From: Alex Williamson <alex.williamson@redhat.com>
To: Liu Yi L <yi.l.liu@intel.com>
Cc: jean-philippe@linaro.org, kevin.tian@intel.com,
ashok.raj@intel.com, kvm@vger.kernel.org, jasowang@redhat.com,
stefanha@gmail.com, iommu@lists.linux-foundation.org,
yi.y.sun@intel.com, hao.wu@intel.com, jun.j.tian@intel.com
Subject: Re: [PATCH v7 03/16] vfio/type1: Report iommu nesting info to userspace
Date: Fri, 11 Sep 2020 14:16:41 -0600 [thread overview]
Message-ID: <20200911141641.6f77f4d3@w520.home> (raw)
In-Reply-To: <1599734733-6431-4-git-send-email-yi.l.liu@intel.com>
On Thu, 10 Sep 2020 03:45:20 -0700
Liu Yi L <yi.l.liu@intel.com> wrote:
> This patch exports iommu nesting capability info to user space through
> VFIO. Userspace 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 container set to be NESTED type.
> Current implementation imposes one limitation - one nesting container
> should include at most one iommu 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.
>
> https://lore.kernel.org/kvm/20200515115924.37e6996d@w520.home/
>
> This patch also changes the NESTING type container behaviour. Something
> that would have succeeded before will now fail: Before this series, if
> user asked for a VFIO_IOMMU_TYPE1_NESTING, it would have succeeded even
> if the SMMU didn't support stage-2, as the driver would have silently
> fallen back on stage-1 mappings (which work exactly the same as stage-2
> only since there was no nesting supported). After the series, we do check
> for DOMAIN_ATTR_NESTING so if user asks for VFIO_IOMMU_TYPE1_NESTING and
> the SMMU doesn't support stage-2, the ioctl fails. But it should be a good
> fix and completely harmless. Detail can be found in below link as well.
>
> https://lore.kernel.org/kvm/20200717090900.GC4850@myrica/
>
> Cc: Kevin Tian <kevin.tian@intel.com>
> CC: Jacob Pan <jacob.jun.pan@linux.intel.com>
> Cc: Alex Williamson <alex.williamson@redhat.com>
> Cc: Eric Auger <eric.auger@redhat.com>
> Cc: Jean-Philippe Brucker <jean-philippe@linaro.org>
> Cc: Joerg Roedel <joro@8bytes.org>
> Cc: Lu Baolu <baolu.lu@linux.intel.com>
> Signed-off-by: Liu Yi L <yi.l.liu@intel.com>
> ---
> v6 -> v7:
> *) using vfio_info_add_capability() for adding nesting cap per suggestion
> from Eric.
>
> v5 -> v6:
> *) address comments against v5 from Eric Auger.
> *) don't report nesting cap to userspace if the nesting_info->format is
> invalid.
>
> 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@x1.home/
>
> v3 -> v4:
> *) address comments against v3.
>
> v1 -> v2:
> *) added in v2
> ---
> drivers/vfio/vfio_iommu_type1.c | 92 +++++++++++++++++++++++++++++++++++------
> include/uapi/linux/vfio.h | 19 +++++++++
> 2 files changed, 99 insertions(+), 12 deletions(-)
>
> diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c
> index c992973..3c0048b 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;
Nit, not as important as the previous alignment, but might as well move
this up with the uint64_t pgsize_bitmap with the bools at the end of
the structure to avoid adding new gaps.
> };
>
> 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)
>
> /*
> @@ -1992,6 +1997,13 @@ 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)
> {
> @@ -2022,6 +2034,12 @@ 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) {
> @@ -2092,6 +2110,25 @@ 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) {
> + int size = sizeof(struct iommu_nesting_info);
> +
> + iommu->nesting_info = kzalloc(size, GFP_KERNEL);
> + if (!iommu->nesting_info) {
> + ret = -ENOMEM;
> + goto out_detach;
> + }
> +
> + /* Now get the nesting info */
> + iommu->nesting_info->argsz = size;
> + ret = iommu_domain_get_attr(domain->domain,
> + DOMAIN_ATTR_NESTING,
> + iommu->nesting_info);
> + if (ret)
> + goto out_detach;
> + }
> +
> /* Get aperture info */
> iommu_domain_get_attr(domain->domain, DOMAIN_ATTR_GEOMETRY, &geo);
>
> @@ -2201,6 +2238,7 @@ 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);
> @@ -2401,6 +2439,8 @@ 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);
> @@ -2609,6 +2649,32 @@ 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_add_nesting_cap(struct vfio_iommu *iommu,
> + struct vfio_info_cap *caps)
> +{
> + struct vfio_iommu_type1_info_cap_nesting nesting_cap;
> + size_t size;
> +
> + /* when nesting_info is null, no need to go further */
> + if (!iommu->nesting_info)
> + return 0;
> +
> + /* when @format of nesting_info is 0, fail the call */
> + if (iommu->nesting_info->format == 0)
> + return -ENOENT;
Should we fail this in the attach_group? Seems the user would be in a
bad situation here if they successfully created a nesting container but
can't get info. Is there backwards compatibility we're trying to
maintain with this?
> +
> + size = offsetof(struct vfio_iommu_type1_info_cap_nesting, info) +
> + iommu->nesting_info->argsz;
> +
> + nesting_cap.header.id = VFIO_IOMMU_TYPE1_INFO_CAP_NESTING;
> + nesting_cap.header.version = 1;
> +
> + memcpy(&nesting_cap.info, iommu->nesting_info,
> + iommu->nesting_info->argsz);
> +
> + return vfio_info_add_capability(caps, &nesting_cap.header, size);
> +}
> +
> static int vfio_iommu_type1_get_info(struct vfio_iommu *iommu,
> unsigned long arg)
> {
> @@ -2644,6 +2710,8 @@ static int vfio_iommu_type1_get_info(struct vfio_iommu *iommu,
> if (!ret)
> ret = vfio_iommu_iova_build_caps(iommu, &caps);
>
> + ret = vfio_iommu_add_nesting_cap(iommu, &caps);
Why don't we follow either the naming scheme or the error handling
scheme of the previous caps? Seems like this should be:
if (!ret)
ret = vfio_iommu_nesting_build_caps(...);
Thanks,
Alex
> +
> mutex_unlock(&iommu->lock);
>
> if (ret)
> diff --git a/include/uapi/linux/vfio.h b/include/uapi/linux/vfio.h
> index 9204705..ff40f9e 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.
> + *
> + * Nested capabilities should be checked by the userspace after
> + * setting VFIO_TYPE1_NESTING_IOMMU.
> + *
> + * @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)
>
> /**
_______________________________________________
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next prev parent reply other threads:[~2020-09-11 20:17 UTC|newest]
Thread overview: 84+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-09-10 10:45 [PATCH v7 00/16] vfio: expose virtual Shared Virtual Addressing to VMs Liu Yi L
2020-09-10 10:45 ` [PATCH v7 01/16] iommu: Report domain nesting info Liu Yi L
2020-09-11 19:38 ` Alex Williamson
2020-09-10 10:45 ` [PATCH v7 02/16] iommu/smmu: Report empty " Liu Yi L
2021-01-12 6:50 ` Vivek Gautam
2021-01-12 9:21 ` Liu, Yi L
2021-01-12 11:05 ` Vivek Gautam
2021-01-13 5:56 ` Liu, Yi L
2021-01-19 10:03 ` Auger Eric
2021-01-23 8:59 ` Liu, Yi L
2021-02-12 7:14 ` Vivek Gautam
2021-02-12 9:57 ` Auger Eric
2021-02-12 10:18 ` Vivek Kumar Gautam
2021-02-12 11:01 ` Vivek Kumar Gautam
2021-03-03 9:44 ` Liu, Yi L
2020-09-10 10:45 ` [PATCH v7 03/16] vfio/type1: Report iommu nesting info to userspace Liu Yi L
2020-09-11 20:16 ` Alex Williamson [this message]
2020-09-12 8:24 ` Liu, Yi L
2020-09-10 10:45 ` [PATCH v7 04/16] vfio: Add PASID allocation/free support Liu Yi L
2020-09-11 20:54 ` Alex Williamson
2020-09-15 4:03 ` Liu, Yi L
2020-09-10 10:45 ` [PATCH v7 05/16] iommu/vt-d: Support setting ioasid set to domain Liu Yi L
2020-09-10 10:45 ` [PATCH v7 06/16] iommu/vt-d: Remove get_task_mm() in bind_gpasid() Liu Yi L
2020-09-10 10:45 ` [PATCH v7 07/16] vfio/type1: Add VFIO_IOMMU_PASID_REQUEST (alloc/free) Liu Yi L
2020-09-11 21:38 ` Alex Williamson
2020-09-12 6:17 ` Liu, Yi L
2020-09-10 10:45 ` [PATCH v7 08/16] iommu: Pass domain to sva_unbind_gpasid() Liu Yi L
2020-09-10 10:45 ` [PATCH v7 09/16] iommu/vt-d: Check ownership for PASIDs from user-space Liu Yi L
2020-09-10 10:45 ` [PATCH v7 10/16] vfio/type1: Support binding guest page tables to PASID Liu Yi L
2020-09-11 22:03 ` Alex Williamson
2020-09-12 6:02 ` Liu, Yi L
2020-09-10 10:45 ` [PATCH v7 11/16] vfio/type1: Allow invalidating first-level/stage IOMMU cache Liu Yi L
2020-09-10 10:45 ` [PATCH v7 12/16] vfio/type1: Add vSVA support for IOMMU-backed mdevs Liu Yi L
2020-09-10 10:45 ` [PATCH v7 13/16] vfio/pci: Expose PCIe PASID capability to guest Liu Yi L
2020-09-11 22:13 ` Alex Williamson
2020-09-12 7:17 ` Liu, Yi L
2020-09-10 10:45 ` [PATCH v7 14/16] vfio: Document dual stage control Liu Yi L
2020-09-10 10:45 ` [PATCH v7 15/16] iommu/vt-d: Only support nesting when nesting caps are consistent across iommu units Liu Yi L
2020-09-10 10:45 ` [PATCH v7 16/16] iommu/vt-d: Support reporting nesting capability info Liu Yi L
2020-09-14 4:20 ` [PATCH v7 00/16] vfio: expose virtual Shared Virtual Addressing to VMs Jason Wang
2020-09-14 8:01 ` Tian, Kevin
2020-09-14 8:57 ` Jason Wang
2020-09-14 10:38 ` Tian, Kevin
2020-09-14 11:38 ` Jason Gunthorpe
2020-09-14 13:31 ` Jean-Philippe Brucker
2020-09-14 13:47 ` Jason Gunthorpe
2020-09-14 16:22 ` Raj, Ashok
2020-09-14 16:33 ` Jason Gunthorpe
2020-09-14 16:58 ` Alex Williamson
2020-09-14 17:41 ` Jason Gunthorpe
2020-09-14 18:23 ` Alex Williamson
2020-09-14 19:00 ` Jason Gunthorpe
2020-09-14 22:33 ` Alex Williamson
2020-09-15 14:29 ` Jason Gunthorpe
2020-09-16 1:19 ` Tian, Kevin
2020-09-16 8:32 ` Jean-Philippe Brucker
2020-09-16 14:51 ` Jason Gunthorpe
2020-09-16 16:20 ` Jean-Philippe Brucker
2020-09-16 16:32 ` Jason Gunthorpe
2020-09-16 16:50 ` Auger Eric
2020-09-16 14:44 ` Jason Gunthorpe
2020-09-17 6:01 ` Tian, Kevin
2020-09-14 22:44 ` Raj, Ashok
2020-09-15 11:33 ` Jason Gunthorpe
2020-09-15 18:11 ` Raj, Ashok
2020-09-15 18:45 ` Jason Gunthorpe
2020-09-15 19:26 ` Raj, Ashok
2020-09-15 23:45 ` Jason Gunthorpe
2020-09-16 2:33 ` Jason Wang
2020-09-15 22:08 ` Jacob Pan
2020-09-15 23:51 ` Jason Gunthorpe
2020-09-16 0:22 ` Jacob Pan (Jun)
2020-09-16 1:46 ` Lu Baolu
2020-09-16 15:07 ` Jason Gunthorpe
2020-09-16 16:33 ` Raj, Ashok
2020-09-16 17:01 ` Jason Gunthorpe
2020-09-16 18:21 ` Jacob Pan (Jun)
2020-09-16 18:38 ` Jason Gunthorpe
2020-09-16 23:09 ` Jacob Pan (Jun)
2020-09-17 3:53 ` Jason Wang
2020-09-17 17:31 ` Jason Gunthorpe
2020-09-17 18:17 ` Jacob Pan (Jun)
2020-09-18 3:58 ` Jason Wang
2020-09-16 2:29 ` Jason Wang
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