[PATCH/RFC 2/2] KVM: push down irq_save from kvm_guest_exit

[Christian Borntraeger <borntraeger@xxxxxxxxxx>]

Some architectures already have irq disabled when calling
kvm_guest_exit. Push down the disabling into the architectures
to avoid double disabling. This also allows to replace
irq_save with irq_disable which might be cheaper.
arm and mips already have interrupts disabled. s390/power/x86
need adoptions.

Signed-off-by: Christian Borntraeger <borntraeger@xxxxxxxxxx>
---
 arch/powerpc/kvm/book3s_hv.c | 2 ++
 arch/powerpc/kvm/book3s_pr.c | 2 ++
 arch/powerpc/kvm/booke.c     | 4 ++--
 arch/s390/kvm/kvm-s390.c     | 2 ++
 arch/x86/kvm/x86.c           | 2 ++
 include/linux/kvm_host.h     | 4 ----
 6 files changed, 10 insertions(+), 6 deletions(-)

diff --git a/arch/powerpc/kvm/book3s_hv.c b/arch/powerpc/kvm/book3s_hv.c
index a5f392d..63b35b1 100644
--- a/arch/powerpc/kvm/book3s_hv.c
+++ b/arch/powerpc/kvm/book3s_hv.c
@@ -1811,7 +1811,9 @@ static void kvmppc_run_core(struct kvmppc_vcore *vc)
 
 	/* make sure updates to secondary vcpu structs are visible now */
 	smp_mb();
+	local_irq_disable();
 	kvm_guest_exit();
+	local_irq_enable();
 
 	preempt_enable();
 	cond_resched();
diff --git a/arch/powerpc/kvm/book3s_pr.c b/arch/powerpc/kvm/book3s_pr.c
index f573839..eafcb8c 100644
--- a/arch/powerpc/kvm/book3s_pr.c
+++ b/arch/powerpc/kvm/book3s_pr.c
@@ -891,7 +891,9 @@ int kvmppc_handle_exit_pr(struct kvm_run *run, struct kvm_vcpu *vcpu,
 
 	/* We get here with MSR.EE=1 */
 
+	local_irq_disable();
 	trace_kvm_exit(exit_nr, vcpu);
+	local_irq_enable();
 	kvm_guest_exit();
 
 	switch (exit_nr) {
diff --git a/arch/powerpc/kvm/booke.c b/arch/powerpc/kvm/booke.c
index 6c1316a..f1d6af3 100644
--- a/arch/powerpc/kvm/booke.c
+++ b/arch/powerpc/kvm/booke.c
@@ -1004,11 +1004,11 @@ int kvmppc_handle_exit(struct kvm_run *run, struct kvm_vcpu *vcpu,
 		break;
 	}
 
-	local_irq_enable();
-
 	trace_kvm_exit(exit_nr, vcpu);
 	kvm_guest_exit();
 
+	local_irq_enable();
+
 	run->exit_reason = KVM_EXIT_UNKNOWN;
 	run->ready_for_interrupt_injection = 1;
 
diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
index 9f4c954..0aa2534 100644
--- a/arch/s390/kvm/kvm-s390.c
+++ b/arch/s390/kvm/kvm-s390.c
@@ -2015,7 +2015,9 @@ static int __vcpu_run(struct kvm_vcpu *vcpu)
 		local_irq_enable();
 		exit_reason = sie64a(vcpu->arch.sie_block,
 				     vcpu->run->s.regs.gprs);
+		local_irq_disable();
 		kvm_guest_exit();
+		local_irq_enable();
 		vcpu->srcu_idx = srcu_read_lock(&vcpu->kvm->srcu);
 
 		rc = vcpu_post_run(vcpu, exit_reason);
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 32bf19e..a5fbd45 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -6351,7 +6351,9 @@ static int vcpu_enter_guest(struct kvm_vcpu *vcpu)
 	 */
 	barrier();
 
+	local_irq_disable();
 	kvm_guest_exit();
+	local_irq_enable();
 
 	preempt_enable();
 
diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index a34bf6ed..fe699fb 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -773,11 +773,7 @@ static inline void kvm_guest_enter(void)
 
 static inline void kvm_guest_exit(void)
 {
-	unsigned long flags;
-
-	local_irq_save(flags);
 	guest_exit();
-	local_irq_restore(flags);
 }
 
 /*
-- 
2.3.0