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