SECONDARY_EXEC_TSC_SCALING; > > + SECONDARY_EXEC_XSAVES; > > /* > > This is wrong because it _always_ disables SECONDARY_EXEC_TSC_SCALING, > even if kvm_has_tsc_control == true. The MSR actually allows 1-setting of the "use TSC scaling" control. So this line is redundant anyway. > > That said, I think a better implementation of this patch is to just add > a version of evmcs_sanitize_exec_ctrls that takes a struct > nested_vmx_msrs *, and call it at the end of nested_vmx_setup_ctl_msrs like > > evmcs_sanitize_nested_vmx_vsrs(msrs); Sanitize at the end might not work because I see some cases in nested_vmx_setup_ctls_msrs() where we want to expose some things to L1 even though the hardware doesn't support it. > > Even better (but I cannot "mentally test it" offhand) would be just > > diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c > index e802f71a9e8d..b3425ce835c5 100644 > --- a/arch/x86/kvm/vmx/vmx.c > +++ b/arch/x86/kvm/vmx/vmx.c > @@ -1862,7 +1862,7 @@ int vmx_get_msr(struct kvm_vcpu *vcpu, struct msr_data *msr_info) > * sanity checking and refuse to boot. Filter all unsupported > * features out. > */ > - if (!msr_info->host_initiated && > + if (static_branch_unlikely(&enable_evmcs) || > vmx->nested.enlightened_vmcs_enabled) > nested_evmcs_filter_control_msr(msr_info->index, > &msr_info->data); I will try this. Thanks, Anirudh. > > I cannot quite understand the host_initiated check, so I'll defer to > Vitaly on why it is needed. Most likely, removing it would cause some > warnings in QEMU with e.g. "-cpu Haswell,+vmx"; but I think it's a > userspace bug and we should remove that part of the condition. You > don't need to worry about that part, we'll cross that bridge if the > above patch works for your case. > > Thanks, > > Paolo
