From 5b92b6ca92b65bef811048c481e4446f4828500a Mon Sep 17 00:00:00 2001 From: Peter Gonda Date: Tue, 21 Sep 2021 08:03:45 -0700 Subject: [PATCH] KVM: SEV: Allow some commands for mirror VM A mirrored SEV-ES VM will need to call KVM_SEV_LAUNCH_UPDATE_VMSA to setup its vCPUs and have them measured, and their VMSAs encrypted. Without this change, it is impossible to have mirror VMs as part of SEV-ES VMs. Also allow the guest status check and debugging commands since they do not change any guest state. Signed-off-by: Peter Gonda Cc: Marc Orr Cc: Nathan Tempelman Cc: Paolo Bonzini Cc: Sean Christopherson Cc: Steve Rutherford Cc: Brijesh Singh Cc: kvm@vger.kernel.org Cc: linux-kernel@vger.kernel.org Cc: stable@vger.kernel.org Fixes: 54526d1fd593 ("KVM: x86: Support KVM VMs sharing SEV context", 2021-04-21) Message-Id: <20210921150345.2221634-3-pgonda@google.com> Signed-off-by: Paolo Bonzini --- arch/x86/kvm/svm/sev.c | 19 +++++++++++++++++-- 1 file changed, 17 insertions(+), 2 deletions(-) diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c index 5ec10ed85862..c36b5fe4c27c 100644 --- a/arch/x86/kvm/svm/sev.c +++ b/arch/x86/kvm/svm/sev.c @@ -1510,6 +1510,20 @@ static int sev_receive_finish(struct kvm *kvm, struct kvm_sev_cmd *argp) return sev_issue_cmd(kvm, SEV_CMD_RECEIVE_FINISH, &data, &argp->error); } +static bool cmd_allowed_from_miror(u32 cmd_id) +{ + /* + * Allow mirrors VM to call KVM_SEV_LAUNCH_UPDATE_VMSA to enable SEV-ES + * active mirror VMs. Also allow the debugging and status commands. + */ + if (cmd_id == KVM_SEV_LAUNCH_UPDATE_VMSA || + cmd_id == KVM_SEV_GUEST_STATUS || cmd_id == KVM_SEV_DBG_DECRYPT || + cmd_id == KVM_SEV_DBG_ENCRYPT) + return true; + + return false; +} + int svm_mem_enc_op(struct kvm *kvm, void __user *argp) { struct kvm_sev_cmd sev_cmd; @@ -1526,8 +1540,9 @@ int svm_mem_enc_op(struct kvm *kvm, void __user *argp) mutex_lock(&kvm->lock); - /* enc_context_owner handles all memory enc operations */ - if (is_mirroring_enc_context(kvm)) { + /* Only the enc_context_owner handles some memory enc operations. */ + if (is_mirroring_enc_context(kvm) && + !cmd_allowed_from_miror(sev_cmd.id)) { r = -EINVAL; goto out; }