Re: [PATCH] powerpc/xive: store server for masked interrupt in kvmppc_xive_set_xive()

[Laurent Vivier]

On 05/12/2017 04:05, Paul Mackerras wrote:
> On Fri, Nov 24, 2017 at 07:38:13AM +1100, Benjamin Herrenschmidt wrote:
>> On Thu, 2017-11-23 at 10:06 +0100, Laurent Vivier wrote:
>>> This is needed to map kvmppc_xive_set_xive() behavior
>>> to kvmppc_xics_set_xive().
>>>
>>> As we store the server, kvmppc_xive_get_xive() can return
>>> the good value and we can also allow kvmppc_xive_int_on().
>>>
>>> Signed-off-by: Laurent Vivier 
>>> ---
>>>  arch/powerpc/kvm/book3s_xive.c | 20 
>>>  1 file changed, 8 insertions(+), 12 deletions(-)
>>>
>>> diff --git a/arch/powerpc/kvm/book3s_xive.c b/arch/powerpc/kvm/book3s_xive.c
>>> index bf457843e032..2781b8733038 100644
>>> --- a/arch/powerpc/kvm/book3s_xive.c
>>> +++ b/arch/powerpc/kvm/book3s_xive.c
>>> @@ -584,10 +584,14 @@ int kvmppc_xive_set_xive(struct kvm *kvm, u32 irq, 
>>> u32 server,
>>>  *   we could initialize interrupts with valid default
>>>  */
>>>  
>>> -   if (new_act_prio != MASKED &&
>>> -   (state->act_server != server ||
>>> -state->act_priority != new_act_prio))
>>> -   rc = xive_target_interrupt(kvm, state, server, new_act_prio);
>>> +   if (state->act_server != server ||
>>> +   state->act_priority != new_act_prio) {
>>> +   if (new_act_prio != MASKED)
>>> +   rc = xive_target_interrupt(kvm, state, server,
>>> +  new_act_prio);
>>> +   if (!rc)
>>> +   state->act_server = server;
>>> +   }
>>
>> That leads to another problem with this code. My current implementation
>> is such that is a target queue is full, it will pick another target.
>> But here, we still update act_server to the passed-in server and
>> not the actual target...
> 
> So does that amount to a NAK?
> 
>>> /*
>>>  * Perform the final unmasking of the interrupt source
>>> @@ -646,14 +650,6 @@ int kvmppc_xive_int_on(struct kvm *kvm, u32 irq)
>>>  
>>> pr_devel("int_on(irq=0x%x)\n", irq);
>>>  
>>> -   /*
>>> -* Check if interrupt was not targetted
>>> -*/
>>> -   if (state->act_priority == MASKED) {
>>> -   pr_devel("int_on on untargetted interrupt\n");
>>> -   return -EINVAL;
>>> -   }
>>> -
>>
>> So my thinking here was that act_priority was never going to be MASKED
>> except if the interrupt had never been targetted anywhere at machine
>> startup time. Thus if act_priority is masked, the act_server field
>> cannot be trusted.
>>
>>> /* If saved_priority is 0xff, do nothing */
>>> if (state->saved_priority == MASKED)
>>> return 0;
> 
> How do you think this should be fixed?
> 
> Laurent, are you reworking the patch at the moment?

Not for the moment.

The easy way is to forbid to set interrupt value to the MASKED one with
xive_set_xive. I think it's allowed by the specs.

I've got another bug in the XICS emulation: when we migrate a guest
under stress, the pending interrupt is lost and the guest hangs on the
destination side. I'm trying to understand why.

Thanks,
Laurent

Re: [PATCH] powerpc/xive: store server for masked interrupt in kvmppc_xive_set_xive()

[Laurent Vivier]

On 05/12/2017 04:05, Paul Mackerras wrote:
> On Fri, Nov 24, 2017 at 07:38:13AM +1100, Benjamin Herrenschmidt wrote:
>> On Thu, 2017-11-23 at 10:06 +0100, Laurent Vivier wrote:
>>> This is needed to map kvmppc_xive_set_xive() behavior
>>> to kvmppc_xics_set_xive().
>>>
>>> As we store the server, kvmppc_xive_get_xive() can return
>>> the good value and we can also allow kvmppc_xive_int_on().
>>>
>>> Signed-off-by: Laurent Vivier 
>>> ---
>>>  arch/powerpc/kvm/book3s_xive.c | 20 
>>>  1 file changed, 8 insertions(+), 12 deletions(-)
>>>
>>> diff --git a/arch/powerpc/kvm/book3s_xive.c b/arch/powerpc/kvm/book3s_xive.c
>>> index bf457843e032..2781b8733038 100644
>>> --- a/arch/powerpc/kvm/book3s_xive.c
>>> +++ b/arch/powerpc/kvm/book3s_xive.c
>>> @@ -584,10 +584,14 @@ int kvmppc_xive_set_xive(struct kvm *kvm, u32 irq, 
>>> u32 server,
>>>  *   we could initialize interrupts with valid default
>>>  */
>>>  
>>> -   if (new_act_prio != MASKED &&
>>> -   (state->act_server != server ||
>>> -state->act_priority != new_act_prio))
>>> -   rc = xive_target_interrupt(kvm, state, server, new_act_prio);
>>> +   if (state->act_server != server ||
>>> +   state->act_priority != new_act_prio) {
>>> +   if (new_act_prio != MASKED)
>>> +   rc = xive_target_interrupt(kvm, state, server,
>>> +  new_act_prio);
>>> +   if (!rc)
>>> +   state->act_server = server;
>>> +   }
>>
>> That leads to another problem with this code. My current implementation
>> is such that is a target queue is full, it will pick another target.
>> But here, we still update act_server to the passed-in server and
>> not the actual target...
> 
> So does that amount to a NAK?
> 
>>> /*
>>>  * Perform the final unmasking of the interrupt source
>>> @@ -646,14 +650,6 @@ int kvmppc_xive_int_on(struct kvm *kvm, u32 irq)
>>>  
>>> pr_devel("int_on(irq=0x%x)\n", irq);
>>>  
>>> -   /*
>>> -* Check if interrupt was not targetted
>>> -*/
>>> -   if (state->act_priority == MASKED) {
>>> -   pr_devel("int_on on untargetted interrupt\n");
>>> -   return -EINVAL;
>>> -   }
>>> -
>>
>> So my thinking here was that act_priority was never going to be MASKED
>> except if the interrupt had never been targetted anywhere at machine
>> startup time. Thus if act_priority is masked, the act_server field
>> cannot be trusted.
>>
>>> /* If saved_priority is 0xff, do nothing */
>>> if (state->saved_priority == MASKED)
>>> return 0;
> 
> How do you think this should be fixed?
> 
> Laurent, are you reworking the patch at the moment?

Not for the moment.

The easy way is to forbid to set interrupt value to the MASKED one with
xive_set_xive. I think it's allowed by the specs.

I've got another bug in the XICS emulation: when we migrate a guest
under stress, the pending interrupt is lost and the guest hangs on the
destination side. I'm trying to understand why.

Thanks,
Laurent

Re: [PATCH] powerpc/xive: store server for masked interrupt in kvmppc_xive_set_xive()

[Paul Mackerras]

On Fri, Nov 24, 2017 at 07:38:13AM +1100, Benjamin Herrenschmidt wrote:
> On Thu, 2017-11-23 at 10:06 +0100, Laurent Vivier wrote:
> > This is needed to map kvmppc_xive_set_xive() behavior
> > to kvmppc_xics_set_xive().
> > 
> > As we store the server, kvmppc_xive_get_xive() can return
> > the good value and we can also allow kvmppc_xive_int_on().
> > 
> > Signed-off-by: Laurent Vivier 
> > ---
> >  arch/powerpc/kvm/book3s_xive.c | 20 
> >  1 file changed, 8 insertions(+), 12 deletions(-)
> > 
> > diff --git a/arch/powerpc/kvm/book3s_xive.c b/arch/powerpc/kvm/book3s_xive.c
> > index bf457843e032..2781b8733038 100644
> > --- a/arch/powerpc/kvm/book3s_xive.c
> > +++ b/arch/powerpc/kvm/book3s_xive.c
> > @@ -584,10 +584,14 @@ int kvmppc_xive_set_xive(struct kvm *kvm, u32 irq, 
> > u32 server,
> >  *   we could initialize interrupts with valid default
> >  */
> >  
> > -   if (new_act_prio != MASKED &&
> > -   (state->act_server != server ||
> > -state->act_priority != new_act_prio))
> > -   rc = xive_target_interrupt(kvm, state, server, new_act_prio);
> > +   if (state->act_server != server ||
> > +   state->act_priority != new_act_prio) {
> > +   if (new_act_prio != MASKED)
> > +   rc = xive_target_interrupt(kvm, state, server,
> > +  new_act_prio);
> > +   if (!rc)
> > +   state->act_server = server;
> > +   }
> 
> That leads to another problem with this code. My current implementation
> is such that is a target queue is full, it will pick another target.
> But here, we still update act_server to the passed-in server and
> not the actual target...

So does that amount to a NAK?

> > /*
> >  * Perform the final unmasking of the interrupt source
> > @@ -646,14 +650,6 @@ int kvmppc_xive_int_on(struct kvm *kvm, u32 irq)
> >  
> > pr_devel("int_on(irq=0x%x)\n", irq);
> >  
> > -   /*
> > -* Check if interrupt was not targetted
> > -*/
> > -   if (state->act_priority == MASKED) {
> > -   pr_devel("int_on on untargetted interrupt\n");
> > -   return -EINVAL;
> > -   }
> > -
> 
> So my thinking here was that act_priority was never going to be MASKED
> except if the interrupt had never been targetted anywhere at machine
> startup time. Thus if act_priority is masked, the act_server field
> cannot be trusted.
> 
> > /* If saved_priority is 0xff, do nothing */
> > if (state->saved_priority == MASKED)
> > return 0;

How do you think this should be fixed?

Laurent, are you reworking the patch at the moment?

Paul.

Re: [PATCH] powerpc/xive: store server for masked interrupt in kvmppc_xive_set_xive()

[Paul Mackerras]

On Fri, Nov 24, 2017 at 07:38:13AM +1100, Benjamin Herrenschmidt wrote:
> On Thu, 2017-11-23 at 10:06 +0100, Laurent Vivier wrote:
> > This is needed to map kvmppc_xive_set_xive() behavior
> > to kvmppc_xics_set_xive().
> > 
> > As we store the server, kvmppc_xive_get_xive() can return
> > the good value and we can also allow kvmppc_xive_int_on().
> > 
> > Signed-off-by: Laurent Vivier 
> > ---
> >  arch/powerpc/kvm/book3s_xive.c | 20 
> >  1 file changed, 8 insertions(+), 12 deletions(-)
> > 
> > diff --git a/arch/powerpc/kvm/book3s_xive.c b/arch/powerpc/kvm/book3s_xive.c
> > index bf457843e032..2781b8733038 100644
> > --- a/arch/powerpc/kvm/book3s_xive.c
> > +++ b/arch/powerpc/kvm/book3s_xive.c
> > @@ -584,10 +584,14 @@ int kvmppc_xive_set_xive(struct kvm *kvm, u32 irq, 
> > u32 server,
> >  *   we could initialize interrupts with valid default
> >  */
> >  
> > -   if (new_act_prio != MASKED &&
> > -   (state->act_server != server ||
> > -state->act_priority != new_act_prio))
> > -   rc = xive_target_interrupt(kvm, state, server, new_act_prio);
> > +   if (state->act_server != server ||
> > +   state->act_priority != new_act_prio) {
> > +   if (new_act_prio != MASKED)
> > +   rc = xive_target_interrupt(kvm, state, server,
> > +  new_act_prio);
> > +   if (!rc)
> > +   state->act_server = server;
> > +   }
> 
> That leads to another problem with this code. My current implementation
> is such that is a target queue is full, it will pick another target.
> But here, we still update act_server to the passed-in server and
> not the actual target...

So does that amount to a NAK?

> > /*
> >  * Perform the final unmasking of the interrupt source
> > @@ -646,14 +650,6 @@ int kvmppc_xive_int_on(struct kvm *kvm, u32 irq)
> >  
> > pr_devel("int_on(irq=0x%x)\n", irq);
> >  
> > -   /*
> > -* Check if interrupt was not targetted
> > -*/
> > -   if (state->act_priority == MASKED) {
> > -   pr_devel("int_on on untargetted interrupt\n");
> > -   return -EINVAL;
> > -   }
> > -
> 
> So my thinking here was that act_priority was never going to be MASKED
> except if the interrupt had never been targetted anywhere at machine
> startup time. Thus if act_priority is masked, the act_server field
> cannot be trusted.
> 
> > /* If saved_priority is 0xff, do nothing */
> > if (state->saved_priority == MASKED)
> > return 0;

How do you think this should be fixed?

Laurent, are you reworking the patch at the moment?

Paul.

Re: [PATCH] powerpc/xive: store server for masked interrupt in kvmppc_xive_set_xive()

[Benjamin Herrenschmidt]

On Thu, 2017-11-23 at 10:06 +0100, Laurent Vivier wrote:
> This is needed to map kvmppc_xive_set_xive() behavior
> to kvmppc_xics_set_xive().
> 
> As we store the server, kvmppc_xive_get_xive() can return
> the good value and we can also allow kvmppc_xive_int_on().
> 
> Signed-off-by: Laurent Vivier 
> ---
>  arch/powerpc/kvm/book3s_xive.c | 20 
>  1 file changed, 8 insertions(+), 12 deletions(-)
> 
> diff --git a/arch/powerpc/kvm/book3s_xive.c b/arch/powerpc/kvm/book3s_xive.c
> index bf457843e032..2781b8733038 100644
> --- a/arch/powerpc/kvm/book3s_xive.c
> +++ b/arch/powerpc/kvm/book3s_xive.c
> @@ -584,10 +584,14 @@ int kvmppc_xive_set_xive(struct kvm *kvm, u32 irq, u32 
> server,
>*   we could initialize interrupts with valid default
>*/
>  
> - if (new_act_prio != MASKED &&
> - (state->act_server != server ||
> -  state->act_priority != new_act_prio))
> - rc = xive_target_interrupt(kvm, state, server, new_act_prio);
> + if (state->act_server != server ||
> + state->act_priority != new_act_prio) {
> + if (new_act_prio != MASKED)
> + rc = xive_target_interrupt(kvm, state, server,
> +new_act_prio);
> + if (!rc)
> + state->act_server = server;
> + }

That leads to another problem with this code. My current implementation
is such that is a target queue is full, it will pick another target.
But here, we still update act_server to the passed-in server and
not the actual target...

>   /*
>* Perform the final unmasking of the interrupt source
> @@ -646,14 +650,6 @@ int kvmppc_xive_int_on(struct kvm *kvm, u32 irq)
>  
>   pr_devel("int_on(irq=0x%x)\n", irq);
>  
> - /*
> -  * Check if interrupt was not targetted
> -  */
> - if (state->act_priority == MASKED) {
> - pr_devel("int_on on untargetted interrupt\n");
> - return -EINVAL;
> - }
> -

So my thinking here was that act_priority was never going to be MASKED
except if the interrupt had never been targetted anywhere at machine
startup time. Thus if act_priority is masked, the act_server field
cannot be trusted.

>   /* If saved_priority is 0xff, do nothing */
>   if (state->saved_priority == MASKED)
>   return 0;

Re: [PATCH] powerpc/xive: store server for masked interrupt in kvmppc_xive_set_xive()

[Benjamin Herrenschmidt]

On Thu, 2017-11-23 at 10:06 +0100, Laurent Vivier wrote:
> This is needed to map kvmppc_xive_set_xive() behavior
> to kvmppc_xics_set_xive().
> 
> As we store the server, kvmppc_xive_get_xive() can return
> the good value and we can also allow kvmppc_xive_int_on().
> 
> Signed-off-by: Laurent Vivier 
> ---
>  arch/powerpc/kvm/book3s_xive.c | 20 
>  1 file changed, 8 insertions(+), 12 deletions(-)
> 
> diff --git a/arch/powerpc/kvm/book3s_xive.c b/arch/powerpc/kvm/book3s_xive.c
> index bf457843e032..2781b8733038 100644
> --- a/arch/powerpc/kvm/book3s_xive.c
> +++ b/arch/powerpc/kvm/book3s_xive.c
> @@ -584,10 +584,14 @@ int kvmppc_xive_set_xive(struct kvm *kvm, u32 irq, u32 
> server,
>*   we could initialize interrupts with valid default
>*/
>  
> - if (new_act_prio != MASKED &&
> - (state->act_server != server ||
> -  state->act_priority != new_act_prio))
> - rc = xive_target_interrupt(kvm, state, server, new_act_prio);
> + if (state->act_server != server ||
> + state->act_priority != new_act_prio) {
> + if (new_act_prio != MASKED)
> + rc = xive_target_interrupt(kvm, state, server,
> +new_act_prio);
> + if (!rc)
> + state->act_server = server;
> + }

That leads to another problem with this code. My current implementation
is such that is a target queue is full, it will pick another target.
But here, we still update act_server to the passed-in server and
not the actual target...

>   /*
>* Perform the final unmasking of the interrupt source
> @@ -646,14 +650,6 @@ int kvmppc_xive_int_on(struct kvm *kvm, u32 irq)
>  
>   pr_devel("int_on(irq=0x%x)\n", irq);
>  
> - /*
> -  * Check if interrupt was not targetted
> -  */
> - if (state->act_priority == MASKED) {
> - pr_devel("int_on on untargetted interrupt\n");
> - return -EINVAL;
> - }
> -

So my thinking here was that act_priority was never going to be MASKED
except if the interrupt had never been targetted anywhere at machine
startup time. Thus if act_priority is masked, the act_server field
cannot be trusted.

>   /* If saved_priority is 0xff, do nothing */
>   if (state->saved_priority == MASKED)
>   return 0;

[PATCH] powerpc/xive: store server for masked interrupt in kvmppc_xive_set_xive()

[Laurent Vivier]

This is needed to map kvmppc_xive_set_xive() behavior
to kvmppc_xics_set_xive().

As we store the server, kvmppc_xive_get_xive() can return
the good value and we can also allow kvmppc_xive_int_on().

Signed-off-by: Laurent Vivier 
---
 arch/powerpc/kvm/book3s_xive.c | 20 
 1 file changed, 8 insertions(+), 12 deletions(-)

diff --git a/arch/powerpc/kvm/book3s_xive.c b/arch/powerpc/kvm/book3s_xive.c
index bf457843e032..2781b8733038 100644
--- a/arch/powerpc/kvm/book3s_xive.c
+++ b/arch/powerpc/kvm/book3s_xive.c
@@ -584,10 +584,14 @@ int kvmppc_xive_set_xive(struct kvm *kvm, u32 irq, u32 
server,
 *   we could initialize interrupts with valid default
 */
 
-   if (new_act_prio != MASKED &&
-   (state->act_server != server ||
-state->act_priority != new_act_prio))
-   rc = xive_target_interrupt(kvm, state, server, new_act_prio);
+   if (state->act_server != server ||
+   state->act_priority != new_act_prio) {
+   if (new_act_prio != MASKED)
+   rc = xive_target_interrupt(kvm, state, server,
+  new_act_prio);
+   if (!rc)
+   state->act_server = server;
+   }
 
/*
 * Perform the final unmasking of the interrupt source
@@ -646,14 +650,6 @@ int kvmppc_xive_int_on(struct kvm *kvm, u32 irq)
 
pr_devel("int_on(irq=0x%x)\n", irq);
 
-   /*
-* Check if interrupt was not targetted
-*/
-   if (state->act_priority == MASKED) {
-   pr_devel("int_on on untargetted interrupt\n");
-   return -EINVAL;
-   }
-
/* If saved_priority is 0xff, do nothing */
if (state->saved_priority == MASKED)
return 0;
-- 
2.13.6

[PATCH] powerpc/xive: store server for masked interrupt in kvmppc_xive_set_xive()

[Laurent Vivier]

This is needed to map kvmppc_xive_set_xive() behavior
to kvmppc_xics_set_xive().

As we store the server, kvmppc_xive_get_xive() can return
the good value and we can also allow kvmppc_xive_int_on().

Signed-off-by: Laurent Vivier 
---
 arch/powerpc/kvm/book3s_xive.c | 20 
 1 file changed, 8 insertions(+), 12 deletions(-)

diff --git a/arch/powerpc/kvm/book3s_xive.c b/arch/powerpc/kvm/book3s_xive.c
index bf457843e032..2781b8733038 100644
--- a/arch/powerpc/kvm/book3s_xive.c
+++ b/arch/powerpc/kvm/book3s_xive.c
@@ -584,10 +584,14 @@ int kvmppc_xive_set_xive(struct kvm *kvm, u32 irq, u32 
server,
 *   we could initialize interrupts with valid default
 */
 
-   if (new_act_prio != MASKED &&
-   (state->act_server != server ||
-state->act_priority != new_act_prio))
-   rc = xive_target_interrupt(kvm, state, server, new_act_prio);
+   if (state->act_server != server ||
+   state->act_priority != new_act_prio) {
+   if (new_act_prio != MASKED)
+   rc = xive_target_interrupt(kvm, state, server,
+  new_act_prio);
+   if (!rc)
+   state->act_server = server;
+   }
 
/*
 * Perform the final unmasking of the interrupt source
@@ -646,14 +650,6 @@ int kvmppc_xive_int_on(struct kvm *kvm, u32 irq)
 
pr_devel("int_on(irq=0x%x)\n", irq);
 
-   /*
-* Check if interrupt was not targetted
-*/
-   if (state->act_priority == MASKED) {
-   pr_devel("int_on on untargetted interrupt\n");
-   return -EINVAL;
-   }
-
/* If saved_priority is 0xff, do nothing */
if (state->saved_priority == MASKED)
return 0;
-- 
2.13.6