Re: [PATCH 24/37] KVM: PPC: booke: rework rescheduling checks

2012-02-28 Thread Alexander Graf 

On 27.02.2012, at 20:28, Scott Wood wrote:

 On 02/24/2012 08:26 AM, Alexander Graf wrote:
 -void kvmppc_core_prepare_to_enter(struct kvm_vcpu *vcpu)
 +int kvmppc_core_prepare_to_enter(struct kvm_vcpu *vcpu)
 {
  unsigned long *pending = vcpu-arch.pending_exceptions;
  unsigned long old_pending = vcpu-arch.pending_exceptions;
 @@ -283,6 +283,8 @@ void kvmppc_core_prepare_to_enter(struct kvm_vcpu *vcpu)
 
  /* Tell the guest about our interrupt status */
  kvmppc_update_int_pending(vcpu, *pending, old_pending);
 +
 +return 0;
 }
 
 pfn_t kvmppc_gfn_to_pfn(struct kvm_vcpu *vcpu, gfn_t gfn)
 diff --git a/arch/powerpc/kvm/booke.c b/arch/powerpc/kvm/booke.c
 index 9979be1..3fcec2c 100644
 --- a/arch/powerpc/kvm/booke.c
 +++ b/arch/powerpc/kvm/booke.c
 @@ -439,8 +439,9 @@ static void kvmppc_core_check_exceptions(struct kvm_vcpu 
 *vcpu)
 }
 
 /* Check pending exceptions and deliver one, if possible. */
 -void kvmppc_core_prepare_to_enter(struct kvm_vcpu *vcpu)
 +int kvmppc_core_prepare_to_enter(struct kvm_vcpu *vcpu)
 {
 +int r = 0;
  WARN_ON_ONCE(!irqs_disabled());
 
  kvmppc_core_check_exceptions(vcpu);
 @@ -451,8 +452,44 @@ void kvmppc_core_prepare_to_enter(struct kvm_vcpu *vcpu)
  local_irq_disable();
 
  kvmppc_set_exit_type(vcpu, EMULATED_MTMSRWE_EXITS);
 -kvmppc_core_check_exceptions(vcpu);
 +r = 1;
  };
 +
 +return r;
 +}
 +
 +/*
 + * Common checks before entering the guest world.  Call with interrupts
 + * disabled.
 + *
 + * returns !0 if a signal is pending and check_signal is true
 + */
 +static int kvmppc_prepare_to_enter(struct kvm_vcpu *vcpu, bool check_signal)
 +{
 +int r = 0;
 +
 +WARN_ON_ONCE(!irqs_disabled());
 +while (true) {
 +if (need_resched()) {
 +local_irq_enable();
 +cond_resched();
 +local_irq_disable();
 +continue;
 +}
 +
 +if (kvmppc_core_prepare_to_enter(vcpu)) {
 +/* interrupts got enabled in between, so we
 +   are back at square 1 */
 +continue;
 +}
 +
 +
 +if (check_signal  signal_pending(current))
 +r = 1;
 
 If there is a signal pending and MSR[WE] is set, we'll loop forever
 without reaching this check.

Good point. How about something like this on top (will fold in later)?

diff --git a/arch/powerpc/kvm/booke.c b/arch/powerpc/kvm/booke.c
index 430055e..9f27258 100644
--- a/arch/powerpc/kvm/booke.c
+++ b/arch/powerpc/kvm/booke.c
@@ -477,15 +477,17 @@ static int kvmppc_prepare_to_enter(struct kvm_vcpu *vcpu)
continue;
}
 
+   if (signal_pending(current)) {
+   r = 1;
+   break;
+   }
+
if (kvmppc_core_prepare_to_enter(vcpu)) {
/* interrupts got enabled in between, so we
   are back at square 1 */
continue;
}
 
-   if (signal_pending(current))
-   r = 1;
-
break;
}
 

Alex

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Re: [PATCH 24/37] KVM: PPC: booke: rework rescheduling checks

2012-02-28 Thread Scott Wood 
On 02/28/2012 05:03 AM, Alexander Graf wrote:
 
 On 27.02.2012, at 20:28, Scott Wood wrote:
 
 If there is a signal pending and MSR[WE] is set, we'll loop forever
 without reaching this check.
 
 Good point. How about something like this on top (will fold in later)?
 
 diff --git a/arch/powerpc/kvm/booke.c b/arch/powerpc/kvm/booke.c
 index 430055e..9f27258 100644
 --- a/arch/powerpc/kvm/booke.c
 +++ b/arch/powerpc/kvm/booke.c
 @@ -477,15 +477,17 @@ static int kvmppc_prepare_to_enter(struct kvm_vcpu 
 *vcpu)
 continue;
 }
  
 +   if (signal_pending(current)) {
 +   r = 1;
 +   break;
 +   }
 +
 if (kvmppc_core_prepare_to_enter(vcpu)) {
 /* interrupts got enabled in between, so we
are back at square 1 */
 continue;
 }
  
 -   if (signal_pending(current))
 -   r = 1;
 -
 break;
 }

Looks OK.

-Scott

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RE: [PATCH 24/37] KVM: PPC: booke: rework rescheduling checks

2012-02-27 Thread Bhushan Bharat-R65777 


 -Original Message-
 From: kvm-ow...@vger.kernel.org [mailto:kvm-ow...@vger.kernel.org] On Behalf 
 Of
 Alexander Graf
 Sent: Friday, February 24, 2012 7:56 PM
 To: kvm-...@vger.kernel.org
 Cc: k...@vger.kernel.org; linuxppc-dev@lists.ozlabs.org; Wood Scott-B07421
 Subject: [PATCH 24/37] KVM: PPC: booke: rework rescheduling checks
 
 Instead of checking whether we should reschedule only when we exited due to an
 interrupt, let's always check before entering the guest back again. This gets
 the target more in line with the other archs.
 
 Also while at it, generalize the whole thing so that eventually we could have 
 a
 single kvmppc_prepare_to_enter function for all ppc targets that does signal 
 and
 reschedule checking for us.
 
 Signed-off-by: Alexander Graf ag...@suse.de
 ---
  arch/powerpc/include/asm/kvm_ppc.h |2 +-
  arch/powerpc/kvm/book3s.c  |4 ++-
  arch/powerpc/kvm/booke.c   |   70 ---
  3 files changed, 52 insertions(+), 24 deletions(-)
 
 diff --git a/arch/powerpc/include/asm/kvm_ppc.h
 b/arch/powerpc/include/asm/kvm_ppc.h
 index e709975..7f0a3da 100644
 --- a/arch/powerpc/include/asm/kvm_ppc.h
 +++ b/arch/powerpc/include/asm/kvm_ppc.h
 @@ -95,7 +95,7 @@ extern int kvmppc_core_vcpu_translate(struct kvm_vcpu *vcpu,
 extern void kvmppc_core_vcpu_load(struct kvm_vcpu *vcpu, int cpu);  extern 
 void
 kvmppc_core_vcpu_put(struct kvm_vcpu *vcpu);
 
 -extern void kvmppc_core_prepare_to_enter(struct kvm_vcpu *vcpu);
 +extern int kvmppc_core_prepare_to_enter(struct kvm_vcpu *vcpu);
  extern int kvmppc_core_pending_dec(struct kvm_vcpu *vcpu);  extern void
 kvmppc_core_queue_program(struct kvm_vcpu *vcpu, ulong flags);  extern void
 kvmppc_core_queue_dec(struct kvm_vcpu *vcpu); diff --git
 a/arch/powerpc/kvm/book3s.c b/arch/powerpc/kvm/book3s.c index 7d54f4e..c8ead7b
 100644
 --- a/arch/powerpc/kvm/book3s.c
 +++ b/arch/powerpc/kvm/book3s.c
 @@ -258,7 +258,7 @@ static bool clear_irqprio(struct kvm_vcpu *vcpu, unsigned
 int priority)
   return true;
  }
 
 -void kvmppc_core_prepare_to_enter(struct kvm_vcpu *vcpu)
 +int kvmppc_core_prepare_to_enter(struct kvm_vcpu *vcpu)
  {
   unsigned long *pending = vcpu-arch.pending_exceptions;
   unsigned long old_pending = vcpu-arch.pending_exceptions; @@ -283,6
 +283,8 @@ void kvmppc_core_prepare_to_enter(struct kvm_vcpu *vcpu)
 
   /* Tell the guest about our interrupt status */
   kvmppc_update_int_pending(vcpu, *pending, old_pending);
 +
 + return 0;
  }
 
  pfn_t kvmppc_gfn_to_pfn(struct kvm_vcpu *vcpu, gfn_t gfn) diff --git
 a/arch/powerpc/kvm/booke.c b/arch/powerpc/kvm/booke.c index 9979be1..3fcec2c
 100644
 --- a/arch/powerpc/kvm/booke.c
 +++ b/arch/powerpc/kvm/booke.c
 @@ -439,8 +439,9 @@ static void kvmppc_core_check_exceptions(struct kvm_vcpu
 *vcpu)  }
 
  /* Check pending exceptions and deliver one, if possible. */ -void
 kvmppc_core_prepare_to_enter(struct kvm_vcpu *vcpu)
 +int kvmppc_core_prepare_to_enter(struct kvm_vcpu *vcpu)
  {
 + int r = 0;
   WARN_ON_ONCE(!irqs_disabled());
 
   kvmppc_core_check_exceptions(vcpu);
 @@ -451,8 +452,44 @@ void kvmppc_core_prepare_to_enter(struct kvm_vcpu *vcpu)
   local_irq_disable();
 
   kvmppc_set_exit_type(vcpu, EMULATED_MTMSRWE_EXITS);
 - kvmppc_core_check_exceptions(vcpu);
 + r = 1;
   };
 +
 + return r;
 +}
 +
 +/*
 + * Common checks before entering the guest world.  Call with interrupts
 + * disabled.
 + *
 + * returns !0 if a signal is pending and check_signal is true  */
 +static int kvmppc_prepare_to_enter(struct kvm_vcpu *vcpu, bool
 +check_signal) {
 + int r = 0;
 +
 + WARN_ON_ONCE(!irqs_disabled());
 + while (true) {
 + if (need_resched()) {
 + local_irq_enable();
 + cond_resched();
 + local_irq_disable();
 + continue;
 + }
 +
 + if (kvmppc_core_prepare_to_enter(vcpu)) {

kvmppc_prepare_to_enter() is called even on heavyweight_exit. Should not this 
be called only on lightweight_exit?

Thanks
-Bharat

 + /* interrupts got enabled in between, so we
 +are back at square 1 */
 + continue;
 + }
 +
 + if (check_signal  signal_pending(current))
 + r = 1;
 +
 + break;
 + }
 +
 + return r;
  }
 
  int kvmppc_vcpu_run(struct kvm_run *kvm_run, struct kvm_vcpu *vcpu) @@ 
 -470,10
 +507,7 @@ int kvmppc_vcpu_run(struct kvm_run *kvm_run, struct kvm_vcpu *vcpu)
   }
 
   local_irq_disable();
 -
 - kvmppc_core_prepare_to_enter(vcpu);
 -
 - if (signal_pending(current)) {
 + if (kvmppc_prepare_to_enter(vcpu, true)) {
   kvm_run-exit_reason = KVM_EXIT_INTR;
   ret = -EINTR;
   goto out;
 @@ -598,25 +632,21 @@ int kvmppc_handle_exit(struct kvm_run *run, struct

Re: [PATCH 24/37] KVM: PPC: booke: rework rescheduling checks

2012-02-27 Thread Alexander Graf 

On 02/27/2012 05:34 PM, Bhushan Bharat-R65777 wrote:



+}
+
+/*
+ * Common checks before entering the guest world.  Call with interrupts
+ * disabled.
+ *
+ * returns !0 if a signal is pending and check_signal is true  */
+static int kvmppc_prepare_to_enter(struct kvm_vcpu *vcpu, bool
+check_signal) {
+   int r = 0;
+
+   WARN_ON_ONCE(!irqs_disabled());
+   while (true) {
+   if (need_resched()) {
+   local_irq_enable();
+   cond_resched();
+   local_irq_disable();
+   continue;
+   }
+
+   if (kvmppc_core_prepare_to_enter(vcpu)) {

kvmppc_prepare_to_enter() is called even on heavyweight_exit. Should not this 
be called only on lightweight_exit?


Yeah, we don't need to call it when exiting anyways. That's a functional 
change though, which this patch is trying not to introduce. So we should 
rather do that as a patch on top.


Alex

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Re: [PATCH 24/37] KVM: PPC: booke: rework rescheduling checks

2012-02-27 Thread Alexander Graf 

On 02/27/2012 06:33 PM, Alexander Graf wrote:

On 02/27/2012 05:34 PM, Bhushan Bharat-R65777 wrote:



+}
+
+/*
+ * Common checks before entering the guest world.  Call with 
interrupts

+ * disabled.
+ *
+ * returns !0 if a signal is pending and check_signal is true  */
+static int kvmppc_prepare_to_enter(struct kvm_vcpu *vcpu, bool
+check_signal) {
+int r = 0;
+
+WARN_ON_ONCE(!irqs_disabled());
+while (true) {
+if (need_resched()) {
+local_irq_enable();
+cond_resched();
+local_irq_disable();
+continue;
+}
+
+if (kvmppc_core_prepare_to_enter(vcpu)) {
kvmppc_prepare_to_enter() is called even on heavyweight_exit. Should 
not this be called only on lightweight_exit?


Yeah, we don't need to call it when exiting anyways. That's a 
functional change though, which this patch is trying not to introduce. 
So we should rather do that as a patch on top.


So how about this (warning! broken whitespace)?


diff --git a/arch/powerpc/kvm/booke.c b/arch/powerpc/kvm/booke.c
index 7a16b56..616aa2d 100644
--- a/arch/powerpc/kvm/booke.c
+++ b/arch/powerpc/kvm/booke.c
@@ -464,7 +464,7 @@ int kvmppc_core_prepare_to_enter(struct kvm_vcpu *vcpu)
  *
  * returns !0 if a signal is pending and check_signal is true
  */
-static int kvmppc_prepare_to_enter(struct kvm_vcpu *vcpu, bool 
check_signal)

+static int kvmppc_prepare_to_enter(struct kvm_vcpu *vcpu)
 {
int r = 0;

@@ -483,7 +483,7 @@ static int kvmppc_prepare_to_enter(struct kvm_vcpu 
*vcpu, bool check_signal)

continue;
}

-   if (check_signal  signal_pending(current))
+   if (signal_pending(current))
r = 1;

break;
@@ -507,7 +507,7 @@ int kvmppc_vcpu_run(struct kvm_run *kvm_run, struct 
kvm_vcpu *vcpu)

}

local_irq_disable();
-   if (kvmppc_prepare_to_enter(vcpu, true)) {
+   if (kvmppc_prepare_to_enter(vcpu)) {
kvm_run-exit_reason = KVM_EXIT_INTR;
ret = -EINTR;
goto out;
@@ -941,13 +941,16 @@ int kvmppc_handle_exit(struct kvm_run *run, struct 
kvm_vcpu *vcpu,

 * To avoid clobbering exit_reason, only check for signals if we
 * aren't already exiting to userspace for some other reason.
 */
-   local_irq_disable();
-   if (kvmppc_prepare_to_enter(vcpu, !(r  RESUME_HOST))) {
-   run-exit_reason = KVM_EXIT_INTR;
-   r = (-EINTR  2) | RESUME_HOST | (r  RESUME_FLAG_NV);
-   kvmppc_account_exit(vcpu, SIGNAL_EXITS);
+   if (!(r  RESUME_HOST)) {
+   local_irq_disable();
+   if (kvmppc_prepare_to_enter(vcpu)) {
+   run-exit_reason = KVM_EXIT_INTR;
+   r = (-EINTR  2) | RESUME_HOST | (r  
RESUME_FLAG_NV);

+   kvmppc_account_exit(vcpu, SIGNAL_EXITS);
+   }
}

+out:
return r;
 }


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RE: [PATCH 24/37] KVM: PPC: booke: rework rescheduling checks

2012-02-27 Thread Bhushan Bharat-R65777 


 -Original Message-
 From: Alexander Graf [mailto:ag...@suse.de]
 Sent: Monday, February 27, 2012 11:53 PM
 To: Bhushan Bharat-R65777
 Cc: kvm-...@vger.kernel.org; k...@vger.kernel.org; 
 linuxppc-dev@lists.ozlabs.org;
 Wood Scott-B07421
 Subject: Re: [PATCH 24/37] KVM: PPC: booke: rework rescheduling checks
 
 On 02/27/2012 06:33 PM, Alexander Graf wrote:
  On 02/27/2012 05:34 PM, Bhushan Bharat-R65777 wrote:
 
  +}
  +
  +/*
  + * Common checks before entering the guest world.  Call with
  interrupts
  + * disabled.
  + *
  + * returns !0 if a signal is pending and check_signal is true  */
  +static int kvmppc_prepare_to_enter(struct kvm_vcpu *vcpu, bool
  +check_signal) {
  +int r = 0;
  +
  +WARN_ON_ONCE(!irqs_disabled());
  +while (true) {
  +if (need_resched()) {
  +local_irq_enable();
  +cond_resched();
  +local_irq_disable();
  +continue;
  +}
  +
  +if (kvmppc_core_prepare_to_enter(vcpu)) {
  kvmppc_prepare_to_enter() is called even on heavyweight_exit. Should
  not this be called only on lightweight_exit?
 
  Yeah, we don't need to call it when exiting anyways. That's a
  functional change though, which this patch is trying not to introduce.
  So we should rather do that as a patch on top.
 
 So how about this (warning! broken whitespace)?
 
 
 diff --git a/arch/powerpc/kvm/booke.c b/arch/powerpc/kvm/booke.c index
 7a16b56..616aa2d 100644
 --- a/arch/powerpc/kvm/booke.c
 +++ b/arch/powerpc/kvm/booke.c
 @@ -464,7 +464,7 @@ int kvmppc_core_prepare_to_enter(struct kvm_vcpu *vcpu)
*
* returns !0 if a signal is pending and check_signal is true
*/
 -static int kvmppc_prepare_to_enter(struct kvm_vcpu *vcpu, bool
 check_signal)
 +static int kvmppc_prepare_to_enter(struct kvm_vcpu *vcpu)
   {
  int r = 0;
 
 @@ -483,7 +483,7 @@ static int kvmppc_prepare_to_enter(struct kvm_vcpu *vcpu,
 bool check_signal)
  continue;
  }
 
 -   if (check_signal  signal_pending(current))
 +   if (signal_pending(current))
  r = 1;
 
  break;
 @@ -507,7 +507,7 @@ int kvmppc_vcpu_run(struct kvm_run *kvm_run, struct 
 kvm_vcpu
 *vcpu)
  }
 
  local_irq_disable();
 -   if (kvmppc_prepare_to_enter(vcpu, true)) {
 +   if (kvmppc_prepare_to_enter(vcpu)) {
  kvm_run-exit_reason = KVM_EXIT_INTR;
  ret = -EINTR;
  goto out;
 @@ -941,13 +941,16 @@ int kvmppc_handle_exit(struct kvm_run *run, struct
 kvm_vcpu *vcpu,
   * To avoid clobbering exit_reason, only check for signals if we
   * aren't already exiting to userspace for some other reason.
   */
 -   local_irq_disable();
 -   if (kvmppc_prepare_to_enter(vcpu, !(r  RESUME_HOST))) {
 -   run-exit_reason = KVM_EXIT_INTR;
 -   r = (-EINTR  2) | RESUME_HOST | (r  RESUME_FLAG_NV);
 -   kvmppc_account_exit(vcpu, SIGNAL_EXITS);
 +   if (!(r  RESUME_HOST)) {
 +   local_irq_disable();
 +   if (kvmppc_prepare_to_enter(vcpu)) {
 +   run-exit_reason = KVM_EXIT_INTR;
 +   r = (-EINTR  2) | RESUME_HOST | (r 
 RESUME_FLAG_NV);
 +   kvmppc_account_exit(vcpu, SIGNAL_EXITS);
 +   }
  }
 
 +out:

Why?
Otherwise looks ok to me.

Thanks
-Bharat

  return r;
   }
 
 


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Re: [PATCH 24/37] KVM: PPC: booke: rework rescheduling checks

2012-02-27 Thread Scott Wood 
On 02/24/2012 08:26 AM, Alexander Graf wrote:
 -void kvmppc_core_prepare_to_enter(struct kvm_vcpu *vcpu)
 +int kvmppc_core_prepare_to_enter(struct kvm_vcpu *vcpu)
  {
   unsigned long *pending = vcpu-arch.pending_exceptions;
   unsigned long old_pending = vcpu-arch.pending_exceptions;
 @@ -283,6 +283,8 @@ void kvmppc_core_prepare_to_enter(struct kvm_vcpu *vcpu)
  
   /* Tell the guest about our interrupt status */
   kvmppc_update_int_pending(vcpu, *pending, old_pending);
 +
 + return 0;
  }
  
  pfn_t kvmppc_gfn_to_pfn(struct kvm_vcpu *vcpu, gfn_t gfn)
 diff --git a/arch/powerpc/kvm/booke.c b/arch/powerpc/kvm/booke.c
 index 9979be1..3fcec2c 100644
 --- a/arch/powerpc/kvm/booke.c
 +++ b/arch/powerpc/kvm/booke.c
 @@ -439,8 +439,9 @@ static void kvmppc_core_check_exceptions(struct kvm_vcpu 
 *vcpu)
  }
  
  /* Check pending exceptions and deliver one, if possible. */
 -void kvmppc_core_prepare_to_enter(struct kvm_vcpu *vcpu)
 +int kvmppc_core_prepare_to_enter(struct kvm_vcpu *vcpu)
  {
 + int r = 0;
   WARN_ON_ONCE(!irqs_disabled());
  
   kvmppc_core_check_exceptions(vcpu);
 @@ -451,8 +452,44 @@ void kvmppc_core_prepare_to_enter(struct kvm_vcpu *vcpu)
   local_irq_disable();
  
   kvmppc_set_exit_type(vcpu, EMULATED_MTMSRWE_EXITS);
 - kvmppc_core_check_exceptions(vcpu);
 + r = 1;
   };
 +
 + return r;
 +}
 +
 +/*
 + * Common checks before entering the guest world.  Call with interrupts
 + * disabled.
 + *
 + * returns !0 if a signal is pending and check_signal is true
 + */
 +static int kvmppc_prepare_to_enter(struct kvm_vcpu *vcpu, bool check_signal)
 +{
 + int r = 0;
 +
 + WARN_ON_ONCE(!irqs_disabled());
 + while (true) {
 + if (need_resched()) {
 + local_irq_enable();
 + cond_resched();
 + local_irq_disable();
 + continue;
 + }
 +
 + if (kvmppc_core_prepare_to_enter(vcpu)) {
 + /* interrupts got enabled in between, so we
 +are back at square 1 */
 + continue;
 + }
 +
 +
 + if (check_signal  signal_pending(current))
 + r = 1;

If there is a signal pending and MSR[WE] is set, we'll loop forever
without reaching this check.

-Scott

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[PATCH 24/37] KVM: PPC: booke: rework rescheduling checks

2012-02-24 Thread Alexander Graf 
Instead of checking whether we should reschedule only when we exited
due to an interrupt, let's always check before entering the guest back
again. This gets the target more in line with the other archs.

Also while at it, generalize the whole thing so that eventually we could
have a single kvmppc_prepare_to_enter function for all ppc targets that
does signal and reschedule checking for us.

Signed-off-by: Alexander Graf ag...@suse.de
---
 arch/powerpc/include/asm/kvm_ppc.h |2 +-
 arch/powerpc/kvm/book3s.c  |4 ++-
 arch/powerpc/kvm/booke.c   |   70 ---
 3 files changed, 52 insertions(+), 24 deletions(-)

diff --git a/arch/powerpc/include/asm/kvm_ppc.h 
b/arch/powerpc/include/asm/kvm_ppc.h
index e709975..7f0a3da 100644
--- a/arch/powerpc/include/asm/kvm_ppc.h
+++ b/arch/powerpc/include/asm/kvm_ppc.h
@@ -95,7 +95,7 @@ extern int kvmppc_core_vcpu_translate(struct kvm_vcpu *vcpu,
 extern void kvmppc_core_vcpu_load(struct kvm_vcpu *vcpu, int cpu);
 extern void kvmppc_core_vcpu_put(struct kvm_vcpu *vcpu);
 
-extern void kvmppc_core_prepare_to_enter(struct kvm_vcpu *vcpu);
+extern int kvmppc_core_prepare_to_enter(struct kvm_vcpu *vcpu);
 extern int kvmppc_core_pending_dec(struct kvm_vcpu *vcpu);
 extern void kvmppc_core_queue_program(struct kvm_vcpu *vcpu, ulong flags);
 extern void kvmppc_core_queue_dec(struct kvm_vcpu *vcpu);
diff --git a/arch/powerpc/kvm/book3s.c b/arch/powerpc/kvm/book3s.c
index 7d54f4e..c8ead7b 100644
--- a/arch/powerpc/kvm/book3s.c
+++ b/arch/powerpc/kvm/book3s.c
@@ -258,7 +258,7 @@ static bool clear_irqprio(struct kvm_vcpu *vcpu, unsigned 
int priority)
return true;
 }
 
-void kvmppc_core_prepare_to_enter(struct kvm_vcpu *vcpu)
+int kvmppc_core_prepare_to_enter(struct kvm_vcpu *vcpu)
 {
unsigned long *pending = vcpu-arch.pending_exceptions;
unsigned long old_pending = vcpu-arch.pending_exceptions;
@@ -283,6 +283,8 @@ void kvmppc_core_prepare_to_enter(struct kvm_vcpu *vcpu)
 
/* Tell the guest about our interrupt status */
kvmppc_update_int_pending(vcpu, *pending, old_pending);
+
+   return 0;
 }
 
 pfn_t kvmppc_gfn_to_pfn(struct kvm_vcpu *vcpu, gfn_t gfn)
diff --git a/arch/powerpc/kvm/booke.c b/arch/powerpc/kvm/booke.c
index 9979be1..3fcec2c 100644
--- a/arch/powerpc/kvm/booke.c
+++ b/arch/powerpc/kvm/booke.c
@@ -439,8 +439,9 @@ static void kvmppc_core_check_exceptions(struct kvm_vcpu 
*vcpu)
 }
 
 /* Check pending exceptions and deliver one, if possible. */
-void kvmppc_core_prepare_to_enter(struct kvm_vcpu *vcpu)
+int kvmppc_core_prepare_to_enter(struct kvm_vcpu *vcpu)
 {
+   int r = 0;
WARN_ON_ONCE(!irqs_disabled());
 
kvmppc_core_check_exceptions(vcpu);
@@ -451,8 +452,44 @@ void kvmppc_core_prepare_to_enter(struct kvm_vcpu *vcpu)
local_irq_disable();
 
kvmppc_set_exit_type(vcpu, EMULATED_MTMSRWE_EXITS);
-   kvmppc_core_check_exceptions(vcpu);
+   r = 1;
};
+
+   return r;
+}
+
+/*
+ * Common checks before entering the guest world.  Call with interrupts
+ * disabled.
+ *
+ * returns !0 if a signal is pending and check_signal is true
+ */
+static int kvmppc_prepare_to_enter(struct kvm_vcpu *vcpu, bool check_signal)
+{
+   int r = 0;
+
+   WARN_ON_ONCE(!irqs_disabled());
+   while (true) {
+   if (need_resched()) {
+   local_irq_enable();
+   cond_resched();
+   local_irq_disable();
+   continue;
+   }
+
+   if (kvmppc_core_prepare_to_enter(vcpu)) {
+   /* interrupts got enabled in between, so we
+  are back at square 1 */
+   continue;
+   }
+
+   if (check_signal  signal_pending(current))
+   r = 1;
+
+   break;
+   }
+
+   return r;
 }
 
 int kvmppc_vcpu_run(struct kvm_run *kvm_run, struct kvm_vcpu *vcpu)
@@ -470,10 +507,7 @@ int kvmppc_vcpu_run(struct kvm_run *kvm_run, struct 
kvm_vcpu *vcpu)
}
 
local_irq_disable();
-
-   kvmppc_core_prepare_to_enter(vcpu);
-
-   if (signal_pending(current)) {
+   if (kvmppc_prepare_to_enter(vcpu, true)) {
kvm_run-exit_reason = KVM_EXIT_INTR;
ret = -EINTR;
goto out;
@@ -598,25 +632,21 @@ int kvmppc_handle_exit(struct kvm_run *run, struct 
kvm_vcpu *vcpu,
 
switch (exit_nr) {
case BOOKE_INTERRUPT_MACHINE_CHECK:
-   kvm_resched(vcpu);
r = RESUME_GUEST;
break;
 
case BOOKE_INTERRUPT_EXTERNAL:
kvmppc_account_exit(vcpu, EXT_INTR_EXITS);
-   kvm_resched(vcpu);
r = RESUME_GUEST;
break;
 
case BOOKE_INTERRUPT_DECREMENTER:
kvmppc_account_exit(vcpu, DEC_EXITS);
-   kvm_resched(vcpu);