linux-kernel - [PATCH 2/3] KVM: selftests: Provide valid inputs for MONITOR/MWAIT regs

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Date:   Mon, 11 Jul 2022 22:57:52 +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, Yuan Yao <yuan.yao@...ux.intel.com>
Subject: [PATCH 2/3] KVM: selftests: Provide valid inputs for MONITOR/MWAIT regs

Provide valid inputs for RAX, RCX, and RDX when testing whether or not
KVM injects a #UD on MONITOR/MWAIT.  SVM has a virtualization hole and
checks for _all_ faults before checking for intercepts, e.g. MONITOR with
an unsupported RCX will #GP before KVM gets a chance to intercept and
emulate.

Fixes: 2325d4dd7321 ("KVM: selftests: Add MONITOR/MWAIT quirk test")
Signed-off-by: Sean Christopherson <seanjc@...gle.com>
---
 tools/testing/selftests/kvm/x86_64/monitor_mwait_test.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/tools/testing/selftests/kvm/x86_64/monitor_mwait_test.c b/tools/testing/selftests/kvm/x86_64/monitor_mwait_test.c
index f5c09cb528ae..6a4ebcdfa374 100644
--- a/tools/testing/selftests/kvm/x86_64/monitor_mwait_test.c
+++ b/tools/testing/selftests/kvm/x86_64/monitor_mwait_test.c
@@ -28,13 +28,17 @@ static void guest_monitor_wait(int testcase)
 
 	GUEST_SYNC(testcase);
 
-	vector = kvm_asm_safe("monitor");
+	/*
+	 * Arbitrarily MONITOR this function, SVM performs fault checks before
+	 * intercept checks, so the inputs for MONITOR and MWAIT must be valid.
+	 */
+	vector = kvm_asm_safe("monitor", "a"(guest_monitor_wait), "c"(0), "d"(0));
 	if (fault_wanted)
 		GUEST_ASSERT_2(vector == UD_VECTOR, testcase, vector);
 	else
 		GUEST_ASSERT_2(!vector, testcase, vector);
 
-	vector = kvm_asm_safe("mwait");
+	vector = kvm_asm_safe("mwait", "a"(guest_monitor_wait), "c"(0), "d"(0));
 	if (fault_wanted)
 		GUEST_ASSERT_2(vector == UD_VECTOR, testcase, vector);
 	else
-- 
2.37.0.144.g8ac04bfd2-goog