Hi Yi, On 7/6/20 3:10 PM, Liu, Yi L wrote: > Hi Eric, > >> From: Auger Eric <eric.auger@xxxxxxxxxx> >> Sent: Monday, July 6, 2020 6:37 PM >> >> 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 > > oh, yes. > >>> , 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@xxxxxxxxx> >>> CC: Jacob Pan <jacob.jun.pan@xxxxxxxxxxxxxxx> >>> Cc: Alex Williamson <alex.williamson@xxxxxxxxxx> >>> Cc: Eric Auger <eric.auger@xxxxxxxxxx> >>> Cc: Jean-Philippe Brucker <jean-philippe@xxxxxxxxxx> >>> Cc: Joerg Roedel <joro@xxxxxxxxxx> >>> Cc: Lu Baolu <baolu.lu@xxxxxxxxxxxxxxx> >>> Signed-off-by: Liu Yi L <yi.l.liu@xxxxxxxxx> >>> --- >>> 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? > > do you mean below? > > + /* domain for external user */ > + struct vfio_domain *external_domain; yes that's what I meant > >>> + 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()? > > got it. > >>> + >>> #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 > > got you. > >>> + 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 > > and maybe no need to free it here as vfio_iommu_release_nesting_info() > will free the nesting_info. > >>> + 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. > > yes, it is. I somehow broke the style. how about below? > > > > /* > * The nesting capability allows to report the related capability > * and info for nesting iommu type. > * > * The structures below define version 1 of this capability. > * > * User space should check this cap for setup nesting iommu type. before setting up stage 1 information? The wording above sounds a bit confusing to me as it can be interpreted as before choosing VFIO_TYPE1_NESTING_IOMMU. You also need to document it returns the capability only after a group is attached - which looks strange by the way -. Thanks Eric > * > * @info: the nesting info provided by IOMMU driver. Today > * it is expected to be a struct iommu_nesting_info > * data. > #define VFIO_IOMMU_TYPE1_INFO_CAP_NESTING 3 > > struct vfio_iommu_type1_info_cap_nesting { > ... > }; > >>> + >>> +/* >>> + * 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? > > honestly, I'm not quite sure on it. I did considered to embed > struct iommu_nesting_info here instead of using info[]. but I > hesitated as using info[] may leave more flexibility on this > struct. how about your opinion? perhaps it's fine to embed the > struct iommu_nesting_info here as long as VFIO is setup nesting > based on IOMMU UAPI. > >>> + */ >>> +struct vfio_iommu_type1_info_cap_nesting { >>> + struct vfio_info_cap_header header; >>> + __u32 flags; >> You may document flags. > > sure. it's reserved for future. > > Regards, > Yi Liu > >>> + __u32 padding; >>> + __u8 info[]; >>> +}; >>> + >>> #define VFIO_IOMMU_GET_INFO _IO(VFIO_TYPE, VFIO_BASE + 12) >>> >>> /** >>> >> Thanks >> >> Eric >
