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Message-ID: <d434cbcc-d3b1-d11d-0304-df2d2c93efa0@redhat.com>
Date: Mon, 6 Jul 2020 12:37:12 +0200
From: Auger Eric <eric.auger@...hat.com>
To: Liu Yi L <yi.l.liu@...el.com>, alex.williamson@...hat.com,
baolu.lu@...ux.intel.com, joro@...tes.org
Cc: kevin.tian@...el.com, jacob.jun.pan@...ux.intel.com,
ashok.raj@...el.com, jun.j.tian@...el.com, yi.y.sun@...el.com,
jean-philippe@...aro.org, peterx@...hat.com, hao.wu@...el.com,
stefanha@...il.com, iommu@...ts.linux-foundation.org,
kvm@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v4 04/15] vfio/type1: Report iommu nesting info to
userspace
Yi,
On 7/4/20 1:26 PM, Liu Yi L wrote:
> This patch exports iommu nesting capability info to user space through
> VFIO. User space is expected to check this info for supported uAPIs (e.g.
> PASID alloc/free, bind page table, and cache invalidation) and the vendor
> specific format information for first level/stage page table that will be
> bound to.
>
> The nesting info is available only after the nesting iommu type is set
> for a container. Current implementation imposes one limitation - one
> nesting container should include at most one group. The philosophy of
> vfio container is having all groups/devices within the container share
> the same IOMMU context. When vSVA is enabled, one IOMMU context could
> include one 2nd-level address space and multiple 1st-level address spaces.
> While the 2nd-leve address space is reasonably sharable by multiple groups
level
> , blindly sharing 1st-level address spaces across all groups within the
> container might instead break the guest expectation. In the future sub/
> super container concept might be introduced to allow partial address space
> sharing within an IOMMU context. But for now let's go with this restriction
> by requiring singleton container for using nesting iommu features. Below
> link has the related discussion about this decision.
>
> https://lkml.org/lkml/2020/5/15/1028
>
> Cc: Kevin Tian <kevin.tian@...el.com>
> CC: Jacob Pan <jacob.jun.pan@...ux.intel.com>
> Cc: Alex Williamson <alex.williamson@...hat.com>
> Cc: Eric Auger <eric.auger@...hat.com>
> Cc: Jean-Philippe Brucker <jean-philippe@...aro.org>
> Cc: Joerg Roedel <joro@...tes.org>
> Cc: Lu Baolu <baolu.lu@...ux.intel.com>
> Signed-off-by: Liu Yi L <yi.l.liu@...el.com>
> ---
> v3 -> v4:
> *) address comments against v3.
>
> v1 -> v2:
> *) added in v2
> ---
>
> drivers/vfio/vfio_iommu_type1.c | 105 +++++++++++++++++++++++++++++++++++-----
> include/uapi/linux/vfio.h | 16 ++++++
> 2 files changed, 109 insertions(+), 12 deletions(-)
>
> diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c
> index 7accb59..80623b8 100644
> --- a/drivers/vfio/vfio_iommu_type1.c
> +++ b/drivers/vfio/vfio_iommu_type1.c
> @@ -62,18 +62,20 @@ MODULE_PARM_DESC(dma_entry_limit,
> "Maximum number of user DMA mappings per container (65535).");
>
> struct vfio_iommu {
> - struct list_head domain_list;
> - struct list_head iova_list;
> - struct vfio_domain *external_domain; /* domain for external user */
> - struct mutex lock;
> - struct rb_root dma_list;
> - struct blocking_notifier_head notifier;
> - unsigned int dma_avail;
> - uint64_t pgsize_bitmap;
> - bool v2;
> - bool nesting;
> - bool dirty_page_tracking;
> - bool pinned_page_dirty_scope;
> + struct list_head domain_list;
> + struct list_head iova_list;
> + struct vfio_domain *external_domain; /* domain for
> + external user */
nit: put the comment before the field?
> + struct mutex lock;
> + struct rb_root dma_list;
> + struct blocking_notifier_head notifier;
> + unsigned int dma_avail;
> + uint64_t pgsize_bitmap;
> + bool v2;
> + bool nesting;
> + bool dirty_page_tracking;
> + bool pinned_page_dirty_scope;
> + struct iommu_nesting_info *nesting_info;
> };
>
> struct vfio_domain {
> @@ -130,6 +132,9 @@ struct vfio_regions {
> #define IS_IOMMU_CAP_DOMAIN_IN_CONTAINER(iommu) \
> (!list_empty(&iommu->domain_list))
>
> +#define IS_DOMAIN_IN_CONTAINER(iommu) ((iommu->external_domain) || \
> + (!list_empty(&iommu->domain_list)))
rename into something like CONTAINER_HAS_DOMAIN()?
> +
> #define DIRTY_BITMAP_BYTES(n) (ALIGN(n, BITS_PER_TYPE(u64)) / BITS_PER_BYTE)
>
> /*
> @@ -1929,6 +1934,13 @@ static void vfio_iommu_iova_insert_copy(struct vfio_iommu *iommu,
>
> list_splice_tail(iova_copy, iova);
> }
> +
> +static void vfio_iommu_release_nesting_info(struct vfio_iommu *iommu)
> +{
> + kfree(iommu->nesting_info);
> + iommu->nesting_info = NULL;
> +}
> +
> static int vfio_iommu_type1_attach_group(void *iommu_data,
> struct iommu_group *iommu_group)
> {
> @@ -1959,6 +1971,12 @@ static int vfio_iommu_type1_attach_group(void *iommu_data,
> }
> }
>
> + /* Nesting type container can include only one group */
> + if (iommu->nesting && IS_DOMAIN_IN_CONTAINER(iommu)) {
> + mutex_unlock(&iommu->lock);
> + return -EINVAL;
> + }
> +
> group = kzalloc(sizeof(*group), GFP_KERNEL);
> domain = kzalloc(sizeof(*domain), GFP_KERNEL);
> if (!group || !domain) {
> @@ -2029,6 +2047,36 @@ static int vfio_iommu_type1_attach_group(void *iommu_data,
> if (ret)
> goto out_domain;
>
> + /* Nesting cap info is available only after attaching */
> + if (iommu->nesting) {
> + struct iommu_nesting_info tmp;
> + struct iommu_nesting_info *info;
> +
> + /* First get the size of vendor specific nesting info */
> + ret = iommu_domain_get_attr(domain->domain,
> + DOMAIN_ATTR_NESTING,
> + &tmp);
> + if (ret)
> + goto out_detach;
> +
> + info = kzalloc(tmp.size, GFP_KERNEL);
nit: you may directly use iommu->nesting_info
> + if (!info) {
> + ret = -ENOMEM;
> + goto out_detach;
> + }
> +
> + /* Now get the nesting info */
> + info->size = tmp.size;
> + ret = iommu_domain_get_attr(domain->domain,
> + DOMAIN_ATTR_NESTING,
> + info);
> + if (ret) {
> + kfree(info);
... and set it back to NULL here if it fails
> + goto out_detach;
> + }
> + iommu->nesting_info = info;
> + }
> +
> /* Get aperture info */
> iommu_domain_get_attr(domain->domain, DOMAIN_ATTR_GEOMETRY, &geo);
>
> @@ -2138,6 +2186,7 @@ static int vfio_iommu_type1_attach_group(void *iommu_data,
> return 0;
>
> out_detach:
> + vfio_iommu_release_nesting_info(iommu);
> vfio_iommu_detach_group(domain, group);
> out_domain:
> iommu_domain_free(domain->domain);
> @@ -2338,6 +2387,8 @@ static void vfio_iommu_type1_detach_group(void *iommu_data,
> vfio_iommu_unmap_unpin_all(iommu);
> else
> vfio_iommu_unmap_unpin_reaccount(iommu);
> +
> + vfio_iommu_release_nesting_info(iommu);
> }
> iommu_domain_free(domain->domain);
> list_del(&domain->next);
> @@ -2546,6 +2597,30 @@ static int vfio_iommu_migration_build_caps(struct vfio_iommu *iommu,
> return vfio_info_add_capability(caps, &cap_mig.header, sizeof(cap_mig));
> }
>
> +static int vfio_iommu_info_add_nesting_cap(struct vfio_iommu *iommu,
> + struct vfio_info_cap *caps)
> +{
> + struct vfio_info_cap_header *header;
> + struct vfio_iommu_type1_info_cap_nesting *nesting_cap;
> + size_t size;
> +
> + size = sizeof(*nesting_cap) + iommu->nesting_info->size;
> +
> + header = vfio_info_cap_add(caps, size,
> + VFIO_IOMMU_TYPE1_INFO_CAP_NESTING, 1);
> + if (IS_ERR(header))
> + return PTR_ERR(header);
> +
> + nesting_cap = container_of(header,
> + struct vfio_iommu_type1_info_cap_nesting,
> + header);
> +
> + memcpy(&nesting_cap->info, iommu->nesting_info,
> + iommu->nesting_info->size);
> +
> + return 0;
> +}
> +
> static int vfio_iommu_type1_get_info(struct vfio_iommu *iommu,
> unsigned long arg)
> {
> @@ -2586,6 +2661,12 @@ static int vfio_iommu_type1_get_info(struct vfio_iommu *iommu,
> if (ret)
> return ret;
>
> + if (iommu->nesting_info) {
> + ret = vfio_iommu_info_add_nesting_cap(iommu, &caps);
> + if (ret)
> + return ret;
> + }
> +
> if (caps.size) {
> info.flags |= VFIO_IOMMU_INFO_CAPS;
>
> diff --git a/include/uapi/linux/vfio.h b/include/uapi/linux/vfio.h
> index 9204705..3e3de9c 100644
> --- a/include/uapi/linux/vfio.h
> +++ b/include/uapi/linux/vfio.h
> @@ -1039,6 +1039,22 @@ struct vfio_iommu_type1_info_cap_migration {
> __u64 max_dirty_bitmap_size; /* in bytes */
> };
>
> +#define VFIO_IOMMU_TYPE1_INFO_CAP_NESTING 3
You may improve the documentation by taking examples from the above caps.
> +
> +/*
> + * Reporting nesting info to user space.
> + *
> + * @info: the nesting info provided by IOMMU driver. Today
> + * it is expected to be a struct iommu_nesting_info
> + * data.
Is it expected to change?
> + */
> +struct vfio_iommu_type1_info_cap_nesting {
> + struct vfio_info_cap_header header;
> + __u32 flags;
You may document flags.
> + __u32 padding;
> + __u8 info[];
> +};
> +
> #define VFIO_IOMMU_GET_INFO _IO(VFIO_TYPE, VFIO_BASE + 12)
>
> /**
>
Thanks
Eric
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