On Thu, Apr 22, 2021, Krish Sadhukhan wrote: > On 4/22/21 11:01 AM, Sean Christopherson wrote: > > offset = svm->nested.ctl.msrpm_base_pa + (p * 4); > > > > if (kvm_vcpu_read_guest(&svm->vcpu, offset, &value, 4)) <- This reads vmcb12 > > return false; > > > > svm->nested.msrpm[p] = svm->msrpm[p] | value; <- Merge vmcb12's bitmap to KVM's bitmap for L2 ... > Getting back to your concern that this patch breaks > nested_svm_vmrun_msrpm(). If L1 passes a valid address in which some bits > in 11:0 are set, the hardware is anyway going to ignore those bits, > irrespective of whether we clear them (before my patch) or pass them as is > (my patch) and therefore what L1 thinks as a valid address will effectively > be an invalid address to the hardware. The only difference my patch makes is > it enables tests to verify hardware behavior. Am missing something ? See the above snippet where KVM reads the effectively vmcb12->msrpm to merge L1's desires with KVM's desires. By removing the code that ensures svm->nested.ctl.msrpm_base_pa is page aligned, the above offset calculation will be wrong.
