[PATCH v5 07/15] vfio/type1: Add VFIO_IOMMU_PASID_REQUEST (alloc/free)

Liu Yi L
2020-07-12T11:16:17Z

This patch allows user space to request PASID allocation/free, e.g. when
serving the request from the guest.

PASIDs that are not freed by userspace are automatically freed when the
IOASID set is destroyed when process exits.

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>
Signed-off-by: Yi Sun <yi.y.sun@linux.intel.com>
Signed-off-by: Jacob Pan <jacob.jun.pan@linux.intel.com>
---
v4 -> v5:
*) address comments from Eric Auger.
*) the comments for the PASID_FREE request is addressed in patch 5/15 of
this series.

v3 -> v4:
*) address comments from v3, except the below comment against the range
of PASID_FREE request. needs more help on it.
"> +if (req.range.min > req.range.max)

Is it exploitable that a user can spin the kernel for a long time in
the case of a free by calling this with [0, MAX_UINT] regardless of
their actual allocations?"
https://lore.kernel.org/linux-iommu/20200702151832.048b44d1@x1.home/

v1 -> v2:
*) move the vfio_mm related code to be a seprate module
*) use a single structure for alloc/free, could support a range of PASIDs
*) fetch vfio_mm at group_attach time instead of at iommu driver open time
---
drivers/vfio/Kconfig | 1 +
drivers/vfio/vfio_iommu_type1.c | 85 +++++++++++++++++++++++++++++++++++++++++
drivers/vfio/vfio_pasid.c | 10 +++++
include/linux/vfio.h | 6 +++
include/uapi/linux/vfio.h | 37 ++++++++++++++++++
5 files changed, 139 insertions(+)

diff --git a/drivers/vfio/Kconfig b/drivers/vfio/Kconfig
index 3d8a108..95d90c6 100644
--- a/drivers/vfio/Kconfig
+++ b/drivers/vfio/Kconfig
@@ -2,6 +2,7 @@
config VFIO_IOMMU_TYPE1
tristate
depends on VFIO
+ select VFIO_PASID if (X86)
default n

config VFIO_IOMMU_SPAPR_TCE
diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c
index ed80104..55b4065 100644
--- a/drivers/vfio/vfio_iommu_type1.c
+++ b/drivers/vfio/vfio_iommu_type1.c
@@ -76,6 +76,7 @@ struct vfio_iommu {
bool dirty_page_tracking;
bool pinned_page_dirty_scope;
struct iommu_nesting_info *nesting_info;
+ struct vfio_mm *vmm;
};

struct vfio_domain {
@@ -1937,6 +1938,11 @@ static void vfio_iommu_iova_insert_copy(struct vfio_iommu *iommu,

static void vfio_iommu_release_nesting_info(struct vfio_iommu *iommu)
{
+ if (iommu->vmm) {
+ vfio_mm_put(iommu->vmm);
+ iommu->vmm = NULL;
+ }
+
kfree(iommu->nesting_info);
iommu->nesting_info = NULL;
}
@@ -2071,6 +2077,26 @@ static int vfio_iommu_type1_attach_group(void *iommu_data,
iommu->nesting_info);
if (ret)
goto out_detach;
+
+ if (iommu->nesting_info->features &
+ IOMMU_NESTING_FEAT_SYSWIDE_PASID) {
+ struct vfio_mm *vmm;
+ int sid;
+
+ vmm = vfio_mm_get_from_task(current);
+ if (IS_ERR(vmm)) {
+ ret = PTR_ERR(vmm);
+ goto out_detach;
+ }
+ iommu->vmm = vmm;
+
+ sid = vfio_mm_ioasid_sid(vmm);
+ ret = iommu_domain_set_attr(domain->domain,
+ DOMAIN_ATTR_IOASID_SID,
+ &sid);
+ if (ret)
+ goto out_detach;
+ }
}

/* Get aperture info */
@@ -2855,6 +2881,63 @@ static int vfio_iommu_type1_dirty_pages(struct vfio_iommu *iommu,
return -EINVAL;
}

+static int vfio_iommu_type1_pasid_alloc(struct vfio_iommu *iommu,
+ unsigned int min,
+ unsigned int max)
+{
+ int ret = -EOPNOTSUPP;
+
+ mutex_lock(&iommu->lock);
+ if (iommu->vmm)
+ ret = vfio_pasid_alloc(iommu->vmm, min, max);
+ mutex_unlock(&iommu->lock);
+ return ret;
+}
+
+static int vfio_iommu_type1_pasid_free(struct vfio_iommu *iommu,
+ unsigned int min,
+ unsigned int max)
+{
+ int ret = -EOPNOTSUPP;
+
+ mutex_lock(&iommu->lock);
+ if (iommu->vmm) {
+ vfio_pasid_free_range(iommu->vmm, min, max);
+ ret = 0;
+ }
+ mutex_unlock(&iommu->lock);
+ return ret;
+}
+
+static int vfio_iommu_type1_pasid_request(struct vfio_iommu *iommu,
+ unsigned long arg)
+{
+ struct vfio_iommu_type1_pasid_request req;
+ unsigned long minsz;
+
+ minsz = offsetofend(struct vfio_iommu_type1_pasid_request, range);
+
+ if (copy_from_user(&req, (void __user *)arg, minsz))
+ return -EFAULT;
+
+ if (req.argsz < minsz || (req.flags & ~VFIO_PASID_REQUEST_MASK))
+ return -EINVAL;
+
+ if (req.range.min > req.range.max)
+ return -EINVAL;
+
+ switch (req.flags & VFIO_PASID_REQUEST_MASK) {
+ case VFIO_IOMMU_FLAG_ALLOC_PASID:
+ return vfio_iommu_type1_pasid_alloc(iommu,
+ req.range.min, req.range.max);
+ case VFIO_IOMMU_FLAG_FREE_PASID:
+ return vfio_iommu_type1_pasid_free(iommu,
+ req.range.min, req.range.max);
+ default:
+ return -EINVAL;
+ }
+}
+
static long vfio_iommu_type1_ioctl(void *iommu_data,
unsigned int cmd, unsigned long arg)
{
@@ -2871,6 +2954,8 @@ static long vfio_iommu_type1_ioctl(void *iommu_data,
return vfio_iommu_type1_unmap_dma(iommu, arg);
case VFIO_IOMMU_DIRTY_PAGES:
return vfio_iommu_type1_dirty_pages(iommu, arg);
+ case VFIO_IOMMU_PASID_REQUEST:
+ return vfio_iommu_type1_pasid_request(iommu, arg);
default:
return -ENOTTY;
}
diff --git a/drivers/vfio/vfio_pasid.c b/drivers/vfio/vfio_pasid.c
index 66e6054e..ebec244 100644
--- a/drivers/vfio/vfio_pasid.c
+++ b/drivers/vfio/vfio_pasid.c
@@ -61,6 +61,7 @@ void vfio_mm_put(struct vfio_mm *vmm)
{
kref_put_mutex(&vmm->kref, vfio_mm_release, &vfio_mm_lock);
}
+EXPORT_SYMBOL_GPL(vfio_mm_put);

static void vfio_mm_get(struct vfio_mm *vmm)
{
@@ -114,6 +115,13 @@ struct vfio_mm *vfio_mm_get_from_task(struct task_struct *task)
mmput(mm);
return vmm;
}
+EXPORT_SYMBOL_GPL(vfio_mm_get_from_task);
+
+int vfio_mm_ioasid_sid(struct vfio_mm *vmm)
+{
+ return vmm->ioasid_sid;
+}
+EXPORT_SYMBOL_GPL(vfio_mm_ioasid_sid);

/*
* Find PASID within @min and @max
@@ -197,6 +205,7 @@ int vfio_pasid_alloc(struct vfio_mm *vmm, int min, int max)

return pasid;
}
+EXPORT_SYMBOL_GPL(vfio_pasid_alloc);

void vfio_pasid_free_range(struct vfio_mm *vmm,
ioasid_t min, ioasid_t max)
@@ -213,6 +222,7 @@ void vfio_pasid_free_range(struct vfio_mm *vmm,
vfio_remove_pasid(vmm, vid);
mutex_unlock(&vmm->pasid_lock);
}
+EXPORT_SYMBOL_GPL(vfio_pasid_free_range);

static int __init vfio_pasid_init(void)
{
diff --git a/include/linux/vfio.h b/include/linux/vfio.h
index 31472a9..a111108 100644
--- a/include/linux/vfio.h
+++ b/include/linux/vfio.h
@@ -101,6 +101,7 @@ struct vfio_mm;
#if IS_ENABLED(CONFIG_VFIO_PASID)
extern struct vfio_mm *vfio_mm_get_from_task(struct task_struct *task);
extern void vfio_mm_put(struct vfio_mm *vmm);
+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);
@@ -114,6 +115,11 @@ static inline void vfio_mm_put(struct vfio_mm *vmm)
{
}

+static inline int vfio_mm_ioasid_sid(struct vfio_mm *vmm)
+{
+ return -ENOTTY;
+}
+
static inline int vfio_pasid_alloc(struct vfio_mm *vmm, int min, int max)
{
return -ENOTTY;
diff --git a/include/uapi/linux/vfio.h b/include/uapi/linux/vfio.h
index 46a78af..96a115f 100644
--- a/include/uapi/linux/vfio.h
+++ b/include/uapi/linux/vfio.h
@@ -1172,6 +1172,43 @@ struct vfio_iommu_type1_dirty_bitmap_get {

#define VFIO_IOMMU_DIRTY_PAGES _IO(VFIO_TYPE, VFIO_BASE + 17)

+/**
+ * VFIO_IOMMU_PASID_REQUEST - _IOWR(VFIO_TYPE, VFIO_BASE + 18,
+ * struct vfio_iommu_type1_pasid_request)
+ *
+ * PASID (Processor Address Space ID) is a PCIe concept for tagging
+ * address spaces in DMA requests. When system-wide PASID allocation
+ * is required by underlying iommu driver (e.g. Intel VT-d), this
+ * provides an interface for userspace to request pasid alloc/free
+ * for its assigned devices. Userspace should check the availability
+ * of this API by checking VFIO_IOMMU_TYPE1_INFO_CAP_NESTING through
+ * VFIO_IOMMU_GET_INFO.
+ *
+ * @flags=VFIO_IOMMU_FLAG_ALLOC_PASID, allocate a single PASID within @range.
+ * @flags=VFIO_IOMMU_FLAG_FREE_PASID, free the PASIDs within @range.
+ * @range is [min, max], which means both @min and @max are inclusive.
+ * ALLOC_PASID and FREE_PASID are mutually exclusive.
+ *
+ * returns: allocated PASID value on success, -errno on failure for
+ * ALLOC_PASID;
+ * 0 for FREE_PASID operation;
+ */
+struct vfio_iommu_type1_pasid_request {
+ __u32 argsz;
+#define VFIO_IOMMU_FLAG_ALLOC_PASID (1 << 0)
+#define VFIO_IOMMU_FLAG_FREE_PASID (1 << 1)
+ __u32 flags;
+ struct {
+ __u32 min;
+ __u32 max;
+ } range;
+};
+
+#define VFIO_PASID_REQUEST_MASK (VFIO_IOMMU_FLAG_ALLOC_PASID | \
+ VFIO_IOMMU_FLAG_FREE_PASID)
+
+#define VFIO_IOMMU_PASID_REQUEST _IO(VFIO_TYPE, VFIO_BASE + 18)
+
/* -------- Additional API for SPAPR TCE (Server POWERPC) IOMMU -------- */

/*
--
2.7.4