Re: [PATCH v5] iommu/virtio: Use page size bitmap supported by endpoint

Michael S. Tsirkin
2020-05-12T14:54:06Z

On Tue, May 05, 2020 at 03:00:04PM +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>
> ---
> v4->v5:
> - Rebase to Linux v5.7-rc4
>
> v3->v4:
> - Fix whitespace error
>
> v2->v3:
> - Fixed error return for incompatible endpoint
> - __u64 changed to __le64 in header file
>
> drivers/iommu/virtio-iommu.c | 48 ++++++++++++++++++++++++++++---
> include/uapi/linux/virtio_iommu.h | 7 +++++
> 2 files changed, 51 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/iommu/virtio-iommu.c b/drivers/iommu/virtio-iommu.c
> index d5cac4f46ca5..9513d2ab819e 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 +416,19 @@ 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)
> @@ -499,6 +513,9 @@ static int viommu_probe_endpoint(struct viommu_dev *viommu, struct device *dev)
> 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);
> }

So given this is necessary early in boot, how about we
add this in the config space? And maybe ACPI too ...

> @@ -630,7 +647,7 @@ static int viommu_domain_finalise(struct viommu_endpoint *vdev,
>
> vdomain->id = (unsigned int)ret;
>
> - domain->pgsize_bitmap = viommu->pgsize_bitmap;
> + domain->pgsize_bitmap = vdev->pgsize_bitmap;
> domain->geometry = viommu->geometry;
>
> vdomain->map_flags = viommu->map_flags;
> @@ -654,6 +671,29 @@ static void viommu_domain_free(struct iommu_domain *domain)
> kfree(vdomain);
> }
>
> +/*
> + * 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%llx\n",
> + vdomain->domain.pgsize_bitmap, vdev->pgsize_bitmap);
> + return false;
> + }
> +
> + return true;
> +}
> +
> static int viommu_attach_dev(struct iommu_domain *domain, struct device *dev)
> {
> int i;
> @@ -670,9 +710,8 @@ 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);
>
> @@ -886,6 +925,7 @@ 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);
> dev_iommu_priv_set(dev, vdev);
>
> diff --git a/include/uapi/linux/virtio_iommu.h b/include/uapi/linux/virtio_iommu.h
> index 48e3c29223b5..2cced7accc99 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];
> + __le64 pgsize_bitmap;
> +};
> +
> #define VIRTIO_IOMMU_RESV_MEM_T_RESERVED 0
> #define VIRTIO_IOMMU_RESV_MEM_T_MSI 1
>
> --
> 2.17.1