diff options
| -rw-r--r-- | arch/x86/kvm/xen.c | 27 |
1 files changed, 22 insertions, 5 deletions
diff --git a/arch/x86/kvm/xen.c b/arch/x86/kvm/xen.c index 9ea9c3dabe37..8f62baebd028 100644 --- a/arch/x86/kvm/xen.c +++ b/arch/x86/kvm/xen.c @@ -190,6 +190,7 @@ void kvm_xen_update_runstate_guest(struct kvm_vcpu *v, int state) int __kvm_xen_has_interrupt(struct kvm_vcpu *v) { + int err; u8 rc = 0; /* @@ -216,13 +217,29 @@ int __kvm_xen_has_interrupt(struct kvm_vcpu *v) if (likely(slots->generation == ghc->generation && !kvm_is_error_hva(ghc->hva) && ghc->memslot)) { /* Fast path */ - __get_user(rc, (u8 __user *)ghc->hva + offset); - } else { - /* Slow path */ - kvm_read_guest_offset_cached(v->kvm, ghc, &rc, offset, - sizeof(rc)); + pagefault_disable(); + err = __get_user(rc, (u8 __user *)ghc->hva + offset); + pagefault_enable(); + if (!err) + return rc; } + /* Slow path */ + + /* + * This function gets called from kvm_vcpu_block() after setting the + * task to TASK_INTERRUPTIBLE, to see if it needs to wake immediately + * from a HLT. So we really mustn't sleep. If the page ended up absent + * at that point, just return 1 in order to trigger an immediate wake, + * and we'll end up getting called again from a context where we *can* + * fault in the page and wait for it. + */ + if (in_atomic() || !task_is_running(current)) + return 1; + + kvm_read_guest_offset_cached(v->kvm, ghc, &rc, offset, + sizeof(rc)); + return rc; } |