Yi, On 7/20/20 9:51 AM, Liu, Yi L wrote: > Hi Eric, > >> From: Auger Eric <eric.auger@xxxxxxxxxx> >> Sent: Saturday, July 18, 2020 1:34 AM >> >> Yi, >> >> On 7/12/20 1:20 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. >> it is not only to check the supported uAPIS but rather to know which >> callbacks it must call upon vIOMMU events and which features are >> supported by the physical IOMMU. > > yes, will refine the description per your comment. > >>> 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. >> to NESTED type > > you mean "The nesting info is available only after container set to be NESTED type." > > right? correct > >> 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-level address space is reasonably sharable by multiple groups >>> , 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. >> >> Maybe add a note about SMMU related changes spotted by Jean. > > I guess you mean the comments Jean gave in patch 3/15, right? I'll > copy his comments and also give the below link as well. > > https://lore.kernel.org/kvm/20200717090900.GC4850@myrica/ correct Thanks Eric > >>> >>> 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> >>> --- >>> v4 -> v5: >>> *) address comments from Eric Auger. >>> *) return struct iommu_nesting_info for >> VFIO_IOMMU_TYPE1_INFO_CAP_NESTING as >>> cap is much "cheap", if needs extension in future, just define another cap. >>> https://lore.kernel.org/kvm/20200708132947.5b7ee954@xxxxxxx/ >>> >>> v3 -> v4: >>> *) address comments against v3. >>> >>> v1 -> v2: >>> *) added in v2 >>> --- >>> drivers/vfio/vfio_iommu_type1.c | 102 >> +++++++++++++++++++++++++++++++++++----- >>> include/uapi/linux/vfio.h | 19 ++++++++ >>> 2 files changed, 109 insertions(+), 12 deletions(-) >>> >>> diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c >>> index 3bd70ff..ed80104 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; >>> + /* domain for external user */ >>> + struct vfio_domain *external_domain; >>> + 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 CONTAINER_HAS_DOMAIN(iommu) (((iommu)->external_domain) || \ >>> + (!list_empty(&(iommu)->domain_list))) >>> + >>> #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 && CONTAINER_HAS_DOMAIN(iommu)) { >>> + mutex_unlock(&iommu->lock); >>> + return -EINVAL; >>> + } >>> + >>> group = kzalloc(sizeof(*group), GFP_KERNEL); >>> domain = kzalloc(sizeof(*domain), GFP_KERNEL); >>> if (!group || !domain) { >>> @@ -2029,6 +2047,32 @@ 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 = { .size = 0, }; >>> + >>> + /* 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; >>> + >>> + iommu->nesting_info = kzalloc(tmp.size, GFP_KERNEL); >>> + if (!iommu->nesting_info) { >>> + ret = -ENOMEM; >>> + goto out_detach; >>> + } >>> + >>> + /* Now get the nesting info */ >>> + iommu->nesting_info->size = tmp.size; >>> + ret = iommu_domain_get_attr(domain->domain, >>> + DOMAIN_ATTR_NESTING, >>> + iommu->nesting_info); >>> + if (ret) >>> + goto out_detach; > > get nesting_info failure will result in group_attach failure.[1] > >>> + } >>> + >>> /* Get aperture info */ >>> iommu_domain_get_attr(domain->domain, DOMAIN_ATTR_GEOMETRY, >> &geo); >>> >>> @@ -2138,6 +2182,7 @@ 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 +2383,8 @@ 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 +2593,31 @@ 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 = offsetof(struct vfio_iommu_type1_info_cap_nesting, info) + >>> + 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); >> you must check whether nesting_info is non NULL before doing that. > > it's now validated in the caller of this function. :-) ah ok sorry I missed that. > >> Besides I agree with Jean on the fact it may be better to not report the >> capability if nested is not supported. > > I see. in this patch, just few lines below [2], vfio only reports nesting > cap when iommu->nesting_info is non-null. so even if userspace selected > nesting type, it may fail at the VFIO_SET_IOMMU phase since group_attach > will be failed for NESTED type container if host iommu doesn’t support > nesting. the code is marked as [1] in this email. OK that's already there then. Thanks Eric > >>> + >>> + return 0; >>> +} >>> + >>> static int vfio_iommu_type1_get_info(struct vfio_iommu *iommu, >>> unsigned long arg) >>> { >>> @@ -2581,6 +2653,12 @@ static int vfio_iommu_type1_get_info(struct >> vfio_iommu *iommu, >>> if (!ret) >>> ret = vfio_iommu_iova_build_caps(iommu, &caps); >>> >>> + if (iommu->nesting_info) { >>> + ret = vfio_iommu_info_add_nesting_cap(iommu, &caps); >>> + if (ret) >>> + return ret; > > here checks nesting_info before reporting nesting cap. [2] > >>> + } >>> + >>> mutex_unlock(&iommu->lock); >>> >>> if (ret) >>> diff --git a/include/uapi/linux/vfio.h b/include/uapi/linux/vfio.h >>> index 9204705..46a78af 100644 >>> --- a/include/uapi/linux/vfio.h >>> +++ b/include/uapi/linux/vfio.h >>> @@ -14,6 +14,7 @@ >>> >>> #include <linux/types.h> >>> #include <linux/ioctl.h> >>> +#include <linux/iommu.h> >>> >>> #define VFIO_API_VERSION 0 >>> >>> @@ -1039,6 +1040,24 @@ struct vfio_iommu_type1_info_cap_migration { >>> __u64 max_dirty_bitmap_size; /* in bytes */ >>> }; >>> >>> +/* >>> + * 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 selected VFIO_TYPE1_NESTING_IOMMU type should check >>> + * this capto get supported features. >> s/capto/capability to get > > got it. > > Regards, > Yi Liu > >>> + * >>> + * @info: the nesting info provided by IOMMU driver. >>> + */ >>> +#define VFIO_IOMMU_TYPE1_INFO_CAP_NESTING 3 >>> + >>> +struct vfio_iommu_type1_info_cap_nesting { >>> + struct vfio_info_cap_header header; >>> + struct iommu_nesting_info info; >>> +}; >>> + >>> #define VFIO_IOMMU_GET_INFO _IO(VFIO_TYPE, VFIO_BASE + 12) >>> >>> /** >>> >> >> Thanks >> >> Eric >
