From: Auger Eric <eric.auger@redhat.com>
To: "Tian, Kevin" <kevin.tian@intel.com>,
Jacob Pan <jacob.jun.pan@linux.intel.com>
Cc: Yi L <yi.l.liu@linux.intel.com>,
Alex Williamson <alex.williamson@redhat.com>,
"Raj, Ashok" <ashok.raj@intel.com>,
David Woodhouse <dwmw2@infradead.org>,
LKML <linux-kernel@vger.kernel.org>,
"iommu@lists.linux-foundation.org"
<iommu@lists.linux-foundation.org>,
Jean-Philippe Brucker <jean-philippe@linaro.com>,
Jonathan Cameron <jic23@kernel.org>
Subject: Re: [PATCH v11 05/10] iommu/vt-d: Add bind guest PASID support
Date: Fri, 17 Apr 2020 09:46:55 +0200 [thread overview]
Message-ID: <2025736d-e7f2-d746-e030-e609b2f465e2@redhat.com> (raw)
In-Reply-To: <AADFC41AFE54684AB9EE6CBC0274A5D19D824106@SHSMSX104.ccr.corp.intel.com>
Hi Kevin,
On 4/17/20 4:45 AM, Tian, Kevin wrote:
>> From: Auger Eric
>> Sent: Thursday, April 16, 2020 6:43 PM
>>
> [...]
>>>>> + if (svm) {
>>>>> + /*
>>>>> + * If we found svm for the PASID, there must be at
>>>>> + * least one device bond, otherwise svm should be
>>>>> freed.
>>>>> + */
>>>>> + if (WARN_ON(list_empty(&svm->devs))) {
>>>>> + ret = -EINVAL;
>>>>> + goto out;
>>>>> + }
>>>>> +
>>>>> + for_each_svm_dev(sdev, svm, dev) {
>>>>> + /* In case of multiple sub-devices of the
>>>>> same pdev
>>>>> + * assigned, we should allow multiple bind
>>>>> calls with
>>>>> + * the same PASID and pdev.
>>>>> + */
>>>>> + sdev->users++;
>>>> What if this is not an mdev device. Is it also allowed?
>>> Yes. IOMMU and VT-d driver is not mdev aware. Here mdev is just an
>>> example of normal use case. You can bind the same PCI device (PF or
>>> SRIOV VF) more than once to the same PASID. Just need to unbind also.
>>
>> I don't get the point of binding a non mdev device several times with
>> the same PASID. Do you intend to allow that at userspace level or
>> prevent this from happening in VFIO?
>
> I feel it's better to prevent this from happening, otherwise VFIO also
> needs to track the bind count and do multiple unbinds at mm_exit.
> But it's not necessary to prevent it in VFIO. We can check here
> upon whether aux_domain is valid, and if not return -EBUSY.
Ah OK. So if we can detect the case here it is even better
Thanks
Eric
>
>>
>> Besides, the comment is a bit misleading as it gives the impression it
>> is only true for mdev and there is no associated check.
>
> Thanks
> Kevin
>
next prev parent reply other threads:[~2020-04-17 7:47 UTC|newest]
Thread overview: 33+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-04-03 18:42 [PATCH v11 00/10] Nested Shared Virtual Address (SVA) VT-d support Jacob Pan
2020-04-03 18:42 ` [PATCH v11 01/10] iommu/vt-d: Move domain helper to header Jacob Pan
2020-04-03 18:42 ` [PATCH v11 02/10] iommu/uapi: Define a mask for bind data Jacob Pan
2020-04-08 13:07 ` Joerg Roedel
2020-04-08 16:11 ` Jacob Pan
2020-04-03 18:42 ` [PATCH v11 03/10] iommu/vt-d: Use a helper function to skip agaw for SL Jacob Pan
2020-04-05 6:37 ` Auger Eric
2020-04-03 18:42 ` [PATCH v11 04/10] iommu/vt-d: Add nested translation helper function Jacob Pan
2020-04-08 13:33 ` Auger Eric
2020-04-03 18:42 ` [PATCH v11 05/10] iommu/vt-d: Add bind guest PASID support Jacob Pan
2020-04-09 7:41 ` Auger Eric
2020-04-10 19:45 ` Jacob Pan
2020-04-16 10:43 ` Auger Eric
2020-04-17 2:45 ` Tian, Kevin
2020-04-17 7:46 ` Auger Eric [this message]
2020-04-17 15:28 ` Jacob Pan
2020-04-17 23:46 ` Tian, Kevin
2020-04-27 17:28 ` Jacob Pan
2020-04-10 21:06 ` Jacob Pan
2020-04-16 10:46 ` Auger Eric
2020-04-03 18:42 ` [PATCH v11 06/10] iommu/vt-d: Support flushing more translation cache types Jacob Pan
2020-04-05 6:37 ` Auger Eric
2020-04-03 18:42 ` [PATCH v11 07/10] iommu/vt-d: Add svm/sva invalidate function Jacob Pan
2020-04-09 8:50 ` Auger Eric
2020-04-10 21:56 ` Jacob Pan
2020-04-16 10:59 ` Auger Eric
2020-04-17 16:14 ` Jacob Pan
2020-04-03 18:42 ` [PATCH v11 08/10] iommu/vt-d: Cache virtual command capability register Jacob Pan
2020-04-09 10:14 ` Auger Eric
2020-04-03 18:42 ` [PATCH v11 09/10] iommu/vt-d: Enlightened PASID allocation Jacob Pan
2020-04-03 18:42 ` [PATCH v11 10/10] iommu/vt-d: Add custom allocator for IOASID Jacob Pan
2020-04-09 10:31 ` Auger Eric
2020-04-05 8:28 ` [PATCH v11 00/10] Nested Shared Virtual Address (SVA) VT-d support Lu Baolu
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