Commit 281106f9 authored by Andrei Vagin's avatar Andrei Vagin Committed by Paolo Bonzini
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selftests: kvm: set rax before vmcall 



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: default avatarAndrei Vagin <avagin@google.com>
Message-Id: <20220722230241.1944655-5-avagin@google.com>
Fixes: ac4a4d6d ("selftests: kvm: test enforcement of paravirtual cpuid features")
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent dd4d1c3b

tools/testing/selftests/kvm/lib/x86_64/processor.c

+1 −1
Original line number Diff line number Diff line
@@ -1184,7 +1184,7 @@ 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;

}