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 5/8] vfio/type1: Report 1st-level/stage-1 format to userspace
Date: Wed, 1 Apr 2020 08:06:51 +0000 [thread overview]
Message-ID: <A2975661238FB949B60364EF0F2C25743A21D793@SHSMSX104.ccr.corp.intel.com> (raw)
In-Reply-To: <AADFC41AFE54684AB9EE6CBC0274A5D19D803F42@SHSMSX104.ccr.corp.intel.com>
> From: Tian, Kevin <kevin.tian@intel.com>
> Sent: Wednesday, April 1, 2020 3:56 PM
> To: Liu, Yi L <yi.l.liu@intel.com>; alex.williamson@redhat.com;
> Subject: RE: [PATCH v1 5/8] vfio/type1: Report 1st-level/stage-1 format to
> userspace
>
> > From: Liu, Yi L <yi.l.liu@intel.com>
> > Sent: Wednesday, April 1, 2020 3:38 PM
> >
> > > From: Tian, Kevin <kevin.tian@intel.com>
> > > Sent: Monday, March 30, 2020 7:49 PM
> > > To: Liu, Yi L <yi.l.liu@intel.com>; alex.williamson@redhat.com;
> > > Subject: RE: [PATCH v1 5/8] vfio/type1: Report 1st-level/stage-1
> > > format to userspace
> > >
> > > > 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>
> > > >
> > > > VFIO exposes IOMMU nesting translation (a.k.a dual stage
> > > > translation) capability to userspace. Thus applications like QEMU
> > > > could support vIOMMU with hardware's nesting translation
> > > > capability for pass-through devices. Before setting up nesting
> > > > translation for pass-through devices, QEMU and other applications
> > > > need to learn the supported
> > > > 1st-lvl/stage-1 translation structure format like page table format.
> > > >
> > > > Take vSVA (virtual Shared Virtual Addressing) as an example, to
> > > > support vSVA for pass-through devices, QEMU setup nesting
> > > > translation for pass- through devices. The guest page table are
> > > > configured to host as 1st-lvl/
> > > > stage-1 page table. Therefore, guest format should be compatible
> > > > with host side.
> > > >
> > > > This patch reports the supported 1st-lvl/stage-1 page table format
> > > > on the current platform to userspace. QEMU and other alike
> > > > applications should use this format info when trying to setup
> > > > IOMMU nesting translation on host IOMMU.
> > > >
> > > > Cc: Kevin Tian <kevin.tian@intel.com>
> > > > CC: Jacob Pan <jacob.jun.pan@linux.intel.com>
> > > > Cc: Alex Williamson <alex.williamson@redhat.com>
> > > > Cc: Eric Auger <eric.auger@redhat.com>
> > > > Cc: Jean-Philippe Brucker <jean-philippe@linaro.org>
> > > > Signed-off-by: Liu Yi L <yi.l.liu@intel.com>
> > > > ---
> > > > drivers/vfio/vfio_iommu_type1.c | 56
> > > > +++++++++++++++++++++++++++++++++++++++++
> > > > include/uapi/linux/vfio.h | 1 +
> > > > 2 files changed, 57 insertions(+)
> > > >
> > > > diff --git a/drivers/vfio/vfio_iommu_type1.c
> > > > b/drivers/vfio/vfio_iommu_type1.c index 9aa2a67..82a9e0b 100644
> > > > --- a/drivers/vfio/vfio_iommu_type1.c
> > > > +++ b/drivers/vfio/vfio_iommu_type1.c
> > > > @@ -2234,11 +2234,66 @@ static int
> > vfio_iommu_type1_pasid_free(struct
> > > > vfio_iommu *iommu,
> > > > return ret;
> > > > }
> > > >
> > > > +static int vfio_iommu_get_stage1_format(struct vfio_iommu *iommu,
> > > > + u32 *stage1_format)
> > > > +{
> > > > + struct vfio_domain *domain;
> > > > + u32 format = 0, tmp_format = 0;
> > > > + int ret;
> > > > +
> > > > + mutex_lock(&iommu->lock);
> > > > + if (list_empty(&iommu->domain_list)) {
> > > > + mutex_unlock(&iommu->lock);
> > > > + return -EINVAL;
> > > > + }
> > > > +
> > > > + list_for_each_entry(domain, &iommu->domain_list, next) {
> > > > + if (iommu_domain_get_attr(domain->domain,
> > > > + DOMAIN_ATTR_PASID_FORMAT, &format)) {
> > > > + ret = -EINVAL;
> > > > + format = 0;
> > > > + goto out_unlock;
> > > > + }
> > > > + /*
> > > > + * format is always non-zero (the first format is
> > > > + * IOMMU_PASID_FORMAT_INTEL_VTD which is 1). For
> > > > + * the reason of potential different backed IOMMU
> > > > + * formats, here we expect to have identical formats
> > > > + * in the domain list, no mixed formats support.
> > > > + * return -EINVAL to fail the attempt of setup
> > > > + * VFIO_TYPE1_NESTING_IOMMU if non-identical formats
> > > > + * are detected.
> > > > + */
> > > > + if (tmp_format && tmp_format != format) {
> > > > + ret = -EINVAL;
> > > > + format = 0;
> > > > + goto out_unlock;
> > > > + }
> > > > +
> > > > + tmp_format = format;
> > > > + }
> > >
> > > this path is invoked only in VFIO_IOMMU_GET_INFO path. If we don't
> > > want
> > to
> > > assume the status quo that one container holds only one device w/
> > vIOMMU
> > > (the prerequisite for vSVA), looks we also need check the format
> > > compatibility when attaching a new group to this container?
> >
> > right. if attaching to a nesting type container (vfio_iommu.nesting
> > bit indicates it), it should check if it is compabile with prior
> > domains in the domain list. But if it is the first one attached to
> > this container, it's fine. is it good?
>
> yes, but my point is whether we should check the format compatibility
> in the attach path...
I guess so. Assume a device has been attached to a container, and
userspace has fetched the nesting cap info. e.g. QEMU will have a
per-container structure to store the nesting info. And then attach
another device from a separate group, if its backend iommu supports
different formats, then it will be a problem. If userspace reads the
nesting cap info again, it will get a different value. It may affect
the prior attched device. If userspace doesn't refresh the nesting
info by re-fetch, then the newly added device may use a format which
its backend iommu doesn't support.
Although, the vendor specific iommu driver should ensure all devices
are backed by iommu units w/ same capability (e.g. format). But it
would better to have a check in vfio side all the same. how about your
opinion so far?:-)
Regards,
Yi Liu
_______________________________________________
iommu mailing list
iommu@lists.linux-foundation.org
https://lists.linuxfoundation.org/mailman/listinfo/iommu
next prev parent reply other threads:[~2020-04-01 8:07 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
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 [this message]
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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