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selftests: kvm: set rax before vmcall

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[ 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>
This commit is contained in:
Andrei Vagin 2022-07-22 16:02:40 -07:00 committed by Greg Kroah-Hartman
parent 9fc8d3bee7
commit 128eeac876
1 changed files with 1 additions and 1 deletions
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tools/testing/selftests/kvm/lib/x86_64/processor.c
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@ -1326,7 +1326,7 @@ 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;
}