Messages in this thread | | | From | Marc Orr <> | Date | Mon, 21 Mar 2022 10:25:22 -0700 | Subject | Re: [PATCH] Add KVM_EXIT_SHUTDOWN metadata for SEV-ES |
| |
On Mon, Mar 21, 2022 at 8:02 AM Peter Gonda <pgonda@google.com> wrote: > > SEV-ES guests can request termination using the GHCB's MSR protocol. See > AMD's GHCB spec section '4.1.13 Termination Request'. Currently when a > guest does this the userspace VMM sees an KVM_EXIT_UNKNOWN (-EVINAL) > return code from KVM_RUN. By adding a KVM_EXIT_SHUTDOWN_ENTRY to kvm_run > struct the userspace VMM can clearly see the guest has requested a SEV-ES > termination including the termination reason code set and reason code. > > Signed-off-by: Peter Gonda <pgonda@google.com> > Cc: Borislav Petkov <bp@alien8.de> > Cc: Tom Lendacky <thomas.lendacky@amd.com> > Cc: Brijesh Singh <brijesh.singh@amd.com> > Cc: Joerg Roedel <jroedel@suse.de> > Cc: Marc Orr <marcorr@google.com> > Cc: Sean Christopherson <seanjc@google.com> > Cc: kvm@vger.kernel.org > Cc: linux-kernel@vger.kernel.org > > --- > > Tested by making an SEV-ES guest call sev_es_terminate() with hardcoded > reason code set and reason code and then observing the codes from the > userspace VMM in the kvm_run.shutdown.data fields. > > --- > arch/x86/kvm/svm/sev.c | 9 +++++++-- > include/uapi/linux/kvm.h | 12 ++++++++++++ > 2 files changed, 19 insertions(+), 2 deletions(-) > > diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c > index 75fa6dd268f0..5f9d37dd3f6f 100644 > --- a/arch/x86/kvm/svm/sev.c > +++ b/arch/x86/kvm/svm/sev.c > @@ -2735,8 +2735,13 @@ static int sev_handle_vmgexit_msr_protocol(struct vcpu_svm *svm) > pr_info("SEV-ES guest requested termination: %#llx:%#llx\n", > reason_set, reason_code); > > - ret = -EINVAL; > - break; > + vcpu->run->exit_reason = KVM_EXIT_SHUTDOWN; > + vcpu->run->shutdown.reason = KVM_SHUTDOWN_SEV_TERM; > + vcpu->run->shutdown.ndata = 2; > + vcpu->run->shutdown.data[0] = reason_set; > + vcpu->run->shutdown.data[1] = reason_code; > + > + return 0;
Maybe I'm missing something, but don't we want to keep returning an error?
rationale: Current behavior: return -EINVAL to userpsace, but userpsace cannot infer where the -EINVAL came from. After this patch: We should still return -EINVAL to userspace, but now userspace can parse this new info in the KVM run struct to properly terminate.
> } > default: > /* Error, keep GHCB MSR value as-is */ > diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h > index 8616af85dc5d..12138b8f290c 100644 > --- a/include/uapi/linux/kvm.h > +++ b/include/uapi/linux/kvm.h > @@ -271,6 +271,12 @@ struct kvm_xen_exit { > #define KVM_EXIT_XEN 34 > #define KVM_EXIT_RISCV_SBI 35 > > +/* For KVM_EXIT_SHUTDOWN */ > +/* Standard VM shutdown request. No additional metadata provided. */ > +#define KVM_SHUTDOWN_REQ 0 > +/* SEV-ES termination request */ > +#define KVM_SHUTDOWN_SEV_TERM 1 > + > /* For KVM_EXIT_INTERNAL_ERROR */ > /* Emulate instruction failed. */ > #define KVM_INTERNAL_ERROR_EMULATION 1 > @@ -311,6 +317,12 @@ struct kvm_run { > struct { > __u64 hardware_exit_reason; > } hw; > + /* KVM_EXIT_SHUTDOWN_ENTRY */ > + struct { > + __u64 reason; > + __u32 ndata; > + __u64 data[16]; > + } shutdown; > /* KVM_EXIT_FAIL_ENTRY */ > struct { > __u64 hardware_entry_failure_reason; > -- > 2.35.1.894.gb6a874cedc-goog >
| |