Commit 04f2f60b authored by Sean Christopherson's avatar Sean Christopherson Committed by Paolo Bonzini
Browse files

KVM: selftests: Remove unnecessary register shuffling in fix_hypercall_test 



Use input constraints to load RAX and RBX when testing that KVM correctly
does/doesn't patch the "wrong" hypercall.  There's no need to manually
load RAX and RBX, and no reason to clobber them either (KVM is not
supposed to modify anything other than RAX).

Signed-off-by: default avatarSean Christopherson <seanjc@google.com>
Reviewed-by: default avatarOliver Upton <oliver.upton@linux.dev>
Message-Id: <20220928233652.783504-4-seanjc@google.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent 39426507

tools/testing/selftests/kvm/x86_64/fix_hypercall_test.c

+8 −14
Original line number Diff line number Diff line
@@ -30,14 +30,11 @@ static uint64_t svm_do_sched_yield(uint8_t apic_id) 
{

	uint64_t ret;



	asm volatile("mov %1, %%rax\n\t"

		     "mov %2, %%rbx\n\t"

		     "svm_hypercall_insn:\n\t"

	asm volatile("svm_hypercall_insn:\n\t"

		     "vmmcall\n\t"

		     "mov %%rax, %0\n\t"

		     : "=r"(ret)

		     : "r"((uint64_t)KVM_HC_SCHED_YIELD), "r"((uint64_t)apic_id)

		     : "rax", "rbx", "memory");

		     : "=a"(ret)

		     : "a"((uint64_t)KVM_HC_SCHED_YIELD), "b"((uint64_t)apic_id)

		     : "memory");



	return ret;

}
@@ -47,14 +44,11 @@ static uint64_t vmx_do_sched_yield(uint8_t apic_id) 
{

	uint64_t ret;



	asm volatile("mov %1, %%rax\n\t"

		     "mov %2, %%rbx\n\t"

		     "vmx_hypercall_insn:\n\t"

	asm volatile("vmx_hypercall_insn:\n\t"

		     "vmcall\n\t"

		     "mov %%rax, %0\n\t"

		     : "=r"(ret)

		     : "r"((uint64_t)KVM_HC_SCHED_YIELD), "r"((uint64_t)apic_id)

		     : "rax", "rbx", "memory");

		     : "=a"(ret)

		     : "a"((uint64_t)KVM_HC_SCHED_YIELD), "b"((uint64_t)apic_id)

		     : "memory");



	return ret;

}