Patchwork [v3,3/3] kvm/ppc: IRQ disabling cleanup

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Submitter Scott Wood
Date May 14, 2013, 12:44 a.m.
Message ID <1368492281-30473-4-git-send-email-scottwood@freescale.com>
Download mbox | patch
Permalink /patch/243550/
State New
Headers show

Comments

Scott Wood - May 14, 2013, 12:44 a.m.
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: Scott Wood <scottwood@freescale.com>
---
v3:
 - local_irq_disable -> hard_irq_disable in MSR_WE code (just for
consistency -- MSR_WE and 64-bit don't overlap).
 - Check that IRQs are hard-disabled before entering the guest.
---
 arch/powerpc/include/asm/kvm_ppc.h |    6 ++++++
 arch/powerpc/kvm/book3s_pr.c       |   12 +++---------
 arch/powerpc/kvm/booke.c           |   11 +++--------
 arch/powerpc/kvm/powerpc.c         |   23 ++++++++++-------------
 4 files changed, 22 insertions(+), 30 deletions(-)

Patch

diff --git a/arch/powerpc/include/asm/kvm_ppc.h b/arch/powerpc/include/asm/kvm_ppc.h
index 6885846..e4474f8 100644
--- a/arch/powerpc/include/asm/kvm_ppc.h
+++ b/arch/powerpc/include/asm/kvm_ppc.h
@@ -404,6 +404,12 @@  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;
diff --git a/arch/powerpc/kvm/book3s_pr.c b/arch/powerpc/kvm/book3s_pr.c
index 0b97ce4..e61e39e 100644
--- a/arch/powerpc/kvm/book3s_pr.c
+++ b/arch/powerpc/kvm/book3s_pr.c
@@ -884,14 +884,11 @@  program_interrupt:
 		 * 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
 			kvmppc_fix_ee_before_entry();
-		}
 	}
 
 	trace_kvm_book3s_reenter(r, vcpu);
@@ -1121,12 +1118,9 @@  int kvmppc_vcpu_run(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;
-	}
 
 	/* Save FPU state in stack */
 	if (current->thread.regs->msr & MSR_FP)
diff --git a/arch/powerpc/kvm/booke.c b/arch/powerpc/kvm/booke.c
index 3817c67..521df2c 100644
--- a/arch/powerpc/kvm/booke.c
+++ b/arch/powerpc/kvm/booke.c
@@ -617,7 +617,7 @@  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;
@@ -666,10 +666,8 @@  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;
 	}
@@ -1154,14 +1152,11 @@  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
 			kvmppc_fix_ee_before_entry();
-		}
 	}
 
 	return r;
diff --git a/arch/powerpc/kvm/powerpc.c b/arch/powerpc/kvm/powerpc.c
index 4e05f8c..2f7a221 100644
--- a/arch/powerpc/kvm/powerpc.c
+++ b/arch/powerpc/kvm/powerpc.c
@@ -64,12 +64,14 @@  int kvmppc_prepare_to_enter(struct kvm_vcpu *vcpu)
 {
 	int r = 1;
 
-	WARN_ON_ONCE(!irqs_disabled());
+	WARN_ON(irqs_disabled());
+	hard_irq_disable();
+
 	while (true) {
 		if (need_resched()) {
 			local_irq_enable();
 			cond_resched();
-			local_irq_disable();
+			hard_irq_disable();
 			continue;
 		}
 
@@ -95,7 +97,7 @@  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;
@@ -108,21 +110,16 @@  int kvmppc_prepare_to_enter(struct kvm_vcpu *vcpu)
 		}
 
 #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;
-		}
+		WARN_ON(lazy_irq_pending());
 #endif
+		/* Can't use irqs_disabled() because we want hard irq state */
+		WARN_ON(mfmsr() & MSR_EE);
 
 		kvm_guest_enter();
-		break;
+		return r;
 	}
 
+	local_irq_enable();
 	return r;
 }
 #endif /* CONFIG_KVM_BOOK3S_64_HV */