[PATCH v4 0/4] vfio-pci support pasid attach/detach

[PATCH v4 0/4] vfio-pci support pasid attach/detach

[Yi Liu]

This adds the pasid attach/detach uAPIs for userspace to attach/detach
a PASID of a device to/from a given ioas/hwpt. Only vfio-pci driver is
enabled in this series. After this series, PASID-capable devices bound
with vfio-pci can report PASID capability to userspace and VM to enable
PASID usages like Shared Virtual Addressing (SVA).

Based on the discussion about reporting the vPASID to VM [1], it's agreed
that we will let the userspace VMM to synthesize the vPASID capability.
The VMM needs to figure out a hole to put the vPASID cap. This includes
the hidden bits handling for some devices. While, it's up to the userspace,
it's not the focus of this series.

This series first adds the helpers for pasid attach in vfio core and then
extends the device cdev attach/detach ioctls for pasid attach/detach. In the
end of this series, the IOMMU_GET_HW_INFO ioctl is extended to report the
PCI PASID capability to the userspace. Userspace should check this before
using any PASID related uAPIs provided by VFIO, which is the agreement in [2].
This series depends on the iommufd pasid attach/detach series [3].

The completed code can be found at [4], tested with a hacky Qemu branch [5].

[1] https://lore.kernel.org/kvm/BN9PR11MB5276318969A212AD0649C7BE8CBE2@BN9PR11MB5276.namprd11.prod.outlook.com/
[2] https://lore.kernel.org/kvm/4f2daf50-a5ad-4599-ab59-bcfc008688d8@intel.com/
[3] https://lore.kernel.org/linux-iommu/20240912131255.13305-1-yi.l.liu@intel.com/
[4] https://github.com/yiliu1765/iommufd/tree/iommufd_pasid
[5] https://github.com/yiliu1765/qemu/tree/wip/zhenzhong/iommufd_nesting_rfcv2-test-pasid

Change log:

v4:
 - Add acked-by for the ida patch from Matthew
 - Add r-b from Kevin and Jason on patch 01, 02 and 04 of v3
 - Add common code to copy user data for the user struct with new fields
 - Extend the VFIO_DEVICE_[AT|DE]TACH_IOMMUFD_PT to support pasid, patch 03
   is updated per this change. Hence drop r-b of it. (Kevin, Alex)
 - Add t-b from Zhangfei for patch 4 of v3
 - Nits from Vasant

v3: https://lore.kernel.org/linux-iommu/20240912131729.14951-1-yi.l.liu@intel.com/
 - Misc enhancement on patch 01 of v2 (Alex, Jason)
 - Add Jason's r-b to patch 03 of v2
 - Drop the logic that report PASID via VFIO_DEVICE_FEATURE ioctl
 - Extend IOMMU_GET_HW_INFO to report PASID support (Kevin, Jason, Alex)

v2: https://lore.kernel.org/kvm/20240412082121.33382-1-yi.l.liu@intel.com/
 - Use IDA to track if PASID is attached or not in VFIO. (Jason)
 - Fix the issue of calling pasid_at[de]tach_ioas callback unconditionally (Alex)
 - Fix the wrong data copy in vfio_df_ioctl_pasid_detach_pt() (Zhenzhong)
 - Minor tweaks in comments (Kevin)

v1: https://lore.kernel.org/kvm/20231127063909.129153-1-yi.l.liu@intel.com/
 - Report PASID capability via VFIO_DEVICE_FEATURE (Alex)

rfc: https://lore.kernel.org/linux-iommu/20230926093121.18676-1-yi.l.liu@intel.com/

Regards,
	Yi Liu

Yi Liu (4):
  ida: Add ida_find_first_range()
  vfio-iommufd: Support pasid [at|de]tach for physical VFIO devices
  vfio: VFIO_DEVICE_[AT|DE]TACH_IOMMUFD_PT support pasid
  iommufd: Extend IOMMU_GET_HW_INFO to report PASID capability

 drivers/iommu/iommufd/device.c | 24 +++++++++++-
 drivers/pci/ats.c              | 33 ++++++++++++++++
 drivers/vfio/device_cdev.c     | 62 +++++++++++++++++++++---------
 drivers/vfio/iommufd.c         | 50 ++++++++++++++++++++++++
 drivers/vfio/pci/vfio_pci.c    |  2 +
 drivers/vfio/vfio.h            | 18 +++++++++
 drivers/vfio/vfio_main.c       | 55 ++++++++++++++++++++++++++
 include/linux/idr.h            | 11 ++++++
 include/linux/pci-ats.h        |  3 ++
 include/linux/vfio.h           | 11 ++++++
 include/uapi/linux/iommufd.h   | 14 ++++++-
 include/uapi/linux/vfio.h      | 29 +++++++++-----
 lib/idr.c                      | 67 ++++++++++++++++++++++++++++++++
 lib/test_ida.c                 | 70 ++++++++++++++++++++++++++++++++++
 14 files changed, 419 insertions(+), 30 deletions(-)

-- 
2.34.1

[PATCH v4 1/4] ida: Add ida_find_first_range()

[Yi Liu]

There is no helpers for user to check if a given ID is allocated or not,
neither a helper to loop all the allocated IDs in an IDA and do something
for cleanup. With the two needs, a helper to get the lowest allocated ID
of a range and two variants based on it.

Caller can check if a given ID is allocated or not by:

	bool ida_exists(struct ida *ida, unsigned int id)

Caller can iterate all allocated IDs by:

	int id;
	while ((id = ida_find_first(&pasid_ida)) >= 0) {
		//anything to do with the allocated ID
		ida_free(pasid_ida, pasid);
	}

Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Suggested-by: Jason Gunthorpe <jgg@nvidia.com>
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Acked-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Yi Liu <yi.l.liu@intel.com>
---
 include/linux/idr.h | 11 +++++++
 lib/idr.c           | 67 +++++++++++++++++++++++++++++++++++++++++++
 lib/test_ida.c      | 70 +++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 148 insertions(+)

diff --git a/include/linux/idr.h b/include/linux/idr.h
index da5f5fa4a3a6..718f9b1b91af 100644
--- a/include/linux/idr.h
+++ b/include/linux/idr.h
@@ -257,6 +257,7 @@ struct ida {
 int ida_alloc_range(struct ida *, unsigned int min, unsigned int max, gfp_t);
 void ida_free(struct ida *, unsigned int id);
 void ida_destroy(struct ida *ida);
+int ida_find_first_range(struct ida *ida, unsigned int min, unsigned int max);
 
 /**
  * ida_alloc() - Allocate an unused ID.
@@ -328,4 +329,14 @@ static inline bool ida_is_empty(const struct ida *ida)
 {
 	return xa_empty(&ida->xa);
 }
+
+static inline bool ida_exists(struct ida *ida, unsigned int id)
+{
+	return ida_find_first_range(ida, id, id) == id;
+}
+
+static inline int ida_find_first(struct ida *ida)
+{
+	return ida_find_first_range(ida, 0, ~0);
+}
 #endif /* __IDR_H__ */
diff --git a/lib/idr.c b/lib/idr.c
index da36054c3ca0..e2adc457abb4 100644
--- a/lib/idr.c
+++ b/lib/idr.c
@@ -476,6 +476,73 @@ int ida_alloc_range(struct ida *ida, unsigned int min, unsigned int max,
 }
 EXPORT_SYMBOL(ida_alloc_range);
 
+/**
+ * ida_find_first_range - Get the lowest used ID.
+ * @ida: IDA handle.
+ * @min: Lowest ID to get.
+ * @max: Highest ID to get.
+ *
+ * Get the lowest used ID between @min and @max, inclusive.  The returned
+ * ID will not exceed %INT_MAX, even if @max is larger.
+ *
+ * Context: Any context. Takes and releases the xa_lock.
+ * Return: The lowest used ID, or errno if no used ID is found.
+ */
+int ida_find_first_range(struct ida *ida, unsigned int min, unsigned int max)
+{
+	unsigned long index = min / IDA_BITMAP_BITS;
+	unsigned int offset = min % IDA_BITMAP_BITS;
+	unsigned long *addr, size, bit;
+	unsigned long tmp = 0;
+	unsigned long flags;
+	void *entry;
+	int ret;
+
+	if ((int)min < 0)
+		return -EINVAL;
+	if ((int)max < 0)
+		max = INT_MAX;
+
+	xa_lock_irqsave(&ida->xa, flags);
+
+	entry = xa_find(&ida->xa, &index, max / IDA_BITMAP_BITS, XA_PRESENT);
+	if (!entry) {
+		ret = -ENOENT;
+		goto err_unlock;
+	}
+
+	if (index > min / IDA_BITMAP_BITS)
+		offset = 0;
+	if (index * IDA_BITMAP_BITS + offset > max) {
+		ret = -ENOENT;
+		goto err_unlock;
+	}
+
+	if (xa_is_value(entry)) {
+		tmp = xa_to_value(entry);
+		addr = &tmp;
+		size = BITS_PER_XA_VALUE;
+	} else {
+		addr = ((struct ida_bitmap *)entry)->bitmap;
+		size = IDA_BITMAP_BITS;
+	}
+
+	bit = find_next_bit(addr, size, offset);
+
+	xa_unlock_irqrestore(&ida->xa, flags);
+
+	if (bit == size ||
+	    index * IDA_BITMAP_BITS + bit > max)
+		return -ENOENT;
+
+	return index * IDA_BITMAP_BITS + bit;
+
+err_unlock:
+	xa_unlock_irqrestore(&ida->xa, flags);
+	return ret;
+}
+EXPORT_SYMBOL(ida_find_first_range);
+
 /**
  * ida_free() - Release an allocated ID.
  * @ida: IDA handle.
diff --git a/lib/test_ida.c b/lib/test_ida.c
index c80155a1956d..63078f8dc13f 100644
--- a/lib/test_ida.c
+++ b/lib/test_ida.c
@@ -189,6 +189,75 @@ static void ida_check_bad_free(struct ida *ida)
 	IDA_BUG_ON(ida, !ida_is_empty(ida));
 }
 
+/*
+ * Check ida_find_first_range() and varriants.
+ */
+static void ida_check_find_first(struct ida *ida)
+{
+	/* IDA is empty; all of the below should be not exist */
+	IDA_BUG_ON(ida, ida_exists(ida, 0));
+	IDA_BUG_ON(ida, ida_exists(ida, 3));
+	IDA_BUG_ON(ida, ida_exists(ida, 63));
+	IDA_BUG_ON(ida, ida_exists(ida, 1023));
+	IDA_BUG_ON(ida, ida_exists(ida, (1 << 20) - 1));
+
+	/* IDA contains a single value entry */
+	IDA_BUG_ON(ida, ida_alloc_min(ida, 3, GFP_KERNEL) != 3);
+	IDA_BUG_ON(ida, ida_exists(ida, 0));
+	IDA_BUG_ON(ida, !ida_exists(ida, 3));
+	IDA_BUG_ON(ida, ida_exists(ida, 63));
+	IDA_BUG_ON(ida, ida_exists(ida, 1023));
+	IDA_BUG_ON(ida, ida_exists(ida, (1 << 20) - 1));
+
+	IDA_BUG_ON(ida, ida_alloc_min(ida, 63, GFP_KERNEL) != 63);
+	IDA_BUG_ON(ida, ida_exists(ida, 0));
+	IDA_BUG_ON(ida, !ida_exists(ida, 3));
+	IDA_BUG_ON(ida, !ida_exists(ida, 63));
+	IDA_BUG_ON(ida, ida_exists(ida, 1023));
+	IDA_BUG_ON(ida, ida_exists(ida, (1 << 20) - 1));
+
+	/* IDA contains a single bitmap */
+	IDA_BUG_ON(ida, ida_alloc_min(ida, 1023, GFP_KERNEL) != 1023);
+	IDA_BUG_ON(ida, ida_exists(ida, 0));
+	IDA_BUG_ON(ida, !ida_exists(ida, 3));
+	IDA_BUG_ON(ida, !ida_exists(ida, 63));
+	IDA_BUG_ON(ida, !ida_exists(ida, 1023));
+	IDA_BUG_ON(ida, ida_exists(ida, (1 << 20) - 1));
+
+	/* IDA contains a tree */
+	IDA_BUG_ON(ida, ida_alloc_min(ida, (1 << 20) - 1, GFP_KERNEL) != (1 << 20) - 1);
+	IDA_BUG_ON(ida, ida_exists(ida, 0));
+	IDA_BUG_ON(ida, !ida_exists(ida, 3));
+	IDA_BUG_ON(ida, !ida_exists(ida, 63));
+	IDA_BUG_ON(ida, !ida_exists(ida, 1023));
+	IDA_BUG_ON(ida, !ida_exists(ida, (1 << 20) - 1));
+
+	/* Now try to find first */
+	IDA_BUG_ON(ida, ida_find_first(ida) != 3);
+	IDA_BUG_ON(ida, ida_find_first_range(ida, -1, 2) != -EINVAL);
+	IDA_BUG_ON(ida, ida_find_first_range(ida, 0, 2) != -ENOENT); // no used ID
+	IDA_BUG_ON(ida, ida_find_first_range(ida, 0, 3) != 3);
+	IDA_BUG_ON(ida, ida_find_first_range(ida, 1, 3) != 3);
+	IDA_BUG_ON(ida, ida_find_first_range(ida, 3, 3) != 3);
+	IDA_BUG_ON(ida, ida_find_first_range(ida, 2, 4) != 3);
+	IDA_BUG_ON(ida, ida_find_first_range(ida, 4, 3) != -ENOENT); // min > max, fail
+	IDA_BUG_ON(ida, ida_find_first_range(ida, 4, 60) != -ENOENT); // no used ID
+	IDA_BUG_ON(ida, ida_find_first_range(ida, 4, 64) != 63);
+	IDA_BUG_ON(ida, ida_find_first_range(ida, 63, 63) != 63);
+	IDA_BUG_ON(ida, ida_find_first_range(ida, 64, 1026) != 1023);
+	IDA_BUG_ON(ida, ida_find_first_range(ida, 1023, 1023) != 1023);
+	IDA_BUG_ON(ida, ida_find_first_range(ida, 1023, (1 << 20) - 1) != 1023);
+	IDA_BUG_ON(ida, ida_find_first_range(ida, 1024, (1 << 20) - 1) != (1 << 20) - 1);
+	IDA_BUG_ON(ida, ida_find_first_range(ida, (1 << 20), INT_MAX) != -ENOENT);
+
+	ida_free(ida, 3);
+	ida_free(ida, 63);
+	ida_free(ida, 1023);
+	ida_free(ida, (1 << 20) - 1);
+
+	IDA_BUG_ON(ida, !ida_is_empty(ida));
+}
+
 static DEFINE_IDA(ida);
 
 static int ida_checks(void)
@@ -202,6 +271,7 @@ static int ida_checks(void)
 	ida_check_max(&ida);
 	ida_check_conv(&ida);
 	ida_check_bad_free(&ida);
+	ida_check_find_first(&ida);
 
 	printk("IDA: %u of %u tests passed\n", tests_passed, tests_run);
 	return (tests_run != tests_passed) ? 0 : -EINVAL;
-- 
2.34.1

[PATCH v4 2/4] vfio-iommufd: Support pasid [at|de]tach for physical VFIO devices

[Yi Liu]

This adds pasid_at|de]tach_ioas ops for attaching hwpt to pasid of a
device and the helpers for it. For now, only vfio-pci supports pasid
attach/detach.

Signed-off-by: Kevin Tian <kevin.tian@intel.com>
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Signed-off-by: Yi Liu <yi.l.liu@intel.com>
---
 drivers/vfio/iommufd.c      | 50 +++++++++++++++++++++++++++++++++++++
 drivers/vfio/pci/vfio_pci.c |  2 ++
 include/linux/vfio.h        | 11 ++++++++
 3 files changed, 63 insertions(+)

diff --git a/drivers/vfio/iommufd.c b/drivers/vfio/iommufd.c
index 82eba6966fa5..2f5cb4f616ce 100644
--- a/drivers/vfio/iommufd.c
+++ b/drivers/vfio/iommufd.c
@@ -119,14 +119,22 @@ int vfio_iommufd_physical_bind(struct vfio_device *vdev,
 	if (IS_ERR(idev))
 		return PTR_ERR(idev);
 	vdev->iommufd_device = idev;
+	ida_init(&vdev->pasids);
 	return 0;
 }
 EXPORT_SYMBOL_GPL(vfio_iommufd_physical_bind);
 
 void vfio_iommufd_physical_unbind(struct vfio_device *vdev)
 {
+	int pasid;
+
 	lockdep_assert_held(&vdev->dev_set->lock);
 
+	while ((pasid = ida_find_first(&vdev->pasids)) >= 0) {
+		iommufd_device_pasid_detach(vdev->iommufd_device, pasid);
+		ida_free(&vdev->pasids, pasid);
+	}
+
 	if (vdev->iommufd_attached) {
 		iommufd_device_detach(vdev->iommufd_device);
 		vdev->iommufd_attached = false;
@@ -168,6 +176,48 @@ void vfio_iommufd_physical_detach_ioas(struct vfio_device *vdev)
 }
 EXPORT_SYMBOL_GPL(vfio_iommufd_physical_detach_ioas);
 
+int vfio_iommufd_physical_pasid_attach_ioas(struct vfio_device *vdev,
+					    u32 pasid, u32 *pt_id)
+{
+	int rc;
+
+	lockdep_assert_held(&vdev->dev_set->lock);
+
+	if (WARN_ON(!vdev->iommufd_device))
+		return -EINVAL;
+
+	if (ida_exists(&vdev->pasids, pasid))
+		return iommufd_device_pasid_replace(vdev->iommufd_device,
+						    pasid, pt_id);
+
+	rc = ida_alloc_range(&vdev->pasids, pasid, pasid, GFP_KERNEL);
+	if (rc < 0)
+		return rc;
+
+	rc = iommufd_device_pasid_attach(vdev->iommufd_device, pasid, pt_id);
+	if (rc)
+		ida_free(&vdev->pasids, pasid);
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(vfio_iommufd_physical_pasid_attach_ioas);
+
+void vfio_iommufd_physical_pasid_detach_ioas(struct vfio_device *vdev,
+					     u32 pasid)
+{
+	lockdep_assert_held(&vdev->dev_set->lock);
+
+	if (WARN_ON(!vdev->iommufd_device))
+		return;
+
+	if (!ida_exists(&vdev->pasids, pasid))
+		return;
+
+	iommufd_device_pasid_detach(vdev->iommufd_device, pasid);
+	ida_free(&vdev->pasids, pasid);
+}
+EXPORT_SYMBOL_GPL(vfio_iommufd_physical_pasid_detach_ioas);
+
 /*
  * The emulated standard ops mean that vfio_device is going to use the
  * "mdev path" and will call vfio_pin_pages()/vfio_dma_rw(). Drivers using this
diff --git a/drivers/vfio/pci/vfio_pci.c b/drivers/vfio/pci/vfio_pci.c
index e727941f589d..6f7ae7e5b7b0 100644
--- a/drivers/vfio/pci/vfio_pci.c
+++ b/drivers/vfio/pci/vfio_pci.c
@@ -144,6 +144,8 @@ static const struct vfio_device_ops vfio_pci_ops = {
 	.unbind_iommufd	= vfio_iommufd_physical_unbind,
 	.attach_ioas	= vfio_iommufd_physical_attach_ioas,
 	.detach_ioas	= vfio_iommufd_physical_detach_ioas,
+	.pasid_attach_ioas	= vfio_iommufd_physical_pasid_attach_ioas,
+	.pasid_detach_ioas	= vfio_iommufd_physical_pasid_detach_ioas,
 };
 
 static int vfio_pci_probe(struct pci_dev *pdev, const struct pci_device_id *id)
diff --git a/include/linux/vfio.h b/include/linux/vfio.h
index 000a6cab2d31..11b3b453752e 100644
--- a/include/linux/vfio.h
+++ b/include/linux/vfio.h
@@ -67,6 +67,7 @@ struct vfio_device {
 	struct inode *inode;
 #if IS_ENABLED(CONFIG_IOMMUFD)
 	struct iommufd_device *iommufd_device;
+	struct ida pasids;
 	u8 iommufd_attached:1;
 #endif
 	u8 cdev_opened:1;
@@ -91,6 +92,8 @@ struct vfio_device {
  *		 bound iommufd. Undo in unbind_iommufd if @detach_ioas is not
  *		 called.
  * @detach_ioas: Opposite of attach_ioas
+ * @pasid_attach_ioas: The pasid variation of attach_ioas
+ * @pasid_detach_ioas: Opposite of pasid_attach_ioas
  * @open_device: Called when the first file descriptor is opened for this device
  * @close_device: Opposite of open_device
  * @read: Perform read(2) on device file descriptor
@@ -115,6 +118,8 @@ struct vfio_device_ops {
 	void	(*unbind_iommufd)(struct vfio_device *vdev);
 	int	(*attach_ioas)(struct vfio_device *vdev, u32 *pt_id);
 	void	(*detach_ioas)(struct vfio_device *vdev);
+	int	(*pasid_attach_ioas)(struct vfio_device *vdev, u32 pasid, u32 *pt_id);
+	void	(*pasid_detach_ioas)(struct vfio_device *vdev, u32 pasid);
 	int	(*open_device)(struct vfio_device *vdev);
 	void	(*close_device)(struct vfio_device *vdev);
 	ssize_t	(*read)(struct vfio_device *vdev, char __user *buf,
@@ -139,6 +144,8 @@ int vfio_iommufd_physical_bind(struct vfio_device *vdev,
 void vfio_iommufd_physical_unbind(struct vfio_device *vdev);
 int vfio_iommufd_physical_attach_ioas(struct vfio_device *vdev, u32 *pt_id);
 void vfio_iommufd_physical_detach_ioas(struct vfio_device *vdev);
+int vfio_iommufd_physical_pasid_attach_ioas(struct vfio_device *vdev, u32 pasid, u32 *pt_id);
+void vfio_iommufd_physical_pasid_detach_ioas(struct vfio_device *vdev, u32 pasid);
 int vfio_iommufd_emulated_bind(struct vfio_device *vdev,
 			       struct iommufd_ctx *ictx, u32 *out_device_id);
 void vfio_iommufd_emulated_unbind(struct vfio_device *vdev);
@@ -166,6 +173,10 @@ vfio_iommufd_get_dev_id(struct vfio_device *vdev, struct iommufd_ctx *ictx)
 	((int (*)(struct vfio_device *vdev, u32 *pt_id)) NULL)
 #define vfio_iommufd_physical_detach_ioas \
 	((void (*)(struct vfio_device *vdev)) NULL)
+#define vfio_iommufd_physical_pasid_attach_ioas \
+	((int (*)(struct vfio_device *vdev, u32 pasid, u32 *pt_id)) NULL)
+#define vfio_iommufd_physical_pasid_detach_ioas \
+	((void (*)(struct vfio_device *vdev, u32 pasid)) NULL)
 #define vfio_iommufd_emulated_bind                                      \
 	((int (*)(struct vfio_device *vdev, struct iommufd_ctx *ictx,   \
 		  u32 *out_device_id)) NULL)
-- 
2.34.1

[PATCH v4 3/4] vfio: VFIO_DEVICE_[AT|DE]TACH_IOMMUFD_PT support pasid

[Yi Liu]

This extends the VFIO_DEVICE_[AT|DE]TACH_IOMMUFD_PT ioctls to attach/detach
a given pasid of a vfio device to/from an IOAS/HWPT.

vfio_copy_from_user() is added to copy the user data for the case in which
the existing user struct has introduced new fields. The rule is not breaking
the existing usersapce. The kernel only copies the new fields when the
corresponding flag is set by the userspace. For the case that has multiple
new fields marked by different flags, kernel checks the flags one by one to
get the correct size to copy besides the minsz. Such logics can be shared by
the other uapi extensions, hence add a helper for it.

Signed-off-by: Yi Liu <yi.l.liu@intel.com>
---
 drivers/vfio/device_cdev.c | 62 +++++++++++++++++++++++++++-----------
 drivers/vfio/vfio.h        | 18 +++++++++++
 drivers/vfio/vfio_main.c   | 55 +++++++++++++++++++++++++++++++++
 include/uapi/linux/vfio.h  | 29 ++++++++++++------
 4 files changed, 136 insertions(+), 28 deletions(-)

diff --git a/drivers/vfio/device_cdev.c b/drivers/vfio/device_cdev.c
index bb1817bd4ff3..bd13ddbfb9e3 100644
--- a/drivers/vfio/device_cdev.c
+++ b/drivers/vfio/device_cdev.c
@@ -159,24 +159,44 @@ void vfio_df_unbind_iommufd(struct vfio_device_file *df)
 	vfio_device_unblock_group(device);
 }
 
+#define VFIO_ATTACH_FLAGS_MASK VFIO_DEVICE_ATTACH_PASID
+static unsigned long
+vfio_attach_xends[ilog2(VFIO_ATTACH_FLAGS_MASK) + 1] = {
+	XEND_SIZE(VFIO_DEVICE_ATTACH_PASID,
+		  struct vfio_device_attach_iommufd_pt, pasid),
+};
+
+#define VFIO_DETACH_FLAGS_MASK VFIO_DEVICE_DETACH_PASID
+static unsigned long
+vfio_detach_xends[ilog2(VFIO_DETACH_FLAGS_MASK) + 1] = {
+	XEND_SIZE(VFIO_DEVICE_DETACH_PASID,
+		  struct vfio_device_detach_iommufd_pt, pasid),
+};
+
 int vfio_df_ioctl_attach_pt(struct vfio_device_file *df,
 			    struct vfio_device_attach_iommufd_pt __user *arg)
 {
-	struct vfio_device *device = df->device;
 	struct vfio_device_attach_iommufd_pt attach;
-	unsigned long minsz;
+	struct vfio_device *device = df->device;
 	int ret;
 
-	minsz = offsetofend(struct vfio_device_attach_iommufd_pt, pt_id);
-
-	if (copy_from_user(&attach, arg, minsz))
-		return -EFAULT;
+	ret = VFIO_COPY_USER_DATA((void __user *)arg, &attach,
+				  struct vfio_device_attach_iommufd_pt,
+				  pt_id, VFIO_ATTACH_FLAGS_MASK,
+				  vfio_attach_xends);
+	if (ret)
+		return ret;
 
-	if (attach.argsz < minsz || attach.flags)
-		return -EINVAL;
+	if ((attach.flags & VFIO_DEVICE_ATTACH_PASID) &&
+	    !device->ops->pasid_attach_ioas)
+		return -EOPNOTSUPP;
 
 	mutex_lock(&device->dev_set->lock);
-	ret = device->ops->attach_ioas(device, &attach.pt_id);
+	if (attach.flags & VFIO_DEVICE_ATTACH_PASID)
+		ret = device->ops->pasid_attach_ioas(device, attach.pasid,
+						     &attach.pt_id);
+	else
+		ret = device->ops->attach_ioas(device, &attach.pt_id);
 	if (ret)
 		goto out_unlock;
 
@@ -198,20 +218,26 @@ int vfio_df_ioctl_attach_pt(struct vfio_device_file *df,
 int vfio_df_ioctl_detach_pt(struct vfio_device_file *df,
 			    struct vfio_device_detach_iommufd_pt __user *arg)
 {
-	struct vfio_device *device = df->device;
 	struct vfio_device_detach_iommufd_pt detach;
-	unsigned long minsz;
-
-	minsz = offsetofend(struct vfio_device_detach_iommufd_pt, flags);
+	struct vfio_device *device = df->device;
+	int ret;
 
-	if (copy_from_user(&detach, arg, minsz))
-		return -EFAULT;
+	ret = VFIO_COPY_USER_DATA((void __user *)arg, &detach,
+				  struct vfio_device_detach_iommufd_pt,
+				  flags, VFIO_DETACH_FLAGS_MASK,
+				  vfio_detach_xends);
+	if (ret)
+		return ret;
 
-	if (detach.argsz < minsz || detach.flags)
-		return -EINVAL;
+	if ((detach.flags & VFIO_DEVICE_DETACH_PASID) &&
+	    !device->ops->pasid_detach_ioas)
+		return -EOPNOTSUPP;
 
 	mutex_lock(&device->dev_set->lock);
-	device->ops->detach_ioas(device);
+	if (detach.flags & VFIO_DEVICE_DETACH_PASID)
+		device->ops->pasid_detach_ioas(device, detach.pasid);
+	else
+		device->ops->detach_ioas(device);
 	mutex_unlock(&device->dev_set->lock);
 
 	return 0;
diff --git a/drivers/vfio/vfio.h b/drivers/vfio/vfio.h
index 50128da18bca..9f081cf01c5a 100644
--- a/drivers/vfio/vfio.h
+++ b/drivers/vfio/vfio.h
@@ -34,6 +34,24 @@ void vfio_df_close(struct vfio_device_file *df);
 struct vfio_device_file *
 vfio_allocate_device_file(struct vfio_device *device);
 
+int vfio_copy_from_user(void *buffer, void __user *arg,
+			unsigned long minsz, u32 flags_mask,
+			unsigned long *xend_array);
+
+#define VFIO_COPY_USER_DATA(_arg, _local_buffer, _struct, _min_last,          \
+			    _flags_mask, _xend_array)                         \
+	vfio_copy_from_user(_local_buffer, _arg,                              \
+			    offsetofend(_struct, _min_last) +                \
+			    BUILD_BUG_ON_ZERO(offsetof(_struct, argsz) !=     \
+					      0) +                            \
+			    BUILD_BUG_ON_ZERO(offsetof(_struct, flags) !=     \
+					      sizeof(u32)),                   \
+			    _flags_mask, _xend_array)
+
+#define XEND_SIZE(_flag, _struct, _xlast)                                    \
+	[ilog2(_flag)] = offsetofend(_struct, _xlast) +                      \
+			 BUILD_BUG_ON_ZERO(_flag == 0)                       \
+
 extern const struct file_operations vfio_device_fops;
 
 #ifdef CONFIG_VFIO_NOIOMMU
diff --git a/drivers/vfio/vfio_main.c b/drivers/vfio/vfio_main.c
index a5a62d9d963f..7df94bf121fd 100644
--- a/drivers/vfio/vfio_main.c
+++ b/drivers/vfio/vfio_main.c
@@ -1694,6 +1694,61 @@ int vfio_dma_rw(struct vfio_device *device, dma_addr_t iova, void *data,
 }
 EXPORT_SYMBOL(vfio_dma_rw);
 
+/**
+ * vfio_copy_from_user - Copy the user struct that may have extended fields
+ *
+ * @buffer: The local buffer to store the data copied from user
+ * @arg: The user buffer pointer
+ * @minsz: The minimum size of the user struct, it should never bump up.
+ * @flags_mask: The combination of all the falgs defined
+ * @xend_array: The array that stores the xend size for set flags.
+ *
+ * This helper requires the user struct put the argsz and flags fields in
+ * the first 8 bytes.
+ *
+ * Return 0 for success, otherwise -errno
+ */
+int vfio_copy_from_user(void *buffer, void __user *arg,
+			unsigned long minsz, u32 flags_mask,
+			unsigned long *xend_array)
+{
+	unsigned long xend = 0;
+	struct user_header {
+		u32 argsz;
+		u32 flags;
+	} *header;
+	unsigned long flags;
+	u32 flag;
+
+	if (copy_from_user(buffer, arg, minsz))
+		return -EFAULT;
+
+	header = (struct user_header *)buffer;
+	if (header->argsz < minsz)
+		return -EINVAL;
+
+	if (header->flags & ~flags_mask)
+		return -EINVAL;
+
+	/* Loop each set flag to decide the xend */
+	flags = header->flags;
+	for_each_set_bit(flag, &flags, BITS_PER_LONG) {
+		if (xend_array[flag])
+			xend = xend_array[flag];
+	}
+
+	if (xend) {
+		if (header->argsz < xend)
+			return -EINVAL;
+
+		if (copy_from_user(buffer + minsz,
+				   arg + minsz, xend - minsz))
+			return -EFAULT;
+	}
+
+	return 0;
+}
+
 /*
  * Module/class support
  */
diff --git a/include/uapi/linux/vfio.h b/include/uapi/linux/vfio.h
index 2b68e6cdf190..40b414e642f5 100644
--- a/include/uapi/linux/vfio.h
+++ b/include/uapi/linux/vfio.h
@@ -931,29 +931,34 @@ struct vfio_device_bind_iommufd {
  * VFIO_DEVICE_ATTACH_IOMMUFD_PT - _IOW(VFIO_TYPE, VFIO_BASE + 19,
  *					struct vfio_device_attach_iommufd_pt)
  * @argsz:	User filled size of this data.
- * @flags:	Must be 0.
+ * @flags:	Flags for attach.
  * @pt_id:	Input the target id which can represent an ioas or a hwpt
  *		allocated via iommufd subsystem.
  *		Output the input ioas id or the attached hwpt id which could
  *		be the specified hwpt itself or a hwpt automatically created
  *		for the specified ioas by kernel during the attachment.
+ * @pasid:	The pasid to be attached, only meaningful when
+ *		VFIO_DEVICE_ATTACH_PASID is set in @flags
  *
  * Associate the device with an address space within the bound iommufd.
  * Undo by VFIO_DEVICE_DETACH_IOMMUFD_PT or device fd close.  This is only
  * allowed on cdev fds.
  *
- * If a vfio device is currently attached to a valid hw_pagetable, without doing
- * a VFIO_DEVICE_DETACH_IOMMUFD_PT, a second VFIO_DEVICE_ATTACH_IOMMUFD_PT ioctl
- * passing in another hw_pagetable (hwpt) id is allowed. This action, also known
- * as a hw_pagetable replacement, will replace the device's currently attached
- * hw_pagetable with a new hw_pagetable corresponding to the given pt_id.
+ * If a vfio device or a pasid of this device is currently attached to a valid
+ * hw_pagetable (hwpt), without doing a VFIO_DEVICE_DETACH_IOMMUFD_PT, a second
+ * VFIO_DEVICE_ATTACH_IOMMUFD_PT ioctl passing in another hwpt id is allowed.
+ * This action, also known as a hw_pagetable replacement, will replace the
+ * currently attached hwpt of the device or the pasid of this device with a new
+ * hwpt corresponding to the given pt_id.
  *
  * Return: 0 on success, -errno on failure.
  */
 struct vfio_device_attach_iommufd_pt {
 	__u32	argsz;
 	__u32	flags;
+#define VFIO_DEVICE_ATTACH_PASID	(1 << 0)
 	__u32	pt_id;
+	__u32	pasid;
 };
 
 #define VFIO_DEVICE_ATTACH_IOMMUFD_PT		_IO(VFIO_TYPE, VFIO_BASE + 19)
@@ -962,17 +967,21 @@ struct vfio_device_attach_iommufd_pt {
  * VFIO_DEVICE_DETACH_IOMMUFD_PT - _IOW(VFIO_TYPE, VFIO_BASE + 20,
  *					struct vfio_device_detach_iommufd_pt)
  * @argsz:	User filled size of this data.
- * @flags:	Must be 0.
+ * @flags:	Flags for detach.
+ * @pasid:	The pasid to be detached, only meaningful when
+ *		VFIO_DEVICE_DETACH_PASID is set in @flags
  *
- * Remove the association of the device and its current associated address
- * space.  After it, the device should be in a blocking DMA state.  This is only
- * allowed on cdev fds.
+ * Remove the association of the device or a pasid of the device and its current
+ * associated address space.  After it, the device or the pasid should be in a
+ * blocking DMA state.  This is only allowed on cdev fds.
  *
  * Return: 0 on success, -errno on failure.
  */
 struct vfio_device_detach_iommufd_pt {
 	__u32	argsz;
 	__u32	flags;
+#define VFIO_DEVICE_DETACH_PASID	(1 << 0)
+	__u32	pasid;
 };
 
 #define VFIO_DEVICE_DETACH_IOMMUFD_PT		_IO(VFIO_TYPE, VFIO_BASE + 20)
-- 
2.34.1

[PATCH v4 4/4] iommufd: Extend IOMMU_GET_HW_INFO to report PASID capability

[Yi Liu]

PASID usage requires PASID support in both device and IOMMU. Since the
iommu drivers always enable the PASID capability for the device if it
is supported, so it is reasonable to extend the IOMMU_GET_HW_INFO to
report the PASID capability to userspace.

Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Tested-by: Zhangfei Gao <zhangfei.gao@linaro.org> #aarch64 platform
Signed-off-by: Yi Liu <yi.l.liu@intel.com>
---
 drivers/iommu/iommufd/device.c | 24 +++++++++++++++++++++++-
 drivers/pci/ats.c              | 33 +++++++++++++++++++++++++++++++++
 include/linux/pci-ats.h        |  3 +++
 include/uapi/linux/iommufd.h   | 14 +++++++++++++-
 4 files changed, 72 insertions(+), 2 deletions(-)

diff --git a/drivers/iommu/iommufd/device.c b/drivers/iommu/iommufd/device.c
index a52937fba366..3620a039d3fa 100644
--- a/drivers/iommu/iommufd/device.c
+++ b/drivers/iommu/iommufd/device.c
@@ -3,6 +3,8 @@
  */
 #include <linux/iommu.h>
 #include <linux/iommufd.h>
+#include <linux/pci.h>
+#include <linux/pci-ats.h>
 #include <linux/slab.h>
 #include <uapi/linux/iommufd.h>
 
@@ -1248,7 +1250,8 @@ int iommufd_get_hw_info(struct iommufd_ucmd *ucmd)
 	void *data;
 	int rc;
 
-	if (cmd->flags || cmd->__reserved)
+	if (cmd->flags || cmd->__reserved[0] || cmd->__reserved[1] ||
+	    cmd->__reserved[2])
 		return -EOPNOTSUPP;
 
 	idev = iommufd_get_device(ucmd, cmd->dev_id);
@@ -1305,6 +1308,25 @@ int iommufd_get_hw_info(struct iommufd_ucmd *ucmd)
 	if (device_iommu_capable(idev->dev, IOMMU_CAP_DIRTY_TRACKING))
 		cmd->out_capabilities |= IOMMU_HW_CAP_DIRTY_TRACKING;
 
+	cmd->out_max_pasid_log2 = 0;
+
+	if (dev_is_pci(idev->dev)) {
+		struct pci_dev *pdev = to_pci_dev(idev->dev);
+		int ctrl;
+
+		ctrl = pci_pasid_ctrl_status(pdev);
+		if (ctrl >= 0 && (ctrl & PCI_PASID_CTRL_ENABLE)) {
+			cmd->out_max_pasid_log2 =
+					ilog2(idev->dev->iommu->max_pasids);
+			if (ctrl & PCI_PASID_CTRL_EXEC)
+				cmd->out_capabilities |=
+						IOMMU_HW_CAP_PCI_PASID_EXEC;
+			if (ctrl & PCI_PASID_CTRL_PRIV)
+				cmd->out_capabilities |=
+						IOMMU_HW_CAP_PCI_PASID_PRIV;
+		}
+	}
+
 	rc = iommufd_ucmd_respond(ucmd, sizeof(*cmd));
 out_free:
 	kfree(data);
diff --git a/drivers/pci/ats.c b/drivers/pci/ats.c
index 6afff1f1b143..c35465120329 100644
--- a/drivers/pci/ats.c
+++ b/drivers/pci/ats.c
@@ -538,4 +538,37 @@ int pci_max_pasids(struct pci_dev *pdev)
 	return (1 << FIELD_GET(PCI_PASID_CAP_WIDTH, supported));
 }
 EXPORT_SYMBOL_GPL(pci_max_pasids);
+
+/**
+ * pci_pasid_ctrl_status - Check the PASID status
+ * @pdev: PCI device structure
+ *
+ * Returns a negative value when no PASID capability is present.
+ * Otherwise the value of the control register is returned.
+ * Status reported are:
+ *
+ * PCI_PASID_CTRL_ENABLE - PASID enabled
+ * PCI_PASID_CTRL_EXEC - Execute permission enabled
+ * PCI_PASID_CTRL_PRIV - Privileged mode enabled
+ */
+int pci_pasid_ctrl_status(struct pci_dev *pdev)
+{
+	int pasid;
+	u16 ctrl;
+
+	if (pdev->is_virtfn)
+		pdev = pci_physfn(pdev);
+
+	pasid = pdev->pasid_cap;
+	if (!pasid)
+		return -EINVAL;
+
+	pci_read_config_word(pdev, pasid + PCI_PASID_CTRL, &ctrl);
+
+	ctrl &= PCI_PASID_CTRL_ENABLE | PCI_PASID_CTRL_EXEC |
+		PCI_PASID_CTRL_PRIV;
+
+	return ctrl;
+}
+EXPORT_SYMBOL_GPL(pci_pasid_ctrl_status);
 #endif /* CONFIG_PCI_PASID */
diff --git a/include/linux/pci-ats.h b/include/linux/pci-ats.h
index 0e8b74e63767..f4e1d2010287 100644
--- a/include/linux/pci-ats.h
+++ b/include/linux/pci-ats.h
@@ -42,6 +42,7 @@ int pci_enable_pasid(struct pci_dev *pdev, int features);
 void pci_disable_pasid(struct pci_dev *pdev);
 int pci_pasid_features(struct pci_dev *pdev);
 int pci_max_pasids(struct pci_dev *pdev);
+int pci_pasid_ctrl_status(struct pci_dev *pdev);
 #else /* CONFIG_PCI_PASID */
 static inline int pci_enable_pasid(struct pci_dev *pdev, int features)
 { return -EINVAL; }
@@ -50,6 +51,8 @@ static inline int pci_pasid_features(struct pci_dev *pdev)
 { return -EINVAL; }
 static inline int pci_max_pasids(struct pci_dev *pdev)
 { return -EINVAL; }
+static inline int pci_pasid_ctrl_status(struct pci_dev *pdev)
+{ return -EINVAL; }
 #endif /* CONFIG_PCI_PASID */
 
 #endif /* LINUX_PCI_ATS_H */
diff --git a/include/uapi/linux/iommufd.h b/include/uapi/linux/iommufd.h
index 0c0ed28ee113..8dd6412ab74a 100644
--- a/include/uapi/linux/iommufd.h
+++ b/include/uapi/linux/iommufd.h
@@ -512,9 +512,17 @@ enum iommu_hw_info_type {
  *                                   IOMMU_HWPT_GET_DIRTY_BITMAP
  *                                   IOMMU_HWPT_SET_DIRTY_TRACKING
  *
+ * @IOMMU_HW_CAP_PASID_EXEC: Execute Permission Supported, user ignores it
+ *                           when the struct iommu_hw_info::out_max_pasid_log2
+ *                           is zero.
+ * @IOMMU_HW_CAP_PASID_PRIV: Privileged Mode Supported, user ignores it
+ *                           when the struct iommu_hw_info::out_max_pasid_log2
+ *                           is zero.
  */
 enum iommufd_hw_capabilities {
 	IOMMU_HW_CAP_DIRTY_TRACKING = 1 << 0,
+	IOMMU_HW_CAP_PCI_PASID_EXEC = 1 << 1,
+	IOMMU_HW_CAP_PCI_PASID_PRIV = 1 << 2,
 };
 
 /**
@@ -530,6 +538,9 @@ enum iommufd_hw_capabilities {
  *                 iommu_hw_info_type.
  * @out_capabilities: Output the generic iommu capability info type as defined
  *                    in the enum iommu_hw_capabilities.
+ * @out_max_pasid_log2: Output the width of PASIDs. 0 means no PASID support.
+ *                      PCI devices turn to out_capabilities to check if the
+ *                      specific capabilities is supported or not.
  * @__reserved: Must be 0
  *
  * Query an iommu type specific hardware information data from an iommu behind
@@ -553,7 +564,8 @@ struct iommu_hw_info {
 	__u32 data_len;
 	__aligned_u64 data_uptr;
 	__u32 out_data_type;
-	__u32 __reserved;
+	__u8 out_max_pasid_log2;
+	__u8 __reserved[3];
 	__aligned_u64 out_capabilities;
 };
 #define IOMMU_GET_HW_INFO _IO(IOMMUFD_TYPE, IOMMUFD_CMD_GET_HW_INFO)
-- 
2.34.1

Re: [PATCH v4 0/4] vfio-pci support pasid attach/detach

[Yi Liu]

On 2024/11/4 21:27, Yi Liu wrote:
> This adds the pasid attach/detach uAPIs for userspace to attach/detach
> a PASID of a device to/from a given ioas/hwpt. Only vfio-pci driver is
> enabled in this series. After this series, PASID-capable devices bound
> with vfio-pci can report PASID capability to userspace and VM to enable
> PASID usages like Shared Virtual Addressing (SVA).
> 
> Based on the discussion about reporting the vPASID to VM [1], it's agreed
> that we will let the userspace VMM to synthesize the vPASID capability.
> The VMM needs to figure out a hole to put the vPASID cap. This includes
> the hidden bits handling for some devices. While, it's up to the userspace,
> it's not the focus of this series.
> 
> This series first adds the helpers for pasid attach in vfio core and then
> extends the device cdev attach/detach ioctls for pasid attach/detach. In the
> end of this series, the IOMMU_GET_HW_INFO ioctl is extended to report the
> PCI PASID capability to the userspace. Userspace should check this before
> using any PASID related uAPIs provided by VFIO, which is the agreement in [2].
> This series depends on the iommufd pasid attach/detach series [3].
> 
> The completed code can be found at [4], tested with a hacky Qemu branch [5].
> 
> [1] https://lore.kernel.org/kvm/BN9PR11MB5276318969A212AD0649C7BE8CBE2@BN9PR11MB5276.namprd11.prod.outlook.com/
> [2] https://lore.kernel.org/kvm/4f2daf50-a5ad-4599-ab59-bcfc008688d8@intel.com/
> [3] https://lore.kernel.org/linux-iommu/20240912131255.13305-1-yi.l.liu@intel.com/

correct the latest link.

https://lore.kernel.org/linux-iommu/20241104132513.15890-1-yi.l.liu@intel.com/

> [4] https://github.com/yiliu1765/iommufd/tree/iommufd_pasid
> [5] https://github.com/yiliu1765/qemu/tree/wip/zhenzhong/iommufd_nesting_rfcv2-test-pasid
> 
> Change log:
> 
> v4:
>   - Add acked-by for the ida patch from Matthew
>   - Add r-b from Kevin and Jason on patch 01, 02 and 04 of v3
>   - Add common code to copy user data for the user struct with new fields
>   - Extend the VFIO_DEVICE_[AT|DE]TACH_IOMMUFD_PT to support pasid, patch 03
>     is updated per this change. Hence drop r-b of it. (Kevin, Alex)
>   - Add t-b from Zhangfei for patch 4 of v3
>   - Nits from Vasant
> 
> v3: https://lore.kernel.org/linux-iommu/20240912131729.14951-1-yi.l.liu@intel.com/
>   - Misc enhancement on patch 01 of v2 (Alex, Jason)
>   - Add Jason's r-b to patch 03 of v2
>   - Drop the logic that report PASID via VFIO_DEVICE_FEATURE ioctl
>   - Extend IOMMU_GET_HW_INFO to report PASID support (Kevin, Jason, Alex)
> 
> v2: https://lore.kernel.org/kvm/20240412082121.33382-1-yi.l.liu@intel.com/
>   - Use IDA to track if PASID is attached or not in VFIO. (Jason)
>   - Fix the issue of calling pasid_at[de]tach_ioas callback unconditionally (Alex)
>   - Fix the wrong data copy in vfio_df_ioctl_pasid_detach_pt() (Zhenzhong)
>   - Minor tweaks in comments (Kevin)
> 
> v1: https://lore.kernel.org/kvm/20231127063909.129153-1-yi.l.liu@intel.com/
>   - Report PASID capability via VFIO_DEVICE_FEATURE (Alex)
> 
> rfc: https://lore.kernel.org/linux-iommu/20230926093121.18676-1-yi.l.liu@intel.com/
> 
> Regards,
> 	Yi Liu
> 
> Yi Liu (4):
>    ida: Add ida_find_first_range()
>    vfio-iommufd: Support pasid [at|de]tach for physical VFIO devices
>    vfio: VFIO_DEVICE_[AT|DE]TACH_IOMMUFD_PT support pasid
>    iommufd: Extend IOMMU_GET_HW_INFO to report PASID capability
> 
>   drivers/iommu/iommufd/device.c | 24 +++++++++++-
>   drivers/pci/ats.c              | 33 ++++++++++++++++
>   drivers/vfio/device_cdev.c     | 62 +++++++++++++++++++++---------
>   drivers/vfio/iommufd.c         | 50 ++++++++++++++++++++++++
>   drivers/vfio/pci/vfio_pci.c    |  2 +
>   drivers/vfio/vfio.h            | 18 +++++++++
>   drivers/vfio/vfio_main.c       | 55 ++++++++++++++++++++++++++
>   include/linux/idr.h            | 11 ++++++
>   include/linux/pci-ats.h        |  3 ++
>   include/linux/vfio.h           | 11 ++++++
>   include/uapi/linux/iommufd.h   | 14 ++++++-
>   include/uapi/linux/vfio.h      | 29 +++++++++-----
>   lib/idr.c                      | 67 ++++++++++++++++++++++++++++++++
>   lib/test_ida.c                 | 70 ++++++++++++++++++++++++++++++++++
>   14 files changed, 419 insertions(+), 30 deletions(-)
> 

-- 
Regards,
Yi Liu

Re: [PATCH v4 2/4] vfio-iommufd: Support pasid [at|de]tach for physical VFIO devices

[Alex Williamson]

On Mon,  4 Nov 2024 05:27:30 -0800
Yi Liu <yi.l.liu@intel.com> wrote:

> This adds pasid_at|de]tach_ioas ops for attaching hwpt to pasid of a
> device and the helpers for it. For now, only vfio-pci supports pasid
> attach/detach.
> 
> Signed-off-by: Kevin Tian <kevin.tian@intel.com>
> Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
> Signed-off-by: Yi Liu <yi.l.liu@intel.com>
> ---
>  drivers/vfio/iommufd.c      | 50 +++++++++++++++++++++++++++++++++++++
>  drivers/vfio/pci/vfio_pci.c |  2 ++
>  include/linux/vfio.h        | 11 ++++++++
>  3 files changed, 63 insertions(+)
> 
> diff --git a/drivers/vfio/iommufd.c b/drivers/vfio/iommufd.c
> index 82eba6966fa5..2f5cb4f616ce 100644
> --- a/drivers/vfio/iommufd.c
> +++ b/drivers/vfio/iommufd.c
> @@ -119,14 +119,22 @@ int vfio_iommufd_physical_bind(struct vfio_device *vdev,
>  	if (IS_ERR(idev))
>  		return PTR_ERR(idev);
>  	vdev->iommufd_device = idev;
> +	ida_init(&vdev->pasids);
>  	return 0;
>  }
>  EXPORT_SYMBOL_GPL(vfio_iommufd_physical_bind);
>  
>  void vfio_iommufd_physical_unbind(struct vfio_device *vdev)
>  {
> +	int pasid;
> +
>  	lockdep_assert_held(&vdev->dev_set->lock);
>  
> +	while ((pasid = ida_find_first(&vdev->pasids)) >= 0) {
> +		iommufd_device_pasid_detach(vdev->iommufd_device, pasid);
> +		ida_free(&vdev->pasids, pasid);
> +	}
> +
>  	if (vdev->iommufd_attached) {
>  		iommufd_device_detach(vdev->iommufd_device);
>  		vdev->iommufd_attached = false;
> @@ -168,6 +176,48 @@ void vfio_iommufd_physical_detach_ioas(struct vfio_device *vdev)
>  }
>  EXPORT_SYMBOL_GPL(vfio_iommufd_physical_detach_ioas);
>  
> +int vfio_iommufd_physical_pasid_attach_ioas(struct vfio_device *vdev,
> +					    u32 pasid, u32 *pt_id)
> +{
> +	int rc;
> +
> +	lockdep_assert_held(&vdev->dev_set->lock);
> +
> +	if (WARN_ON(!vdev->iommufd_device))
> +		return -EINVAL;
> +
> +	if (ida_exists(&vdev->pasids, pasid))
> +		return iommufd_device_pasid_replace(vdev->iommufd_device,
> +						    pasid, pt_id);
> +
> +	rc = ida_alloc_range(&vdev->pasids, pasid, pasid, GFP_KERNEL);
> +	if (rc < 0)
> +		return rc;
> +
> +	rc = iommufd_device_pasid_attach(vdev->iommufd_device, pasid, pt_id);
> +	if (rc)
> +		ida_free(&vdev->pasids, pasid);
> +
> +	return 0;

I think you meant to return rc here.  Thanks,

Alex

> +}
> +EXPORT_SYMBOL_GPL(vfio_iommufd_physical_pasid_attach_ioas);
> +
> +void vfio_iommufd_physical_pasid_detach_ioas(struct vfio_device *vdev,
> +					     u32 pasid)
> +{
> +	lockdep_assert_held(&vdev->dev_set->lock);
> +
> +	if (WARN_ON(!vdev->iommufd_device))
> +		return;
> +
> +	if (!ida_exists(&vdev->pasids, pasid))
> +		return;
> +
> +	iommufd_device_pasid_detach(vdev->iommufd_device, pasid);
> +	ida_free(&vdev->pasids, pasid);
> +}
> +EXPORT_SYMBOL_GPL(vfio_iommufd_physical_pasid_detach_ioas);
> +
>  /*
>   * The emulated standard ops mean that vfio_device is going to use the
>   * "mdev path" and will call vfio_pin_pages()/vfio_dma_rw(). Drivers using this
> diff --git a/drivers/vfio/pci/vfio_pci.c b/drivers/vfio/pci/vfio_pci.c
> index e727941f589d..6f7ae7e5b7b0 100644
> --- a/drivers/vfio/pci/vfio_pci.c
> +++ b/drivers/vfio/pci/vfio_pci.c
> @@ -144,6 +144,8 @@ static const struct vfio_device_ops vfio_pci_ops = {
>  	.unbind_iommufd	= vfio_iommufd_physical_unbind,
>  	.attach_ioas	= vfio_iommufd_physical_attach_ioas,
>  	.detach_ioas	= vfio_iommufd_physical_detach_ioas,
> +	.pasid_attach_ioas	= vfio_iommufd_physical_pasid_attach_ioas,
> +	.pasid_detach_ioas	= vfio_iommufd_physical_pasid_detach_ioas,
>  };
>  
>  static int vfio_pci_probe(struct pci_dev *pdev, const struct pci_device_id *id)
> diff --git a/include/linux/vfio.h b/include/linux/vfio.h
> index 000a6cab2d31..11b3b453752e 100644
> --- a/include/linux/vfio.h
> +++ b/include/linux/vfio.h
> @@ -67,6 +67,7 @@ struct vfio_device {
>  	struct inode *inode;
>  #if IS_ENABLED(CONFIG_IOMMUFD)
>  	struct iommufd_device *iommufd_device;
> +	struct ida pasids;
>  	u8 iommufd_attached:1;
>  #endif
>  	u8 cdev_opened:1;
> @@ -91,6 +92,8 @@ struct vfio_device {
>   *		 bound iommufd. Undo in unbind_iommufd if @detach_ioas is not
>   *		 called.
>   * @detach_ioas: Opposite of attach_ioas
> + * @pasid_attach_ioas: The pasid variation of attach_ioas
> + * @pasid_detach_ioas: Opposite of pasid_attach_ioas
>   * @open_device: Called when the first file descriptor is opened for this device
>   * @close_device: Opposite of open_device
>   * @read: Perform read(2) on device file descriptor
> @@ -115,6 +118,8 @@ struct vfio_device_ops {
>  	void	(*unbind_iommufd)(struct vfio_device *vdev);
>  	int	(*attach_ioas)(struct vfio_device *vdev, u32 *pt_id);
>  	void	(*detach_ioas)(struct vfio_device *vdev);
> +	int	(*pasid_attach_ioas)(struct vfio_device *vdev, u32 pasid, u32 *pt_id);
> +	void	(*pasid_detach_ioas)(struct vfio_device *vdev, u32 pasid);
>  	int	(*open_device)(struct vfio_device *vdev);
>  	void	(*close_device)(struct vfio_device *vdev);
>  	ssize_t	(*read)(struct vfio_device *vdev, char __user *buf,
> @@ -139,6 +144,8 @@ int vfio_iommufd_physical_bind(struct vfio_device *vdev,
>  void vfio_iommufd_physical_unbind(struct vfio_device *vdev);
>  int vfio_iommufd_physical_attach_ioas(struct vfio_device *vdev, u32 *pt_id);
>  void vfio_iommufd_physical_detach_ioas(struct vfio_device *vdev);
> +int vfio_iommufd_physical_pasid_attach_ioas(struct vfio_device *vdev, u32 pasid, u32 *pt_id);
> +void vfio_iommufd_physical_pasid_detach_ioas(struct vfio_device *vdev, u32 pasid);
>  int vfio_iommufd_emulated_bind(struct vfio_device *vdev,
>  			       struct iommufd_ctx *ictx, u32 *out_device_id);
>  void vfio_iommufd_emulated_unbind(struct vfio_device *vdev);
> @@ -166,6 +173,10 @@ vfio_iommufd_get_dev_id(struct vfio_device *vdev, struct iommufd_ctx *ictx)
>  	((int (*)(struct vfio_device *vdev, u32 *pt_id)) NULL)
>  #define vfio_iommufd_physical_detach_ioas \
>  	((void (*)(struct vfio_device *vdev)) NULL)
> +#define vfio_iommufd_physical_pasid_attach_ioas \
> +	((int (*)(struct vfio_device *vdev, u32 pasid, u32 *pt_id)) NULL)
> +#define vfio_iommufd_physical_pasid_detach_ioas \
> +	((void (*)(struct vfio_device *vdev, u32 pasid)) NULL)
>  #define vfio_iommufd_emulated_bind                                      \
>  	((int (*)(struct vfio_device *vdev, struct iommufd_ctx *ictx,   \
>  		  u32 *out_device_id)) NULL)

Re: [PATCH v4 3/4] vfio: VFIO_DEVICE_[AT|DE]TACH_IOMMUFD_PT support pasid

[Alex Williamson]

On Mon,  4 Nov 2024 05:27:31 -0800
Yi Liu <yi.l.liu@intel.com> wrote:

> This extends the VFIO_DEVICE_[AT|DE]TACH_IOMMUFD_PT ioctls to attach/detach
> a given pasid of a vfio device to/from an IOAS/HWPT.
> 
> vfio_copy_from_user() is added to copy the user data for the case in which
> the existing user struct has introduced new fields. The rule is not breaking
> the existing usersapce. The kernel only copies the new fields when the
> corresponding flag is set by the userspace. For the case that has multiple
> new fields marked by different flags, kernel checks the flags one by one to
> get the correct size to copy besides the minsz. Such logics can be shared by
> the other uapi extensions, hence add a helper for it.
> 
> Signed-off-by: Yi Liu <yi.l.liu@intel.com>
> ---
>  drivers/vfio/device_cdev.c | 62 +++++++++++++++++++++++++++-----------
>  drivers/vfio/vfio.h        | 18 +++++++++++
>  drivers/vfio/vfio_main.c   | 55 +++++++++++++++++++++++++++++++++
>  include/uapi/linux/vfio.h  | 29 ++++++++++++------
>  4 files changed, 136 insertions(+), 28 deletions(-)
> 
> diff --git a/drivers/vfio/device_cdev.c b/drivers/vfio/device_cdev.c
> index bb1817bd4ff3..bd13ddbfb9e3 100644
> --- a/drivers/vfio/device_cdev.c
> +++ b/drivers/vfio/device_cdev.c
> @@ -159,24 +159,44 @@ void vfio_df_unbind_iommufd(struct vfio_device_file *df)
>  	vfio_device_unblock_group(device);
>  }
>  
> +#define VFIO_ATTACH_FLAGS_MASK VFIO_DEVICE_ATTACH_PASID
> +static unsigned long
> +vfio_attach_xends[ilog2(VFIO_ATTACH_FLAGS_MASK) + 1] = {
> +	XEND_SIZE(VFIO_DEVICE_ATTACH_PASID,
> +		  struct vfio_device_attach_iommufd_pt, pasid),
> +};
> +
> +#define VFIO_DETACH_FLAGS_MASK VFIO_DEVICE_DETACH_PASID
> +static unsigned long
> +vfio_detach_xends[ilog2(VFIO_DETACH_FLAGS_MASK) + 1] = {
> +	XEND_SIZE(VFIO_DEVICE_DETACH_PASID,
> +		  struct vfio_device_detach_iommufd_pt, pasid),
> +};

Doesn't this rather imply that every valid flag bit indicates some new
structure field?

For example, we start out with:

struct vfio_device_attach_iommufd_pt {
        __u32   argsz;
        __u32   flags;
        __u32   pt_id;
};

And then here it becomes:

struct vfio_device_attach_iommufd_pt {
	__u32	argsz;
	__u32	flags;
#define VFIO_DEVICE_ATTACH_PASID	(1 << 0)
	__u32	pt_id;
	__u32	pasid;
};

What if the next flag is simply related to the processing of @pt_id and
doesn't require @pasid?

The xend array necessarily expands, but what's the value?  Logically it
would be offsetofend(, pt_id), so the array becomes { 16, 12 }.

Similarly, rather than pasid we might have reused a previously
reserved field, for instance what if we already expanded the structure
as:

struct vfio_device_attach_iommufd_pt {
	__u32	argsz;
	__u32	flags;
#define VFIO_DEVICE_ATTACH_FOO		(1 << 0)
	__u32	pt_id;
	__u32	reserved;
	__u64	foo;
};

If we then want to add @pasid, we might really prefer to take advantage
of that reserved field and the array becomes { 24, 16 }.

I think these can work (see below), but this seems like a pretty
complicated generalization.  It might make sense to initially open code
the handling for @pasid with a follow-on patch with this sort of
generalization so we can evaluate them separately.

BTW, don't feel obligated to use "xend" based on my email sample code.

> +
>  int vfio_df_ioctl_attach_pt(struct vfio_device_file *df,
>  			    struct vfio_device_attach_iommufd_pt __user *arg)
>  {
> -	struct vfio_device *device = df->device;
>  	struct vfio_device_attach_iommufd_pt attach;
> -	unsigned long minsz;
> +	struct vfio_device *device = df->device;
>  	int ret;
>  
> -	minsz = offsetofend(struct vfio_device_attach_iommufd_pt, pt_id);
> -
> -	if (copy_from_user(&attach, arg, minsz))
> -		return -EFAULT;
> +	ret = VFIO_COPY_USER_DATA((void __user *)arg, &attach,
> +				  struct vfio_device_attach_iommufd_pt,
> +				  pt_id, VFIO_ATTACH_FLAGS_MASK,
> +				  vfio_attach_xends);
> +	if (ret)
> +		return ret;
>  
> -	if (attach.argsz < minsz || attach.flags)
> -		return -EINVAL;
> +	if ((attach.flags & VFIO_DEVICE_ATTACH_PASID) &&
> +	    !device->ops->pasid_attach_ioas)
> +		return -EOPNOTSUPP;
>  
>  	mutex_lock(&device->dev_set->lock);
> -	ret = device->ops->attach_ioas(device, &attach.pt_id);
> +	if (attach.flags & VFIO_DEVICE_ATTACH_PASID)
> +		ret = device->ops->pasid_attach_ioas(device, attach.pasid,
> +						     &attach.pt_id);
> +	else
> +		ret = device->ops->attach_ioas(device, &attach.pt_id);
>  	if (ret)
>  		goto out_unlock;
>  
> @@ -198,20 +218,26 @@ int vfio_df_ioctl_attach_pt(struct vfio_device_file *df,
>  int vfio_df_ioctl_detach_pt(struct vfio_device_file *df,
>  			    struct vfio_device_detach_iommufd_pt __user *arg)
>  {
> -	struct vfio_device *device = df->device;
>  	struct vfio_device_detach_iommufd_pt detach;
> -	unsigned long minsz;
> -
> -	minsz = offsetofend(struct vfio_device_detach_iommufd_pt, flags);
> +	struct vfio_device *device = df->device;
> +	int ret;
>  
> -	if (copy_from_user(&detach, arg, minsz))
> -		return -EFAULT;
> +	ret = VFIO_COPY_USER_DATA((void __user *)arg, &detach,
> +				  struct vfio_device_detach_iommufd_pt,
> +				  flags, VFIO_DETACH_FLAGS_MASK,
> +				  vfio_detach_xends);
> +	if (ret)
> +		return ret;
>  
> -	if (detach.argsz < minsz || detach.flags)
> -		return -EINVAL;
> +	if ((detach.flags & VFIO_DEVICE_DETACH_PASID) &&
> +	    !device->ops->pasid_detach_ioas)
> +		return -EOPNOTSUPP;
>  
>  	mutex_lock(&device->dev_set->lock);
> -	device->ops->detach_ioas(device);
> +	if (detach.flags & VFIO_DEVICE_DETACH_PASID)
> +		device->ops->pasid_detach_ioas(device, detach.pasid);
> +	else
> +		device->ops->detach_ioas(device);
>  	mutex_unlock(&device->dev_set->lock);
>  
>  	return 0;
> diff --git a/drivers/vfio/vfio.h b/drivers/vfio/vfio.h
> index 50128da18bca..9f081cf01c5a 100644
> --- a/drivers/vfio/vfio.h
> +++ b/drivers/vfio/vfio.h
> @@ -34,6 +34,24 @@ void vfio_df_close(struct vfio_device_file *df);
>  struct vfio_device_file *
>  vfio_allocate_device_file(struct vfio_device *device);
>  
> +int vfio_copy_from_user(void *buffer, void __user *arg,
> +			unsigned long minsz, u32 flags_mask,
> +			unsigned long *xend_array);
> +
> +#define VFIO_COPY_USER_DATA(_arg, _local_buffer, _struct, _min_last,          \
> +			    _flags_mask, _xend_array)                         \
> +	vfio_copy_from_user(_local_buffer, _arg,                              \
> +			    offsetofend(_struct, _min_last) +                \
> +			    BUILD_BUG_ON_ZERO(offsetof(_struct, argsz) !=     \
> +					      0) +                            \
> +			    BUILD_BUG_ON_ZERO(offsetof(_struct, flags) !=     \
> +					      sizeof(u32)),                   \
> +			    _flags_mask, _xend_array)

We have a precedence in vfio_alloc_device() that macros wrapping
functions don't need to be all caps.

> +
> +#define XEND_SIZE(_flag, _struct, _xlast)                                    \
> +	[ilog2(_flag)] = offsetofend(_struct, _xlast) +                      \
> +			 BUILD_BUG_ON_ZERO(_flag == 0)                       \
> +
>  extern const struct file_operations vfio_device_fops;
>  
>  #ifdef CONFIG_VFIO_NOIOMMU
> diff --git a/drivers/vfio/vfio_main.c b/drivers/vfio/vfio_main.c
> index a5a62d9d963f..7df94bf121fd 100644
> --- a/drivers/vfio/vfio_main.c
> +++ b/drivers/vfio/vfio_main.c
> @@ -1694,6 +1694,61 @@ int vfio_dma_rw(struct vfio_device *device, dma_addr_t iova, void *data,
>  }
>  EXPORT_SYMBOL(vfio_dma_rw);
>  
> +/**
> + * vfio_copy_from_user - Copy the user struct that may have extended fields
> + *
> + * @buffer: The local buffer to store the data copied from user
> + * @arg: The user buffer pointer
> + * @minsz: The minimum size of the user struct, it should never bump up.
> + * @flags_mask: The combination of all the falgs defined
> + * @xend_array: The array that stores the xend size for set flags.
> + *
> + * This helper requires the user struct put the argsz and flags fields in
> + * the first 8 bytes.
> + *
> + * Return 0 for success, otherwise -errno
> + */
> +int vfio_copy_from_user(void *buffer, void __user *arg,
> +			unsigned long minsz, u32 flags_mask,
> +			unsigned long *xend_array)
> +{
> +	unsigned long xend = 0;
> +	struct user_header {
> +		u32 argsz;
> +		u32 flags;
> +	} *header;
> +	unsigned long flags;
> +	u32 flag;
> +
> +	if (copy_from_user(buffer, arg, minsz))
> +		return -EFAULT;
> +
> +	header = (struct user_header *)buffer;
> +	if (header->argsz < minsz)
> +		return -EINVAL;
> +
> +	if (header->flags & ~flags_mask)
> +		return -EINVAL;
> +
> +	/* Loop each set flag to decide the xend */
> +	flags = header->flags;
> +	for_each_set_bit(flag, &flags, BITS_PER_LONG) {

I suppose it doesn't matter, but there's a logical inconsistency
searching BITS_PER_LONG on a buffer initialized by a u32.

> +		if (xend_array[flag])

Given the earlier concern, this should be:

		if (xend_array[flags] > xend)

Thanks,
Alex

> +			xend = xend_array[flag];
> +	}
> +
> +	if (xend) {
> +		if (header->argsz < xend)
> +			return -EINVAL;
> +
> +		if (copy_from_user(buffer + minsz,
> +				   arg + minsz, xend - minsz))
> +			return -EFAULT;
> +	}
> +
> +	return 0;
> +}
> +
>  /*
>   * Module/class support
>   */
> diff --git a/include/uapi/linux/vfio.h b/include/uapi/linux/vfio.h
> index 2b68e6cdf190..40b414e642f5 100644
> --- a/include/uapi/linux/vfio.h
> +++ b/include/uapi/linux/vfio.h
> @@ -931,29 +931,34 @@ struct vfio_device_bind_iommufd {
>   * VFIO_DEVICE_ATTACH_IOMMUFD_PT - _IOW(VFIO_TYPE, VFIO_BASE + 19,
>   *					struct vfio_device_attach_iommufd_pt)
>   * @argsz:	User filled size of this data.
> - * @flags:	Must be 0.
> + * @flags:	Flags for attach.
>   * @pt_id:	Input the target id which can represent an ioas or a hwpt
>   *		allocated via iommufd subsystem.
>   *		Output the input ioas id or the attached hwpt id which could
>   *		be the specified hwpt itself or a hwpt automatically created
>   *		for the specified ioas by kernel during the attachment.
> + * @pasid:	The pasid to be attached, only meaningful when
> + *		VFIO_DEVICE_ATTACH_PASID is set in @flags
>   *
>   * Associate the device with an address space within the bound iommufd.
>   * Undo by VFIO_DEVICE_DETACH_IOMMUFD_PT or device fd close.  This is only
>   * allowed on cdev fds.
>   *
> - * If a vfio device is currently attached to a valid hw_pagetable, without doing
> - * a VFIO_DEVICE_DETACH_IOMMUFD_PT, a second VFIO_DEVICE_ATTACH_IOMMUFD_PT ioctl
> - * passing in another hw_pagetable (hwpt) id is allowed. This action, also known
> - * as a hw_pagetable replacement, will replace the device's currently attached
> - * hw_pagetable with a new hw_pagetable corresponding to the given pt_id.
> + * If a vfio device or a pasid of this device is currently attached to a valid
> + * hw_pagetable (hwpt), without doing a VFIO_DEVICE_DETACH_IOMMUFD_PT, a second
> + * VFIO_DEVICE_ATTACH_IOMMUFD_PT ioctl passing in another hwpt id is allowed.
> + * This action, also known as a hw_pagetable replacement, will replace the
> + * currently attached hwpt of the device or the pasid of this device with a new
> + * hwpt corresponding to the given pt_id.
>   *
>   * Return: 0 on success, -errno on failure.
>   */
>  struct vfio_device_attach_iommufd_pt {
>  	__u32	argsz;
>  	__u32	flags;
> +#define VFIO_DEVICE_ATTACH_PASID	(1 << 0)
>  	__u32	pt_id;
> +	__u32	pasid;
>  };
>  
>  #define VFIO_DEVICE_ATTACH_IOMMUFD_PT		_IO(VFIO_TYPE, VFIO_BASE + 19)
> @@ -962,17 +967,21 @@ struct vfio_device_attach_iommufd_pt {
>   * VFIO_DEVICE_DETACH_IOMMUFD_PT - _IOW(VFIO_TYPE, VFIO_BASE + 20,
>   *					struct vfio_device_detach_iommufd_pt)
>   * @argsz:	User filled size of this data.
> - * @flags:	Must be 0.
> + * @flags:	Flags for detach.
> + * @pasid:	The pasid to be detached, only meaningful when
> + *		VFIO_DEVICE_DETACH_PASID is set in @flags
>   *
> - * Remove the association of the device and its current associated address
> - * space.  After it, the device should be in a blocking DMA state.  This is only
> - * allowed on cdev fds.
> + * Remove the association of the device or a pasid of the device and its current
> + * associated address space.  After it, the device or the pasid should be in a
> + * blocking DMA state.  This is only allowed on cdev fds.
>   *
>   * Return: 0 on success, -errno on failure.
>   */
>  struct vfio_device_detach_iommufd_pt {
>  	__u32	argsz;
>  	__u32	flags;
> +#define VFIO_DEVICE_DETACH_PASID	(1 << 0)
> +	__u32	pasid;
>  };
>  
>  #define VFIO_DEVICE_DETACH_IOMMUFD_PT		_IO(VFIO_TYPE, VFIO_BASE + 20)

Re: [PATCH v4 2/4] vfio-iommufd: Support pasid [at|de]tach for physical VFIO devices

[Yi Liu]

On 2024/11/5 04:59, Alex Williamson wrote:
> On Mon,  4 Nov 2024 05:27:30 -0800
> Yi Liu <yi.l.liu@intel.com> wrote:
> 
>> This adds pasid_at|de]tach_ioas ops for attaching hwpt to pasid of a
>> device and the helpers for it. For now, only vfio-pci supports pasid
>> attach/detach.
>>
>> Signed-off-by: Kevin Tian <kevin.tian@intel.com>
>> Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
>> Signed-off-by: Yi Liu <yi.l.liu@intel.com>
>> ---
>>   drivers/vfio/iommufd.c      | 50 +++++++++++++++++++++++++++++++++++++
>>   drivers/vfio/pci/vfio_pci.c |  2 ++
>>   include/linux/vfio.h        | 11 ++++++++
>>   3 files changed, 63 insertions(+)
>>
>> diff --git a/drivers/vfio/iommufd.c b/drivers/vfio/iommufd.c
>> index 82eba6966fa5..2f5cb4f616ce 100644
>> --- a/drivers/vfio/iommufd.c
>> +++ b/drivers/vfio/iommufd.c
>> @@ -119,14 +119,22 @@ int vfio_iommufd_physical_bind(struct vfio_device *vdev,
>>   	if (IS_ERR(idev))
>>   		return PTR_ERR(idev);
>>   	vdev->iommufd_device = idev;
>> +	ida_init(&vdev->pasids);
>>   	return 0;
>>   }
>>   EXPORT_SYMBOL_GPL(vfio_iommufd_physical_bind);
>>   
>>   void vfio_iommufd_physical_unbind(struct vfio_device *vdev)
>>   {
>> +	int pasid;
>> +
>>   	lockdep_assert_held(&vdev->dev_set->lock);
>>   
>> +	while ((pasid = ida_find_first(&vdev->pasids)) >= 0) {
>> +		iommufd_device_pasid_detach(vdev->iommufd_device, pasid);
>> +		ida_free(&vdev->pasids, pasid);
>> +	}
>> +
>>   	if (vdev->iommufd_attached) {
>>   		iommufd_device_detach(vdev->iommufd_device);
>>   		vdev->iommufd_attached = false;
>> @@ -168,6 +176,48 @@ void vfio_iommufd_physical_detach_ioas(struct vfio_device *vdev)
>>   }
>>   EXPORT_SYMBOL_GPL(vfio_iommufd_physical_detach_ioas);
>>   
>> +int vfio_iommufd_physical_pasid_attach_ioas(struct vfio_device *vdev,
>> +					    u32 pasid, u32 *pt_id)
>> +{
>> +	int rc;
>> +
>> +	lockdep_assert_held(&vdev->dev_set->lock);
>> +
>> +	if (WARN_ON(!vdev->iommufd_device))
>> +		return -EINVAL;
>> +
>> +	if (ida_exists(&vdev->pasids, pasid))
>> +		return iommufd_device_pasid_replace(vdev->iommufd_device,
>> +						    pasid, pt_id);
>> +
>> +	rc = ida_alloc_range(&vdev->pasids, pasid, pasid, GFP_KERNEL);
>> +	if (rc < 0)
>> +		return rc;
>> +
>> +	rc = iommufd_device_pasid_attach(vdev->iommufd_device, pasid, pt_id);
>> +	if (rc)
>> +		ida_free(&vdev->pasids, pasid);
>> +
>> +	return 0;
> 
> I think you meant to return rc here.  Thanks,

you are absolutely right. :)

-- 
Regards,
Yi Liu

Re: [PATCH v4 3/4] vfio: VFIO_DEVICE_[AT|DE]TACH_IOMMUFD_PT support pasid

[Yi Liu]

On 2024/11/5 05:00, Alex Williamson wrote:
> On Mon,  4 Nov 2024 05:27:31 -0800
> Yi Liu <yi.l.liu@intel.com> wrote:
> 
>> This extends the VFIO_DEVICE_[AT|DE]TACH_IOMMUFD_PT ioctls to attach/detach
>> a given pasid of a vfio device to/from an IOAS/HWPT.
>>
>> vfio_copy_from_user() is added to copy the user data for the case in which
>> the existing user struct has introduced new fields. The rule is not breaking
>> the existing usersapce. The kernel only copies the new fields when the
>> corresponding flag is set by the userspace. For the case that has multiple
>> new fields marked by different flags, kernel checks the flags one by one to
>> get the correct size to copy besides the minsz. Such logics can be shared by
>> the other uapi extensions, hence add a helper for it.
>>
>> Signed-off-by: Yi Liu <yi.l.liu@intel.com>
>> ---
>>   drivers/vfio/device_cdev.c | 62 +++++++++++++++++++++++++++-----------
>>   drivers/vfio/vfio.h        | 18 +++++++++++
>>   drivers/vfio/vfio_main.c   | 55 +++++++++++++++++++++++++++++++++
>>   include/uapi/linux/vfio.h  | 29 ++++++++++++------
>>   4 files changed, 136 insertions(+), 28 deletions(-)
>>
>> diff --git a/drivers/vfio/device_cdev.c b/drivers/vfio/device_cdev.c
>> index bb1817bd4ff3..bd13ddbfb9e3 100644
>> --- a/drivers/vfio/device_cdev.c
>> +++ b/drivers/vfio/device_cdev.c
>> @@ -159,24 +159,44 @@ void vfio_df_unbind_iommufd(struct vfio_device_file *df)
>>   	vfio_device_unblock_group(device);
>>   }
>>   
>> +#define VFIO_ATTACH_FLAGS_MASK VFIO_DEVICE_ATTACH_PASID
>> +static unsigned long
>> +vfio_attach_xends[ilog2(VFIO_ATTACH_FLAGS_MASK) + 1] = {
>> +	XEND_SIZE(VFIO_DEVICE_ATTACH_PASID,
>> +		  struct vfio_device_attach_iommufd_pt, pasid),
>> +};
>> +
>> +#define VFIO_DETACH_FLAGS_MASK VFIO_DEVICE_DETACH_PASID
>> +static unsigned long
>> +vfio_detach_xends[ilog2(VFIO_DETACH_FLAGS_MASK) + 1] = {
>> +	XEND_SIZE(VFIO_DEVICE_DETACH_PASID,
>> +		  struct vfio_device_detach_iommufd_pt, pasid),
>> +};
> 
> Doesn't this rather imply that every valid flag bit indicates some new
> structure field?
> 
> For example, we start out with:
> 
> struct vfio_device_attach_iommufd_pt {
>          __u32   argsz;
>          __u32   flags;
>          __u32   pt_id;
> };
> 
> And then here it becomes:
> 
> struct vfio_device_attach_iommufd_pt {
> 	__u32	argsz;
> 	__u32	flags;
> #define VFIO_DEVICE_ATTACH_PASID	(1 << 0)
> 	__u32	pt_id;
> 	__u32	pasid;
> };
> 
> What if the next flag is simply related to the processing of @pt_id and
> doesn't require @pasid?
> 
> The xend array necessarily expands, but what's the value?  Logically it
> would be offsetofend(, pt_id), so the array becomes { 16, 12 }.

You are right.

> 
> Similarly, rather than pasid we might have reused a previously
> reserved field, for instance what if we already expanded the structure
> as:
> 
> struct vfio_device_attach_iommufd_pt {
> 	__u32	argsz;
> 	__u32	flags;
> #define VFIO_DEVICE_ATTACH_FOO		(1 << 0)
> 	__u32	pt_id;
> 	__u32	reserved;
> 	__u64	foo;
> };
> 
> If we then want to add @pasid, we might really prefer to take advantage
> of that reserved field and the array becomes { 24, 16 }.

yes.

> I think these can work (see below), but this seems like a pretty
> complicated generalization.  It might make sense to initially open code
> the handling for @pasid with a follow-on patch with this sort of
> generalization so we can evaluate them separately.

sure. If don't mind, I'd like to mention the two examples in the commit
message when adding the generalization. To let future people understand
how should the array be programmed.

> 
> BTW, don't feel obligated to use "xend" based on my email sample code.

TBH. I don't see a better name besides it yet. :) If you don't mind, I
may keep using it in later versions.

> 
>> +
>>   int vfio_df_ioctl_attach_pt(struct vfio_device_file *df,
>>   			    struct vfio_device_attach_iommufd_pt __user *arg)
>>   {
>> -	struct vfio_device *device = df->device;
>>   	struct vfio_device_attach_iommufd_pt attach;
>> -	unsigned long minsz;
>> +	struct vfio_device *device = df->device;
>>   	int ret;
>>   
>> -	minsz = offsetofend(struct vfio_device_attach_iommufd_pt, pt_id);
>> -
>> -	if (copy_from_user(&attach, arg, minsz))
>> -		return -EFAULT;
>> +	ret = VFIO_COPY_USER_DATA((void __user *)arg, &attach,
>> +				  struct vfio_device_attach_iommufd_pt,
>> +				  pt_id, VFIO_ATTACH_FLAGS_MASK,
>> +				  vfio_attach_xends);
>> +	if (ret)
>> +		return ret;
>>   
>> -	if (attach.argsz < minsz || attach.flags)
>> -		return -EINVAL;
>> +	if ((attach.flags & VFIO_DEVICE_ATTACH_PASID) &&
>> +	    !device->ops->pasid_attach_ioas)
>> +		return -EOPNOTSUPP;
>>   
>>   	mutex_lock(&device->dev_set->lock);
>> -	ret = device->ops->attach_ioas(device, &attach.pt_id);
>> +	if (attach.flags & VFIO_DEVICE_ATTACH_PASID)
>> +		ret = device->ops->pasid_attach_ioas(device, attach.pasid,
>> +						     &attach.pt_id);
>> +	else
>> +		ret = device->ops->attach_ioas(device, &attach.pt_id);
>>   	if (ret)
>>   		goto out_unlock;
>>   
>> @@ -198,20 +218,26 @@ int vfio_df_ioctl_attach_pt(struct vfio_device_file *df,
>>   int vfio_df_ioctl_detach_pt(struct vfio_device_file *df,
>>   			    struct vfio_device_detach_iommufd_pt __user *arg)
>>   {
>> -	struct vfio_device *device = df->device;
>>   	struct vfio_device_detach_iommufd_pt detach;
>> -	unsigned long minsz;
>> -
>> -	minsz = offsetofend(struct vfio_device_detach_iommufd_pt, flags);
>> +	struct vfio_device *device = df->device;
>> +	int ret;
>>   
>> -	if (copy_from_user(&detach, arg, minsz))
>> -		return -EFAULT;
>> +	ret = VFIO_COPY_USER_DATA((void __user *)arg, &detach,
>> +				  struct vfio_device_detach_iommufd_pt,
>> +				  flags, VFIO_DETACH_FLAGS_MASK,
>> +				  vfio_detach_xends);
>> +	if (ret)
>> +		return ret;
>>   
>> -	if (detach.argsz < minsz || detach.flags)
>> -		return -EINVAL;
>> +	if ((detach.flags & VFIO_DEVICE_DETACH_PASID) &&
>> +	    !device->ops->pasid_detach_ioas)
>> +		return -EOPNOTSUPP;
>>   
>>   	mutex_lock(&device->dev_set->lock);
>> -	device->ops->detach_ioas(device);
>> +	if (detach.flags & VFIO_DEVICE_DETACH_PASID)
>> +		device->ops->pasid_detach_ioas(device, detach.pasid);
>> +	else
>> +		device->ops->detach_ioas(device);
>>   	mutex_unlock(&device->dev_set->lock);
>>   
>>   	return 0;
>> diff --git a/drivers/vfio/vfio.h b/drivers/vfio/vfio.h
>> index 50128da18bca..9f081cf01c5a 100644
>> --- a/drivers/vfio/vfio.h
>> +++ b/drivers/vfio/vfio.h
>> @@ -34,6 +34,24 @@ void vfio_df_close(struct vfio_device_file *df);
>>   struct vfio_device_file *
>>   vfio_allocate_device_file(struct vfio_device *device);
>>   
>> +int vfio_copy_from_user(void *buffer, void __user *arg,
>> +			unsigned long minsz, u32 flags_mask,
>> +			unsigned long *xend_array);
>> +
>> +#define VFIO_COPY_USER_DATA(_arg, _local_buffer, _struct, _min_last,          \
>> +			    _flags_mask, _xend_array)                         \
>> +	vfio_copy_from_user(_local_buffer, _arg,                              \
>> +			    offsetofend(_struct, _min_last) +                \
>> +			    BUILD_BUG_ON_ZERO(offsetof(_struct, argsz) !=     \
>> +					      0) +                            \
>> +			    BUILD_BUG_ON_ZERO(offsetof(_struct, flags) !=     \
>> +					      sizeof(u32)),                   \
>> +			    _flags_mask, _xend_array)
> 
> We have a precedence in vfio_alloc_device() that macros wrapping
> functions don't need to be all caps.

got it. :)

> 
>> +
>> +#define XEND_SIZE(_flag, _struct, _xlast)                                    \
>> +	[ilog2(_flag)] = offsetofend(_struct, _xlast) +                      \
>> +			 BUILD_BUG_ON_ZERO(_flag == 0)                       \
>> +
>>   extern const struct file_operations vfio_device_fops;
>>   
>>   #ifdef CONFIG_VFIO_NOIOMMU
>> diff --git a/drivers/vfio/vfio_main.c b/drivers/vfio/vfio_main.c
>> index a5a62d9d963f..7df94bf121fd 100644
>> --- a/drivers/vfio/vfio_main.c
>> +++ b/drivers/vfio/vfio_main.c
>> @@ -1694,6 +1694,61 @@ int vfio_dma_rw(struct vfio_device *device, dma_addr_t iova, void *data,
>>   }
>>   EXPORT_SYMBOL(vfio_dma_rw);
>>   
>> +/**
>> + * vfio_copy_from_user - Copy the user struct that may have extended fields
>> + *
>> + * @buffer: The local buffer to store the data copied from user
>> + * @arg: The user buffer pointer
>> + * @minsz: The minimum size of the user struct, it should never bump up.
>> + * @flags_mask: The combination of all the falgs defined
>> + * @xend_array: The array that stores the xend size for set flags.
>> + *
>> + * This helper requires the user struct put the argsz and flags fields in
>> + * the first 8 bytes.
>> + *
>> + * Return 0 for success, otherwise -errno
>> + */
>> +int vfio_copy_from_user(void *buffer, void __user *arg,
>> +			unsigned long minsz, u32 flags_mask,
>> +			unsigned long *xend_array)
>> +{
>> +	unsigned long xend = 0;
>> +	struct user_header {
>> +		u32 argsz;
>> +		u32 flags;
>> +	} *header;
>> +	unsigned long flags;
>> +	u32 flag;
>> +
>> +	if (copy_from_user(buffer, arg, minsz))
>> +		return -EFAULT;
>> +
>> +	header = (struct user_header *)buffer;
>> +	if (header->argsz < minsz)
>> +		return -EINVAL;
>> +
>> +	if (header->flags & ~flags_mask)
>> +		return -EINVAL;
>> +
>> +	/* Loop each set flag to decide the xend */
>> +	flags = header->flags;
>> +	for_each_set_bit(flag, &flags, BITS_PER_LONG) {
> 
> I suppose it doesn't matter, but there's a logical inconsistency
> searching BITS_PER_LONG on a buffer initialized by a u32.

how about using BITS_PER_TYPE(u32) or hard-code 32 here?

> 
>> +		if (xend_array[flag])
> 
> Given the earlier concern, this should be:
> 
> 		if (xend_array[flags] > xend)

yes.

> 
> Thanks,
> Alex
> 
>> +			xend = xend_array[flag];
>> +	}
>> +
>> +	if (xend) {

I may change this check as the below. Hence we don't bother to
do the check and funtion call at all.

	if (xend != minsz) {

>> +		if (header->argsz < xend)
>> +			return -EINVAL;
>> +
>> +		if (copy_from_user(buffer + minsz,
>> +				   arg + minsz, xend - minsz))
>> +			return -EFAULT;
>> +	}
>> +
>> +	return 0;
>> +}
>> +
>>   /*
>>    * Module/class support
>>    */

-- 
Regards,
Yi Liu