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authorAlexander Graf <agraf@suse.de>2011-12-19 13:36:55 +0100
committerAvi Kivity <avi@redhat.com>2012-03-05 13:52:30 +0100
commite371f713db6523d99d8ffae8f9da564055e6de17 (patch)
tree87cf4fa16c010640611033c27a8353848bd8cd33 /arch/powerpc/kvm
parentKVM: PPC: align vcpu_kick with x86 (diff)
downloadlinux-e371f713db6523d99d8ffae8f9da564055e6de17.tar.xz
linux-e371f713db6523d99d8ffae8f9da564055e6de17.zip
KVM: PPC: Book3S: PR: Fix signal check race
As Scott put it: > If we get a signal after the check, we want to be sure that we don't > receive the reschedule IPI until after we're in the guest, so that it > will cause another signal check. we need to have interrupts disabled from the point we do signal_check() all the way until we actually enter the guest. This patch fixes potential signal loss races. Reported-by: Scott Wood <scottwood@freescale.com> Signed-off-by: Alexander Graf <agraf@suse.de> Signed-off-by: Avi Kivity <avi@redhat.com>
Diffstat (limited to 'arch/powerpc/kvm')
-rw-r--r--arch/powerpc/kvm/book3s_pr.c20
1 files changed, 20 insertions, 0 deletions
diff --git a/arch/powerpc/kvm/book3s_pr.c b/arch/powerpc/kvm/book3s_pr.c
index 0c31507be908..2da670405727 100644
--- a/arch/powerpc/kvm/book3s_pr.c
+++ b/arch/powerpc/kvm/book3s_pr.c
@@ -51,6 +51,8 @@ static int kvmppc_handle_ext(struct kvm_vcpu *vcpu, unsigned int exit_nr,
#define MSR_USER32 MSR_USER
#define MSR_USER64 MSR_USER
#define HW_PAGE_SIZE PAGE_SIZE
+#define __hard_irq_disable local_irq_disable
+#define __hard_irq_enable local_irq_enable
#endif
void kvmppc_core_vcpu_load(struct kvm_vcpu *vcpu, int cpu)
@@ -776,7 +778,16 @@ program_interrupt:
/* To avoid clobbering exit_reason, only check for signals if
* we aren't already exiting to userspace for some other
* reason. */
+
+ /*
+ * Interrupts could be timers for the guest which we have to
+ * inject again, so let's postpone them until we're in the guest
+ * and if we really did time things so badly, then we just exit
+ * again due to a host external interrupt.
+ */
+ __hard_irq_disable();
if (signal_pending(current)) {
+ __hard_irq_enable();
#ifdef EXIT_DEBUG
printk(KERN_EMERG "KVM: Going back to host\n");
#endif
@@ -959,8 +970,17 @@ int kvmppc_vcpu_run(struct kvm_run *kvm_run, struct kvm_vcpu *vcpu)
kvmppc_core_prepare_to_enter(vcpu);
+ /*
+ * Interrupts could be timers for the guest which we have to inject
+ * again, so let's postpone them until we're in the guest and if we
+ * really did time things so badly, then we just exit again due to
+ * a host external interrupt.
+ */
+ __hard_irq_disable();
+
/* No need to go into the guest when all we do is going out */
if (signal_pending(current)) {
+ __hard_irq_enable();
kvm_run->exit_reason = KVM_EXIT_INTR;
ret = -EINTR;
goto out;