From: "Liu, Yi L" <yi.l.liu@intel.com>
To: "Tian, Kevin" <kevin.tian@intel.com>,
"alex.williamson@redhat.com" <alex.williamson@redhat.com>,
"eric.auger@redhat.com" <eric.auger@redhat.com>
Cc: "jean-philippe@linaro.org" <jean-philippe@linaro.org>,
"Raj, Ashok" <ashok.raj@intel.com>,
"kvm@vger.kernel.org" <kvm@vger.kernel.org>,
"Tian, Jun J" <jun.j.tian@intel.com>,
"iommu@lists.linux-foundation.org"
<iommu@lists.linux-foundation.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"Sun, Yi Y" <yi.y.sun@intel.com>, "Wu, Hao" <hao.wu@intel.com>
Subject: RE: [PATCH v1 1/8] vfio: Add VFIO_IOMMU_PASID_REQUEST(alloc/free)
Date: Wed, 1 Apr 2020 05:48:52 +0000 [thread overview]
Message-ID: <A2975661238FB949B60364EF0F2C25743A21C370@SHSMSX104.ccr.corp.intel.com> (raw)
In-Reply-To: <AADFC41AFE54684AB9EE6CBC0274A5D19D803B6A@SHSMSX104.ccr.corp.intel.com>
> From: Tian, Kevin <kevin.tian@intel.com>
> Sent: Wednesday, April 1, 2020 1:43 PM
> To: Liu, Yi L <yi.l.liu@intel.com>; alex.williamson@redhat.com;
> Subject: RE: [PATCH v1 1/8] vfio: Add VFIO_IOMMU_PASID_REQUEST(alloc/free)
>
> > From: Liu, Yi L <yi.l.liu@intel.com>
> > Sent: Tuesday, March 31, 2020 9:22 PM
> >
> > > From: Tian, Kevin <kevin.tian@intel.com>
> > > Sent: Tuesday, March 31, 2020 1:41 PM
> > > To: Liu, Yi L <yi.l.liu@intel.com>; alex.williamson@redhat.com;
> > > eric.auger@redhat.com
> > > Subject: RE: [PATCH v1 1/8] vfio: Add
> > VFIO_IOMMU_PASID_REQUEST(alloc/free)
> > >
> > > > From: Liu, Yi L <yi.l.liu@intel.com>
> > > > Sent: Monday, March 30, 2020 10:37 PM
> > > >
> > > > > From: Tian, Kevin <kevin.tian@intel.com>
> > > > > Sent: Monday, March 30, 2020 4:32 PM
> > > > > To: Liu, Yi L <yi.l.liu@intel.com>; alex.williamson@redhat.com;
> > > > > Subject: RE: [PATCH v1 1/8] vfio: Add
> > > > VFIO_IOMMU_PASID_REQUEST(alloc/free)
> > > > >
> > > > > > From: Liu, Yi L <yi.l.liu@intel.com>
> > > > > > Sent: Sunday, March 22, 2020 8:32 PM
> > > > > >
> > > > > > From: Liu Yi L <yi.l.liu@intel.com>
> > > > > >
> > > > > > For a long time, devices have only one DMA address space from
> > > > > > platform IOMMU's point of view. This is true for both bare
> > > > > > metal and directed- access in virtualization environment.
> > > > > > Reason is the source ID of DMA in PCIe are BDF (bus/dev/fnc
> > > > > > ID), which results in only device granularity
[...]
> > >
> > > >
> > > > > > +
> > > > > > + switch (req.flags & VFIO_PASID_REQUEST_MASK) {
> > > > > > + case VFIO_IOMMU_PASID_ALLOC:
> > > > > > + {
> > > > > > + int ret = 0, result;
> > > > > > +
> > > > > > + result =
> > vfio_iommu_type1_pasid_alloc(iommu,
> > > > > > +
> > req.alloc_pasid.min,
> > > > > > +
> > req.alloc_pasid.max);
> > > > > > + if (result > 0) {
> > > > > > + offset = offsetof(
> > > > > > + struct
> > > > > > vfio_iommu_type1_pasid_request,
> > > > > > + alloc_pasid.result);
> > > > > > + ret = copy_to_user(
> > > > > > + (void __user *) (arg +
> > offset),
> > > > > > + &result, sizeof(result));
> > > > > > + } else {
> > > > > > + pr_debug("%s: PASID alloc failed\n",
> > > > > > __func__);
> > > > > > + ret = -EFAULT;
> > > > >
> > > > > no, this branch is not for copy_to_user error. it is about pasid
> > > > > alloc failure. you should handle both.
> > > >
> > > > Emmm, I just want to fail the IOCTL in such case, so the @result
> > > > field is meaningless in the user side. How about using another
> > > > return value (e.g. ENOSPC) to indicate the IOCTL failure?
> > >
> > > If pasid_alloc fails, you return its result to userspace if
> > > copy_to_user fails, then return -EFAULT.
> > >
> > > however, above you return -EFAULT for pasid_alloc failure, and then
> > > the number of not-copied bytes for copy_to_user.
> >
> > not quite get. Let me re-paste the code. :-)
> >
> > + case VFIO_IOMMU_PASID_ALLOC:
> > + {
> > + int ret = 0, result;
> > +
> > + result = vfio_iommu_type1_pasid_alloc(iommu,
> > + req.alloc_pasid.min,
> > + req.alloc_pasid.max);
> > + if (result > 0) {
> > + offset = offsetof(
> > + struct
> > vfio_iommu_type1_pasid_request,
> > + alloc_pasid.result);
> > + ret = copy_to_user(
> > + (void __user *) (arg + offset),
> > + &result, sizeof(result));
> > if copy_to_user failed, ret is the number of uncopied bytes and will
> > be returned to userspace to indicate failure. userspace will not use
> > the data in result field. perhaps, I should check the ret here and
> > return -EFAULT or another errno, instead of return the number of
> > un-copied bytes.
>
> here should return -EFAULT.
got it. so if any failure, the return value of this ioctl is a -ERROR_VAL.
>
> > + } else {
> > + pr_debug("%s: PASID alloc failed\n",
> > __func__);
> > + ret = -EFAULT;
> > if vfio_iommu_type1_pasid_alloc() failed, no doubt, return -EFAULT to
> > userspace to indicate failure.
>
> pasid_alloc has its own error types returned. why blindly replace it with -EFAULT?
right, should use its own error types.
Thanks,
Yi Liu
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iommu@lists.linux-foundation.org
https://lists.linuxfoundation.org/mailman/listinfo/iommu
next prev parent reply other threads:[~2020-04-01 5:49 UTC|newest]
Thread overview: 110+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-03-22 12:31 [PATCH v1 0/8] vfio: expose virtual Shared Virtual Addressing to VMs Liu, Yi L
2020-03-22 12:31 ` [PATCH v1 1/8] vfio: Add VFIO_IOMMU_PASID_REQUEST(alloc/free) Liu, Yi L
2020-03-22 16:21 ` kbuild test robot
2020-03-30 8:32 ` Tian, Kevin
2020-03-30 14:36 ` Liu, Yi L
2020-03-31 5:40 ` Tian, Kevin
2020-03-31 13:22 ` Liu, Yi L
2020-04-01 5:43 ` Tian, Kevin
2020-04-01 5:48 ` Liu, Yi L [this message]
2020-03-31 7:53 ` Christoph Hellwig
2020-03-31 8:17 ` Liu, Yi L
2020-03-31 8:32 ` Liu, Yi L
2020-03-31 8:36 ` Liu, Yi L
2020-03-31 9:15 ` Christoph Hellwig
2020-04-02 13:52 ` Jean-Philippe Brucker
2020-04-03 11:56 ` Liu, Yi L
2020-04-03 12:39 ` Jean-Philippe Brucker
2020-04-03 12:44 ` Liu, Yi L
2020-04-02 17:50 ` Alex Williamson
2020-04-03 5:58 ` Tian, Kevin
2020-04-03 15:14 ` Alex Williamson
2020-04-07 4:42 ` Tian, Kevin
2020-04-07 15:14 ` Alex Williamson
2020-04-03 13:12 ` Liu, Yi L
2020-04-03 17:50 ` Alex Williamson
2020-04-07 4:52 ` Tian, Kevin
2020-04-08 0:52 ` Liu, Yi L
2020-03-22 12:31 ` [PATCH v1 2/8] vfio/type1: Add vfio_iommu_type1 parameter for quota tuning Liu, Yi L
2020-03-22 17:20 ` kbuild test robot
2020-03-30 8:40 ` Tian, Kevin
2020-03-30 8:52 ` Liu, Yi L
2020-03-30 9:19 ` Tian, Kevin
2020-03-30 9:26 ` Liu, Yi L
2020-03-30 11:44 ` Tian, Kevin
2020-04-02 17:58 ` Alex Williamson
2020-04-03 8:15 ` Liu, Yi L
2020-03-22 12:32 ` [PATCH v1 3/8] vfio/type1: Report PASID alloc/free support to userspace Liu, Yi L
2020-03-30 9:43 ` Tian, Kevin
2020-04-01 7:46 ` Liu, Yi L
2020-04-01 9:41 ` Auger Eric
2020-04-01 13:13 ` Liu, Yi L
2020-04-02 18:01 ` Alex Williamson
2020-04-03 8:17 ` Liu, Yi L
2020-04-03 17:28 ` Alex Williamson
2020-04-04 11:36 ` Liu, Yi L
2020-03-22 12:32 ` [PATCH v1 4/8] vfio: Check nesting iommu uAPI version Liu, Yi L
2020-03-22 18:30 ` kbuild test robot
2020-03-22 12:32 ` [PATCH v1 5/8] vfio/type1: Report 1st-level/stage-1 format to userspace Liu, Yi L
2020-03-22 16:44 ` kbuild test robot
2020-03-30 11:48 ` Tian, Kevin
2020-04-01 7:38 ` Liu, Yi L
2020-04-01 7:56 ` Tian, Kevin
2020-04-01 8:06 ` Liu, Yi L
2020-04-01 8:08 ` Tian, Kevin
2020-04-01 8:09 ` Liu, Yi L
2020-04-01 8:51 ` Auger Eric
2020-04-01 12:51 ` Liu, Yi L
2020-04-01 13:01 ` Auger Eric
2020-04-03 8:23 ` Jean-Philippe Brucker
2020-04-07 9:43 ` Liu, Yi L
2020-04-08 1:02 ` Liu, Yi L
2020-04-08 10:27 ` Auger Eric
2020-04-09 8:14 ` Jean-Philippe Brucker
2020-04-09 9:01 ` Auger Eric
2020-04-09 12:47 ` Liu, Yi L
2020-04-10 3:28 ` Auger Eric
2020-04-10 3:48 ` Liu, Yi L
2020-04-10 12:30 ` Liu, Yi L
2020-04-02 19:20 ` Alex Williamson
2020-04-03 11:59 ` Liu, Yi L
2020-03-22 12:32 ` [PATCH v1 6/8] vfio/type1: Bind guest page tables to host Liu, Yi L
2020-03-22 18:10 ` kbuild test robot
2020-03-30 12:46 ` Tian, Kevin
2020-04-01 9:13 ` Liu, Yi L
2020-04-02 2:12 ` Tian, Kevin
2020-04-02 8:05 ` Liu, Yi L
2020-04-03 8:34 ` Jean-Philippe Brucker
2020-04-07 10:33 ` Liu, Yi L
2020-04-09 8:28 ` Jean-Philippe Brucker
2020-04-09 9:15 ` Liu, Yi L
2020-04-09 9:38 ` Jean-Philippe Brucker
2020-04-02 19:57 ` Alex Williamson
2020-04-03 13:30 ` Liu, Yi L
2020-04-03 18:11 ` Alex Williamson
2020-04-04 10:28 ` Liu, Yi L
2020-04-11 5:52 ` Liu, Yi L
2020-03-22 12:32 ` [PATCH v1 7/8] vfio/type1: Add VFIO_IOMMU_CACHE_INVALIDATE Liu, Yi L
2020-03-30 12:58 ` Tian, Kevin
2020-04-01 7:49 ` Liu, Yi L
2020-03-31 7:56 ` Christoph Hellwig
2020-03-31 10:48 ` Liu, Yi L
2020-04-02 20:24 ` Alex Williamson
2020-04-03 6:39 ` Tian, Kevin
2020-04-03 15:31 ` Jacob Pan
2020-04-03 15:34 ` Alex Williamson
2020-04-08 2:28 ` Liu, Yi L
2020-04-16 10:40 ` Liu, Yi L
2020-04-16 12:09 ` Tian, Kevin
2020-04-16 12:42 ` Auger Eric
2020-04-16 13:28 ` Tian, Kevin
2020-04-16 15:12 ` Auger Eric
2020-04-16 14:40 ` Alex Williamson
2020-04-16 14:48 ` Alex Williamson
2020-04-17 6:03 ` Liu, Yi L
2020-03-22 12:32 ` [PATCH v1 8/8] vfio/type1: Add vSVA support for IOMMU-backed mdevs Liu, Yi L
2020-03-30 13:18 ` Tian, Kevin
2020-04-01 7:51 ` Liu, Yi L
2020-04-02 20:33 ` Alex Williamson
2020-04-03 13:39 ` Liu, Yi L
2020-03-26 12:56 ` [PATCH v1 0/8] vfio: expose virtual Shared Virtual Addressing to VMs Liu, Yi L
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