Commit 5b92b6ca authored by Peter Gonda's avatar Peter Gonda Committed by Paolo Bonzini
Browse files

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: default avatarPeter Gonda <pgonda@google.com>
Cc: Marc Orr <marcorr@google.com>
Cc: Nathan Tempelman <natet@google.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Sean Christopherson <seanjc@google.com>
Cc: Steve Rutherford <srutherford@google.com>
Cc: Brijesh Singh <brijesh.singh@amd.com>
Cc: kvm@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Cc: stable@vger.kernel.org
Fixes: 54526d1f ("KVM: x86: Support KVM VMs sharing SEV context", 2021-04-21)
Message-Id: <20210921150345.2221634-3-pgonda@google.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent f43c887c

arch/x86/kvm/svm/sev.c

+17 −2
Original line number Diff line number Diff line
@@ -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;

	}