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Date: Thu, 2 Apr 2020 03:53:40 +0000
From: Bharat Bhushan <bbhushan2@...vell.com>
To: Jean-Philippe Brucker <jean-philippe@...aro.org>,
Robin Murphy <robin.murphy@....com>
CC: "joro@...tes.org" <joro@...tes.org>,
"mst@...hat.com" <mst@...hat.com>,
"jasowang@...hat.com" <jasowang@...hat.com>,
"virtualization@...ts.linux-foundation.org"
<virtualization@...ts.linux-foundation.org>,
"iommu@...ts.linux-foundation.org" <iommu@...ts.linux-foundation.org>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
"eric.auger.pro@...il.com" <eric.auger.pro@...il.com>,
"eric.auger@...hat.com" <eric.auger@...hat.com>
Subject: RE: [EXT] Re: [RFC PATCH v2] iommu/virtio: Use page size bitmap
supported by endpoint
> -----Original Message-----
> From: Jean-Philippe Brucker <jean-philippe@...aro.org>
> Sent: Wednesday, April 1, 2020 9:20 PM
> To: Robin Murphy <robin.murphy@....com>
> Cc: Bharat Bhushan <bbhushan2@...vell.com>; joro@...tes.org;
> mst@...hat.com; jasowang@...hat.com; virtualization@...ts.linux-
> foundation.org; iommu@...ts.linux-foundation.org; linux-kernel@...r.kernel.org;
> eric.auger.pro@...il.com; eric.auger@...hat.com
> Subject: [EXT] Re: [RFC PATCH v2] iommu/virtio: Use page size bitmap supported by
> endpoint
>
> External Email
>
> ----------------------------------------------------------------------
> On Wed, Apr 01, 2020 at 02:00:13PM +0100, Robin Murphy wrote:
> > On 2020-04-01 12:38 pm, Bharat Bhushan wrote:
> > > Different endpoint can support different page size, probe endpoint
> > > if it supports specific page size otherwise use global page sizes.
> > >
> > > Signed-off-by: Bharat Bhushan <bbhushan2@...vell.com>
> > > ---
> > > drivers/iommu/virtio-iommu.c | 33 +++++++++++++++++++++++++++----
> > > include/uapi/linux/virtio_iommu.h | 7 +++++++
> > > 2 files changed, 36 insertions(+), 4 deletions(-)
> > >
> > > diff --git a/drivers/iommu/virtio-iommu.c
> > > b/drivers/iommu/virtio-iommu.c index cce329d71fba..c794cb5b7b3e
> > > 100644
> > > --- a/drivers/iommu/virtio-iommu.c
> > > +++ b/drivers/iommu/virtio-iommu.c
> > > @@ -78,6 +78,7 @@ struct viommu_endpoint {
> > > struct viommu_dev *viommu;
> > > struct viommu_domain *vdomain;
> > > struct list_head resv_regions;
> > > + u64 pgsize_bitmap;
> > > };
> > > struct viommu_request {
> > > @@ -415,6 +416,20 @@ static int viommu_replay_mappings(struct
> viommu_domain *vdomain)
> > > return ret;
> > > }
> > > +static int viommu_set_pgsize_bitmap(struct viommu_endpoint *vdev,
> > > + struct virtio_iommu_probe_pgsize_mask *mask,
> > > + size_t len)
> > > +
> > > +{
> > > + u64 pgsize_bitmap = le64_to_cpu(mask->pgsize_bitmap);
> > > +
> > > + if (len < sizeof(*mask))
> > > + return -EINVAL;
> > > +
> > > + vdev->pgsize_bitmap = pgsize_bitmap;
> > > + return 0;
> > > +}
> > > +
> > > static int viommu_add_resv_mem(struct viommu_endpoint *vdev,
> > > struct virtio_iommu_probe_resv_mem *mem,
> > > size_t len)
> > > @@ -494,11 +509,13 @@ static int viommu_probe_endpoint(struct
> viommu_dev *viommu, struct device *dev)
> > > while (type != VIRTIO_IOMMU_PROBE_T_NONE &&
> > > cur < viommu->probe_size) {
> > > len = le16_to_cpu(prop->length) + sizeof(*prop);
> > > -
>
> Whitespace change
>
> > > switch (type) {
> > > case VIRTIO_IOMMU_PROBE_T_RESV_MEM:
> > > ret = viommu_add_resv_mem(vdev, (void *)prop, len);
> > > break;
> > > + case VIRTIO_IOMMU_PROBE_T_PAGE_SIZE_MASK:
> > > + ret = viommu_set_pgsize_bitmap(vdev, (void *)prop, len);
> > > + break;
> > > default:
> > > dev_err(dev, "unknown viommu prop 0x%x\n", type);
> > > }
> > > @@ -607,16 +624,23 @@ static struct iommu_domain
> *viommu_domain_alloc(unsigned type)
> > > return &vdomain->domain;
> > > }
> > > -static int viommu_domain_finalise(struct viommu_dev *viommu,
> > > +static int viommu_domain_finalise(struct viommu_endpoint *vdev,
> > > struct iommu_domain *domain)
> > > {
> > > int ret;
> > > struct viommu_domain *vdomain = to_viommu_domain(domain);
> > > + struct viommu_dev *viommu = vdev->viommu;
> > > vdomain->viommu = viommu;
> > > vdomain->map_flags = viommu->map_flags;
> > > - domain->pgsize_bitmap = viommu->pgsize_bitmap;
> > > + /* Devices in same domain must support same size pages */
> >
> > AFAICS what the code appears to do is enforce that the first endpoint
> > attached to any domain has the same pgsize_bitmap as the most recently
> > probed viommu_dev instance, then ignore any subsequent endpoints
> > attached to the same domain. Thus I'm not sure that comment is accurate.
> >
>
> Yes viommu_domain_finalise() is only called once. What I had in mind is
> something like:
Ohh, I did not realized that viommu_domain_finalise().
I have included below suggested changes
>
> ---- 8< ----
> diff --git a/drivers/iommu/virtio-iommu.c b/drivers/iommu/virtio-iommu.c index
> 750f69c49b95..8303b7b513ff 100644
> --- a/drivers/iommu/virtio-iommu.c
> +++ b/drivers/iommu/virtio-iommu.c
> @@ -639,6 +639,29 @@ static int viommu_domain_finalise(struct
> viommu_endpoint *vdev,
> return 0;
> }
>
> +/*
> + * Check whether the endpoint's capabilities are compatible with other
> +endpoints
> + * in the domain. Report any inconsistency.
> + */
> +static bool viommu_endpoint_is_compatible(struct viommu_endpoint *vdev,
> + struct viommu_domain *vdomain)
> +{
> + struct device *dev = vdev->dev;
> +
> + if (vdomain->viommu != vdev->viommu) {
> + dev_err(dev, "cannot attach to foreign vIOMMU\n");
> + return false;
> + }
> +
> + if (vdomain->domain.pgsize_bitmap != vdev->pgsize_bitmap) {
> + dev_err(dev, "incompatible domain bitmap 0x%lx != 0x%lx\n",
> + vdomain->domain.pgsize_bitmap, vdev->pgsize_bitmap);
> + return false;
> + }
> +
> + return true;
> +}
> +
> static void viommu_domain_free(struct iommu_domain *domain) {
> struct viommu_domain *vdomain = to_viommu_domain(domain); @@ -
> 670,9 +693,8 @@ static int viommu_attach_dev(struct iommu_domain *domain,
> struct device *dev)
> * owns it.
> */
> ret = viommu_domain_finalise(vdev, domain);
> - } else if (vdomain->viommu != vdev->viommu) {
> - dev_err(dev, "cannot attach to foreign vIOMMU\n");
> - ret = -EXDEV;
> + } else if (!viommu_endpoint_is_compatible(vdev, vdomain)) {
> + ret = -EINVAL;
> }
> mutex_unlock(&vdomain->mutex);
> ---- >8 ----
>
> >
> > > + if ((domain->pgsize_bitmap != viommu->pgsize_bitmap) &&
> > > + (domain->pgsize_bitmap != vdev->pgsize_bitmap))
> > > + return -EINVAL;
> > > +
> > > + domain->pgsize_bitmap = vdev->pgsize_bitmap;
> > > +
> > > domain->geometry = viommu->geometry;
> > > ret = ida_alloc_range(&viommu->domain_ids, viommu->first_domain,
> > > @@ -657,7 +681,7 @@ static int viommu_attach_dev(struct iommu_domain
> *domain, struct device *dev)
> > > * Properly initialize the domain now that we know which viommu
> > > * owns it.
> > > */
> > > - ret = viommu_domain_finalise(vdev->viommu, domain);
> > > + ret = viommu_domain_finalise(vdev, domain);
> > > } else if (vdomain->viommu != vdev->viommu) {
> > > dev_err(dev, "cannot attach to foreign vIOMMU\n");
> > > ret = -EXDEV;
> > > @@ -875,6 +899,7 @@ static int viommu_add_device(struct device *dev)
> > > vdev->dev = dev;
> > > vdev->viommu = viommu;
> > > + vdev->pgsize_bitmap = viommu->pgsize_bitmap;
> > > INIT_LIST_HEAD(&vdev->resv_regions);
> > > fwspec->iommu_priv = vdev;
> > > diff --git a/include/uapi/linux/virtio_iommu.h
> > > b/include/uapi/linux/virtio_iommu.h
> > > index 237e36a280cb..dc9d3f40bcd8 100644
> > > --- a/include/uapi/linux/virtio_iommu.h
> > > +++ b/include/uapi/linux/virtio_iommu.h
> > > @@ -111,6 +111,7 @@ struct virtio_iommu_req_unmap {
> > > #define VIRTIO_IOMMU_PROBE_T_NONE 0
> > > #define VIRTIO_IOMMU_PROBE_T_RESV_MEM 1
> > > +#define VIRTIO_IOMMU_PROBE_T_PAGE_SIZE_MASK 2
> > > #define VIRTIO_IOMMU_PROBE_T_MASK 0xfff
> > > @@ -119,6 +120,12 @@ struct virtio_iommu_probe_property {
> > > __le16 length;
> > > };
> > > +struct virtio_iommu_probe_pgsize_mask {
> > > + struct virtio_iommu_probe_property head;
> > > + __u8 reserved[4];
> > > + __u64 pgsize_bitmap;
>
> Should be __le64
Based on" iommu/virtio: Fix sparse warning" patch https://www.spinics.net/lists/linux-virtualization/msg41944.html changed to __u64 (not __le64)
Will keep __le64.
Thanks
-Bharat
>
> Thanks,
> Jean
>
> > > +};
> > > +
> > > #define VIRTIO_IOMMU_RESV_MEM_T_RESERVED 0
> > > #define VIRTIO_IOMMU_RESV_MEM_T_MSI 1
> > >
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