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Commit 313dbd49 authored by Avi Kivity's avatar Avi Kivity
Browse files

KVM: VMX: Avoid vmwrite(HOST_RSP) when possible 



Usually HOST_RSP retains its value across guest entries.  Take advantage
of this and avoid a vmwrite() when this is so.

Signed-off-by: default avatarAvi Kivity <avi@qumranet.com>
parent 3b4bd796

arch/x86/kvm/vmx.c

+6 −0
Original line number Diff line number Diff line
@@ -58,6 +58,7 @@ struct vmcs { 
struct vcpu_vmx {

	struct kvm_vcpu       vcpu;

	struct list_head      local_vcpus_link;

	unsigned long         host_rsp;

	int                   launched;

	u8                    fail;

	u32                   idt_vectoring_info;
@@ -2982,7 +2983,11 @@ static void vmx_vcpu_run(struct kvm_vcpu *vcpu, struct kvm_run *kvm_run) 
		/* Store host registers */

		"push %%"R"dx; push %%"R"bp;"

		"push %%"R"cx \n\t"

		"cmp %%"R"sp, %c[host_rsp](%0) \n\t"

		"je 1f \n\t"

		"mov %%"R"sp, %c[host_rsp](%0) \n\t"

		__ex(ASM_VMX_VMWRITE_RSP_RDX) "\n\t"

		"1: \n\t"

		/* Check if vmlaunch of vmresume is needed */

		"cmpl $0, %c[launched](%0) \n\t"

		/* Load guest registers.  Don't clobber flags. */
@@ -3039,6 +3044,7 @@ static void vmx_vcpu_run(struct kvm_vcpu *vcpu, struct kvm_run *kvm_run) 
	      : : "c"(vmx), "d"((unsigned long)HOST_RSP),

		[launched]"i"(offsetof(struct vcpu_vmx, launched)),

		[fail]"i"(offsetof(struct vcpu_vmx, fail)),

		[host_rsp]"i"(offsetof(struct vcpu_vmx, host_rsp)),

		[rax]"i"(offsetof(struct vcpu_vmx, vcpu.arch.regs[VCPU_REGS_RAX])),

		[rbx]"i"(offsetof(struct vcpu_vmx, vcpu.arch.regs[VCPU_REGS_RBX])),

		[rcx]"i"(offsetof(struct vcpu_vmx, vcpu.arch.regs[VCPU_REGS_RCX])),