On Tue, Feb 21, 2023, Yu Zhang wrote: > > Sorry, why guest_cpuid_is_intel(vcpu)? Is it becasue that a AMD host with virtual > > VMSAVE/VMLOAD capability will always expose this feature for all AMD guests? > > Oh, sorry. I missed the guest_cpuid_has() in kvm_governed_feature_check_and_set(). > So please just ignore my 2nd question. > > As to the check of guest_cpuid_is_intel(), is it necessary? Yes? The comment in init_vmcb_after_set_cpuid() says: /* * We must intercept SYSENTER_EIP and SYSENTER_ESP * accesses because the processor only stores 32 bits. * For the same reason we cannot use virtual VMLOAD/VMSAVE. */ but I'm struggling to connect the dots to SYSENTER. I suspect the comment is misleading and has nothing to do 32-bit vs. 64-bit (or I'm reading it wrong) and should be something like: /* * Disable virtual VMLOAD/VMSAVE and intercept VMLOAD/VMSAVE if the * guest CPU is Intel in order to inject #UD. */ In other words, a non-SVM guest shouldn't be allowed to execute VMLOAD/VMSAVE.
