[PATCH 1/4] KVM: PPC: Book3s: PR: Disable preemption in vcpu_run

[Alexander Graf <agraf@suse.de>]

When entering the guest, we want to make sure we're not getting preempted
away, so let's disable preemption on entry, but enable it again while handling
guest exits.

Reported-by: Jörg Sommer <joerg@alea.gnuu.de>
Signed-off-by: Alexander Graf <agraf@suse.de>
---
 arch/powerpc/kvm/book3s_pr.c |    7 +++++++
 1 files changed, 7 insertions(+), 0 deletions(-)

diff --git a/arch/powerpc/kvm/book3s_pr.c b/arch/powerpc/kvm/book3s_pr.c
index 726512b..8e4f800 100644
--- a/arch/powerpc/kvm/book3s_pr.c
+++ b/arch/powerpc/kvm/book3s_pr.c
@@ -519,6 +519,7 @@ int kvmppc_handle_exit(struct kvm_run *run, struct kvm_vcpu *vcpu,
 	run->ready_for_interrupt_injection = 1;
 
 	trace_kvm_book3s_exit(exit_nr, vcpu);
+	preempt_enable();
 	kvm_resched(vcpu);
 	switch (exit_nr) {
 	case BOOK3S_INTERRUPT_INST_STORAGE:
@@ -763,6 +764,8 @@ program_interrupt:
 			run->exit_reason = KVM_EXIT_INTR;
 			r = -EINTR;
 		} else {
+			preempt_disable();
+
 			/* In case an interrupt came in that was triggered
 			 * from userspace (like DEC), we need to check what
 			 * to inject now! */
@@ -925,6 +928,8 @@ int kvmppc_vcpu_run(struct kvm_run *kvm_run, struct kvm_vcpu *vcpu)
 #endif
 	ulong ext_msr;
 
+	preempt_disable();
+
 	/* Check if we can run the vcpu at all */
 	if (!vcpu->arch.sane) {
 		kvm_run->exit_reason = KVM_EXIT_INTERNAL_ERROR;
@@ -1006,6 +1011,8 @@ int kvmppc_vcpu_run(struct kvm_run *kvm_run, struct kvm_vcpu *vcpu)
 	current->thread.used_vsr = used_vsr;
 #endif
 
+	preempt_enable();
+
 	return ret;
 }
 
-- 
1.6.0.2