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| author | Alexander Graf <agraf@suse.de> | 2011-12-19 13:36:55 +0100 |
|---|---|---|
| committer | Avi Kivity <avi@redhat.com> | 2012-03-05 14:52:30 +0200 |
| commit | e371f713db6523d99d8ffae8f9da564055e6de17 (patch) | |
| tree | 87cf4fa16c010640611033c27a8353848bd8cd33 /arch | |
| parent | ae21216bece0a623d09980c120b9c98790a860b9 (diff) | |
| download | linux-stable-e371f713db6523d99d8ffae8f9da564055e6de17.tar.gz linux-stable-e371f713db6523d99d8ffae8f9da564055e6de17.tar.bz2 linux-stable-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')
| -rw-r--r-- | arch/powerpc/kvm/book3s_pr.c | 20 |
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; |