From: Alex Williamson <alex.williamson@redhat.com>
To: "Liu, Yi L" <yi.l.liu@intel.com>
Cc: "jean-philippe@linaro.org" <jean-philippe@linaro.org>,
"Tian, Kevin" <kevin.tian@intel.com>,
"Raj, Ashok" <ashok.raj@intel.com>,
"kvm@vger.kernel.org" <kvm@vger.kernel.org>,
"Tian, Jun J" <jun.j.tian@intel.com>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"iommu@lists.linux-foundation.org"
<iommu@lists.linux-foundation.org>,
"Sun, Yi Y" <yi.y.sun@intel.com>, "Wu, Hao" <hao.wu@intel.com>
Subject: Re: [PATCH v1 7/8] vfio/type1: Add VFIO_IOMMU_CACHE_INVALIDATE
Date: Thu, 16 Apr 2020 08:48:11 -0600 [thread overview]
Message-ID: <20200416084811.5acf4424@w520.home> (raw)
In-Reply-To: <20200416084031.7266ad40@w520.home>
On Thu, 16 Apr 2020 08:40:31 -0600
Alex Williamson <alex.williamson@redhat.com> wrote:
> On Thu, 16 Apr 2020 10:40:03 +0000
> "Liu, Yi L" <yi.l.liu@intel.com> wrote:
>
> > Hi Alex,
> > Still have a direction question with you. Better get agreement with you
> > before heading forward.
> >
> > > From: Alex Williamson <alex.williamson@redhat.com>
> > > Sent: Friday, April 3, 2020 11:35 PM
> > [...]
> > > > > > + *
> > > > > > + * returns: 0 on success, -errno on failure.
> > > > > > + */
> > > > > > +struct vfio_iommu_type1_cache_invalidate {
> > > > > > + __u32 argsz;
> > > > > > + __u32 flags;
> > > > > > + struct iommu_cache_invalidate_info cache_info;
> > > > > > +};
> > > > > > +#define VFIO_IOMMU_CACHE_INVALIDATE _IO(VFIO_TYPE,
> > > VFIO_BASE
> > > > > + 24)
> > > > >
> > > > > The future extension capabilities of this ioctl worry me, I wonder if
> > > > > we should do another data[] with flag defining that data as CACHE_INFO.
> > > >
> > > > Can you elaborate? Does it mean with this way we don't rely on iommu
> > > > driver to provide version_to_size conversion and instead we just pass
> > > > data[] to iommu driver for further audit?
> > >
> > > No, my concern is that this ioctl has a single function, strictly tied
> > > to the iommu uapi. If we replace cache_info with data[] then we can
> > > define a flag to specify that data[] is struct
> > > iommu_cache_invalidate_info, and if we need to, a different flag to
> > > identify data[] as something else. For example if we get stuck
> > > expanding cache_info to meet new demands and develop a new uapi to
> > > solve that, how would we expand this ioctl to support it rather than
> > > also create a new ioctl? There's also a trade-off in making the ioctl
> > > usage more difficult for the user. I'd still expect the vfio layer to
> > > check the flag and interpret data[] as indicated by the flag rather
> > > than just passing a blob of opaque data to the iommu layer though.
> > > Thanks,
> >
> > Based on your comments about defining a single ioctl and a unified
> > vfio structure (with a @data[] field) for pasid_alloc/free, bind/
> > unbind_gpasid, cache_inv. After some offline trying, I think it would
> > be good for bind/unbind_gpasid and cache_inv as both of them use the
> > iommu uapi definition. While the pasid alloc/free operation doesn't.
> > It would be weird to put all of them together. So pasid alloc/free
> > may have a separate ioctl. It would look as below. Does this direction
> > look good per your opinion?
> >
> > ioctl #22: VFIO_IOMMU_PASID_REQUEST
> > /**
> > * @pasid: used to return the pasid alloc result when flags == ALLOC_PASID
> > * specify a pasid to be freed when flags == FREE_PASID
> > * @range: specify the allocation range when flags == ALLOC_PASID
> > */
> > struct vfio_iommu_pasid_request {
> > __u32 argsz;
> > #define VFIO_IOMMU_ALLOC_PASID (1 << 0)
> > #define VFIO_IOMMU_FREE_PASID (1 << 1)
> > __u32 flags;
> > __u32 pasid;
> > struct {
> > __u32 min;
> > __u32 max;
> > } range;
> > };
>
> Can't the ioctl return the pasid valid on alloc (like GET_DEVICE_FD)?
s/valid/value/
> Would it be useful to support freeing a range of pasids? If so then we
> could simply use range for both, ie. allocate a pasid from this range
> and return it, or free all pasids in this range? vfio already needs to
> track pasids to free them on release, so presumably this is something
> we could support easily.
>
> > ioctl #23: VFIO_IOMMU_NESTING_OP
> > struct vfio_iommu_type1_nesting_op {
> > __u32 argsz;
> > __u32 flags;
> > __u32 op;
> > __u8 data[];
> > };
>
> data only has 4-byte alignment, I think we really want it at an 8-byte
> alignment. This is why I embedded the "op" into the flag for
> DEVICE_FEATURE. Thanks,
>
> Alex
>
> >
> > /* Nesting Ops */
> > #define VFIO_IOMMU_NESTING_OP_BIND_PGTBL 0
> > #define VFIO_IOMMU_NESTING_OP_UNBIND_PGTBL 1
> > #define VFIO_IOMMU_NESTING_OP_CACHE_INVLD 2
> >
> > Thanks,
> > Yi Liu
> >
>
> _______________________________________________
> iommu mailing list
> iommu@lists.linux-foundation.org
> https://lists.linuxfoundation.org/mailman/listinfo/iommu
>
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next prev parent reply other threads:[~2020-04-16 14:48 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
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 [this message]
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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