RE: [PATCH v8 23/29] vfio: VFIO_IOMMU_CACHE_INVALIDATE

Liu, Yi L
2019-06-14T12:38:55Z

Hi Eric,

> From: Eric Auger [mailto:eric.auger@redhat.com]
> Sent: Monday, May 27, 2019 12:10 AM
> Subject: [PATCH v8 23/29] vfio: VFIO_IOMMU_CACHE_INVALIDATE
>
> From: "Liu, Yi L" <yi.l.liu@linux.intel.com>
>
> When the guest "owns" the stage 1 translation structures, the host IOMMU driver
> has no knowledge of caching structure updates unless the guest invalidation
> requests are trapped and passed down to the host.
>
> This patch adds the VFIO_IOMMU_CACHE_INVALIDATE ioctl with aims at
> propagating guest stage1 IOMMU cache invalidations to the host.
>
> Signed-off-by: Liu, Yi L <yi.l.liu@linux.intel.com>
> Signed-off-by: Eric Auger <eric.auger@redhat.com>
>
> ---
> v6 -> v7:
> - Use iommu_capsule struct
> - renamed vfio_iommu_for_each_dev into vfio_iommu_lookup_dev
> due to checkpatch error related to for_each_dev suffix
>
> v2 -> v3:
> - introduce vfio_iommu_for_each_dev back in this patch
>
> v1 -> v2:
> - s/TLB/CACHE
> - remove vfio_iommu_task usage
> - commit message rewording
> ---
> drivers/vfio/vfio_iommu_type1.c | 55 +++++++++++++++++++++++++++++++++
> include/uapi/linux/vfio.h | 13 ++++++++
> 2 files changed, 68 insertions(+)
>
> diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c
> index b2d609d6fe83..6fda4fbc9bfa 100644
> --- a/drivers/vfio/vfio_iommu_type1.c
> +++ b/drivers/vfio/vfio_iommu_type1.c
> @@ -120,6 +120,34 @@ struct vfio_regions {
> #define IS_IOMMU_CAP_DOMAIN_IN_CONTAINER(iommu) \
> (!list_empty(&iommu->domain_list))
>
> +struct domain_capsule {
> + struct iommu_domain *domain;
> + void *data;
> +};
> +
> +/* iommu->lock must be held */
> +static int
> +vfio_iommu_lookup_dev(struct vfio_iommu *iommu,
> + int (*fn)(struct device *dev, void *data),
> + void *data)
> +{
> + struct domain_capsule dc = {.data = data};
> + struct vfio_domain *d;
> + struct vfio_group *g;
> + int ret = 0;
> +
> + list_for_each_entry(d, &iommu->domain_list, next) {
> + dc.domain = d->domain;
> + list_for_each_entry(g, &d->group_list, next) {
> + ret = iommu_group_for_each_dev(g->iommu_group,
> + &dc, fn);
> + if (ret)
> + break;
> + }
> + }
> + return ret;
> +}
> +
> static int put_pfn(unsigned long pfn, int prot);
>
> /*
> @@ -1795,6 +1823,15 @@ vfio_attach_pasid_table(struct vfio_iommu *iommu,
> return ret;
> }
>
> +static int vfio_cache_inv_fn(struct device *dev, void *data) {
> + struct domain_capsule *dc = (struct domain_capsule *)data;
> + struct vfio_iommu_type1_cache_invalidate *ustruct =
> + (struct vfio_iommu_type1_cache_invalidate *)dc->data;
> +
> + return iommu_cache_invalidate(dc->domain, dev, &ustruct->info); }
> +
> static long vfio_iommu_type1_ioctl(void *iommu_data,
> unsigned int cmd, unsigned long arg) { @@ -
> 1881,6 +1918,24 @@ static long vfio_iommu_type1_ioctl(void *iommu_data,
> } else if (cmd == VFIO_IOMMU_DETACH_PASID_TABLE) {
> vfio_detach_pasid_table(iommu);
> return 0;
> + } else if (cmd == VFIO_IOMMU_CACHE_INVALIDATE) {
> + struct vfio_iommu_type1_cache_invalidate ustruct;
> + int ret;
> +
> + minsz = offsetofend(struct vfio_iommu_type1_cache_invalidate,
> + info);
> +
> + if (copy_from_user(&ustruct, (void __user *)arg, minsz))
> + return -EFAULT;
> +
> + if (ustruct.argsz < minsz || ustruct.flags)

May remove the flags field?

> + return -EINVAL;
> +
> + mutex_lock(&iommu->lock);
> + ret = vfio_iommu_lookup_dev(iommu, vfio_cache_inv_fn,
> + &ustruct);
> + mutex_unlock(&iommu->lock);
> + return ret;
> }
>
> return -ENOTTY;
> diff --git a/include/uapi/linux/vfio.h b/include/uapi/linux/vfio.h index
> 4316dd8cb5b5..055aa9b9745a 100644
> --- a/include/uapi/linux/vfio.h
> +++ b/include/uapi/linux/vfio.h
> @@ -785,6 +785,19 @@ struct vfio_iommu_type1_attach_pasid_table {
> */
> #define VFIO_IOMMU_DETACH_PASID_TABLE _IO(VFIO_TYPE, VFIO_BASE + 23)
>
> +/**
> + * VFIO_IOMMU_CACHE_INVALIDATE - _IOWR(VFIO_TYPE, VFIO_BASE + 24,
> + * struct vfio_iommu_type1_cache_invalidate)
> + *
> + * Propagate guest IOMMU cache invalidation to the host.
> + */
> +struct vfio_iommu_type1_cache_invalidate {
> + __u32 argsz;
> + __u32 flags;

Looks like there is no more usage on "flags". is it?

Regards,
Yi Liu

> + struct iommu_cache_invalidate_info info; };
> +#define VFIO_IOMMU_CACHE_INVALIDATE _IO(VFIO_TYPE, VFIO_BASE + 24)
> +
> /* -------- Additional API for SPAPR TCE (Server POWERPC) IOMMU -------- */
>
> /*
> --
> 2.20.1