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    SubjectRE: [PATCH v3 09/14] vfio/type1: Support binding guest page tables to PASID
    Date
    Hi Alex,

    > From: Alex Williamson <alex.williamson@redhat.com>
    > Sent: Friday, July 3, 2020 5:20 AM
    >
    > On Wed, 24 Jun 2020 01:55:22 -0700
    > Liu Yi L <yi.l.liu@intel.com> wrote:
    >
    > > Nesting translation allows two-levels/stages page tables, with 1st
    > > level for guest translations (e.g. GVA->GPA), 2nd level for host
    > > translations (e.g. GPA->HPA). This patch adds interface for binding
    > > guest page tables to a PASID. This PASID must have been allocated to
    > > user space before the binding request.
    > >
    > > 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: Jean-Philippe Brucker <jean-philippe@linaro.com>
    > > Signed-off-by: Liu Yi L <yi.l.liu@intel.com>
    > > Signed-off-by: Jacob Pan <jacob.jun.pan@linux.intel.com>
    > > ---
    > > v2 -> v3:
    > > *) use __iommu_sva_unbind_gpasid() for unbind call issued by VFIO
    > > https://lore.kernel.org/linux-iommu/1592931837-58223-6-git-send-email-
    > > jacob.jun.pan@linux.intel.com/
    > >
    > > v1 -> v2:
    > > *) rename subject from "vfio/type1: Bind guest page tables to host"
    > > *) remove VFIO_IOMMU_BIND, introduce VFIO_IOMMU_NESTING_OP to
    > support bind/
    > > unbind guet page table
    > > *) replaced vfio_iommu_for_each_dev() with a group level loop since this
    > > series enforces one group per container w/ nesting type as start.
    > > *) rename vfio_bind/unbind_gpasid_fn() to
    > > vfio_dev_bind/unbind_gpasid_fn()
    > > *) vfio_dev_unbind_gpasid() always successful
    > > *) use vfio_mm->pasid_lock to avoid race between PASID free and page table
    > > bind/unbind
    > > ---
    > > drivers/vfio/vfio_iommu_type1.c | 169
    > ++++++++++++++++++++++++++++++++++++++++
    > > drivers/vfio/vfio_pasid.c | 30 +++++++
    > > include/linux/vfio.h | 20 +++++
    > > include/uapi/linux/vfio.h | 30 +++++++
    > > 4 files changed, 249 insertions(+)
    > >
    > > diff --git a/drivers/vfio/vfio_iommu_type1.c
    > > b/drivers/vfio/vfio_iommu_type1.c index d0891c5..5926533 100644
    > > --- a/drivers/vfio/vfio_iommu_type1.c
    > > +++ b/drivers/vfio/vfio_iommu_type1.c
    > > @@ -148,6 +148,33 @@ struct vfio_regions {
    > > #define DIRTY_BITMAP_PAGES_MAX ((u64)INT_MAX)
    > > #define DIRTY_BITMAP_SIZE_MAX
    > DIRTY_BITMAP_BYTES(DIRTY_BITMAP_PAGES_MAX)
    > >
    > > +struct domain_capsule {
    > > + struct vfio_group *group;
    > > + struct iommu_domain *domain;
    > > + void *data;
    > > +};
    > > +
    > > +/* iommu->lock must be held */
    > > +static struct vfio_group *vfio_find_nesting_group(struct vfio_iommu
    > > +*iommu) {
    > > + struct vfio_domain *d;
    > > + struct vfio_group *g, *group = NULL;
    > > +
    > > + if (!iommu->nesting_info)
    > > + return NULL;
    > > +
    > > + /* only support singleton container with nesting type */
    > > + list_for_each_entry(d, &iommu->domain_list, next) {
    > > + list_for_each_entry(g, &d->group_list, next) {
    > > + if (!group) {
    > > + group = g;
    > > + break;
    > > + }
    >
    >
    > We break out of the inner loop only to pointlessly continue in the outer loop
    > when we could simply return g and remove the second group pointer altogether
    > (use "group" instead of "g" if so).

    how about below? :-)

    /* only support singleton container with nesting type */
    list_for_each_entry(d, &iommu->domain_list, next) {
    list_for_each_entry(group, &d->group_list, next) {
    break;
    }
    }

    >
    > > + }
    > > + }
    > > + return group;
    > > +}
    > > +
    > > static int put_pfn(unsigned long pfn, int prot);
    > >
    > > static struct vfio_group *vfio_iommu_find_iommu_group(struct
    > > vfio_iommu *iommu, @@ -2351,6 +2378,48 @@ static int
    > vfio_iommu_resv_refresh(struct vfio_iommu *iommu,
    > > return ret;
    > > }
    > >
    > > +static int vfio_dev_bind_gpasid_fn(struct device *dev, void *data) {
    > > + struct domain_capsule *dc = (struct domain_capsule *)data;
    > > + unsigned long arg = *(unsigned long *) dc->data;
    > > +
    > > + return iommu_sva_bind_gpasid(dc->domain, dev, (void __user *) arg);
    > > +}
    > > +
    > > +static int vfio_dev_unbind_gpasid_fn(struct device *dev, void *data)
    > > +{
    > > + struct domain_capsule *dc = (struct domain_capsule *)data;
    > > + unsigned long arg = *(unsigned long *) dc->data;
    > > +
    > > + iommu_sva_unbind_gpasid(dc->domain, dev, (void __user *) arg);
    > > + return 0;
    > > +}
    > > +
    > > +static int __vfio_dev_unbind_gpasid_fn(struct device *dev, void
    > > +*data) {
    > > + struct domain_capsule *dc = (struct domain_capsule *)data;
    > > + struct iommu_gpasid_bind_data *unbind_data =
    > > + (struct iommu_gpasid_bind_data *) dc->data;
    > > +
    > > + __iommu_sva_unbind_gpasid(dc->domain, dev, unbind_data);
    > > + return 0;
    > > +}
    > > +
    > > +static void vfio_group_unbind_gpasid_fn(ioasid_t pasid, void *data) {
    > > + struct domain_capsule *dc = (struct domain_capsule *) data;
    > > + struct iommu_gpasid_bind_data unbind_data;
    > > +
    > > + unbind_data.argsz = offsetof(struct iommu_gpasid_bind_data, vendor);
    > > + unbind_data.flags = 0;
    > > + unbind_data.hpasid = pasid;
    > > +
    > > + dc->data = &unbind_data;
    > > +
    > > + iommu_group_for_each_dev(dc->group->iommu_group,
    > > + dc, __vfio_dev_unbind_gpasid_fn); }
    > > +
    > > static void vfio_iommu_type1_detach_group(void *iommu_data,
    > > struct iommu_group *iommu_group)
    > { @@ -2394,6 +2463,21 @@
    > > static void vfio_iommu_type1_detach_group(void *iommu_data,
    > > if (!group)
    > > continue;
    > >
    > > + if (iommu->nesting_info && iommu->vmm &&
    > > + (iommu->nesting_info->features &
    > > + IOMMU_NESTING_FEAT_BIND_PGTBL)) {
    > > + struct domain_capsule dc = { .group = group,
    > > + .domain = domain->domain,
    > > + .data = NULL };
    > > +
    > > + /*
    > > + * Unbind page tables bound with system wide PASIDs
    > > + * which are allocated to user space.
    > > + */
    > > + vfio_mm_for_each_pasid(iommu->vmm, &dc,
    > > + vfio_group_unbind_gpasid_fn);
    > > + }
    > > +
    > > vfio_iommu_detach_group(domain, group);
    > > update_dirty_scope = !group->pinned_page_dirty_scope;
    > > list_del(&group->next);
    > > @@ -2942,6 +3026,89 @@ static int vfio_iommu_type1_pasid_request(struct
    > vfio_iommu *iommu,
    > > }
    > > }
    > >
    > > +static long vfio_iommu_handle_pgtbl_op(struct vfio_iommu *iommu,
    > > + bool is_bind, unsigned long arg) {
    > > + struct iommu_nesting_info *info;
    > > + struct domain_capsule dc = { .data = &arg };
    > > + struct vfio_group *group;
    > > + struct vfio_domain *domain;
    > > + int ret;
    > > +
    > > + mutex_lock(&iommu->lock);
    > > +
    > > + info = iommu->nesting_info;
    > > + if (!info || !(info->features & IOMMU_NESTING_FEAT_BIND_PGTBL)) {
    > > + ret = -ENOTSUPP;
    > > + goto out_unlock_iommu;
    > > + }
    > > +
    > > + if (!iommu->vmm) {
    > > + ret = -EINVAL;
    > > + goto out_unlock_iommu;
    > > + }
    > > +
    > > + group = vfio_find_nesting_group(iommu);
    > > + if (!group) {
    > > + ret = -EINVAL;
    > > + goto out_unlock_iommu;
    > > + }
    > > +
    > > + domain = list_first_entry(&iommu->domain_list,
    > > + struct vfio_domain, next);
    > > + dc.group = group;
    > > + dc.domain = domain->domain;
    > > +
    > > + /* Avoid race with other containers within the same process */
    > > + vfio_mm_pasid_lock(iommu->vmm);
    > > +
    > > + if (is_bind) {
    > > + ret = iommu_group_for_each_dev(group->iommu_group, &dc,
    > > + vfio_dev_bind_gpasid_fn);
    > > + if (ret)
    > > + iommu_group_for_each_dev(group->iommu_group,
    > &dc,
    > > + vfio_dev_unbind_gpasid_fn);
    > > + } else {
    > > + iommu_group_for_each_dev(group->iommu_group,
    > > + &dc, vfio_dev_unbind_gpasid_fn);
    > > + ret = 0;
    > > + }
    > > +
    > > + vfio_mm_pasid_unlock(iommu->vmm);
    > > +out_unlock_iommu:
    > > + mutex_unlock(&iommu->lock);
    > > + return ret;
    > > +}
    > > +
    > > +static long vfio_iommu_type1_nesting_op(struct vfio_iommu *iommu,
    > > + unsigned long arg)
    > > +{
    > > + struct vfio_iommu_type1_nesting_op hdr;
    > > + unsigned int minsz;
    > > + int ret;
    > > +
    > > + minsz = offsetofend(struct vfio_iommu_type1_nesting_op, flags);
    > > +
    > > + if (copy_from_user(&hdr, (void __user *)arg, minsz))
    > > + return -EFAULT;
    > > +
    > > + if (hdr.argsz < minsz || hdr.flags & ~VFIO_NESTING_OP_MASK)
    > > + return -EINVAL;
    > > +
    > > + switch (hdr.flags & VFIO_NESTING_OP_MASK) {
    > > + case VFIO_IOMMU_NESTING_OP_BIND_PGTBL:
    > > + ret = vfio_iommu_handle_pgtbl_op(iommu, true, arg + minsz);
    > > + break;
    > > + case VFIO_IOMMU_NESTING_OP_UNBIND_PGTBL:
    > > + ret = vfio_iommu_handle_pgtbl_op(iommu, false, arg + minsz);
    > > + break;
    > > + default:
    > > + ret = -EINVAL;
    > > + }
    > > +
    > > + return ret;
    > > +}
    > > +
    > > static long vfio_iommu_type1_ioctl(void *iommu_data,
    > > unsigned int cmd, unsigned long arg) { @@ -
    > 2960,6 +3127,8 @@
    > > static long vfio_iommu_type1_ioctl(void *iommu_data,
    > > return vfio_iommu_type1_dirty_pages(iommu, arg);
    > > case VFIO_IOMMU_PASID_REQUEST:
    > > return vfio_iommu_type1_pasid_request(iommu, arg);
    > > + case VFIO_IOMMU_NESTING_OP:
    > > + return vfio_iommu_type1_nesting_op(iommu, arg);
    > > }
    > >
    > > return -ENOTTY;
    > > diff --git a/drivers/vfio/vfio_pasid.c b/drivers/vfio/vfio_pasid.c
    > > index 2ea9f1a..20f1e72 100644
    > > --- a/drivers/vfio/vfio_pasid.c
    > > +++ b/drivers/vfio/vfio_pasid.c
    > > @@ -30,6 +30,7 @@ struct vfio_mm {
    > > struct kref kref;
    > > struct vfio_mm_token token;
    > > int ioasid_sid;
    > > + struct mutex pasid_lock;
    >
    >
    > Introducing holes in the data structure again, mind the alignment.
    > This wastes 8 byte. Thanks,

    sure. also it's likely to remove @pasid_quota. so it should avoid the
    hole as well.

    Regards,
    Yi Liu

    > Alex
    >
    >
    > > int pasid_quota;
    > > struct list_head next;
    > > };
    > > @@ -97,6 +98,7 @@ struct vfio_mm *vfio_mm_get_from_task(struct
    > task_struct *task)
    > > kref_init(&vmm->kref);
    > > vmm->token.val = (unsigned long long) mm;
    > > vmm->pasid_quota = pasid_quota;
    > > + mutex_init(&vmm->pasid_lock);
    > >
    > > list_add(&vmm->next, &vfio_pasid.vfio_mm_list);
    > > out:
    > > @@ -134,12 +136,40 @@ void vfio_pasid_free_range(struct vfio_mm *vmm,
    > > * IOASID core will notify PASID users (e.g. IOMMU driver) to
    > > * teardown necessary structures depending on the to-be-freed
    > > * PASID.
    > > + * Hold pasid_lock to avoid race with PASID usages like bind/
    > > + * unbind page tables to requested PASID.
    > > */
    > > + mutex_lock(&vmm->pasid_lock);
    > > for (; pasid <= max; pasid++)
    > > ioasid_free(pasid);
    > > + mutex_unlock(&vmm->pasid_lock);
    > > }
    > > EXPORT_SYMBOL_GPL(vfio_pasid_free_range);
    > >
    > > +int vfio_mm_for_each_pasid(struct vfio_mm *vmm, void *data,
    > > + void (*fn)(ioasid_t id, void *data)) {
    > > + int ret;
    > > +
    > > + mutex_lock(&vmm->pasid_lock);
    > > + ret = ioasid_set_for_each_ioasid(vmm->ioasid_sid, fn, data);
    > > + mutex_unlock(&vmm->pasid_lock);
    > > + return ret;
    > > +}
    > > +EXPORT_SYMBOL_GPL(vfio_mm_for_each_pasid);
    > > +
    > > +void vfio_mm_pasid_lock(struct vfio_mm *vmm) {
    > > + mutex_lock(&vmm->pasid_lock);
    > > +}
    > > +EXPORT_SYMBOL_GPL(vfio_mm_pasid_lock);
    > > +
    > > +void vfio_mm_pasid_unlock(struct vfio_mm *vmm) {
    > > + mutex_unlock(&vmm->pasid_lock);
    > > +}
    > > +EXPORT_SYMBOL_GPL(vfio_mm_pasid_unlock);
    > > +
    > > static int __init vfio_pasid_init(void) {
    > > mutex_init(&vfio_pasid.vfio_mm_lock);
    > > diff --git a/include/linux/vfio.h b/include/linux/vfio.h index
    > > 8e60a32..9028a09 100644
    > > --- a/include/linux/vfio.h
    > > +++ b/include/linux/vfio.h
    > > @@ -105,6 +105,11 @@ int vfio_mm_ioasid_sid(struct vfio_mm *vmm);
    > > extern int vfio_pasid_alloc(struct vfio_mm *vmm, int min, int max);
    > > extern void vfio_pasid_free_range(struct vfio_mm *vmm,
    > > ioasid_t min, ioasid_t max);
    > > +extern int vfio_mm_for_each_pasid(struct vfio_mm *vmm, void *data,
    > > + void (*fn)(ioasid_t id, void *data)); extern void
    > > +vfio_mm_pasid_lock(struct vfio_mm *vmm); extern void
    > > +vfio_mm_pasid_unlock(struct vfio_mm *vmm);
    > > +
    > > #else
    > > static inline struct vfio_mm *vfio_mm_get_from_task(struct
    > > task_struct *task) { @@ -129,6 +134,21 @@ static inline void
    > > vfio_pasid_free_range(struct vfio_mm *vmm,
    > > ioasid_t min, ioasid_t max)
    > > {
    > > }
    > > +
    > > +static inline int vfio_mm_for_each_pasid(struct vfio_mm *vmm, void *data,
    > > + void (*fn)(ioasid_t id, void *data)) {
    > > + return -ENOTTY;
    > > +}
    > > +
    > > +static inline void vfio_mm_pasid_lock(struct vfio_mm *vmm) { }
    > > +
    > > +static inline void vfio_mm_pasid_unlock(struct vfio_mm *vmm) { }
    > > +
    > > #endif /* CONFIG_VFIO_PASID */
    > >
    > > /*
    > > diff --git a/include/uapi/linux/vfio.h b/include/uapi/linux/vfio.h
    > > index 657b2db..2c9def8 100644
    > > --- a/include/uapi/linux/vfio.h
    > > +++ b/include/uapi/linux/vfio.h
    > > @@ -1198,6 +1198,36 @@ struct vfio_iommu_type1_pasid_request {
    > >
    > > #define VFIO_IOMMU_PASID_REQUEST _IO(VFIO_TYPE, VFIO_BASE + 18)
    > >
    > > +/**
    > > + * VFIO_IOMMU_NESTING_OP - _IOW(VFIO_TYPE, VFIO_BASE + 19,
    > > + * struct vfio_iommu_type1_nesting_op)
    > > + *
    > > + * This interface allows user space to utilize the nesting IOMMU
    > > + * capabilities as reported through VFIO_IOMMU_GET_INFO.
    > > + *
    > > + * @data[] types defined for each op:
    > > + *
    > +=================+===========================================
    > ====+
    > > + * | NESTING OP | @data[] |
    > > + *
    > +=================+===========================================
    > ====+
    > > + * | BIND_PGTBL | struct iommu_gpasid_bind_data |
    > > + * +-----------------+-----------------------------------------------+
    > > + * | UNBIND_PGTBL | struct iommu_gpasid_bind_data |
    > > + *
    > > ++-----------------+-----------------------------------------------+
    > > + *
    > > + * returns: 0 on success, -errno on failure.
    > > + */
    > > +struct vfio_iommu_type1_nesting_op {
    > > + __u32 argsz;
    > > + __u32 flags;
    > > +#define VFIO_NESTING_OP_MASK (0xffff) /* lower 16-bits for op */
    > > + __u8 data[];
    > > +};
    > > +
    > > +#define VFIO_IOMMU_NESTING_OP_BIND_PGTBL (0)
    > > +#define VFIO_IOMMU_NESTING_OP_UNBIND_PGTBL (1)
    > > +
    > > +#define VFIO_IOMMU_NESTING_OP _IO(VFIO_TYPE,
    > VFIO_BASE + 19)
    > > +
    > > /* -------- Additional API for SPAPR TCE (Server POWERPC) IOMMU
    > > -------- */
    > >
    > > /*

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