From: Sean Christopherson Date: Wed, 28 Sep 2022 23:36:48 +0000 (+0000) Subject: KVM: selftests: Remove unnecessary register shuffling in fix_hypercall_test X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=04f2f60befc9af274c1790e626cc79334b1f4489;p=linux.git 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: Sean Christopherson Reviewed-by: Oliver Upton Message-Id: <20220928233652.783504-4-seanjc@google.com> Signed-off-by: Paolo Bonzini --- diff --git a/tools/testing/selftests/kvm/x86_64/fix_hypercall_test.c b/tools/testing/selftests/kvm/x86_64/fix_hypercall_test.c index e0004bd265360..6864eb0d5d14e 100644 --- a/tools/testing/selftests/kvm/x86_64/fix_hypercall_test.c +++ b/tools/testing/selftests/kvm/x86_64/fix_hypercall_test.c @@ -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; }