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Commit f2485b3e authored by Paolo Bonzini's avatar Paolo Bonzini
Browse files

KVM: x86: use guest_exit_irqoff 



This gains a few clock cycles per vmexit.  On Intel there is no need
anymore to enable the interrupts in vmx_handle_external_intr, since
we are using the "acknowledge interrupt on exit" feature.  AMD
needs to do that, and must be careful to avoid the interrupt shadow.

Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent 91fa0f8e

arch/x86/kvm/svm.c

+6 −0
Original line number Diff line number Diff line
@@ -4935,6 +4935,12 @@ static int svm_check_intercept(struct kvm_vcpu *vcpu, 
static void svm_handle_external_intr(struct kvm_vcpu *vcpu)

{

	local_irq_enable();

	/*

	 * We must have an instruction with interrupts enabled, so

	 * the timer interrupt isn't delayed by the interrupt shadow.

	 */

	asm("nop");

	local_irq_disable();

}



static void svm_sched_in(struct kvm_vcpu *vcpu, int cpu)

arch/x86/kvm/vmx.c

+1 −3
Original line number Diff line number Diff line
@@ -8574,7 +8574,6 @@ static void vmx_handle_external_intr(struct kvm_vcpu *vcpu) 
			"push %[sp]\n\t"

#endif

			"pushf\n\t"

			"orl $0x200, (%%" _ASM_SP ")\n\t"

			__ASM_SIZE(push) " $%c[cs]\n\t"

			"call *%[entry]\n\t"

			:
@@ -8587,8 +8586,7 @@ static void vmx_handle_external_intr(struct kvm_vcpu *vcpu) 
			[ss]"i"(__KERNEL_DS),

			[cs]"i"(__KERNEL_CS)

			);

	} else

		local_irq_enable();

	}

}



static bool vmx_has_high_real_mode_segbase(void)

arch/x86/kvm/x86.c

+2 −9
Original line number Diff line number Diff line
@@ -6709,16 +6709,9 @@ static int vcpu_enter_guest(struct kvm_vcpu *vcpu) 


	++vcpu->stat.exits;



	/*

	 * We must have an instruction between local_irq_enable() and

	 * kvm_guest_exit(), so the timer interrupt isn't delayed by

	 * the interrupt shadow.  The stat.exits increment will do nicely.

	 * But we need to prevent reordering, hence this barrier():

	 */

	barrier();



	guest_exit();

	guest_exit_irqoff();



	local_irq_enable();

	preempt_enable();



	vcpu->srcu_idx = srcu_read_lock(&vcpu->kvm->srcu);