This patch allows userspace 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@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>
Signed-off-by: Yi Sun <yi.y.sun@xxxxxxxxxxxxxxx>
Signed-off-by: Jacob Pan <jacob.jun.pan@xxxxxxxxxxxxxxx>
---
v6 -> v7:
*) current VFIO returns allocated pasid via signed int, thus VFIO UAPI
can only support 31 bits pasid. If user space gives min,max which is
wider than 31 bits, should fail the allocation or free request.
v5 -> v6:
*) address comments from Eric against v5. remove the alloc/free helper.
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@xxxxxxx/
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 | 76 +++++++++++++++++++++++++++++++++++++++++
drivers/vfio/vfio_pasid.c | 10 ++++++
include/linux/vfio.h | 6 ++++
include/uapi/linux/vfio.h | 43 +++++++++++++++++++++++
5 files changed, 136 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 3c0048b..bd4b668 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 {
@@ -2000,6 +2001,11 @@ 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;
}
@@ -2127,6 +2133,26 @@ 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;
+ struct ioasid_set *set;
+
+ vmm = vfio_mm_get_from_task(current);
+ if (IS_ERR(vmm)) {
+ ret = PTR_ERR(vmm);
+ goto out_detach;
+ }
+ iommu->vmm = vmm;
+
+ set = vfio_mm_ioasid_set(vmm);
+ ret = iommu_domain_set_attr(domain->domain,
+ DOMAIN_ATTR_IOASID_SET,
+ set);
+ if (ret)
+ goto out_detach;
+ }
}
/* Get aperture info */
@@ -2908,6 +2934,54 @@ static int vfio_iommu_type1_dirty_pages(struct vfio_iommu *iommu,
return -EINVAL;
}
+static int vfio_iommu_type1_pasid_request(struct vfio_iommu *iommu,
+ unsigned long arg)
+{
+ struct vfio_iommu_type1_pasid_request req;
+ unsigned long minsz;
+ int ret;
+
+ 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;
+
+ /*
+ * Current VFIO_IOMMU_PASID_REQUEST only supports at most
+ * 31 bits PASID. The min,max value from userspace should
+ * not exceed 31 bits.
+ */
+ if (req.range.min > req.range.max ||
+ req.range.min > (1 << VFIO_IOMMU_PASID_BITS) ||
+ req.range.max > (1 << VFIO_IOMMU_PASID_BITS))
+ return -EINVAL;
+
+ mutex_lock(&iommu->lock);
+ if (!iommu->vmm) {
+ mutex_unlock(&iommu->lock);
+ return -EOPNOTSUPP;
+ }
+
+ switch (req.flags & VFIO_PASID_REQUEST_MASK) {
+ case VFIO_IOMMU_FLAG_ALLOC_PASID:
+ ret = vfio_pasid_alloc(iommu->vmm, req.range.min,
+ req.range.max);
+ break;
+ case VFIO_IOMMU_FLAG_FREE_PASID:
+ vfio_pasid_free_range(iommu->vmm, req.range.min,
+ req.range.max);
+ ret = 0;
+ break;
+ default:
+ ret = -EINVAL;
+ }
+ mutex_unlock(&iommu->lock);
+ return ret;
+}
+
static long vfio_iommu_type1_ioctl(void *iommu_data,
unsigned int cmd, unsigned long arg)
{
@@ -2924,6 +2998,8 @@ 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 44ecdd5..0ec4660 100644
--- a/drivers/vfio/vfio_pasid.c
+++ b/drivers/vfio/vfio_pasid.c
@@ -60,6 +60,7 @@ 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)
{
@@ -113,6 +114,13 @@ struct vfio_mm *vfio_mm_get_from_task(struct task_struct *task)
mmput(mm);
return vmm;
}
+EXPORT_SYMBOL_GPL(vfio_mm_get_from_task);
+
+struct ioasid_set *vfio_mm_ioasid_set(struct vfio_mm *vmm)
+{
+ return vmm->ioasid_set;
+}
+EXPORT_SYMBOL_GPL(vfio_mm_ioasid_set);
/*
* Find PASID within @min and @max
@@ -201,6 +209,7 @@ 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)
@@ -217,6 +226,7 @@ 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..5c3d7a8 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);
+extern struct ioasid_set *vfio_mm_ioasid_set(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 struct ioasid_set *vfio_mm_ioasid_set(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 ff40f9e..a4bc42e 100644
--- a/include/uapi/linux/vfio.h
+++ b/include/uapi/linux/vfio.h
@@ -1172,6 +1172,49 @@ 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 the 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.
+ *
+ * Current interface supports at most 31 bits PASID bits as returning
+ * PASID allocation result via signed int. PCIe spec defines 20 bits
+ * for PASID width, so 31 bits is enough. As a result user space should
+ * provide min, max no more than 31 bits.
+ * 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_BITS 31
+
+#define VFIO_IOMMU_PASID_REQUEST _IO(VFIO_TYPE, VFIO_BASE + 18)
+
/* -------- Additional API for SPAPR TCE (Server POWERPC) IOMMU -------- */
/*
--
2.7.4
