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Date: Mon, 24 Jun 2013 15:19:26 +0800
From: Zhenzhong Duan <zhenzhong.duan@...cle.com>
To: Stefano Stabellini <stefano.stabellini@...citrix.com>
CC: Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>,
David Vrabel <david.vrabel@...rix.com>,
"xen-devel@...ts.xensource.com" <xen-devel@...ts.xensource.com>,
Feng Jin <joe.jin@...cle.com>,
Yuval Shaia <yuval.shaia@...cle.com>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
Chien Yen <chien.yen@...cle.com>,
Ingo Molnar <mingo@...hat.com>,
"H. Peter Anvin" <hpa@...or.com>,
Thomas Gleixner <tglx@...utronix.de>
Subject: Re: [Xen-devel] [PATCH] xen: reuse the same pirq allocated when driver
load first time
On 2013-06-20 22:21, Stefano Stabellini wrote:
> On Thu, 20 Jun 2013, Zhenzhong Duan wrote:
>> On 2013-06-05 20:50, Stefano Stabellini wrote:
>>> On Wed, 5 Jun 2013, Zhenzhong Duan wrote:
>>>> Stefano Stabellini wrote:
>>>>
>>>> On Tue, 21 May 2013, Stefano Stabellini wrote:
>>>>
>>>> On Tue, 21 May 2013, Konrad Rzeszutek Wilk wrote:
>>>>
>>>> Looking at the hypervisor code I couldn't see anything obviously wrong.
>>>>
>>>> I think the culprit is "physdev_unmap_pirq":
>>>>
>>>> if ( is_hvm_domain(d) )
>>>> {
>>>> spin_lock(&d->event_lock);
>>>> gdprintk(XENLOG_WARNING,"d%d, pirq: %d is %x %s, irq: %d\n",
>>>> d->domain_id, pirq, domain_pirq_to_emuirq(d, pirq),
>>>> domain_pirq_to_emuirq(d, pirq) == IRQ_UNBOUND ? "unbound" :
>>>> "",
>>>> domain_pirq_to_irq(d, pirq));
>>>> if
>>>> ( domain_pirq_to_emuirq(d, pirq) != IRQ_UNBOUND )
>>>> ret = unmap_domain_pirq_emuirq(d, pirq);
>>>> spin_unlock(&d->event_lock);
>>>> if ( domid == DOMID_SELF || ret )
>>>> goto free_domain;
>>>>
>>>> It always tells me unbound:
>>>>
>>>> (XEN) physdev.c:237:d14 14, pirq: 54 is ffffffff
>>>> (XEN) irq.c:1873:d14 14, nr_pirqs: 56
>>>> (XEN) physdev.c:237:d14 14, pirq: 53 is ffffffff
>>>> (XEN) irq.c:1873:d14 14, nr_pirqs: 56
>>>> (XEN) physdev.c:237:d14 14, pirq: 52 is ffffffff
>>>> (XEN) irq.c:1873:d14 14, nr_pirqs: 56
>>>> (XEN) physdev.c:237:d14 14, pirq: 51 is ffffffff
>>>> (XEN) irq.c:1873:d14 14, nr_pirqs: 56
>>>> (XEN) physdev.c:237:d14 14, pirq: 50 is ffffffff
>>>> (XEN) irq.c:1873:d14 14, nr_pirqs: 56
>>>> (a bit older debug code, so the 'unbound' does not show up here).
>>>>
>>>> Which means that the call to unmap_domain_pirq_emuirq does not happen.
>>>> The checks in unmap_domain_pirq_emuirq also look to be depend
>>>> on the code being IRQ_UNBOUND.
>>>>
>>>> In other words, all of that code looks to only clear things when
>>>> they are !IRQ_UNBOUND.
>>>>
>>>> But the other logic (IRQ_UNBOUND) looks to be missing a removal
>>>> in the radix tree:
>>>>
>>>> if ( emuirq != IRQ_PT )
>>>> radix_tree_delete(&d->arch.hvm_domain.emuirq_pirq, emuirq);
>>>> And
>>>> I think that is what is causing the leak - the radix tree
>>>> needs to be pruned? Or perhaps the allocate_pirq should check
>>>> the radix tree for IRQ_UNBOUND ones and re-use them?
>>>>
>>>> I think that you are looking in the wrong place.
>>>> The issue is that QEMU doesn't call pt_msi_disable in
>>>> pt_msgctrl_reg_write if (!val & PCI_MSI_FLAGS_ENABLE).
>>>>
>>>> The code above is correct as is because it is trying to handle emulated
>>>> IRQs and MSIs, not real passthrough MSIs. They latter are not added to
>>>> that radix tree, see physdev_hvm_map_pirq and physdev_map_pirq.
>>>>
>>>>
>>>> This patch fixes the issue, I have only tested MSI (MSI-X completely
>>>> untested).
>>>>
>>>>
>>>> diff --git a/hw/pass-through.c b/hw/pass-through.c
>>>> index 304c438..079e465 100644
>>>> --- a/hw/pass-through.c
>>>> +++ b/hw/pass-through.c
>>>> @@ -3866,7 +3866,11 @@ static int pt_msgctrl_reg_write(struct pt_dev
>>>> *ptdev,
>>>> ptdev->msi->flags |= PCI_MSI_FLAGS_ENABLE;
>>>> }
>>>> else
>>>> - ptdev->msi->flags &= ~PCI_MSI_FLAGS_ENABLE;
>>>> + {
>>>> + if (ptdev->msi->flags & PT_MSI_MAPPED) {
>>>> + pt_msi_disable(ptdev);
>>>> + }
>>>> + }
>>>> /* pass through MSI_ENABLE bit when no MSI-INTx translation */
>>>> if (!ptdev->msi_trans_en) {
>>>> @@ -4013,6 +4017,8 @@ static int pt_msixctrl_reg_write(struct pt_dev
>>>> *ptdev,
>>>> pt_disable_msi_translate(ptdev);
>>>> }
>>>> pt_msix_update(ptdev);
>>>> + } else if (!(*value & PCI_MSIX_ENABLE) && ptdev->msix->enabled) {
>>>> + pt_msix_delete(ptdev);
>>>>
>>>> Hi Stefano,
>>>> I made a test with this patch, os reboot when driver reload. If use
>>>> pt_msix_disable
>>>> instead of pt_msix_delete, driver could be reloaded.
>>>> But I still see some error in qemu.log and xen console. Seems four IRQs
>>>> are not freed
>>>> when unmap.
>>>> --------------first load---------------------------
>>>> pt_msix_update_one: pt_msix_update_one requested pirq = 103
>>>> pt_msix_update_one: Update msix entry 0 with pirq 67 gvec 0
>>>> pt_msix_update_one: pt_msix_update_one requested pirq = 102
>>>> pt_msix_update_one: Update msix entry 1 with pirq 66 gvec 0
>>>> pt_msix_update_one: pt_msix_update_one requested pirq = 101
>>>> pt_msix_update_one: Update msix entry 2 with pirq 65 gvec 0
>>>> pt_msix_update_one: pt_msix_update_one requested pirq = 100
>>>> pt_msix_update_one: Update msix entry 3 with pirq 64 gvec 0
>>>> ------------- first unload---------------------------
>>>> pt_msix_disable: Unbind msix with pirq 67, gvec 0
>>>> pt_msix_disable: Unmap msix with pirq 67
>>>> pt_msix_disable: Error: Unmapping of MSI-X failed. [00:04.0]
>>>> pt_msix_disable: Unbind msix with pirq 66, gvec 0
>>>> pt_msix_disable: Unmap msix with pirq 66
>>>> pt_msix_disable: Error: Unmapping of MSI-X failed. [00:04.0]
>>>> pt_msix_disable: Unbind msix with pirq 65, gvec 0
>>>> pt_msix_disable: Unmap msix with pirq 65
>>>> pt_msix_disable: Error: Unmapping of MSI-X failed. [00:04.0]
>>>> pt_msix_disable: Unbind msix with pirq 64, gvec 0
>>>> pt_msix_disable: Unmap msix with pirq 64
>>>> pt_msix_disable: Error: Unmapping of MSI-X failed. [00:04.0]
>>> Can you add some printks in Xen (the hypercall name is
>>> PHYSDEVOP_unmap_pirq) to figure out exactly why they are failing?
>> Did some test, domain_pirq_to_emuirq(d, unmap->pirq) = IRQ_UNBOUND in
>> physdev_unmap_pirq.
> That means that Linux didn't call irq_enable on the MSI-X in question:
>
> irq_enable -> __startup_pirq -> EVTCHNOP_bind_pirq
>
> EVTCHNOP_bind_pirq is implemented by evtchn_bind_pirq in Xen and calls
> map_domain_emuirq_pirq, so domain_pirq_to_emuirq(d, unmap->pirq) should
> be IRQ_PT.
>
> I don't know if that's a normal condition, but in any case it should
> not create any problems to physdev_unmap_pirq, in fact the folloing
> check:
>
> if ( domid == DOMID_SELF || ret )
> goto free_domain;
>
> should fail so Xen should continue and execute unmap_domain_pirq. That's
> what we want.
From linux side, request_irq-> request_threaded_irq-> __setup_irq->
irq_startup-> startup_pirq-> EVTCHNOP_bind_pirq
If irq_enable isn't called, how does the driver receive interrupt, I did
see four interrupts in /proc/interrupt and driver works ok.
Could you have a look if there is something wrong in xen side of
clearing the mapping?
zduan
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