linux-kernel - [PATCH] KVM: selftests: Don't skip L2's VMCALL in SMM test for SVM guest

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Date:   Tue, 25 Jan 2022 22:17:25 +0000
From:   Sean Christopherson <seanjc@...gle.com>
To:     Paolo Bonzini <pbonzini@...hat.com>
Cc:     Sean Christopherson <seanjc@...gle.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>,
        Joerg Roedel <joro@...tes.org>, kvm@...r.kernel.org,
        linux-kernel@...r.kernel.org, Maxim Levitsky <mlevitsk@...hat.com>
Subject: [PATCH] KVM: selftests: Don't skip L2's VMCALL in SMM test for SVM guest

Don't skip the vmcall() in l2_guest_code() prior to re-entering L2, doing
so will result in L2 running to completion, popping '0' off the stack for
RET, jumping to address '0', and ultimately dying with a triple fault
shutdown.

It's not at all obvious why the test re-enters L2 and re-executes VMCALL,
but presumably it serves a purpose.  The VMX path doesn't skip vmcall(),
and the test can't possibly have passed on SVM, so just do what VMX does.

Fixes: d951b2210c1a ("KVM: selftests: smm_test: Test SMM enter from L2")
Cc: Maxim Levitsky <mlevitsk@...hat.com>
Signed-off-by: Sean Christopherson <seanjc@...gle.com>
---
 tools/testing/selftests/kvm/x86_64/smm_test.c | 1 -
 1 file changed, 1 deletion(-)

diff --git a/tools/testing/selftests/kvm/x86_64/smm_test.c b/tools/testing/selftests/kvm/x86_64/smm_test.c
index 2da8eb8e2d96..a626d40fdb48 100644
--- a/tools/testing/selftests/kvm/x86_64/smm_test.c
+++ b/tools/testing/selftests/kvm/x86_64/smm_test.c
@@ -105,7 +105,6 @@ static void guest_code(void *arg)
 
 		if (cpu_has_svm()) {
 			run_guest(svm->vmcb, svm->vmcb_gpa);
-			svm->vmcb->save.rip += 3;
 			run_guest(svm->vmcb, svm->vmcb_gpa);
 		} else {
 			vmlaunch();

base-commit: e2e83a73d7ce66f62c7830a85619542ef59c90e4
-- 
2.35.0.rc0.227.g00780c9af4-goog