KVM: Let host know whether the guest can handle async PF in non-userspace context.
If guest can detect that it runs in non-preemptable context it can
handle async PFs at any time, so let host know that it can send async
PF even if guest cpu is not in userspace.
Acked-by: Rik van Riel <riel@redhat.com>
Signed-off-by: Gleb Natapov <gleb@redhat.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
diff --git a/arch/x86/kernel/kvm.c b/arch/x86/kernel/kvm.c
index 47ea93e..91b3d65 100644
--- a/arch/x86/kernel/kvm.c
+++ b/arch/x86/kernel/kvm.c
@@ -449,6 +449,9 @@
if (kvm_para_has_feature(KVM_FEATURE_ASYNC_PF) && kvmapf) {
u64 pa = __pa(&__get_cpu_var(apf_reason));
+#ifdef CONFIG_PREEMPT
+ pa |= KVM_ASYNC_PF_SEND_ALWAYS;
+#endif
wrmsrl(MSR_KVM_ASYNC_PF_EN, pa | KVM_ASYNC_PF_ENABLED);
__get_cpu_var(apf_reason).enabled = 1;
printk(KERN_INFO"KVM setup async PF for cpu %d\n",