[PATCH] RFC: Create kvm_arch_vcpu_runnable() function

[PATCH] RFC: Create kvm_arch_vcpu_runnable() function

[Hollis Blanchard]

Signed-off-by: Hollis Blanchard <hollisb-r/Jw6+rmf7HQT0dZR+AlfA@public.gmane.org>
---
vcpu->mp_state looks like an arch-specific field, so what do we think about
this patch? It might make sense to fold the kvm_cpu_has_interrupt() test inside
kvm_arch_vcpu_runnable() as well.

2 files changed, 9 insertions(+), 3 deletions(-)
drivers/kvm/kvm_main.c |    3 +--
drivers/kvm/x86.h      |    9 ++++++++-


diff --git a/drivers/kvm/kvm_main.c b/drivers/kvm/kvm_main.c
--- a/drivers/kvm/kvm_main.c
+++ b/drivers/kvm/kvm_main.c
@@ -643,8 +643,7 @@ void kvm_vcpu_block(struct kvm_vcpu *vcp
 	 */
 	while (!kvm_cpu_has_interrupt(vcpu)
 	       && !signal_pending(current)
-	       && vcpu->mp_state != VCPU_MP_STATE_RUNNABLE
-	       && vcpu->mp_state != VCPU_MP_STATE_SIPI_RECEIVED) {
+	       && !kvm_arch_vcpu_runnable(vcpu)) {
 		set_current_state(TASK_INTERRUPTIBLE);
 		vcpu_put(vcpu);
 		schedule();
diff --git a/drivers/kvm/x86.h b/drivers/kvm/x86.h
--- a/drivers/kvm/x86.h
+++ b/drivers/kvm/x86.h
@@ -471,4 +471,11 @@ static inline u32 get_rdx_init_val(void)
 #define TSS_IOPB_SIZE (65536 / 8)
 #define TSS_REDIRECTION_SIZE (256 / 8)
 #define RMODE_TSS_SIZE (TSS_BASE_SIZE + TSS_REDIRECTION_SIZE + TSS_IOPB_SIZE + 1)
-#endif
+
+static inline int kvm_arch_vcpu_runnable(struct kvm_vcpu *vcpu)
+{
+	return vcpu->mp_state == VCPU_MP_STATE_RUNNABLE
+	       || vcpu->mp_state == VCPU_MP_STATE_SIPI_RECEIVED;
+}
+
+#endif

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Re: [PATCH] RFC: Create kvm_arch_vcpu_runnable() function

[Carsten Otte]

Hollis Blanchard wrote:
> Signed-off-by: Hollis Blanchard <hollisb-r/Jw6+rmf7HQT0dZR+AlfA@public.gmane.org>
Acked-by: Carsten Otte <cotte-tA70FqPdS9bQT0dZR+AlfA@public.gmane.org>

We'll need this too on big iron.

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Re: [PATCH] RFC: Create kvm_arch_vcpu_runnable() function

[Avi Kivity]

Carsten Otte wrote:
> Hollis Blanchard wrote:
>> Signed-off-by: Hollis Blanchard <hollisb-r/Jw6+rmf7HQT0dZR+AlfA@public.gmane.org>
> Acked-by: Carsten Otte <cotte-tA70FqPdS9bQT0dZR+AlfA@public.gmane.org>
>
> We'll need this too on big iron.

What about merging kvm_cpu_has_interrupt() into _runnable()?

My feeling is that we can keep it separated.

-- 
error compiling committee.c: too many arguments to function


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Re: [PATCH] RFC: Create kvm_arch_vcpu_runnable() function

[Carsten Otte]

Avi Kivity wrote:
> What about merging kvm_cpu_has_interrupt() into _runnable()?
> 
> My feeling is that we can keep it separated.
On s390 there is a difference between has_interrupt and not runnable: 
CPUs can be in stopped state, and they can be in enabled wait (enabled 
for interrupts, similar to hlt state on x86) or in disabled wait 
state. All those states indicate that the CPU is not runnable.
Interrupts on the other hand are typically floating between all 
virtual CPUs and can be accepted by running CPUs only (that is either 
running, or in enabled wait).

I agree that we should keep it seperated.

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Re: [PATCH] RFC: Create kvm_arch_vcpu_runnable() function

[Avi Kivity]

Carsten Otte wrote:
> Avi Kivity wrote:
>   
>> What about merging kvm_cpu_has_interrupt() into _runnable()?
>>
>> My feeling is that we can keep it separated.
>>     
> On s390 there is a difference between has_interrupt and not runnable: 
> CPUs can be in stopped state, and they can be in enabled wait (enabled 
> for interrupts, similar to hlt state on x86) or in disabled wait 
> state. All those states indicate that the CPU is not runnable.
> Interrupts on the other hand are typically floating between all 
> virtual CPUs and can be accepted by running CPUs only (that is either 
> running, or in enabled wait).
>
> I agree that we should keep it seperated.
>   

On x86, running hlt with interrupts disabled is similar to your disabled 
wait.  Interrupts in general are directed towards a specific cpu, though 
older processors supported round-robin or priority based dispatching.  
With extensive caches this is a performance loss, so the feature is not 
missed.

Thanks for the clarification.

-- 
error compiling committee.c: too many arguments to function


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Re: [PATCH] RFC: Create kvm_arch_vcpu_runnable() function

[Avi Kivity]

Hollis Blanchard wrote:
> Signed-off-by: Hollis Blanchard <hollisb-r/Jw6+rmf7HQT0dZR+AlfA@public.gmane.org>
>   

Applied, thanks.  Note that there is free advertising space between the 
summary and the signoff that you can use to explain the change.


-- 
error compiling committee.c: too many arguments to function


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