From: Jan Beulich <jbeulich@suse.com>
To: "Roger Pau Monné" <roger.pau@citrix.com>
Cc: Andrew Cooper <andrew.cooper3@citrix.com>, Wei Liu <wl@xen.org>,
Jun Nakajima <jun.nakajima@intel.com>,
Kevin Tian <kevin.tian@intel.com>,
xen-devel@lists.xenproject.org
Subject: Re: [PATCH v3 09/11] x86/vpt: switch interrupt injection model
Date: Wed, 14 Apr 2021 16:05:20 +0200 [thread overview]
Message-ID: <4c65efcf-28fa-147d-8c82-7498cad19aeb@suse.com> (raw)
In-Reply-To: <YHbwII1L1O7AjJhl@Air-de-Roger>
On 14.04.2021 15:37, Roger Pau Monné wrote:
> On Wed, Apr 14, 2021 at 12:28:43PM +0200, Jan Beulich wrote:
>> On 31.03.2021 12:33, Roger Pau Monne wrote:
>>> ---
>>> xen/arch/x86/hvm/svm/intr.c | 3 -
>>> xen/arch/x86/hvm/vmx/intr.c | 59 ------
>>> xen/arch/x86/hvm/vpt.c | 334 ++++++++++++++--------------------
>>> xen/include/asm-x86/hvm/vpt.h | 5 +-
>>> 4 files changed, 143 insertions(+), 258 deletions(-)
>>
>> Nice.
>>
>>> @@ -285,189 +238,144 @@ static void pt_irq_fired(struct vcpu *v, struct periodic_time *pt)
>>> list_del(&pt->list);
>>> pt->on_list = false;
>>> pt->pending_intr_nr = 0;
>>> +
>>> + return;
>>> }
>>> - else if ( mode_is(v->domain, one_missed_tick_pending) ||
>>> - mode_is(v->domain, no_missed_ticks_pending) )
>>> +
>>> + if ( mode_is(v->domain, one_missed_tick_pending) ||
>>> + mode_is(v->domain, no_missed_ticks_pending) )
>>> {
>>> - pt->last_plt_gtime = hvm_get_guest_time(v);
>>> pt_process_missed_ticks(pt);
>>> pt->pending_intr_nr = 0; /* 'collapse' all missed ticks */
>>> + }
>>> + else if ( !pt->pending_intr_nr )
>>> + pt_process_missed_ticks(pt);
>>
>> Did you lose a -- here? I.e. does the condition mean to match ...
>>
>>> + if ( !pt->pending_intr_nr )
>>> set_timer(&pt->timer, pt->scheduled);
>>> +}
>>> +
>>> +static void pt_timer_fn(void *data)
>>> +{
>>> + struct periodic_time *pt = data;
>>> + struct vcpu *v;
>>> + time_cb *cb = NULL;
>>> + void *cb_priv;
>>> + unsigned int irq;
>>> +
>>> + pt_lock(pt);
>>> +
>>> + v = pt->vcpu;
>>> + irq = pt->irq;
>>> +
>>> + if ( inject_interrupt(pt) )
>>> + {
>>> + pt->scheduled += pt->period;
>>> + pt->do_not_freeze = 0;
>>> + cb = pt->cb;
>>> + cb_priv = pt->priv;
>>> }
>>> else
>>> {
>>> - pt->last_plt_gtime += pt->period;
>>> - if ( --pt->pending_intr_nr == 0 )
>>
>> ... this original code? Otherwise I can't see why the condition
>> guards a pt_process_missed_ticks() invocation.
>
> I think the logic here changed enough to not match anymore. Certainly
> pending_intr_nr shouldn't be decreased there, as pt_irq_fired is
> invoked after an EOI in this patch, instead of being invoked when a
> vpt related interrupt was injected. I think I should better rename
> pt_irq_fired to pt_irq_eoi and that would make it clearer.
But pt_process_missed_ticks() should be called only when a tick was
missed, shouldn't it? Or actually, looking at the function, I guess
I'm confused. Does your patch change the meaning of the field?
> FWIW, decreasing pending_intr_nr should only be done after an
> inject_interrupt call.
Then this line (which you leave in place)
pt->pending_intr_nr = 0; /* 'collapse' all missed ticks */
is contradicting the (new) model.
Jan
next prev parent reply other threads:[~2021-04-14 14:05 UTC|newest]
Thread overview: 51+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-03-31 10:32 [PATCH v3 00/11] x86/intr: introduce EOI callbacks and fix vPT Roger Pau Monne
2021-03-31 10:32 ` [PATCH v3 01/11] x86/hvm: drop vcpu parameter from vlapic EOI callbacks Roger Pau Monne
2021-03-31 16:02 ` Jan Beulich
2021-03-31 16:24 ` Andrew Cooper
2021-04-01 9:12 ` Roger Pau Monné
2021-04-01 11:06 ` Jan Beulich
2021-04-07 7:41 ` Roger Pau Monné
2021-04-07 8:19 ` Jan Beulich
2021-03-31 10:32 ` [PATCH v3 02/11] x86/hvm: drop domain parameter from vioapic/vpic " Roger Pau Monne
2021-03-31 16:04 ` Jan Beulich
2021-04-01 9:15 ` Roger Pau Monné
2021-04-01 9:28 ` Jan Beulich
2021-03-31 10:32 ` [PATCH v3 03/11] x86/vlapic: introduce an EOI callback mechanism Roger Pau Monne
2021-03-31 11:47 ` Andrew Cooper
2021-03-31 12:50 ` Roger Pau Monné
2021-04-07 14:55 ` Jan Beulich
2021-04-07 16:27 ` Roger Pau Monné
2021-04-08 6:20 ` Jan Beulich
2021-04-08 9:12 ` Roger Pau Monné
2021-04-08 10:49 ` Jan Beulich
2021-04-08 10:56 ` Roger Pau Monné
2021-03-31 10:32 ` [PATCH v3 04/11] x86/vmsi: use the newly introduced EOI callbacks Roger Pau Monne
2021-04-07 14:59 ` Jan Beulich
2021-03-31 10:32 ` [PATCH v3 05/11] x86/vioapic: switch to use the EOI callback mechanism Roger Pau Monne
2021-04-07 15:19 ` Jan Beulich
2021-04-07 16:46 ` Roger Pau Monné
2021-04-08 6:27 ` Jan Beulich
2021-04-08 8:59 ` Roger Pau Monné
2021-04-08 10:52 ` Jan Beulich
2021-03-31 10:32 ` [PATCH v3 06/11] x86/hvm: allowing registering EOI callbacks for GSIs Roger Pau Monne
2021-04-07 15:51 ` Jan Beulich
2021-04-07 17:08 ` Roger Pau Monné
2021-04-08 6:34 ` Jan Beulich
2021-04-15 16:04 ` Roger Pau Monné
2021-04-16 7:29 ` Jan Beulich
2021-04-19 8:31 ` Roger Pau Monné
2021-04-08 12:52 ` Roger Pau Monné
2021-04-08 14:31 ` Jan Beulich
2021-04-08 15:06 ` Roger Pau Monné
2021-03-31 10:32 ` [PATCH v3 07/11] x86/dpci: move code Roger Pau Monne
2021-03-31 10:33 ` [PATCH v3 08/11] x86/dpci: switch to use a GSI EOI callback Roger Pau Monne
2021-04-08 14:49 ` Jan Beulich
2021-04-08 15:23 ` Roger Pau Monné
2021-03-31 10:33 ` [PATCH v3 09/11] x86/vpt: switch interrupt injection model Roger Pau Monne
2021-04-14 10:28 ` Jan Beulich
2021-04-14 13:37 ` Roger Pau Monné
2021-04-14 14:05 ` Jan Beulich [this message]
2021-04-14 14:20 ` Roger Pau Monné
2021-03-31 10:33 ` [PATCH v3 10/11] x86/vpt: remove vPT timers per-vCPU lists Roger Pau Monne
2021-04-14 10:38 ` Jan Beulich
2021-03-31 10:33 ` [PATCH v3 11/11] x86/vpt: introduce a per-vPT lock Roger Pau Monne
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