Liran Alon <liran.alon@xxxxxxxxxx> writes: >> On 16 Jan 2020, at 1:27, Sean Christopherson <sean.j.christopherson@xxxxxxxxx> wrote: >> >> On Wed, Jan 15, 2020 at 06:10:13PM +0100, Vitaly Kuznetsov wrote: >>> With fine grained VMX feature enablement QEMU>=4.2 tries to do KVM_SET_MSRS >>> with default (matching CPU model) values and in case eVMCS is also enabled, >>> fails. >> >> As in, Qemu is blindly throwing values at KVM and complains on failure? >> That seems like a Qemu bug, especially since Qemu needs to explicitly do >> KVM_CAP_HYPERV_ENLIGHTENED_VMCS to enable eVMCS. > > See: https://patchwork.kernel.org/patch/11316021/ > For more context. Ya, while it would certainly be possible to require that userspace takes into account KVM_CAP_HYPERV_ENLIGHTENED_VMCS (which is an opt-in) when doing KVM_SET_MSRS there doesn't seem to be an existing (easy) way to figure out which VMX controls were filtered out after enabling KVM_CAP_HYPERV_ENLIGHTENED_VMCS: KVM_GET_MSRS returns global &vmcs_config.nested values for VMX MSRs (vmx_get_msr_feature()). -- Vitaly
