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Date: Tue, 25 Jun 2013 13:33:03 +0800
From: DuanZhenzhong <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>
Subject: Re: [Xen-devel] [PATCH] xen: reuse the same pirq allocated when driver
load first time
Stefano Stabellini wrote:
> Trimming some of the people in CC
>
> On Mon, 24 Jun 2013, Zhenzhong Duan wrote:
>
>> 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.
>>
>
> Good to know
>
>
>> Could you have a look if there is something wrong in xen side of clearing the
>> mapping?
>>
>
> What I am saying is that the error you are getting:
>
> 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]
>
> cannot be caused by domain_pirq_to_emuirq(d, pirq) returning
> IRQ_UNBOUND.
> So, why are you getting this error? What is failing?
> I am ready to believe the problem is in Xen but Without understanding
> why you are getting the error it's hard to find a solution.
>
I found the reason, you are looking at xen-unstable, I was working with
4.1.30-OVM, it has patch of CVE-2012-4536 / XSA-21.
That patch set ret to -EINVAL initially. After remove that line, unmap
succeed.
But we still need below patch to let driver reload succeed everytime.
Without that, 1st reload failed, 2nd succeed, 3 failed, ...
diff -up --new-file ./hw/pt-msi.c.old1 ./hw/pt-msi.c
--- ./hw/pt-msi.c.old1 2013-06-26 01:36:08.000000000 +0800
+++ ./hw/pt-msi.c 2013-06-26 01:37:41.000000000 +0800
@@ -469,7 +469,7 @@ static void pci_msix_writel(void *opaque
return;
}
- if ( offset != 3 && entry->io_mem[offset] != val )
+ if ( offset != 3 && (entry->io_mem[offset] != val || entry->pirq ==
-1))
entry->flags = 1;
entry->io_mem[offset] = val;
zduan
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