Instead of exchanging the guest and host rcx, have separate storage for each. This allows us to avoid using the xchg instruction, which is is a little slower than normal operations. Signed-off-by: Avi Kivity <avi@xxxxxxxxxx> --- arch/x86/kvm/vmx.c | 7 +++++-- 1 files changed, 5 insertions(+), 2 deletions(-) diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c index 0d56fe0..d9fd4e6 100644 --- a/arch/x86/kvm/vmx.c +++ b/arch/x86/kvm/vmx.c @@ -3991,6 +3991,7 @@ static void vmx_vcpu_run(struct kvm_vcpu *vcpu) asm( /* Store host registers */ "push %%"R"dx; push %%"R"bp;" + "push %%"R"cx \n\t" /* placeholder for guest rcx */ "push %%"R"cx \n\t" "cmp %%"R"sp, %c[host_rsp](%0) \n\t" "je 1f \n\t" @@ -4032,7 +4033,8 @@ static void vmx_vcpu_run(struct kvm_vcpu *vcpu) ".Llaunched: " __ex(ASM_VMX_VMRESUME) "\n\t" ".Lkvm_vmx_return: " /* Save guest registers, load host registers, keep flags */ - "xchg %0, (%%"R"sp) \n\t" + "mov %0, %c[wordsize](%%"R"sp) \n\t" + "pop %0 \n\t" "mov %%"R"ax, %c[rax](%0) \n\t" "mov %%"R"bx, %c[rbx](%0) \n\t" "pop"Q" %c[rcx](%0) \n\t" @@ -4076,7 +4078,8 @@ static void vmx_vcpu_run(struct kvm_vcpu *vcpu) [r14]"i"(offsetof(struct vcpu_vmx, vcpu.arch.regs[VCPU_REGS_R14])), [r15]"i"(offsetof(struct vcpu_vmx, vcpu.arch.regs[VCPU_REGS_R15])), #endif - [cr2]"i"(offsetof(struct vcpu_vmx, vcpu.arch.cr2)) + [cr2]"i"(offsetof(struct vcpu_vmx, vcpu.arch.cr2)), + [wordsize]"i"(sizeof(ulong)) : "cc", "memory" , R"ax", R"bx", R"di", R"si" #ifdef CONFIG_X86_64 -- 1.7.1 -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
