[PATCH 13/52] KVM: PPC: Move prepare_to_enter call site into subarch code

Alexander Graf
2012-01-13T14:58:37Z

From: Scott Wood <scottwood@freescale.com>

This function should be called with interrupts disabled, to avoid
a race where an exception is delivered after we check, but the
resched kick is received before we disable interrupts (and thus doesn't
actually trigger the exit code that would recheck exceptions).

booke already does this properly in the lightweight exit case, but
not on initial entry.

For now, move the call of prepare_to_enter into subarch-specific code so
that booke can do the right thing here. Ideally book3s would do the same
thing, but I'm having a hard time seeing where it does any interrupt
disabling of this sort (plus it has several additional call sites), so
I'm deferring the book3s fix to someone more familiar with that code.
book3s behavior should be unchanged by this patch.

Signed-off-by: Scott Wood <scottwood@freescale.com>
Signed-off-by: Alexander Graf <agraf@suse.de>
---
arch/powerpc/kvm/book3s_hv.c | 2 ++
arch/powerpc/kvm/book3s_pr.c | 2 ++
arch/powerpc/kvm/booke.c | 4 ++++
arch/powerpc/kvm/powerpc.c | 2 --
4 files changed, 8 insertions(+), 2 deletions(-)

diff --git a/arch/powerpc/kvm/book3s_hv.c b/arch/powerpc/kvm/book3s_hv.c
index 536adee..b1e3b9c 100644
--- a/arch/powerpc/kvm/book3s_hv.c
+++ b/arch/powerpc/kvm/book3s_hv.c
@@ -836,6 +836,8 @@ int kvmppc_vcpu_run(struct kvm_run *run, struct kvm_vcpu *vcpu)
return -EINVAL;
}

+ kvmppc_core_prepare_to_enter(vcpu);
+
/* No need to go into the guest when all we'll do is come back out */
if (signal_pending(current)) {
run->exit_reason = KVM_EXIT_INTR;
diff --git a/arch/powerpc/kvm/book3s_pr.c b/arch/powerpc/kvm/book3s_pr.c
index f362858..203a7b7 100644
--- a/arch/powerpc/kvm/book3s_pr.c
+++ b/arch/powerpc/kvm/book3s_pr.c
@@ -929,6 +929,8 @@ int kvmppc_vcpu_run(struct kvm_run *kvm_run, struct kvm_vcpu *vcpu)
return -EINVAL;
}

+ kvmppc_core_prepare_to_enter(vcpu);
+
/* No need to go into the guest when all we do is going out */
if (signal_pending(current)) {
kvm_run->exit_reason = KVM_EXIT_INTR;
diff --git a/arch/powerpc/kvm/booke.c b/arch/powerpc/kvm/booke.c
index e082e34..feaefc4 100644
--- a/arch/powerpc/kvm/booke.c
+++ b/arch/powerpc/kvm/booke.c
@@ -295,6 +295,8 @@ void kvmppc_core_prepare_to_enter(struct kvm_vcpu *vcpu)
unsigned long old_pending = vcpu->arch.pending_exceptions;
unsigned int priority;

+ WARN_ON_ONCE(!irqs_disabled());
+
priority = __ffs(*pending);
while (priority <= BOOKE_IRQPRIO_MAX) {
if (kvmppc_booke_irqprio_deliver(vcpu, priority))
@@ -323,6 +325,8 @@ int kvmppc_vcpu_run(struct kvm_run *kvm_run, struct kvm_vcpu *vcpu)

local_irq_disable();

+ kvmppc_core_prepare_to_enter(vcpu);
+
if (signal_pending(current)) {
kvm_run->exit_reason = KVM_EXIT_INTR;
ret = -EINTR;
diff --git a/arch/powerpc/kvm/powerpc.c b/arch/powerpc/kvm/powerpc.c
index 6186ec0..7411bdd 100644
--- a/arch/powerpc/kvm/powerpc.c
+++ b/arch/powerpc/kvm/powerpc.c
@@ -559,8 +559,6 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu, struct kvm_run *run)
vcpu->arch.hcall_needed = 0;
}

- kvmppc_core_prepare_to_enter(vcpu);
-
r = kvmppc_vcpu_run(run, vcpu);

if (vcpu->sigset_active)
--
1.6.0.2