Commit ea25ace7 authored by Vishal Annapurve's avatar Vishal Annapurve Committed by Sean Christopherson
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KVM: selftests: x86: Use host's native hypercall instruction in kvm_hypercall() 



Use the host CPU's native hypercall instruction, i.e. VMCALL vs. VMMCALL,
in kvm_hypercall(), as relying on KVM to patch in the native hypercall on
a #UD for the "wrong" hypercall requires KVM_X86_QUIRK_FIX_HYPERCALL_INSN
to be enabled and flat out doesn't work if guest memory is encrypted with
a private key, e.g. for SEV VMs.

Suggested-by: default avatarSean Christopherson <seanjc@google.com>
Reviewed-by: default avatarDavid Matlack <dmatlack@google.com>
Signed-off-by: default avatarVishal Annapurve <vannapurve@google.com>
Link: https://lore.kernel.org/r/20230111004445.416840-4-vannapurve@google.com


Signed-off-by: default avatarSean Christopherson <seanjc@google.com>
parent e6df2ae3

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

+8 −2
Original line number Diff line number Diff line
@@ -1144,9 +1144,15 @@ uint64_t kvm_hypercall(uint64_t nr, uint64_t a0, uint64_t a1, uint64_t a2, 
{

	uint64_t r;



	asm volatile("vmcall"

	asm volatile("test %[use_vmmcall], %[use_vmmcall]\n\t"

		     "jnz 1f\n\t"

		     "vmcall\n\t"

		     "jmp 2f\n\t"

		     "1: vmmcall\n\t"

		     "2:"

		     : "=a"(r)

		     : "a"(nr), "b"(a0), "c"(a1), "d"(a2), "S"(a3));

		     : "a"(nr), "b"(a0), "c"(a1), "d"(a2), "S"(a3),

		       [use_vmmcall] "r" (host_cpu_is_amd));

	return r;

}