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Commit 6c85f52b authored by Scott Wood's avatar Scott Wood Committed by Alexander Graf
Browse files

kvm/ppc: IRQ disabling cleanup 



Simplify the handling of lazy EE by going directly from fully-enabled
to hard-disabled.  This replaces the lazy_irq_pending() check
(including its misplaced kvm_guest_exit() call).

As suggested by Tiejun Chen, move the interrupt disabling into
kvmppc_prepare_to_enter() rather than have each caller do it.  Also
move the IRQ enabling on heavyweight exit into
kvmppc_prepare_to_enter().

Signed-off-by: default avatarScott Wood <scottwood@freescale.com>
Signed-off-by: default avatarAlexander Graf <agraf@suse.de>
parent 70713fe3

arch/powerpc/include/asm/kvm_ppc.h

+6 −0
Original line number Diff line number Diff line
@@ -456,6 +456,12 @@ static inline void kvmppc_fix_ee_before_entry(void) 
	trace_hardirqs_on();



#ifdef CONFIG_PPC64

	/*

	 * To avoid races, the caller must have gone directly from having

	 * interrupts fully-enabled to hard-disabled.

	 */

	WARN_ON(local_paca->irq_happened != PACA_IRQ_HARD_DIS);



	/* Only need to enable IRQs by hard enabling them after this */

	local_paca->irq_happened = 0;

	local_paca->soft_enabled = 1;

arch/powerpc/kvm/book3s_pr.c

+6 −8
Original line number Diff line number Diff line
@@ -999,14 +999,14 @@ int kvmppc_handle_exit_pr(struct kvm_run *run, struct kvm_vcpu *vcpu, 
		 * and if we really did time things so badly, then we just exit

		 * again due to a host external interrupt.

		 */

		local_irq_disable();

		s = kvmppc_prepare_to_enter(vcpu);

		if (s <= 0) {

			local_irq_enable();

		if (s <= 0)

			r = s;

		} else {

		else {

			/* interrupts now hard-disabled */

			kvmppc_fix_ee_before_entry();

		}



		kvmppc_handle_lost_ext(vcpu);

	}
@@ -1219,12 +1219,10 @@ static int kvmppc_vcpu_run_pr(struct kvm_run *kvm_run, struct kvm_vcpu *vcpu) 
	 * really did time things so badly, then we just exit again due to

	 * a host external interrupt.

	 */

	local_irq_disable();

	ret = kvmppc_prepare_to_enter(vcpu);

	if (ret <= 0) {

		local_irq_enable();

	if (ret <= 0)

		goto out;

	}

	/* interrupts now hard-disabled */



	/* Save FPU state in thread_struct */

	if (current->thread.regs->msr & MSR_FP)

arch/powerpc/kvm/booke.c

+5 −7
Original line number Diff line number Diff line
@@ -643,7 +643,7 @@ int kvmppc_core_prepare_to_enter(struct kvm_vcpu *vcpu) 
		local_irq_enable();

		kvm_vcpu_block(vcpu);

		clear_bit(KVM_REQ_UNHALT, &vcpu->requests);

		local_irq_disable();

		hard_irq_disable();



		kvmppc_set_exit_type(vcpu, EMULATED_MTMSRWE_EXITS);

		r = 1;
@@ -688,13 +688,12 @@ int kvmppc_vcpu_run(struct kvm_run *kvm_run, struct kvm_vcpu *vcpu) 
		return -EINVAL;

	}



	local_irq_disable();

	s = kvmppc_prepare_to_enter(vcpu);

	if (s <= 0) {

		local_irq_enable();

		ret = s;

		goto out;

	}

	/* interrupts now hard-disabled */



#ifdef CONFIG_PPC_FPU

	/* Save userspace FPU state in stack */
@@ -1187,12 +1186,11 @@ int kvmppc_handle_exit(struct kvm_run *run, struct kvm_vcpu *vcpu, 
	 * aren't already exiting to userspace for some other reason.

	 */

	if (!(r & RESUME_HOST)) {

		local_irq_disable();

		s = kvmppc_prepare_to_enter(vcpu);

		if (s <= 0) {

			local_irq_enable();

		if (s <= 0)

			r = (s << 2) | RESUME_HOST | (r & RESUME_FLAG_NV);

		} else {

		else {

			/* interrupts now hard-disabled */

			kvmppc_fix_ee_before_entry();

		}

	}

arch/powerpc/kvm/powerpc.c

+9 −17
Original line number Diff line number Diff line
@@ -68,14 +68,16 @@ int kvm_arch_vcpu_should_kick(struct kvm_vcpu *vcpu) 
 */

int kvmppc_prepare_to_enter(struct kvm_vcpu *vcpu)

{

	int r = 1;

	int r;



	WARN_ON(irqs_disabled());

	hard_irq_disable();



	WARN_ON_ONCE(!irqs_disabled());

	while (true) {

		if (need_resched()) {

			local_irq_enable();

			cond_resched();

			local_irq_disable();

			hard_irq_disable();

			continue;

		}
@@ -101,7 +103,7 @@ int kvmppc_prepare_to_enter(struct kvm_vcpu *vcpu) 
			local_irq_enable();

			trace_kvm_check_requests(vcpu);

			r = kvmppc_core_check_requests(vcpu);

			local_irq_disable();

			hard_irq_disable();

			if (r > 0)

				continue;

			break;
@@ -113,22 +115,12 @@ int kvmppc_prepare_to_enter(struct kvm_vcpu *vcpu) 
			continue;

		}



#ifdef CONFIG_PPC64

		/* lazy EE magic */

		hard_irq_disable();

		if (lazy_irq_pending()) {

			/* Got an interrupt in between, try again */

			local_irq_enable();

			local_irq_disable();

			kvm_guest_exit();

			continue;

		}

#endif



		kvm_guest_enter();

		break;

		return 1;

	}



	/* return to host */

	local_irq_enable();

	return r;

}

EXPORT_SYMBOL_GPL(kvmppc_prepare_to_enter);