Re: [EXT] Re: [PATCH RFC] iommu/virtio: Use page size bitmap supported by endpoint

[Jean-Philippe Brucker <jean-philippe@linaro.org>]

On Mon, Mar 23, 2020 at 05:25:17PM +0000, Bharat Bhushan wrote:
> Hi Jean,
> 
> > -----Original Message-----
> > From: Jean-Philippe Brucker <jean-philippe@linaro.org>
> > Sent: Monday, March 23, 2020 3:30 PM
> > To: Bharat Bhushan <bbhushan2@marvell.com>
> > Cc: joro@8bytes.org; mst@redhat.com; jasowang@redhat.com;
> > virtualization@lists.linux-foundation.org; iommu@lists.linux-foundation.org;
> > eric.auger@redhat.com
> > Subject: [EXT] Re: [PATCH RFC] iommu/virtio: Use page size bitmap supported by
> > endpoint
> > 
> > External Email
> > 
> > ----------------------------------------------------------------------
> > Hi Bharat,
> > 
> > Please add the IOMMU list on your next posting
> 
> iommu@lists.linux-foundation.org is there, any other mailing list we need to add?

I added that address when replying :) It doesn't look like your patch
reached the list:
https://lore.kernel.org/linux-iommu/20200323095943.GA2038940@myrica/T/
But virtualization and iommu lists are enough.

Thanks,
Jean

> 
> > 
> > On Mon, Mar 23, 2020 at 02:11:08PM +0530, 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@marvell.com>
> > > ---
> > >  drivers/iommu/virtio-iommu.c      | 24 ++++++++++++++++++++----
> > >  include/uapi/linux/virtio_iommu.h |  6 ++++++
> > >  2 files changed, 26 insertions(+), 4 deletions(-)
> > >
> > > diff --git a/drivers/iommu/virtio-iommu.c
> > > b/drivers/iommu/virtio-iommu.c index cce329d71fba..e69347ca4ee6 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 +416,14 @@ 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)
> > > +
> > > +{
> > > +	vdev->pgsize_bitmap = mask->pgsize_bitmap;
> > 
> > We need to read this through le64_to_cpu(). Also check that the length of the field
> > provided by the device is >= sizeof(mask) (like
> > viommu_add_resv_mem() does)
> 
> Will take care of all the comments in next verions
> 
> Thank
> -Bharat
> 
> > 
> > > +	return 0;
> > > +}
> > > +
> > >  static int viommu_add_resv_mem(struct viommu_endpoint *vdev,
> > >  			       struct virtio_iommu_probe_resv_mem *mem,
> > >  			       size_t len)
> > > @@ -494,11 +503,13 @@ 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);
> > > -
> > >  		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);
> > > +			break;
> > >  		default:
> > >  			dev_err(dev, "unknown viommu prop 0x%x\n", type);
> > >  		}
> > > @@ -607,16 +618,21 @@ 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;
> > > +	if (vdev->pgsize_bitmap)
> > > +		domain->pgsize_bitmap = vdev->pgsize_bitmap;
> > > +	else
> > > +		domain->pgsize_bitmap	= viommu->pgsize_bitmap;
> > > +
> > 
> > nit: it could be nicer to initialize vdev->pgsize_bitmap in add_device(), override it
> > in probe_endpoint(), and just copy it here.
> > 
> > >  	domain->geometry	= viommu->geometry;
> > >
> > >  	ret = ida_alloc_range(&viommu->domain_ids, viommu->first_domain, @@
> > > -657,7 +673,7 @@ 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);
> > 
> > Attaching additional endpoints with different masks to the domain should return
> > an error
> > 
> > >  	} else if (vdomain->viommu != vdev->viommu) {
> > >  		dev_err(dev, "cannot attach to foreign vIOMMU\n");
> > >  		ret = -EXDEV;
> > > diff --git a/include/uapi/linux/virtio_iommu.h
> > > b/include/uapi/linux/virtio_iommu.h
> > > index 237e36a280cb..aff3db0ef54b 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 +120,11 @@ struct virtio_iommu_probe_property {
> > >  	__le16					length;
> > >  };
> > >
> > > +struct virtio_iommu_probe_pgsize_mask {
> > > +	struct virtio_iommu_probe_property	head;
> > 
> > Compilers will introduce 4 bytes of padding here, to align the next field.
> > We need to make them explicit by adding a 4-bytes 'reserved' field.
> > 
> > > +	uint64_t				pgsize_bitmap;
> > 
> > __le64
> > 
> > Thanks,
> > Jean
> > 
> > > +};
> > > +
> > >  #define VIRTIO_IOMMU_RESV_MEM_T_RESERVED	0
> > >  #define VIRTIO_IOMMU_RESV_MEM_T_MSI		1
> > >
> > > --
> > > 2.17.1
> > >
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