[PATCH 5.18 0811/1095] selftests: kvm: set rax before vmcall

Greg Kroah-Hartman
2022-08-15T22:28:19Z

From: Andrei Vagin <avagin@google.com>

[ Upstream commit 281106f938d3daaea6f8b6723a8217a2a1ef6936 ]

kvm_hypercall has to place the hypercall number in rax.

Trace events show that kvm_pv_test doesn't work properly:
kvm_pv_test-53132: kvm_hypercall: nr 0x0 a0 0x0 a1 0x0 a2 0x0 a3 0x0
kvm_pv_test-53132: kvm_hypercall: nr 0x0 a0 0x0 a1 0x0 a2 0x0 a3 0x0
kvm_pv_test-53132: kvm_hypercall: nr 0x0 a0 0x0 a1 0x0 a2 0x0 a3 0x0

With this change, it starts working as expected:
kvm_pv_test-54285: kvm_hypercall: nr 0x5 a0 0x0 a1 0x0 a2 0x0 a3 0x0
kvm_pv_test-54285: kvm_hypercall: nr 0xa a0 0x0 a1 0x0 a2 0x0 a3 0x0
kvm_pv_test-54285: kvm_hypercall: nr 0xb a0 0x0 a1 0x0 a2 0x0 a3 0x0

Signed-off-by: Andrei Vagin <avagin@google.com>
Message-Id: <20220722230241.1944655-5-avagin@google.com>
Fixes: ac4a4d6de22e ("selftests: kvm: test enforcement of paravirtual cpuid features")
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
tools/testing/selftests/kvm/lib/x86_64/processor.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tools/testing/selftests/kvm/lib/x86_64/processor.c b/tools/testing/selftests/kvm/lib/x86_64/processor.c
index 33ea5e9955d9..b9984124a294 100644
--- a/tools/testing/selftests/kvm/lib/x86_64/processor.c
+++ b/tools/testing/selftests/kvm/lib/x86_64/processor.c
@@ -1423,7 +1423,7 @@ uint64_t kvm_hypercall(uint64_t nr, uint64_t a0, uint64_t a1, uint64_t a2,

asm volatile("vmcall"
: "=a"(r)
- : "b"(a0), "c"(a1), "d"(a2), "S"(a3));
+ : "a"(nr), "b"(a0), "c"(a1), "d"(a2), "S"(a3));
return r;
}

--
2.35.1