[PATCH v16 Kernel 0/7] KABIs to support migration for VFIO devices

[PATCH v16 Kernel 0/7] KABIs to support migration for VFIO devices

[Kirti Wankhede]

Hi,

This patch set adds:
* New IOCTL VFIO_IOMMU_DIRTY_PAGES to get dirty pages bitmap with
  respect to IOMMU container rather than per device. All pages pinned by
  vendor driver through vfio_pin_pages external API has to be marked as
  dirty during  migration. When IOMMU capable device is present in the
  container and all pages are pinned and mapped, then all pages are marked
  dirty.
  When there are CPU writes, CPU dirty page tracking can identify dirtied
  pages, but any page pinned by vendor driver can also be written by
  device. As of now there is no device which has hardware support for
  dirty page tracking. So all pages which are pinned should be considered
  as dirty.
  This ioctl is also used to start/stop dirty pages tracking for pinned and
  unpinned pages while migration is active.

* Updated IOCTL VFIO_IOMMU_UNMAP_DMA to get dirty pages bitmap before
  unmapping IO virtual address range.
  With vIOMMU, during pre-copy phase of migration, while CPUs are still
  running, IO virtual address unmap can happen while device still keeping
  reference of guest pfns. Those pages should be reported as dirty before
  unmap, so that VFIO user space application can copy content of those
  pages from source to destination.

* Patch 7 detect if IOMMU capable device driver is smart to report pages
  to be marked dirty by pinning pages using vfio_pin_pages() API.


Yet TODO:
Since there is no device which has hardware support for system memmory
dirty bitmap tracking, right now there is no other API from vendor driver
to VFIO IOMMU module to report dirty pages. In future, when such hardware
support will be implemented, an API will be required such that vendor
driver could report dirty pages to VFIO module during migration phases.

Adding revision history from previous QEMU patch set to understand KABI
changes done till now

v15 -> v16
- Minor edits and nit picks (Auger Eric)
- On copying bitmap to user, re-populated bitmap only for pinned pages,
  excluding unmapped pages and CPU dirtied pages.
- Patches are on tag: next-20200318 and 1-3 patches from Yan's series
  https://lkml.org/lkml/2020/3/12/1255

v14 -> v15
- Minor edits and nit picks.
- In the verification of user allocated bitmap memory, added check of
   maximum size.
- Patches are on tag: next-20200318 and 1-3 patches from Yan's series
  https://lkml.org/lkml/2020/3/12/1255

v13 -> v14
- Added struct vfio_bitmap to kabi. updated structure
  vfio_iommu_type1_dirty_bitmap_get and vfio_iommu_type1_dma_unmap.
- All small changes suggested by Alex.
- Patches are on tag: next-20200318 and 1-3 patches from Yan's series
  https://lkml.org/lkml/2020/3/12/1255

v12 -> v13
- Changed bitmap allocation in vfio_iommu_type1 to per vfio_dma
- Changed VFIO_IOMMU_DIRTY_PAGES ioctl behaviour to be per vfio_dma range.
- Changed vfio_iommu_type1_dirty_bitmap structure to have separate data
  field.

v11 -> v12
- Changed bitmap allocation in vfio_iommu_type1.
- Remove atomicity of ref_count.
- Updated comments for migration device state structure about error
  reporting.
- Nit picks from v11 reviews

v10 -> v11
- Fix pin pages API to free vpfn if it is marked as unpinned tracking page.
- Added proposal to detect if IOMMU capable device calls external pin pages
  API to mark pages dirty.
- Nit picks from v10 reviews

v9 -> v10:
- Updated existing VFIO_IOMMU_UNMAP_DMA ioctl to get dirty pages bitmap
  during unmap while migration is active
- Added flag in VFIO_IOMMU_GET_INFO to indicate driver support dirty page
  tracking.
- If iommu_mapped, mark all pages dirty.
- Added unpinned pages tracking while migration is active.
- Updated comments for migration device state structure with bit
  combination table and state transition details.

v8 -> v9:
- Split patch set in 2 sets, Kernel and QEMU.
- Dirty pages bitmap is queried from IOMMU container rather than from
  vendor driver for per device. Added 2 ioctls to achieve this.

v7 -> v8:
- Updated comments for KABI
- Added BAR address validation check during PCI device's config space load
  as suggested by Dr. David Alan Gilbert.
- Changed vfio_migration_set_state() to set or clear device state flags.
- Some nit fixes.

v6 -> v7:
- Fix build failures.

v5 -> v6:
- Fix build failure.

v4 -> v5:
- Added decriptive comment about the sequence of access of members of
  structure vfio_device_migration_info to be followed based on Alex's
  suggestion
- Updated get dirty pages sequence.
- As per Cornelia Huck's suggestion, added callbacks to VFIODeviceOps to
  get_object, save_config and load_config.
- Fixed multiple nit picks.
- Tested live migration with multiple vfio device assigned to a VM.

v3 -> v4:
- Added one more bit for _RESUMING flag to be set explicitly.
- data_offset field is read-only for user space application.
- data_size is read for every iteration before reading data from migration,
  that is removed assumption that data will be till end of migration
  region.
- If vendor driver supports mappable sparsed region, map those region
  during setup state of save/load, similarly unmap those from cleanup
  routines.
- Handles race condition that causes data corruption in migration region
  during save device state by adding mutex and serialiaing save_buffer and
  get_dirty_pages routines.
- Skip called get_dirty_pages routine for mapped MMIO region of device.
- Added trace events.
- Split into multiple functional patches.

v2 -> v3:
- Removed enum of VFIO device states. Defined VFIO device state with 2
  bits.
- Re-structured vfio_device_migration_info to keep it minimal and defined
  action on read and write access on its members.

v1 -> v2:
- Defined MIGRATION region type and sub-type which should be used with
  region type capability.
- Re-structured vfio_device_migration_info. This structure will be placed
  at 0th offset of migration region.
- Replaced ioctl with read/write for trapped part of migration region.
- Added both type of access support, trapped or mmapped, for data section
  of the region.
- Moved PCI device functions to pci file.
- Added iteration to get dirty page bitmap until bitmap for all requested
  pages are copied.

Thanks,
Kirti


Kirti Wankhede (7):
  vfio: KABI for migration interface for device state
  vfio iommu: Remove atomicity of ref_count of pinned pages
  vfio iommu: Add ioctl definition for dirty pages tracking.
  vfio iommu: Implementation of ioctl for dirty pages tracking.
  vfio iommu: Update UNMAP_DMA ioctl to get dirty bitmap before unmap
  vfio iommu: Adds flag to indicate dirty pages tracking capability
    support
  vfio: Selective dirty page tracking if IOMMU backed device pins pages

 drivers/vfio/vfio.c             |  13 +-
 drivers/vfio/vfio_iommu_type1.c | 421 ++++++++++++++++++++++++++++++++++++++--
 include/linux/vfio.h            |   4 +-
 include/uapi/linux/vfio.h       | 299 +++++++++++++++++++++++++++-
 4 files changed, 715 insertions(+), 22 deletions(-)

-- 
2.7.0

[PATCH v16 Kernel 1/7] vfio: KABI for migration interface for device state

[Kirti Wankhede]

- Defined MIGRATION region type and sub-type.

- Defined vfio_device_migration_info structure which will be placed at the
  0th offset of migration region to get/set VFIO device related
  information. Defined members of structure and usage on read/write access.

- Defined device states and state transition details.

- Defined sequence to be followed while saving and resuming VFIO device.

Signed-off-by: Kirti Wankhede <kwankhede@nvidia.com>
Reviewed-by: Neo Jia <cjia@nvidia.com>
---
 include/uapi/linux/vfio.h | 228 ++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 228 insertions(+)

diff --git a/include/uapi/linux/vfio.h b/include/uapi/linux/vfio.h
index 9e843a147ead..8641e022c3b0 100644
--- a/include/uapi/linux/vfio.h
+++ b/include/uapi/linux/vfio.h
@@ -305,6 +305,7 @@ struct vfio_region_info_cap_type {
 #define VFIO_REGION_TYPE_PCI_VENDOR_MASK	(0xffff)
 #define VFIO_REGION_TYPE_GFX                    (1)
 #define VFIO_REGION_TYPE_CCW			(2)
+#define VFIO_REGION_TYPE_MIGRATION              (3)
 
 /* sub-types for VFIO_REGION_TYPE_PCI_* */
 
@@ -379,6 +380,233 @@ struct vfio_region_gfx_edid {
 /* sub-types for VFIO_REGION_TYPE_CCW */
 #define VFIO_REGION_SUBTYPE_CCW_ASYNC_CMD	(1)
 
+/* sub-types for VFIO_REGION_TYPE_MIGRATION */
+#define VFIO_REGION_SUBTYPE_MIGRATION           (1)
+
+/*
+ * The structure vfio_device_migration_info is placed at the 0th offset of
+ * the VFIO_REGION_SUBTYPE_MIGRATION region to get and set VFIO device related
+ * migration information. Field accesses from this structure are only supported
+ * at their native width and alignment. Otherwise, the result is undefined and
+ * vendor drivers should return an error.
+ *
+ * device_state: (read/write)
+ *      - The user application writes to this field to inform the vendor driver
+ *        about the device state to be transitioned to.
+ *      - The vendor driver should take the necessary actions to change the
+ *        device state. After successful transition to a given state, the
+ *        vendor driver should return success on write(device_state, state)
+ *        system call. If the device state transition fails, the vendor driver
+ *        should return an appropriate -errno for the fault condition.
+ *      - On the user application side, if the device state transition fails,
+ *	  that is, if write(device_state, state) returns an error, read
+ *	  device_state again to determine the current state of the device from
+ *	  the vendor driver.
+ *      - The vendor driver should return previous state of the device unless
+ *        the vendor driver has encountered an internal error, in which case
+ *        the vendor driver may report the device_state VFIO_DEVICE_STATE_ERROR.
+ *      - The user application must use the device reset ioctl to recover the
+ *        device from VFIO_DEVICE_STATE_ERROR state. If the device is
+ *        indicated to be in a valid device state by reading device_state, the
+ *        user application may attempt to transition the device to any valid
+ *        state reachable from the current state or terminate itself.
+ *
+ *      device_state consists of 3 bits:
+ *      - If bit 0 is set, it indicates the _RUNNING state. If bit 0 is clear,
+ *        it indicates the _STOP state. When the device state is changed to
+ *        _STOP, driver should stop the device before write() returns.
+ *      - If bit 1 is set, it indicates the _SAVING state, which means that the
+ *        driver should start gathering device state information that will be
+ *        provided to the VFIO user application to save the device's state.
+ *      - If bit 2 is set, it indicates the _RESUMING state, which means that
+ *        the driver should prepare to resume the device. Data provided through
+ *        the migration region should be used to resume the device.
+ *      Bits 3 - 31 are reserved for future use. To preserve them, the user
+ *      application should perform a read-modify-write operation on this
+ *      field when modifying the specified bits.
+ *
+ *  +------- _RESUMING
+ *  |+------ _SAVING
+ *  ||+----- _RUNNING
+ *  |||
+ *  000b => Device Stopped, not saving or resuming
+ *  001b => Device running, which is the default state
+ *  010b => Stop the device & save the device state, stop-and-copy state
+ *  011b => Device running and save the device state, pre-copy state
+ *  100b => Device stopped and the device state is resuming
+ *  101b => Invalid state
+ *  110b => Error state
+ *  111b => Invalid state
+ *
+ * State transitions:
+ *
+ *              _RESUMING  _RUNNING    Pre-copy    Stop-and-copy   _STOP
+ *                (100b)     (001b)     (011b)        (010b)       (000b)
+ * 0. Running or default state
+ *                             |
+ *
+ * 1. Normal Shutdown (optional)
+ *                             |------------------------------------->|
+ *
+ * 2. Save the state or suspend
+ *                             |------------------------->|---------->|
+ *
+ * 3. Save the state during live migration
+ *                             |----------->|------------>|---------->|
+ *
+ * 4. Resuming
+ *                  |<---------|
+ *
+ * 5. Resumed
+ *                  |--------->|
+ *
+ * 0. Default state of VFIO device is _RUNNNG when the user application starts.
+ * 1. During normal shutdown of the user application, the user application may
+ *    optionally change the VFIO device state from _RUNNING to _STOP. This
+ *    transition is optional. The vendor driver must support this transition but
+ *    must not require it.
+ * 2. When the user application saves state or suspends the application, the
+ *    device state transitions from _RUNNING to stop-and-copy and then to _STOP.
+ *    On state transition from _RUNNING to stop-and-copy, driver must stop the
+ *    device, save the device state and send it to the application through the
+ *    migration region. The sequence to be followed for such transition is given
+ *    below.
+ * 3. In live migration of user application, the state transitions from _RUNNING
+ *    to pre-copy, to stop-and-copy, and to _STOP.
+ *    On state transition from _RUNNING to pre-copy, the driver should start
+ *    gathering the device state while the application is still running and send
+ *    the device state data to application through the migration region.
+ *    On state transition from pre-copy to stop-and-copy, the driver must stop
+ *    the device, save the device state and send it to the user application
+ *    through the migration region.
+ *    Vendor drivers must support the pre-copy state even for implementations
+ *    where no data is provided to the user before the stop-and-copy state. The
+ *    user must not be required to consume all migration data before the device
+ *    transitions to a new state, including the stop-and-copy state.
+ *    The sequence to be followed for above two transitions is given below.
+ * 4. To start the resuming phase, the device state should be transitioned from
+ *    the _RUNNING to the _RESUMING state.
+ *    In the _RESUMING state, the driver should use the device state data
+ *    received through the migration region to resume the device.
+ * 5. After providing saved device data to the driver, the application should
+ *    change the state from _RESUMING to _RUNNING.
+ *
+ * reserved:
+ *      Reads on this field return zero and writes are ignored.
+ *
+ * pending_bytes: (read only)
+ *      The number of pending bytes still to be migrated from the vendor driver.
+ *
+ * data_offset: (read only)
+ *      The user application should read data_offset field from the migration
+ *      region. The user application should read the device data from this
+ *      offset within the migration region during the _SAVING state or write
+ *      the device data during the _RESUMING state. See below for details of
+ *      sequence to be followed.
+ *
+ * data_size: (read/write)
+ *      The user application should read data_size to get the size in bytes of
+ *      the data copied in the migration region during the _SAVING state and
+ *      write the size in bytes of the data copied in the migration region
+ *      during the _RESUMING state.
+ *
+ * The format of the migration region is as follows:
+ *  ------------------------------------------------------------------
+ * |vfio_device_migration_info|    data section                      |
+ * |                          |     ///////////////////////////////  |
+ * ------------------------------------------------------------------
+ *   ^                              ^
+ *  offset 0-trapped part        data_offset
+ *
+ * The structure vfio_device_migration_info is always followed by the data
+ * section in the region, so data_offset will always be nonzero. The offset
+ * from where the data is copied is decided by the kernel driver. The data
+ * section can be trapped, mmapped, or partitioned, depending on how the kernel
+ * driver defines the data section. The data section partition can be defined
+ * as mapped by the sparse mmap capability. If mmapped, data_offset must be
+ * page aligned, whereas initial section which contains the
+ * vfio_device_migration_info structure, might not end at the offset, which is
+ * page aligned. The user is not required to access through mmap regardless
+ * of the capabilities of the region mmap.
+ * The vendor driver should determine whether and how to partition the data
+ * section. The vendor driver should return data_offset accordingly.
+ *
+ * The sequence to be followed while in pre-copy state and stop-and-copy state
+ * is as follows:
+ * a. Read pending_bytes, indicating the start of a new iteration to get device
+ *    data. Repeated read on pending_bytes at this stage should have no side
+ *    effects.
+ *    If pending_bytes == 0, the user application should not iterate to get data
+ *    for that device.
+ *    If pending_bytes > 0, perform the following steps.
+ * b. Read data_offset, indicating that the vendor driver should make data
+ *    available through the data section. The vendor driver should return this
+ *    read operation only after data is available from (region + data_offset)
+ *    to (region + data_offset + data_size).
+ * c. Read data_size, which is the amount of data in bytes available through
+ *    the migration region.
+ *    Read on data_offset and data_size should return the offset and size of
+ *    the current buffer if the user application reads data_offset and
+ *    data_size more than once here.
+ * d. Read data_size bytes of data from (region + data_offset) from the
+ *    migration region.
+ * e. Process the data.
+ * f. Read pending_bytes, which indicates that the data from the previous
+ *    iteration has been read. If pending_bytes > 0, go to step b.
+ *
+ * The user application can transition from the _SAVING|_RUNNING
+ * (pre-copy state) to the _SAVING (stop-and-copy) state regardless of the
+ * number of pending bytes. The user application should iterate in _SAVING
+ * (stop-and-copy) until pending_bytes is 0.
+ *
+ * The sequence to be followed while _RESUMING device state is as follows:
+ * While data for this device is available, repeat the following steps:
+ * a. Read data_offset from where the user application should write data.
+ * b. Write migration data starting at the migration region + data_offset for
+ *    the length determined by data_size from the migration source.
+ * c. Write data_size, which indicates to the vendor driver that data is
+ *    written in the migration region. Vendor driver must return this write
+ *    operations on consuming data. Vendor driver should apply the
+ *    user-provided migration region data to the device resume state.
+ *
+ * If an error occurs during the above sequences, the vendor driver can return
+ * an error code for next read() or write() operation, which will terminate the
+ * loop. The user application should then take the next necessary action, for
+ * example, failing migration or terminating the user application.
+ *
+ * For the user application, data is opaque. The user application should write
+ * data in the same order as the data is received and the data should be of
+ * same transaction size at the source.
+ */
+
+struct vfio_device_migration_info {
+	__u32 device_state;         /* VFIO device state */
+#define VFIO_DEVICE_STATE_STOP      (0)
+#define VFIO_DEVICE_STATE_RUNNING   (1 << 0)
+#define VFIO_DEVICE_STATE_SAVING    (1 << 1)
+#define VFIO_DEVICE_STATE_RESUMING  (1 << 2)
+#define VFIO_DEVICE_STATE_MASK      (VFIO_DEVICE_STATE_RUNNING | \
+				     VFIO_DEVICE_STATE_SAVING |  \
+				     VFIO_DEVICE_STATE_RESUMING)
+
+#define VFIO_DEVICE_STATE_VALID(state) \
+	(state & VFIO_DEVICE_STATE_RESUMING ? \
+	(state & VFIO_DEVICE_STATE_MASK) == VFIO_DEVICE_STATE_RESUMING : 1)
+
+#define VFIO_DEVICE_STATE_IS_ERROR(state) \
+	((state & VFIO_DEVICE_STATE_MASK) == (VFIO_DEVICE_STATE_SAVING | \
+					      VFIO_DEVICE_STATE_RESUMING))
+
+#define VFIO_DEVICE_STATE_SET_ERROR(state) \
+	((state & ~VFIO_DEVICE_STATE_MASK) | VFIO_DEVICE_SATE_SAVING | \
+					     VFIO_DEVICE_STATE_RESUMING)
+
+	__u32 reserved;
+	__u64 pending_bytes;
+	__u64 data_offset;
+	__u64 data_size;
+} __attribute__((packed));
+
 /*
  * The MSIX mappable capability informs that MSIX data of a BAR can be mmapped
  * which allows direct access to non-MSIX registers which happened to be within
-- 
2.7.0

[PATCH v16 Kernel 2/7] vfio iommu: Remove atomicity of ref_count of pinned pages

[Kirti Wankhede]

vfio_pfn.ref_count is always updated by holding iommu->lock, using atomic
variable is overkill.

Signed-off-by: Kirti Wankhede <kwankhede@nvidia.com>
Reviewed-by: Neo Jia <cjia@nvidia.com>
Reviewed-by: Eric Auger <eric.auger@redhat.com>
---
 drivers/vfio/vfio_iommu_type1.c | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c
index 9fdfae1cb17a..70aeab921d0f 100644
--- a/drivers/vfio/vfio_iommu_type1.c
+++ b/drivers/vfio/vfio_iommu_type1.c
@@ -112,7 +112,7 @@ struct vfio_pfn {
 	struct rb_node		node;
 	dma_addr_t		iova;		/* Device address */
 	unsigned long		pfn;		/* Host pfn */
-	atomic_t		ref_count;
+	unsigned int		ref_count;
 };
 
 struct vfio_regions {
@@ -233,7 +233,7 @@ static int vfio_add_to_pfn_list(struct vfio_dma *dma, dma_addr_t iova,
 
 	vpfn->iova = iova;
 	vpfn->pfn = pfn;
-	atomic_set(&vpfn->ref_count, 1);
+	vpfn->ref_count = 1;
 	vfio_link_pfn(dma, vpfn);
 	return 0;
 }
@@ -251,7 +251,7 @@ static struct vfio_pfn *vfio_iova_get_vfio_pfn(struct vfio_dma *dma,
 	struct vfio_pfn *vpfn = vfio_find_vpfn(dma, iova);
 
 	if (vpfn)
-		atomic_inc(&vpfn->ref_count);
+		vpfn->ref_count++;
 	return vpfn;
 }
 
@@ -259,7 +259,8 @@ static int vfio_iova_put_vfio_pfn(struct vfio_dma *dma, struct vfio_pfn *vpfn)
 {
 	int ret = 0;
 
-	if (atomic_dec_and_test(&vpfn->ref_count)) {
+	vpfn->ref_count--;
+	if (!vpfn->ref_count) {
 		ret = put_pfn(vpfn->pfn, dma->prot);
 		vfio_remove_from_pfn_list(dma, vpfn);
 	}
-- 
2.7.0

[PATCH v16 Kernel 3/7] vfio iommu: Add ioctl definition for dirty pages tracking.

[Kirti Wankhede]

IOMMU container maintains a list of all pages pinned by vfio_pin_pages API.
All pages pinned by vendor driver through this API should be considered as
dirty during migration. When container consists of IOMMU capable device and
all pages are pinned and mapped, then all pages are marked dirty.
Added support to start/stop dirtied pages tracking and to get bitmap of all
dirtied pages for requested IO virtual address range.

Signed-off-by: Kirti Wankhede <kwankhede@nvidia.com>
Reviewed-by: Neo Jia <cjia@nvidia.com>
---
 include/uapi/linux/vfio.h | 56 +++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 56 insertions(+)

diff --git a/include/uapi/linux/vfio.h b/include/uapi/linux/vfio.h
index 8641e022c3b0..0018721fb744 100644
--- a/include/uapi/linux/vfio.h
+++ b/include/uapi/linux/vfio.h
@@ -996,6 +996,12 @@ struct vfio_iommu_type1_dma_map {
 
 #define VFIO_IOMMU_MAP_DMA _IO(VFIO_TYPE, VFIO_BASE + 13)
 
+struct vfio_bitmap {
+	__u64        pgsize;	/* page size for bitmap in bytes */
+	__u64        size;	/* in bytes */
+	__u64 __user *data;	/* one bit per page */
+};
+
 /**
  * VFIO_IOMMU_UNMAP_DMA - _IOWR(VFIO_TYPE, VFIO_BASE + 14,
  *							struct vfio_dma_unmap)
@@ -1022,6 +1028,56 @@ struct vfio_iommu_type1_dma_unmap {
 #define VFIO_IOMMU_ENABLE	_IO(VFIO_TYPE, VFIO_BASE + 15)
 #define VFIO_IOMMU_DISABLE	_IO(VFIO_TYPE, VFIO_BASE + 16)
 
+/**
+ * VFIO_IOMMU_DIRTY_PAGES - _IOWR(VFIO_TYPE, VFIO_BASE + 17,
+ *                                     struct vfio_iommu_type1_dirty_bitmap)
+ * IOCTL is used for dirty pages tracking.
+ * Caller should set flag depending on which operation to perform, details as
+ * below:
+ *
+ * When IOCTL is called with VFIO_IOMMU_DIRTY_PAGES_FLAG_START set, indicates
+ * migration is active and IOMMU module should track pages which are dirtied or
+ * potentially dirtied by device.
+ * Dirty pages are tracked until tracking is stopped by user application by
+ * setting VFIO_IOMMU_DIRTY_PAGES_FLAG_STOP flag.
+ *
+ * When IOCTL is called with VFIO_IOMMU_DIRTY_PAGES_FLAG_STOP set, indicates
+ * IOMMU should stop tracking dirtied pages.
+ *
+ * When IOCTL is called with VFIO_IOMMU_DIRTY_PAGES_FLAG_GET_BITMAP flag set,
+ * IOCTL returns dirty pages bitmap for IOMMU container during migration for
+ * given IOVA range. User must provide data[] as the structure
+ * vfio_iommu_type1_dirty_bitmap_get through which user provides IOVA range and
+ * pgsize. IOVA range must match to that used in original mapping call. This
+ * interface supports to get bitmap of smallest supported pgsize only and can
+ * be modified in future to get bitmap of specified pgsize.
+ * User must allocate memory for bitmap and set size of allocated memory in
+ * bitmap.size field. One bit is used to represent one page consecutively
+ * starting from iova offset. User should provide page size in bitmap.pgsize
+ * field. Bit set in bitmap indicates page at that offset from iova is
+ * dirty. Caller must set argsz including size of structure
+ * vfio_iommu_type1_dirty_bitmap_get.
+ *
+ * Only one of the flags _START, STOP and _GET may be specified at a time.
+ *
+ */
+struct vfio_iommu_type1_dirty_bitmap {
+	__u32        argsz;
+	__u32        flags;
+#define VFIO_IOMMU_DIRTY_PAGES_FLAG_START	(1 << 0)
+#define VFIO_IOMMU_DIRTY_PAGES_FLAG_STOP	(1 << 1)
+#define VFIO_IOMMU_DIRTY_PAGES_FLAG_GET_BITMAP	(1 << 2)
+	__u8         data[];
+};
+
+struct vfio_iommu_type1_dirty_bitmap_get {
+	__u64              iova;	/* IO virtual address */
+	__u64              size;	/* Size of iova range */
+	struct vfio_bitmap bitmap;
+};
+
+#define VFIO_IOMMU_DIRTY_PAGES             _IO(VFIO_TYPE, VFIO_BASE + 17)
+
 /* -------- Additional API for SPAPR TCE (Server POWERPC) IOMMU -------- */
 
 /*
-- 
2.7.0

[PATCH v16 Kernel 4/7] vfio iommu: Implementation of ioctl for dirty pages tracking.

[Kirti Wankhede]

VFIO_IOMMU_DIRTY_PAGES ioctl performs three operations:
- Start dirty pages tracking while migration is active
- Stop dirty pages tracking.
- Get dirty pages bitmap. Its user space application's responsibility to
  copy content of dirty pages from source to destination during migration.

To prevent DoS attack, memory for bitmap is allocated per vfio_dma
structure. Bitmap size is calculated considering smallest supported page
size. Bitmap is allocated for all vfio_dmas when dirty logging is enabled

Bitmap is populated for already pinned pages when bitmap is allocated for
a vfio_dma with the smallest supported page size. Update bitmap from
pinning functions when tracking is enabled. When user application queries
bitmap, check if requested page size is same as page size used to
populated bitmap. If it is equal, copy bitmap, but if not equal, return
error.

Signed-off-by: Kirti Wankhede <kwankhede@nvidia.com>
Reviewed-by: Neo Jia <cjia@nvidia.com>
---
 drivers/vfio/vfio_iommu_type1.c | 265 +++++++++++++++++++++++++++++++++++++++-
 1 file changed, 259 insertions(+), 6 deletions(-)

diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c
index 70aeab921d0f..27ed069c5053 100644
--- a/drivers/vfio/vfio_iommu_type1.c
+++ b/drivers/vfio/vfio_iommu_type1.c
@@ -71,6 +71,7 @@ struct vfio_iommu {
 	unsigned int		dma_avail;
 	bool			v2;
 	bool			nesting;
+	bool			dirty_page_tracking;
 };
 
 struct vfio_domain {
@@ -91,6 +92,7 @@ struct vfio_dma {
 	bool			lock_cap;	/* capable(CAP_IPC_LOCK) */
 	struct task_struct	*task;
 	struct rb_root		pfn_list;	/* Ex-user pinned pfn list */
+	unsigned long		*bitmap;
 };
 
 struct vfio_group {
@@ -125,7 +127,21 @@ struct vfio_regions {
 #define IS_IOMMU_CAP_DOMAIN_IN_CONTAINER(iommu)	\
 					(!list_empty(&iommu->domain_list))
 
+#define DIRTY_BITMAP_BYTES(n)	(ALIGN(n, BITS_PER_TYPE(u64)) / BITS_PER_BYTE)
+
+/*
+ * Input argument of number of bits to bitmap_set() is unsigned integer, which
+ * further casts to signed integer for unaligned multi-bit operation,
+ * __bitmap_set().
+ * Then maximum bitmap size supported is 2^31 bits divided by 2^3 bits/byte,
+ * that is 2^28 (256 MB) which maps to 2^31 * 2^12 = 2^43 (8TB) on 4K page
+ * system.
+ */
+#define DIRTY_BITMAP_PAGES_MAX	(uint64_t)(INT_MAX - 1)
+#define DIRTY_BITMAP_SIZE_MAX	 DIRTY_BITMAP_BYTES(DIRTY_BITMAP_PAGES_MAX)
+
 static int put_pfn(unsigned long pfn, int prot);
+static unsigned long vfio_pgsize_bitmap(struct vfio_iommu *iommu);
 
 /*
  * This code handles mapping and unmapping of user data buffers
@@ -175,6 +191,77 @@ static void vfio_unlink_dma(struct vfio_iommu *iommu, struct vfio_dma *old)
 	rb_erase(&old->node, &iommu->dma_list);
 }
 
+
+static int vfio_dma_bitmap_alloc(struct vfio_dma *dma, uint64_t pgsize)
+{
+	uint64_t npages = dma->size / pgsize;
+
+	if (npages > DIRTY_BITMAP_PAGES_MAX)
+		return -EINVAL;
+
+	dma->bitmap = kvzalloc(DIRTY_BITMAP_BYTES(npages), GFP_KERNEL);
+	if (!dma->bitmap)
+		return -ENOMEM;
+
+	return 0;
+}
+
+static void vfio_dma_bitmap_free(struct vfio_dma *dma)
+{
+	kfree(dma->bitmap);
+	dma->bitmap = NULL;
+}
+
+static void vfio_dma_populate_bitmap(struct vfio_dma *dma, uint64_t pgsize)
+{
+	struct rb_node *p;
+
+	if (RB_EMPTY_ROOT(&dma->pfn_list))
+		return;
+
+	for (p = rb_first(&dma->pfn_list); p; p = rb_next(p)) {
+		struct vfio_pfn *vpfn = rb_entry(p, struct vfio_pfn, node);
+
+		bitmap_set(dma->bitmap, (vpfn->iova - dma->iova) / pgsize, 1);
+	}
+}
+
+static int vfio_dma_bitmap_alloc_all(struct vfio_iommu *iommu, uint64_t pgsize)
+{
+	struct rb_node *n = rb_first(&iommu->dma_list);
+
+	for (; n; n = rb_next(n)) {
+		struct vfio_dma *dma = rb_entry(n, struct vfio_dma, node);
+		int ret;
+
+		ret = vfio_dma_bitmap_alloc(dma, pgsize);
+		if (ret) {
+			struct rb_node *p = rb_prev(n);
+
+			for (; p; p = rb_prev(p)) {
+				struct vfio_dma *dma = rb_entry(n,
+							struct vfio_dma, node);
+
+				vfio_dma_bitmap_free(dma);
+			}
+			return ret;
+		}
+		vfio_dma_populate_bitmap(dma, pgsize);
+	}
+	return 0;
+}
+
+static void vfio_dma_bitmap_free_all(struct vfio_iommu *iommu)
+{
+	struct rb_node *n = rb_first(&iommu->dma_list);
+
+	for (; n; n = rb_next(n)) {
+		struct vfio_dma *dma = rb_entry(n, struct vfio_dma, node);
+
+		vfio_dma_bitmap_free(dma);
+	}
+}
+
 /*
  * Helper Functions for host iova-pfn list
  */
@@ -567,6 +654,18 @@ static int vfio_iommu_type1_pin_pages(void *iommu_data,
 			vfio_unpin_page_external(dma, iova, do_accounting);
 			goto pin_unwind;
 		}
+
+		if (iommu->dirty_page_tracking) {
+			unsigned long pgshift =
+					 __ffs(vfio_pgsize_bitmap(iommu));
+
+			/*
+			 * Bitmap populated with the smallest supported page
+			 * size
+			 */
+			bitmap_set(dma->bitmap,
+				   (vpfn->iova - dma->iova) >> pgshift, 1);
+		}
 	}
 
 	ret = i;
@@ -801,6 +900,7 @@ static void vfio_remove_dma(struct vfio_iommu *iommu, struct vfio_dma *dma)
 	vfio_unmap_unpin(iommu, dma, true);
 	vfio_unlink_dma(iommu, dma);
 	put_task_struct(dma->task);
+	vfio_dma_bitmap_free(dma);
 	kfree(dma);
 	iommu->dma_avail++;
 }
@@ -831,6 +931,56 @@ static unsigned long vfio_pgsize_bitmap(struct vfio_iommu *iommu)
 	return bitmap;
 }
 
+static int vfio_iova_dirty_bitmap(struct vfio_iommu *iommu, dma_addr_t iova,
+				  size_t size, uint64_t pgsize,
+				  u64 __user *bitmap)
+{
+	struct vfio_dma *dma;
+	unsigned long pgshift = __ffs(pgsize);
+	unsigned int npages, bitmap_size;
+
+	dma = vfio_find_dma(iommu, iova, 1);
+
+	if (!dma)
+		return -EINVAL;
+
+	if (dma->iova != iova || dma->size != size)
+		return -EINVAL;
+
+	npages = dma->size >> pgshift;
+	bitmap_size = DIRTY_BITMAP_BYTES(npages);
+
+	/* mark all pages dirty if all pages are pinned and mapped. */
+	if (dma->iommu_mapped)
+		bitmap_set(dma->bitmap, 0, npages);
+
+	if (copy_to_user((void __user *)bitmap, dma->bitmap, bitmap_size))
+		return -EFAULT;
+
+	/*
+	 * Re-populate bitmap to include all pinned pages which are considered
+	 * as dirty but exclude pages which are unpinned and pages which are
+	 * marked dirty by vfio_dma_rw()
+	 */
+	vfio_dma_populate_bitmap(dma, pgsize);
+	return 0;
+}
+
+static int verify_bitmap_size(uint64_t npages, uint64_t bitmap_size)
+{
+	uint64_t bsize;
+
+	if (!npages || !bitmap_size || (bitmap_size > DIRTY_BITMAP_SIZE_MAX))
+		return -EINVAL;
+
+	bsize = DIRTY_BITMAP_BYTES(npages);
+
+	if (bitmap_size < bsize)
+		return -EINVAL;
+
+	return 0;
+}
+
 static int vfio_dma_do_unmap(struct vfio_iommu *iommu,
 			     struct vfio_iommu_type1_dma_unmap *unmap)
 {
@@ -1038,16 +1188,16 @@ static int vfio_dma_do_map(struct vfio_iommu *iommu,
 	unsigned long vaddr = map->vaddr;
 	size_t size = map->size;
 	int ret = 0, prot = 0;
-	uint64_t mask;
+	uint64_t pgsize;
 	struct vfio_dma *dma;
 
 	/* Verify that none of our __u64 fields overflow */
 	if (map->size != size || map->vaddr != vaddr || map->iova != iova)
 		return -EINVAL;
 
-	mask = ((uint64_t)1 << __ffs(vfio_pgsize_bitmap(iommu))) - 1;
+	pgsize = (uint64_t)1 << __ffs(vfio_pgsize_bitmap(iommu));
 
-	WARN_ON(mask & PAGE_MASK);
+	WARN_ON((pgsize - 1) & PAGE_MASK);
 
 	/* READ/WRITE from device perspective */
 	if (map->flags & VFIO_DMA_MAP_FLAG_WRITE)
@@ -1055,7 +1205,7 @@ static int vfio_dma_do_map(struct vfio_iommu *iommu,
 	if (map->flags & VFIO_DMA_MAP_FLAG_READ)
 		prot |= IOMMU_READ;
 
-	if (!prot || !size || (size | iova | vaddr) & mask)
+	if (!prot || !size || (size | iova | vaddr) & (pgsize - 1))
 		return -EINVAL;
 
 	/* Don't allow IOVA or virtual address wrap */
@@ -1130,6 +1280,12 @@ static int vfio_dma_do_map(struct vfio_iommu *iommu,
 	else
 		ret = vfio_pin_map_dma(iommu, dma, size);
 
+	if (!ret && iommu->dirty_page_tracking) {
+		ret = vfio_dma_bitmap_alloc(dma, pgsize);
+		if (ret)
+			vfio_remove_dma(iommu, dma);
+	}
+
 out_unlock:
 	mutex_unlock(&iommu->lock);
 	return ret;
@@ -2278,6 +2434,93 @@ static long vfio_iommu_type1_ioctl(void *iommu_data,
 
 		return copy_to_user((void __user *)arg, &unmap, minsz) ?
 			-EFAULT : 0;
+	} else if (cmd == VFIO_IOMMU_DIRTY_PAGES) {
+		struct vfio_iommu_type1_dirty_bitmap dirty;
+		uint32_t mask = VFIO_IOMMU_DIRTY_PAGES_FLAG_START |
+				VFIO_IOMMU_DIRTY_PAGES_FLAG_STOP |
+				VFIO_IOMMU_DIRTY_PAGES_FLAG_GET_BITMAP;
+		int ret = 0;
+
+		if (!iommu->v2)
+			return -EACCES;
+
+		minsz = offsetofend(struct vfio_iommu_type1_dirty_bitmap,
+				    flags);
+
+		if (copy_from_user(&dirty, (void __user *)arg, minsz))
+			return -EFAULT;
+
+		if (dirty.argsz < minsz || dirty.flags & ~mask)
+			return -EINVAL;
+
+		/* only one flag should be set at a time */
+		if (__ffs(dirty.flags) != __fls(dirty.flags))
+			return -EINVAL;
+
+		if (dirty.flags & VFIO_IOMMU_DIRTY_PAGES_FLAG_START) {
+			uint64_t pgsize = 1 << __ffs(vfio_pgsize_bitmap(iommu));
+
+			mutex_lock(&iommu->lock);
+			if (!iommu->dirty_page_tracking) {
+				ret = vfio_dma_bitmap_alloc_all(iommu, pgsize);
+				if (!ret)
+					iommu->dirty_page_tracking = true;
+			}
+			mutex_unlock(&iommu->lock);
+			return ret;
+		} else if (dirty.flags & VFIO_IOMMU_DIRTY_PAGES_FLAG_STOP) {
+			mutex_lock(&iommu->lock);
+			if (iommu->dirty_page_tracking) {
+				iommu->dirty_page_tracking = false;
+				vfio_dma_bitmap_free_all(iommu);
+			}
+			mutex_unlock(&iommu->lock);
+			return 0;
+		} else if (dirty.flags &
+				 VFIO_IOMMU_DIRTY_PAGES_FLAG_GET_BITMAP) {
+			struct vfio_iommu_type1_dirty_bitmap_get range;
+			unsigned long pgshift;
+			size_t data_size = dirty.argsz - minsz;
+			uint64_t iommu_pgsize =
+					 1 << __ffs(vfio_pgsize_bitmap(iommu));
+
+			if (!data_size || data_size < sizeof(range))
+				return -EINVAL;
+
+			if (copy_from_user(&range, (void __user *)(arg + minsz),
+					   sizeof(range)))
+				return -EFAULT;
+
+			/* allow only smallest supported pgsize */
+			if (range.bitmap.pgsize != iommu_pgsize)
+				return -EINVAL;
+			if (range.iova & (iommu_pgsize - 1))
+				return -EINVAL;
+			if (!range.size || range.size & (iommu_pgsize - 1))
+				return -EINVAL;
+			if (range.iova + range.size < range.iova)
+				return -EINVAL;
+			if (!access_ok((void __user *)range.bitmap.data,
+				       range.bitmap.size))
+				return -EINVAL;
+
+			pgshift = __ffs(range.bitmap.pgsize);
+			ret = verify_bitmap_size(range.size >> pgshift,
+						 range.bitmap.size);
+			if (ret)
+				return ret;
+
+			mutex_lock(&iommu->lock);
+			if (iommu->dirty_page_tracking)
+				ret = vfio_iova_dirty_bitmap(iommu, range.iova,
+						range.size, range.bitmap.pgsize,
+						range.bitmap.data);
+			else
+				ret = -EINVAL;
+			mutex_unlock(&iommu->lock);
+
+			return ret;
+		}
 	}
 
 	return -ENOTTY;
@@ -2345,10 +2588,20 @@ static int vfio_iommu_type1_dma_rw_chunk(struct vfio_iommu *iommu,
 
 	vaddr = dma->vaddr + offset;
 
-	if (write)
+	if (write) {
 		*copied = __copy_to_user((void __user *)vaddr, data,
 					 count) ? 0 : count;
-	else
+		if (*copied && iommu->dirty_page_tracking) {
+			unsigned long pgshift =
+				__ffs(vfio_pgsize_bitmap(iommu));
+			/*
+			 * Bitmap populated with the smallest supported page
+			 * size
+			 */
+			bitmap_set(dma->bitmap, offset >> pgshift,
+				   *copied >> pgshift);
+		}
+	} else
 		*copied = __copy_from_user(data, (void __user *)vaddr,
 					   count) ? 0 : count;
 	if (kthread)
-- 
2.7.0

[PATCH v16 Kernel 5/7] vfio iommu: Update UNMAP_DMA ioctl to get dirty bitmap before unmap

[Kirti Wankhede]

DMA mapped pages, including those pinned by mdev vendor drivers, might
get unpinned and unmapped while migration is active and device is still
running. For example, in pre-copy phase while guest driver could access
those pages, host device or vendor driver can dirty these mapped pages.
Such pages should be marked dirty so as to maintain memory consistency
for a user making use of dirty page tracking.

To get bitmap during unmap, user should allocate memory for bitmap, set
size of allocated memory, set page size to be considered for bitmap and
set flag VFIO_DMA_UNMAP_FLAG_GET_DIRTY_BITMAP.

Signed-off-by: Kirti Wankhede <kwankhede@nvidia.com>
Reviewed-by: Neo Jia <cjia@nvidia.com>
---
 drivers/vfio/vfio_iommu_type1.c | 54 ++++++++++++++++++++++++++++++++++++++---
 include/uapi/linux/vfio.h       | 10 ++++++++
 2 files changed, 60 insertions(+), 4 deletions(-)

diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c
index 27ed069c5053..b98a8d79e13a 100644
--- a/drivers/vfio/vfio_iommu_type1.c
+++ b/drivers/vfio/vfio_iommu_type1.c
@@ -982,7 +982,8 @@ static int verify_bitmap_size(uint64_t npages, uint64_t bitmap_size)
 }
 
 static int vfio_dma_do_unmap(struct vfio_iommu *iommu,
-			     struct vfio_iommu_type1_dma_unmap *unmap)
+			     struct vfio_iommu_type1_dma_unmap *unmap,
+			     struct vfio_bitmap *bitmap)
 {
 	uint64_t mask;
 	struct vfio_dma *dma, *dma_last = NULL;
@@ -1033,6 +1034,10 @@ static int vfio_dma_do_unmap(struct vfio_iommu *iommu,
 	 * will be returned if these conditions are not met.  The v2 interface
 	 * will only return success and a size of zero if there were no
 	 * mappings within the range.
+	 *
+	 * When VFIO_DMA_UNMAP_FLAG_GET_DIRTY_BITMAP flag is set, unmap request
+	 * must be for single mapping. Multiple mappings with this flag set is
+	 * not supported.
 	 */
 	if (iommu->v2) {
 		dma = vfio_find_dma(iommu, unmap->iova, 1);
@@ -1040,6 +1045,13 @@ static int vfio_dma_do_unmap(struct vfio_iommu *iommu,
 			ret = -EINVAL;
 			goto unlock;
 		}
+
+		if ((unmap->flags & VFIO_DMA_UNMAP_FLAG_GET_DIRTY_BITMAP) &&
+		    (dma->iova != unmap->iova || dma->size != unmap->size)) {
+			ret = -EINVAL;
+			goto unlock;
+		}
+
 		dma = vfio_find_dma(iommu, unmap->iova + unmap->size - 1, 0);
 		if (dma && dma->iova + dma->size != unmap->iova + unmap->size) {
 			ret = -EINVAL;
@@ -1057,6 +1069,11 @@ static int vfio_dma_do_unmap(struct vfio_iommu *iommu,
 		if (dma->task->mm != current->mm)
 			break;
 
+		if ((unmap->flags & VFIO_DMA_UNMAP_FLAG_GET_DIRTY_BITMAP) &&
+		     iommu->dirty_page_tracking)
+			vfio_iova_dirty_bitmap(iommu, dma->iova, dma->size,
+						bitmap->pgsize, bitmap->data);
+
 		if (!RB_EMPTY_ROOT(&dma->pfn_list)) {
 			struct vfio_iommu_type1_dma_unmap nb_unmap;
 
@@ -2418,17 +2435,46 @@ static long vfio_iommu_type1_ioctl(void *iommu_data,
 
 	} else if (cmd == VFIO_IOMMU_UNMAP_DMA) {
 		struct vfio_iommu_type1_dma_unmap unmap;
-		long ret;
+		struct vfio_bitmap bitmap = { 0 };
+		int ret;
 
 		minsz = offsetofend(struct vfio_iommu_type1_dma_unmap, size);
 
 		if (copy_from_user(&unmap, (void __user *)arg, minsz))
 			return -EFAULT;
 
-		if (unmap.argsz < minsz || unmap.flags)
+		if (unmap.argsz < minsz ||
+		    unmap.flags & ~VFIO_DMA_UNMAP_FLAG_GET_DIRTY_BITMAP)
 			return -EINVAL;
 
-		ret = vfio_dma_do_unmap(iommu, &unmap);
+		if (unmap.flags & VFIO_DMA_UNMAP_FLAG_GET_DIRTY_BITMAP) {
+			unsigned long pgshift;
+			uint64_t iommu_pgsize =
+					 1 << __ffs(vfio_pgsize_bitmap(iommu));
+
+			if (unmap.argsz < (minsz + sizeof(bitmap)))
+				return -EINVAL;
+
+			if (copy_from_user(&bitmap,
+					   (void __user *)(arg + minsz),
+					   sizeof(bitmap)))
+				return -EFAULT;
+
+			/* allow only min supported pgsize */
+			if (bitmap.pgsize != iommu_pgsize)
+				return -EINVAL;
+			if (!access_ok((void __user *)bitmap.data, bitmap.size))
+				return -EINVAL;
+
+			pgshift = __ffs(bitmap.pgsize);
+			ret = verify_bitmap_size(unmap.size >> pgshift,
+						 bitmap.size);
+			if (ret)
+				return ret;
+
+		}
+
+		ret = vfio_dma_do_unmap(iommu, &unmap, &bitmap);
 		if (ret)
 			return ret;
 
diff --git a/include/uapi/linux/vfio.h b/include/uapi/linux/vfio.h
index 0018721fb744..7c888041136f 100644
--- a/include/uapi/linux/vfio.h
+++ b/include/uapi/linux/vfio.h
@@ -1011,12 +1011,22 @@ struct vfio_bitmap {
  * field.  No guarantee is made to the user that arbitrary unmaps of iova
  * or size different from those used in the original mapping call will
  * succeed.
+ * VFIO_DMA_UNMAP_FLAG_GET_DIRTY_BITMAP should be set to get dirty bitmap
+ * before unmapping IO virtual addresses. When this flag is set, user must
+ * provide data[] as structure vfio_bitmap. User must allocate memory to get
+ * bitmap and must set size of allocated memory in vfio_bitmap.size field.
+ * A bit in bitmap represents one page of user provided page size in 'pgsize',
+ * consecutively starting from iova offset. Bit set indicates page at that
+ * offset from iova is dirty. Bitmap of pages in the range of unmapped size is
+ * returned in vfio_bitmap.data
  */
 struct vfio_iommu_type1_dma_unmap {
 	__u32	argsz;
 	__u32	flags;
+#define VFIO_DMA_UNMAP_FLAG_GET_DIRTY_BITMAP (1 << 0)
 	__u64	iova;				/* IO virtual address */
 	__u64	size;				/* Size of mapping (bytes) */
+	__u8    data[];
 };
 
 #define VFIO_IOMMU_UNMAP_DMA _IO(VFIO_TYPE, VFIO_BASE + 14)
-- 
2.7.0

[PATCH v16 Kernel 6/7] vfio iommu: Adds flag to indicate dirty pages tracking capability support

[Kirti Wankhede]

Flag VFIO_IOMMU_INFO_DIRTY_PGS in VFIO_IOMMU_GET_INFO indicates that driver
support dirty pages tracking.

Signed-off-by: Kirti Wankhede <kwankhede@nvidia.com>
Reviewed-by: Neo Jia <cjia@nvidia.com>
---
 drivers/vfio/vfio_iommu_type1.c | 3 ++-
 include/uapi/linux/vfio.h       | 5 +++--
 2 files changed, 5 insertions(+), 3 deletions(-)

diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c
index b98a8d79e13a..5b233ded7a9a 100644
--- a/drivers/vfio/vfio_iommu_type1.c
+++ b/drivers/vfio/vfio_iommu_type1.c
@@ -2388,7 +2388,8 @@ static long vfio_iommu_type1_ioctl(void *iommu_data,
 			info.cap_offset = 0; /* output, no-recopy necessary */
 		}
 
-		info.flags = VFIO_IOMMU_INFO_PGSIZES;
+		info.flags = VFIO_IOMMU_INFO_PGSIZES |
+			     VFIO_IOMMU_INFO_DIRTY_PGS;
 
 		info.iova_pgsizes = vfio_pgsize_bitmap(iommu);
 
diff --git a/include/uapi/linux/vfio.h b/include/uapi/linux/vfio.h
index 7c888041136f..39bd734a5064 100644
--- a/include/uapi/linux/vfio.h
+++ b/include/uapi/linux/vfio.h
@@ -948,8 +948,9 @@ struct vfio_device_ioeventfd {
 struct vfio_iommu_type1_info {
 	__u32	argsz;
 	__u32	flags;
-#define VFIO_IOMMU_INFO_PGSIZES (1 << 0)	/* supported page sizes info */
-#define VFIO_IOMMU_INFO_CAPS	(1 << 1)	/* Info supports caps */
+#define VFIO_IOMMU_INFO_PGSIZES   (1 << 0) /* supported page sizes info */
+#define VFIO_IOMMU_INFO_CAPS      (1 << 1) /* Info supports caps */
+#define VFIO_IOMMU_INFO_DIRTY_PGS (1 << 2) /* supports dirty page tracking */
 	__u64	iova_pgsizes;	/* Bitmap of supported page sizes */
 	__u32   cap_offset;	/* Offset within info struct of first cap */
 };
-- 
2.7.0

[PATCH v16 Kernel 7/7] vfio: Selective dirty page tracking if IOMMU backed device pins pages

[Kirti Wankhede]

Added a check such that only singleton IOMMU groups can pin pages.
From the point when vendor driver pins any pages, consider IOMMU group
dirty page scope to be limited to pinned pages.

To optimize to avoid walking list often, added flag
pinned_page_dirty_scope to indicate if all of the vfio_groups for each
vfio_domain in the domain_list dirty page scope is limited to pinned
pages. This flag is updated on first pinned pages request for that IOMMU
group and on attaching/detaching group.

Signed-off-by: Kirti Wankhede <kwankhede@nvidia.com>
Reviewed-by: Neo Jia <cjia@nvidia.com>
---
 drivers/vfio/vfio.c             | 13 ++++--
 drivers/vfio/vfio_iommu_type1.c | 94 +++++++++++++++++++++++++++++++++++++++--
 include/linux/vfio.h            |  4 +-
 3 files changed, 104 insertions(+), 7 deletions(-)

diff --git a/drivers/vfio/vfio.c b/drivers/vfio/vfio.c
index 210fcf426643..311b5e4e111e 100644
--- a/drivers/vfio/vfio.c
+++ b/drivers/vfio/vfio.c
@@ -85,6 +85,7 @@ struct vfio_group {
 	atomic_t			opened;
 	wait_queue_head_t		container_q;
 	bool				noiommu;
+	unsigned int			dev_counter;
 	struct kvm			*kvm;
 	struct blocking_notifier_head	notifier;
 };
@@ -555,6 +556,7 @@ struct vfio_device *vfio_group_create_device(struct vfio_group *group,
 
 	mutex_lock(&group->device_lock);
 	list_add(&device->group_next, &group->device_list);
+	group->dev_counter++;
 	mutex_unlock(&group->device_lock);
 
 	return device;
@@ -567,6 +569,7 @@ static void vfio_device_release(struct kref *kref)
 	struct vfio_group *group = device->group;
 
 	list_del(&device->group_next);
+	group->dev_counter--;
 	mutex_unlock(&group->device_lock);
 
 	dev_set_drvdata(device->dev, NULL);
@@ -1933,6 +1936,9 @@ int vfio_pin_pages(struct device *dev, unsigned long *user_pfn, int npage,
 	if (!group)
 		return -ENODEV;
 
+	if (group->dev_counter > 1)
+		return -EINVAL;
+
 	ret = vfio_group_add_container_user(group);
 	if (ret)
 		goto err_pin_pages;
@@ -1940,7 +1946,8 @@ int vfio_pin_pages(struct device *dev, unsigned long *user_pfn, int npage,
 	container = group->container;
 	driver = container->iommu_driver;
 	if (likely(driver && driver->ops->pin_pages))
-		ret = driver->ops->pin_pages(container->iommu_data, user_pfn,
+		ret = driver->ops->pin_pages(container->iommu_data,
+					     group->iommu_group, user_pfn,
 					     npage, prot, phys_pfn);
 	else
 		ret = -ENOTTY;
@@ -2038,8 +2045,8 @@ int vfio_group_pin_pages(struct vfio_group *group,
 	driver = container->iommu_driver;
 	if (likely(driver && driver->ops->pin_pages))
 		ret = driver->ops->pin_pages(container->iommu_data,
-					     user_iova_pfn, npage,
-					     prot, phys_pfn);
+					     group->iommu_group, user_iova_pfn,
+					     npage, prot, phys_pfn);
 	else
 		ret = -ENOTTY;
 
diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c
index 5b233ded7a9a..a6b1f6930e6a 100644
--- a/drivers/vfio/vfio_iommu_type1.c
+++ b/drivers/vfio/vfio_iommu_type1.c
@@ -72,6 +72,7 @@ struct vfio_iommu {
 	bool			v2;
 	bool			nesting;
 	bool			dirty_page_tracking;
+	bool			pinned_page_dirty_scope;
 };
 
 struct vfio_domain {
@@ -99,6 +100,7 @@ struct vfio_group {
 	struct iommu_group	*iommu_group;
 	struct list_head	next;
 	bool			mdev_group;	/* An mdev group */
+	bool			pinned_page_dirty_scope;
 };
 
 struct vfio_iova {
@@ -143,6 +145,10 @@ struct vfio_regions {
 static int put_pfn(unsigned long pfn, int prot);
 static unsigned long vfio_pgsize_bitmap(struct vfio_iommu *iommu);
 
+static struct vfio_group *vfio_iommu_find_iommu_group(struct vfio_iommu *iommu,
+					       struct iommu_group *iommu_group);
+
+static void update_pinned_page_dirty_scope(struct vfio_iommu *iommu);
 /*
  * This code handles mapping and unmapping of user data buffers
  * into DMA'ble space using the IOMMU
@@ -589,11 +595,13 @@ static int vfio_unpin_page_external(struct vfio_dma *dma, dma_addr_t iova,
 }
 
 static int vfio_iommu_type1_pin_pages(void *iommu_data,
+				      struct iommu_group *iommu_group,
 				      unsigned long *user_pfn,
 				      int npage, int prot,
 				      unsigned long *phys_pfn)
 {
 	struct vfio_iommu *iommu = iommu_data;
+	struct vfio_group *group;
 	int i, j, ret;
 	unsigned long remote_vaddr;
 	struct vfio_dma *dma;
@@ -667,8 +675,14 @@ static int vfio_iommu_type1_pin_pages(void *iommu_data,
 				   (vpfn->iova - dma->iova) >> pgshift, 1);
 		}
 	}
-
 	ret = i;
+
+	group = vfio_iommu_find_iommu_group(iommu, iommu_group);
+	if (!group->pinned_page_dirty_scope) {
+		group->pinned_page_dirty_scope = true;
+		update_pinned_page_dirty_scope(iommu);
+	}
+
 	goto pin_done;
 
 pin_unwind:
@@ -950,8 +964,11 @@ static int vfio_iova_dirty_bitmap(struct vfio_iommu *iommu, dma_addr_t iova,
 	npages = dma->size >> pgshift;
 	bitmap_size = DIRTY_BITMAP_BYTES(npages);
 
-	/* mark all pages dirty if all pages are pinned and mapped. */
-	if (dma->iommu_mapped)
+	/*
+	 * mark all pages dirty if any IOMMU capable device is not able
+	 * to report dirty pages and all pages are pinned and mapped.
+	 */
+	if (!iommu->pinned_page_dirty_scope && dma->iommu_mapped)
 		bitmap_set(dma->bitmap, 0, npages);
 
 	if (copy_to_user((void __user *)bitmap, dma->bitmap, bitmap_size))
@@ -1441,6 +1458,51 @@ static struct vfio_group *find_iommu_group(struct vfio_domain *domain,
 	return NULL;
 }
 
+static struct vfio_group *vfio_iommu_find_iommu_group(struct vfio_iommu *iommu,
+					       struct iommu_group *iommu_group)
+{
+	struct vfio_domain *domain;
+	struct vfio_group *group = NULL;
+
+	list_for_each_entry(domain, &iommu->domain_list, next) {
+		group = find_iommu_group(domain, iommu_group);
+		if (group)
+			return group;
+	}
+
+	if (iommu->external_domain)
+		group = find_iommu_group(iommu->external_domain, iommu_group);
+
+	return group;
+}
+
+static void update_pinned_page_dirty_scope(struct vfio_iommu *iommu)
+{
+	struct vfio_domain *domain;
+	struct vfio_group *group;
+
+	list_for_each_entry(domain, &iommu->domain_list, next) {
+		list_for_each_entry(group, &domain->group_list, next) {
+			if (!group->pinned_page_dirty_scope) {
+				iommu->pinned_page_dirty_scope = false;
+				return;
+			}
+		}
+	}
+
+	if (iommu->external_domain) {
+		domain = iommu->external_domain;
+		list_for_each_entry(group, &domain->group_list, next) {
+			if (!group->pinned_page_dirty_scope) {
+				iommu->pinned_page_dirty_scope = false;
+				return;
+			}
+		}
+	}
+
+	iommu->pinned_page_dirty_scope = true;
+}
+
 static bool vfio_iommu_has_sw_msi(struct list_head *group_resv_regions,
 				  phys_addr_t *base)
 {
@@ -1847,6 +1909,16 @@ static int vfio_iommu_type1_attach_group(void *iommu_data,
 
 			list_add(&group->next,
 				 &iommu->external_domain->group_list);
+			/*
+			 * Non-iommu backed group cannot dirty memory directly,
+			 * it can only use interfaces that provide dirty
+			 * tracking.
+			 * The iommu scope can only be promoted with the
+			 * addition of a dirty tracking group.
+			 */
+			group->pinned_page_dirty_scope = true;
+			if (!iommu->pinned_page_dirty_scope)
+				update_pinned_page_dirty_scope(iommu);
 			mutex_unlock(&iommu->lock);
 
 			return 0;
@@ -1969,6 +2041,13 @@ static int vfio_iommu_type1_attach_group(void *iommu_data,
 done:
 	/* Delete the old one and insert new iova list */
 	vfio_iommu_iova_insert_copy(iommu, &iova_copy);
+
+	/*
+	 * An iommu backed group can dirty memory directly and therefore
+	 * demotes the iommu scope until it declares itself dirty tracking
+	 * capable via the page pinning interface.
+	 */
+	iommu->pinned_page_dirty_scope = false;
 	mutex_unlock(&iommu->lock);
 	vfio_iommu_resv_free(&group_resv_regions);
 
@@ -2121,6 +2200,7 @@ static void vfio_iommu_type1_detach_group(void *iommu_data,
 	struct vfio_iommu *iommu = iommu_data;
 	struct vfio_domain *domain;
 	struct vfio_group *group;
+	bool update_dirty_scope = false;
 	LIST_HEAD(iova_copy);
 
 	mutex_lock(&iommu->lock);
@@ -2128,6 +2208,7 @@ static void vfio_iommu_type1_detach_group(void *iommu_data,
 	if (iommu->external_domain) {
 		group = find_iommu_group(iommu->external_domain, iommu_group);
 		if (group) {
+			update_dirty_scope = !group->pinned_page_dirty_scope;
 			list_del(&group->next);
 			kfree(group);
 
@@ -2157,6 +2238,7 @@ static void vfio_iommu_type1_detach_group(void *iommu_data,
 			continue;
 
 		vfio_iommu_detach_group(domain, group);
+		update_dirty_scope = !group->pinned_page_dirty_scope;
 		list_del(&group->next);
 		kfree(group);
 		/*
@@ -2187,6 +2269,12 @@ static void vfio_iommu_type1_detach_group(void *iommu_data,
 		vfio_iommu_iova_free(&iova_copy);
 
 detach_group_done:
+	/*
+	 * Removal of a group without dirty tracking may allow the iommu scope
+	 * to be promoted.
+	 */
+	if (update_dirty_scope)
+		update_pinned_page_dirty_scope(iommu);
 	mutex_unlock(&iommu->lock);
 }
 
diff --git a/include/linux/vfio.h b/include/linux/vfio.h
index be2bd358b952..702e1d7b6e8b 100644
--- a/include/linux/vfio.h
+++ b/include/linux/vfio.h
@@ -72,7 +72,9 @@ struct vfio_iommu_driver_ops {
 					struct iommu_group *group);
 	void		(*detach_group)(void *iommu_data,
 					struct iommu_group *group);
-	int		(*pin_pages)(void *iommu_data, unsigned long *user_pfn,
+	int		(*pin_pages)(void *iommu_data,
+				     struct iommu_group *group,
+				     unsigned long *user_pfn,
 				     int npage, int prot,
 				     unsigned long *phys_pfn);
 	int		(*unpin_pages)(void *iommu_data,
-- 
2.7.0

Re: [PATCH v16 Kernel 4/7] vfio iommu: Implementation of ioctl for dirty pages tracking.

[Alex Williamson]

On Wed, 25 Mar 2020 01:02:36 +0530
Kirti Wankhede <kwankhede@nvidia.com> wrote:

> VFIO_IOMMU_DIRTY_PAGES ioctl performs three operations:
> - Start dirty pages tracking while migration is active
> - Stop dirty pages tracking.
> - Get dirty pages bitmap. Its user space application's responsibility to
>   copy content of dirty pages from source to destination during migration.
> 
> To prevent DoS attack, memory for bitmap is allocated per vfio_dma
> structure. Bitmap size is calculated considering smallest supported page
> size. Bitmap is allocated for all vfio_dmas when dirty logging is enabled
> 
> Bitmap is populated for already pinned pages when bitmap is allocated for
> a vfio_dma with the smallest supported page size. Update bitmap from
> pinning functions when tracking is enabled. When user application queries
> bitmap, check if requested page size is same as page size used to
> populated bitmap. If it is equal, copy bitmap, but if not equal, return
> error.
> 
> Signed-off-by: Kirti Wankhede <kwankhede@nvidia.com>
> Reviewed-by: Neo Jia <cjia@nvidia.com>
> ---
>  drivers/vfio/vfio_iommu_type1.c | 265 +++++++++++++++++++++++++++++++++++++++-
>  1 file changed, 259 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c
> index 70aeab921d0f..27ed069c5053 100644
> --- a/drivers/vfio/vfio_iommu_type1.c
> +++ b/drivers/vfio/vfio_iommu_type1.c
> @@ -71,6 +71,7 @@ struct vfio_iommu {
>  	unsigned int		dma_avail;
>  	bool			v2;
>  	bool			nesting;
> +	bool			dirty_page_tracking;
>  };
>  
>  struct vfio_domain {
> @@ -91,6 +92,7 @@ struct vfio_dma {
>  	bool			lock_cap;	/* capable(CAP_IPC_LOCK) */
>  	struct task_struct	*task;
>  	struct rb_root		pfn_list;	/* Ex-user pinned pfn list */
> +	unsigned long		*bitmap;
>  };
>  
>  struct vfio_group {
> @@ -125,7 +127,21 @@ struct vfio_regions {
>  #define IS_IOMMU_CAP_DOMAIN_IN_CONTAINER(iommu)	\
>  					(!list_empty(&iommu->domain_list))
>  
> +#define DIRTY_BITMAP_BYTES(n)	(ALIGN(n, BITS_PER_TYPE(u64)) / BITS_PER_BYTE)
> +
> +/*
> + * Input argument of number of bits to bitmap_set() is unsigned integer, which
> + * further casts to signed integer for unaligned multi-bit operation,
> + * __bitmap_set().
> + * Then maximum bitmap size supported is 2^31 bits divided by 2^3 bits/byte,
> + * that is 2^28 (256 MB) which maps to 2^31 * 2^12 = 2^43 (8TB) on 4K page
> + * system.
> + */
> +#define DIRTY_BITMAP_PAGES_MAX	(uint64_t)(INT_MAX - 1)
> +#define DIRTY_BITMAP_SIZE_MAX	 DIRTY_BITMAP_BYTES(DIRTY_BITMAP_PAGES_MAX)
> +
>  static int put_pfn(unsigned long pfn, int prot);
> +static unsigned long vfio_pgsize_bitmap(struct vfio_iommu *iommu);
>  
>  /*
>   * This code handles mapping and unmapping of user data buffers
> @@ -175,6 +191,77 @@ static void vfio_unlink_dma(struct vfio_iommu *iommu, struct vfio_dma *old)
>  	rb_erase(&old->node, &iommu->dma_list);
>  }
>  
> +
> +static int vfio_dma_bitmap_alloc(struct vfio_dma *dma, uint64_t pgsize)
> +{
> +	uint64_t npages = dma->size / pgsize;
> +
> +	if (npages > DIRTY_BITMAP_PAGES_MAX)
> +		return -EINVAL;
> +
> +	dma->bitmap = kvzalloc(DIRTY_BITMAP_BYTES(npages), GFP_KERNEL);
> +	if (!dma->bitmap)
> +		return -ENOMEM;
> +
> +	return 0;
> +}
> +
> +static void vfio_dma_bitmap_free(struct vfio_dma *dma)
> +{
> +	kfree(dma->bitmap);
> +	dma->bitmap = NULL;
> +}
> +
> +static void vfio_dma_populate_bitmap(struct vfio_dma *dma, uint64_t pgsize)
> +{
> +	struct rb_node *p;
> +
> +	if (RB_EMPTY_ROOT(&dma->pfn_list))
> +		return;
> +
> +	for (p = rb_first(&dma->pfn_list); p; p = rb_next(p)) {
> +		struct vfio_pfn *vpfn = rb_entry(p, struct vfio_pfn, node);
> +
> +		bitmap_set(dma->bitmap, (vpfn->iova - dma->iova) / pgsize, 1);
> +	}
> +}
> +
> +static int vfio_dma_bitmap_alloc_all(struct vfio_iommu *iommu, uint64_t pgsize)
> +{
> +	struct rb_node *n = rb_first(&iommu->dma_list);
> +
> +	for (; n; n = rb_next(n)) {
> +		struct vfio_dma *dma = rb_entry(n, struct vfio_dma, node);
> +		int ret;
> +
> +		ret = vfio_dma_bitmap_alloc(dma, pgsize);
> +		if (ret) {
> +			struct rb_node *p = rb_prev(n);
> +
> +			for (; p; p = rb_prev(p)) {
> +				struct vfio_dma *dma = rb_entry(n,
> +							struct vfio_dma, node);
> +
> +				vfio_dma_bitmap_free(dma);
> +			}
> +			return ret;
> +		}
> +		vfio_dma_populate_bitmap(dma, pgsize);
> +	}
> +	return 0;
> +}
> +
> +static void vfio_dma_bitmap_free_all(struct vfio_iommu *iommu)
> +{
> +	struct rb_node *n = rb_first(&iommu->dma_list);
> +
> +	for (; n; n = rb_next(n)) {
> +		struct vfio_dma *dma = rb_entry(n, struct vfio_dma, node);
> +
> +		vfio_dma_bitmap_free(dma);
> +	}
> +}
> +
>  /*
>   * Helper Functions for host iova-pfn list
>   */
> @@ -567,6 +654,18 @@ static int vfio_iommu_type1_pin_pages(void *iommu_data,
>  			vfio_unpin_page_external(dma, iova, do_accounting);
>  			goto pin_unwind;
>  		}
> +
> +		if (iommu->dirty_page_tracking) {
> +			unsigned long pgshift =
> +					 __ffs(vfio_pgsize_bitmap(iommu));
> +
> +			/*
> +			 * Bitmap populated with the smallest supported page
> +			 * size
> +			 */
> +			bitmap_set(dma->bitmap,
> +				   (vpfn->iova - dma->iova) >> pgshift, 1);
> +		}
>  	}
>  
>  	ret = i;
> @@ -801,6 +900,7 @@ static void vfio_remove_dma(struct vfio_iommu *iommu, struct vfio_dma *dma)
>  	vfio_unmap_unpin(iommu, dma, true);
>  	vfio_unlink_dma(iommu, dma);
>  	put_task_struct(dma->task);
> +	vfio_dma_bitmap_free(dma);
>  	kfree(dma);
>  	iommu->dma_avail++;
>  }
> @@ -831,6 +931,56 @@ static unsigned long vfio_pgsize_bitmap(struct vfio_iommu *iommu)
>  	return bitmap;
>  }
>  
> +static int vfio_iova_dirty_bitmap(struct vfio_iommu *iommu, dma_addr_t iova,
> +				  size_t size, uint64_t pgsize,
> +				  u64 __user *bitmap)
> +{
> +	struct vfio_dma *dma;
> +	unsigned long pgshift = __ffs(pgsize);
> +	unsigned int npages, bitmap_size;
> +
> +	dma = vfio_find_dma(iommu, iova, 1);
> +
> +	if (!dma)
> +		return -EINVAL;
> +
> +	if (dma->iova != iova || dma->size != size)
> +		return -EINVAL;
> +
> +	npages = dma->size >> pgshift;
> +	bitmap_size = DIRTY_BITMAP_BYTES(npages);
> +
> +	/* mark all pages dirty if all pages are pinned and mapped. */
> +	if (dma->iommu_mapped)
> +		bitmap_set(dma->bitmap, 0, npages);
> +
> +	if (copy_to_user((void __user *)bitmap, dma->bitmap, bitmap_size))
> +		return -EFAULT;
> +
> +	/*
> +	 * Re-populate bitmap to include all pinned pages which are considered
> +	 * as dirty but exclude pages which are unpinned and pages which are
> +	 * marked dirty by vfio_dma_rw()
> +	 */
> +	vfio_dma_populate_bitmap(dma, pgsize);

vfio_dma_populate_bitmap() only sets bits, it doesn't clear them.
Shouldn't we do a memset() zero before calling this?  Thanks,

Alex

> +	return 0;
> +}
> +
> +static int verify_bitmap_size(uint64_t npages, uint64_t bitmap_size)
> +{
> +	uint64_t bsize;
> +
> +	if (!npages || !bitmap_size || (bitmap_size > DIRTY_BITMAP_SIZE_MAX))
> +		return -EINVAL;
> +
> +	bsize = DIRTY_BITMAP_BYTES(npages);
> +
> +	if (bitmap_size < bsize)
> +		return -EINVAL;
> +
> +	return 0;
> +}
> +
>  static int vfio_dma_do_unmap(struct vfio_iommu *iommu,
>  			     struct vfio_iommu_type1_dma_unmap *unmap)
>  {
> @@ -1038,16 +1188,16 @@ static int vfio_dma_do_map(struct vfio_iommu *iommu,
>  	unsigned long vaddr = map->vaddr;
>  	size_t size = map->size;
>  	int ret = 0, prot = 0;
> -	uint64_t mask;
> +	uint64_t pgsize;
>  	struct vfio_dma *dma;
>  
>  	/* Verify that none of our __u64 fields overflow */
>  	if (map->size != size || map->vaddr != vaddr || map->iova != iova)
>  		return -EINVAL;
>  
> -	mask = ((uint64_t)1 << __ffs(vfio_pgsize_bitmap(iommu))) - 1;
> +	pgsize = (uint64_t)1 << __ffs(vfio_pgsize_bitmap(iommu));
>  
> -	WARN_ON(mask & PAGE_MASK);
> +	WARN_ON((pgsize - 1) & PAGE_MASK);
>  
>  	/* READ/WRITE from device perspective */
>  	if (map->flags & VFIO_DMA_MAP_FLAG_WRITE)
> @@ -1055,7 +1205,7 @@ static int vfio_dma_do_map(struct vfio_iommu *iommu,
>  	if (map->flags & VFIO_DMA_MAP_FLAG_READ)
>  		prot |= IOMMU_READ;
>  
> -	if (!prot || !size || (size | iova | vaddr) & mask)
> +	if (!prot || !size || (size | iova | vaddr) & (pgsize - 1))
>  		return -EINVAL;
>  
>  	/* Don't allow IOVA or virtual address wrap */
> @@ -1130,6 +1280,12 @@ static int vfio_dma_do_map(struct vfio_iommu *iommu,
>  	else
>  		ret = vfio_pin_map_dma(iommu, dma, size);
>  
> +	if (!ret && iommu->dirty_page_tracking) {
> +		ret = vfio_dma_bitmap_alloc(dma, pgsize);
> +		if (ret)
> +			vfio_remove_dma(iommu, dma);
> +	}
> +
>  out_unlock:
>  	mutex_unlock(&iommu->lock);
>  	return ret;
> @@ -2278,6 +2434,93 @@ static long vfio_iommu_type1_ioctl(void *iommu_data,
>  
>  		return copy_to_user((void __user *)arg, &unmap, minsz) ?
>  			-EFAULT : 0;
> +	} else if (cmd == VFIO_IOMMU_DIRTY_PAGES) {
> +		struct vfio_iommu_type1_dirty_bitmap dirty;
> +		uint32_t mask = VFIO_IOMMU_DIRTY_PAGES_FLAG_START |
> +				VFIO_IOMMU_DIRTY_PAGES_FLAG_STOP |
> +				VFIO_IOMMU_DIRTY_PAGES_FLAG_GET_BITMAP;
> +		int ret = 0;
> +
> +		if (!iommu->v2)
> +			return -EACCES;
> +
> +		minsz = offsetofend(struct vfio_iommu_type1_dirty_bitmap,
> +				    flags);
> +
> +		if (copy_from_user(&dirty, (void __user *)arg, minsz))
> +			return -EFAULT;
> +
> +		if (dirty.argsz < minsz || dirty.flags & ~mask)
> +			return -EINVAL;
> +
> +		/* only one flag should be set at a time */
> +		if (__ffs(dirty.flags) != __fls(dirty.flags))
> +			return -EINVAL;
> +
> +		if (dirty.flags & VFIO_IOMMU_DIRTY_PAGES_FLAG_START) {
> +			uint64_t pgsize = 1 << __ffs(vfio_pgsize_bitmap(iommu));
> +
> +			mutex_lock(&iommu->lock);
> +			if (!iommu->dirty_page_tracking) {
> +				ret = vfio_dma_bitmap_alloc_all(iommu, pgsize);
> +				if (!ret)
> +					iommu->dirty_page_tracking = true;
> +			}
> +			mutex_unlock(&iommu->lock);
> +			return ret;
> +		} else if (dirty.flags & VFIO_IOMMU_DIRTY_PAGES_FLAG_STOP) {
> +			mutex_lock(&iommu->lock);
> +			if (iommu->dirty_page_tracking) {
> +				iommu->dirty_page_tracking = false;
> +				vfio_dma_bitmap_free_all(iommu);
> +			}
> +			mutex_unlock(&iommu->lock);
> +			return 0;
> +		} else if (dirty.flags &
> +				 VFIO_IOMMU_DIRTY_PAGES_FLAG_GET_BITMAP) {
> +			struct vfio_iommu_type1_dirty_bitmap_get range;
> +			unsigned long pgshift;
> +			size_t data_size = dirty.argsz - minsz;
> +			uint64_t iommu_pgsize =
> +					 1 << __ffs(vfio_pgsize_bitmap(iommu));
> +
> +			if (!data_size || data_size < sizeof(range))
> +				return -EINVAL;
> +
> +			if (copy_from_user(&range, (void __user *)(arg + minsz),
> +					   sizeof(range)))
> +				return -EFAULT;
> +
> +			/* allow only smallest supported pgsize */
> +			if (range.bitmap.pgsize != iommu_pgsize)
> +				return -EINVAL;
> +			if (range.iova & (iommu_pgsize - 1))
> +				return -EINVAL;
> +			if (!range.size || range.size & (iommu_pgsize - 1))
> +				return -EINVAL;
> +			if (range.iova + range.size < range.iova)
> +				return -EINVAL;
> +			if (!access_ok((void __user *)range.bitmap.data,
> +				       range.bitmap.size))
> +				return -EINVAL;
> +
> +			pgshift = __ffs(range.bitmap.pgsize);
> +			ret = verify_bitmap_size(range.size >> pgshift,
> +						 range.bitmap.size);
> +			if (ret)
> +				return ret;
> +
> +			mutex_lock(&iommu->lock);
> +			if (iommu->dirty_page_tracking)
> +				ret = vfio_iova_dirty_bitmap(iommu, range.iova,
> +						range.size, range.bitmap.pgsize,
> +						range.bitmap.data);
> +			else
> +				ret = -EINVAL;
> +			mutex_unlock(&iommu->lock);
> +
> +			return ret;
> +		}
>  	}
>  
>  	return -ENOTTY;
> @@ -2345,10 +2588,20 @@ static int vfio_iommu_type1_dma_rw_chunk(struct vfio_iommu *iommu,
>  
>  	vaddr = dma->vaddr + offset;
>  
> -	if (write)
> +	if (write) {
>  		*copied = __copy_to_user((void __user *)vaddr, data,
>  					 count) ? 0 : count;
> -	else
> +		if (*copied && iommu->dirty_page_tracking) {
> +			unsigned long pgshift =
> +				__ffs(vfio_pgsize_bitmap(iommu));
> +			/*
> +			 * Bitmap populated with the smallest supported page
> +			 * size
> +			 */
> +			bitmap_set(dma->bitmap, offset >> pgshift,
> +				   *copied >> pgshift);
> +		}
> +	} else
>  		*copied = __copy_from_user(data, (void __user *)vaddr,
>  					   count) ? 0 : count;
>  	if (kthread)

Re: [PATCH v16 Kernel 4/7] vfio iommu: Implementation of ioctl for dirty pages tracking.

[Alex Williamson]

On Tue, 24 Mar 2020 14:37:16 -0600
Alex Williamson <alex.williamson@redhat.com> wrote:

> On Wed, 25 Mar 2020 01:02:36 +0530
> Kirti Wankhede <kwankhede@nvidia.com> wrote:
> 
> > VFIO_IOMMU_DIRTY_PAGES ioctl performs three operations:
> > - Start dirty pages tracking while migration is active
> > - Stop dirty pages tracking.
> > - Get dirty pages bitmap. Its user space application's responsibility to
> >   copy content of dirty pages from source to destination during migration.
> > 
> > To prevent DoS attack, memory for bitmap is allocated per vfio_dma
> > structure. Bitmap size is calculated considering smallest supported page
> > size. Bitmap is allocated for all vfio_dmas when dirty logging is enabled
> > 
> > Bitmap is populated for already pinned pages when bitmap is allocated for
> > a vfio_dma with the smallest supported page size. Update bitmap from
> > pinning functions when tracking is enabled. When user application queries
> > bitmap, check if requested page size is same as page size used to
> > populated bitmap. If it is equal, copy bitmap, but if not equal, return
> > error.
> > 
> > Signed-off-by: Kirti Wankhede <kwankhede@nvidia.com>
> > Reviewed-by: Neo Jia <cjia@nvidia.com>
> > ---
> >  drivers/vfio/vfio_iommu_type1.c | 265 +++++++++++++++++++++++++++++++++++++++-
> >  1 file changed, 259 insertions(+), 6 deletions(-)
> > 
> > diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c
> > index 70aeab921d0f..27ed069c5053 100644
> > --- a/drivers/vfio/vfio_iommu_type1.c
> > +++ b/drivers/vfio/vfio_iommu_type1.c
> > @@ -71,6 +71,7 @@ struct vfio_iommu {
> >  	unsigned int		dma_avail;
> >  	bool			v2;
> >  	bool			nesting;
> > +	bool			dirty_page_tracking;
> >  };
> >  
> >  struct vfio_domain {
> > @@ -91,6 +92,7 @@ struct vfio_dma {
> >  	bool			lock_cap;	/* capable(CAP_IPC_LOCK) */
> >  	struct task_struct	*task;
> >  	struct rb_root		pfn_list;	/* Ex-user pinned pfn list */
> > +	unsigned long		*bitmap;
> >  };
> >  
> >  struct vfio_group {
> > @@ -125,7 +127,21 @@ struct vfio_regions {
> >  #define IS_IOMMU_CAP_DOMAIN_IN_CONTAINER(iommu)	\
> >  					(!list_empty(&iommu->domain_list))
> >  
> > +#define DIRTY_BITMAP_BYTES(n)	(ALIGN(n, BITS_PER_TYPE(u64)) / BITS_PER_BYTE)
> > +
> > +/*
> > + * Input argument of number of bits to bitmap_set() is unsigned integer, which
> > + * further casts to signed integer for unaligned multi-bit operation,
> > + * __bitmap_set().
> > + * Then maximum bitmap size supported is 2^31 bits divided by 2^3 bits/byte,
> > + * that is 2^28 (256 MB) which maps to 2^31 * 2^12 = 2^43 (8TB) on 4K page
> > + * system.
> > + */
> > +#define DIRTY_BITMAP_PAGES_MAX	(uint64_t)(INT_MAX - 1)
> > +#define DIRTY_BITMAP_SIZE_MAX	 DIRTY_BITMAP_BYTES(DIRTY_BITMAP_PAGES_MAX)
> > +
> >  static int put_pfn(unsigned long pfn, int prot);
> > +static unsigned long vfio_pgsize_bitmap(struct vfio_iommu *iommu);
> >  
> >  /*
> >   * This code handles mapping and unmapping of user data buffers
> > @@ -175,6 +191,77 @@ static void vfio_unlink_dma(struct vfio_iommu *iommu, struct vfio_dma *old)
> >  	rb_erase(&old->node, &iommu->dma_list);
> >  }
> >  
> > +
> > +static int vfio_dma_bitmap_alloc(struct vfio_dma *dma, uint64_t pgsize)
> > +{
> > +	uint64_t npages = dma->size / pgsize;
> > +
> > +	if (npages > DIRTY_BITMAP_PAGES_MAX)
> > +		return -EINVAL;
> > +
> > +	dma->bitmap = kvzalloc(DIRTY_BITMAP_BYTES(npages), GFP_KERNEL);
> > +	if (!dma->bitmap)
> > +		return -ENOMEM;
> > +
> > +	return 0;
> > +}
> > +
> > +static void vfio_dma_bitmap_free(struct vfio_dma *dma)
> > +{
> > +	kfree(dma->bitmap);
> > +	dma->bitmap = NULL;
> > +}
> > +
> > +static void vfio_dma_populate_bitmap(struct vfio_dma *dma, uint64_t pgsize)
> > +{
> > +	struct rb_node *p;
> > +
> > +	if (RB_EMPTY_ROOT(&dma->pfn_list))
> > +		return;
> > +
> > +	for (p = rb_first(&dma->pfn_list); p; p = rb_next(p)) {
> > +		struct vfio_pfn *vpfn = rb_entry(p, struct vfio_pfn, node);
> > +
> > +		bitmap_set(dma->bitmap, (vpfn->iova - dma->iova) / pgsize, 1);
> > +	}
> > +}
> > +
> > +static int vfio_dma_bitmap_alloc_all(struct vfio_iommu *iommu, uint64_t pgsize)
> > +{
> > +	struct rb_node *n = rb_first(&iommu->dma_list);
> > +
> > +	for (; n; n = rb_next(n)) {
> > +		struct vfio_dma *dma = rb_entry(n, struct vfio_dma, node);
> > +		int ret;
> > +
> > +		ret = vfio_dma_bitmap_alloc(dma, pgsize);
> > +		if (ret) {
> > +			struct rb_node *p = rb_prev(n);
> > +
> > +			for (; p; p = rb_prev(p)) {
> > +				struct vfio_dma *dma = rb_entry(n,
> > +							struct vfio_dma, node);
> > +
> > +				vfio_dma_bitmap_free(dma);
> > +			}
> > +			return ret;
> > +		}
> > +		vfio_dma_populate_bitmap(dma, pgsize);
> > +	}
> > +	return 0;
> > +}
> > +
> > +static void vfio_dma_bitmap_free_all(struct vfio_iommu *iommu)
> > +{
> > +	struct rb_node *n = rb_first(&iommu->dma_list);
> > +
> > +	for (; n; n = rb_next(n)) {
> > +		struct vfio_dma *dma = rb_entry(n, struct vfio_dma, node);
> > +
> > +		vfio_dma_bitmap_free(dma);
> > +	}
> > +}
> > +
> >  /*
> >   * Helper Functions for host iova-pfn list
> >   */
> > @@ -567,6 +654,18 @@ static int vfio_iommu_type1_pin_pages(void *iommu_data,
> >  			vfio_unpin_page_external(dma, iova, do_accounting);
> >  			goto pin_unwind;
> >  		}
> > +
> > +		if (iommu->dirty_page_tracking) {
> > +			unsigned long pgshift =
> > +					 __ffs(vfio_pgsize_bitmap(iommu));
> > +
> > +			/*
> > +			 * Bitmap populated with the smallest supported page
> > +			 * size
> > +			 */
> > +			bitmap_set(dma->bitmap,
> > +				   (vpfn->iova - dma->iova) >> pgshift, 1);
> > +		}
> >  	}
> >  
> >  	ret = i;
> > @@ -801,6 +900,7 @@ static void vfio_remove_dma(struct vfio_iommu *iommu, struct vfio_dma *dma)
> >  	vfio_unmap_unpin(iommu, dma, true);
> >  	vfio_unlink_dma(iommu, dma);
> >  	put_task_struct(dma->task);
> > +	vfio_dma_bitmap_free(dma);
> >  	kfree(dma);
> >  	iommu->dma_avail++;
> >  }
> > @@ -831,6 +931,56 @@ static unsigned long vfio_pgsize_bitmap(struct vfio_iommu *iommu)
> >  	return bitmap;
> >  }
> >  
> > +static int vfio_iova_dirty_bitmap(struct vfio_iommu *iommu, dma_addr_t iova,
> > +				  size_t size, uint64_t pgsize,
> > +				  u64 __user *bitmap)
> > +{
> > +	struct vfio_dma *dma;
> > +	unsigned long pgshift = __ffs(pgsize);
> > +	unsigned int npages, bitmap_size;
> > +
> > +	dma = vfio_find_dma(iommu, iova, 1);
> > +
> > +	if (!dma)
> > +		return -EINVAL;
> > +
> > +	if (dma->iova != iova || dma->size != size)
> > +		return -EINVAL;
> > +
> > +	npages = dma->size >> pgshift;
> > +	bitmap_size = DIRTY_BITMAP_BYTES(npages);
> > +
> > +	/* mark all pages dirty if all pages are pinned and mapped. */
> > +	if (dma->iommu_mapped)
> > +		bitmap_set(dma->bitmap, 0, npages);
> > +
> > +	if (copy_to_user((void __user *)bitmap, dma->bitmap, bitmap_size))
> > +		return -EFAULT;
> > +
> > +	/*
> > +	 * Re-populate bitmap to include all pinned pages which are considered
> > +	 * as dirty but exclude pages which are unpinned and pages which are
> > +	 * marked dirty by vfio_dma_rw()
> > +	 */
> > +	vfio_dma_populate_bitmap(dma, pgsize);  
> 
> vfio_dma_populate_bitmap() only sets bits, it doesn't clear them.
> Shouldn't we do a memset() zero before calling this?  Thanks,

Or a bitmap_clear() would be better given we use bitmap_set() above.
Thanks,

Alex

Re: [PATCH v16 Kernel 4/7] vfio iommu: Implementation of ioctl for dirty pages tracking.

[Kirti Wankhede]

On 3/25/2020 2:15 AM, Alex Williamson wrote:
> On Tue, 24 Mar 2020 14:37:16 -0600
> Alex Williamson <alex.williamson@redhat.com> wrote:
> 
>> On Wed, 25 Mar 2020 01:02:36 +0530
>> Kirti Wankhede <kwankhede@nvidia.com> wrote:
>>
>>> VFIO_IOMMU_DIRTY_PAGES ioctl performs three operations:
>>> - Start dirty pages tracking while migration is active
>>> - Stop dirty pages tracking.
>>> - Get dirty pages bitmap. Its user space application's responsibility to
>>>    copy content of dirty pages from source to destination during migration.
>>>
>>> To prevent DoS attack, memory for bitmap is allocated per vfio_dma
>>> structure. Bitmap size is calculated considering smallest supported page
>>> size. Bitmap is allocated for all vfio_dmas when dirty logging is enabled
>>>
>>> Bitmap is populated for already pinned pages when bitmap is allocated for
>>> a vfio_dma with the smallest supported page size. Update bitmap from
>>> pinning functions when tracking is enabled. When user application queries
>>> bitmap, check if requested page size is same as page size used to
>>> populated bitmap. If it is equal, copy bitmap, but if not equal, return
>>> error.
>>>
>>> Signed-off-by: Kirti Wankhede <kwankhede@nvidia.com>
>>> Reviewed-by: Neo Jia <cjia@nvidia.com>
>>> ---
>>>   drivers/vfio/vfio_iommu_type1.c | 265 +++++++++++++++++++++++++++++++++++++++-
>>>   1 file changed, 259 insertions(+), 6 deletions(-)
>>>
>>> diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c
>>> index 70aeab921d0f..27ed069c5053 100644
>>> --- a/drivers/vfio/vfio_iommu_type1.c
>>> +++ b/drivers/vfio/vfio_iommu_type1.c
>>> @@ -71,6 +71,7 @@ struct vfio_iommu {
>>>   	unsigned int		dma_avail;
>>>   	bool			v2;
>>>   	bool			nesting;
>>> +	bool			dirty_page_tracking;
>>>   };
>>>   
>>>   struct vfio_domain {
>>> @@ -91,6 +92,7 @@ struct vfio_dma {
>>>   	bool			lock_cap;	/* capable(CAP_IPC_LOCK) */
>>>   	struct task_struct	*task;
>>>   	struct rb_root		pfn_list;	/* Ex-user pinned pfn list */
>>> +	unsigned long		*bitmap;
>>>   };
>>>   
>>>   struct vfio_group {
>>> @@ -125,7 +127,21 @@ struct vfio_regions {
>>>   #define IS_IOMMU_CAP_DOMAIN_IN_CONTAINER(iommu)	\
>>>   					(!list_empty(&iommu->domain_list))
>>>   
>>> +#define DIRTY_BITMAP_BYTES(n)	(ALIGN(n, BITS_PER_TYPE(u64)) / BITS_PER_BYTE)
>>> +
>>> +/*
>>> + * Input argument of number of bits to bitmap_set() is unsigned integer, which
>>> + * further casts to signed integer for unaligned multi-bit operation,
>>> + * __bitmap_set().
>>> + * Then maximum bitmap size supported is 2^31 bits divided by 2^3 bits/byte,
>>> + * that is 2^28 (256 MB) which maps to 2^31 * 2^12 = 2^43 (8TB) on 4K page
>>> + * system.
>>> + */
>>> +#define DIRTY_BITMAP_PAGES_MAX	(uint64_t)(INT_MAX - 1)
>>> +#define DIRTY_BITMAP_SIZE_MAX	 DIRTY_BITMAP_BYTES(DIRTY_BITMAP_PAGES_MAX)
>>> +
>>>   static int put_pfn(unsigned long pfn, int prot);
>>> +static unsigned long vfio_pgsize_bitmap(struct vfio_iommu *iommu);
>>>   
>>>   /*
>>>    * This code handles mapping and unmapping of user data buffers
>>> @@ -175,6 +191,77 @@ static void vfio_unlink_dma(struct vfio_iommu *iommu, struct vfio_dma *old)
>>>   	rb_erase(&old->node, &iommu->dma_list);
>>>   }
>>>   
>>> +
>>> +static int vfio_dma_bitmap_alloc(struct vfio_dma *dma, uint64_t pgsize)
>>> +{
>>> +	uint64_t npages = dma->size / pgsize;
>>> +
>>> +	if (npages > DIRTY_BITMAP_PAGES_MAX)
>>> +		return -EINVAL;
>>> +
>>> +	dma->bitmap = kvzalloc(DIRTY_BITMAP_BYTES(npages), GFP_KERNEL);
>>> +	if (!dma->bitmap)
>>> +		return -ENOMEM;
>>> +
>>> +	return 0;
>>> +}
>>> +
>>> +static void vfio_dma_bitmap_free(struct vfio_dma *dma)
>>> +{
>>> +	kfree(dma->bitmap);
>>> +	dma->bitmap = NULL;
>>> +}
>>> +
>>> +static void vfio_dma_populate_bitmap(struct vfio_dma *dma, uint64_t pgsize)
>>> +{
>>> +	struct rb_node *p;
>>> +
>>> +	if (RB_EMPTY_ROOT(&dma->pfn_list))
>>> +		return;
>>> +
>>> +	for (p = rb_first(&dma->pfn_list); p; p = rb_next(p)) {
>>> +		struct vfio_pfn *vpfn = rb_entry(p, struct vfio_pfn, node);
>>> +
>>> +		bitmap_set(dma->bitmap, (vpfn->iova - dma->iova) / pgsize, 1);
>>> +	}
>>> +}
>>> +
>>> +static int vfio_dma_bitmap_alloc_all(struct vfio_iommu *iommu, uint64_t pgsize)
>>> +{
>>> +	struct rb_node *n = rb_first(&iommu->dma_list);
>>> +
>>> +	for (; n; n = rb_next(n)) {
>>> +		struct vfio_dma *dma = rb_entry(n, struct vfio_dma, node);
>>> +		int ret;
>>> +
>>> +		ret = vfio_dma_bitmap_alloc(dma, pgsize);
>>> +		if (ret) {
>>> +			struct rb_node *p = rb_prev(n);
>>> +
>>> +			for (; p; p = rb_prev(p)) {
>>> +				struct vfio_dma *dma = rb_entry(n,
>>> +							struct vfio_dma, node);
>>> +
>>> +				vfio_dma_bitmap_free(dma);
>>> +			}
>>> +			return ret;
>>> +		}
>>> +		vfio_dma_populate_bitmap(dma, pgsize);
>>> +	}
>>> +	return 0;
>>> +}
>>> +
>>> +static void vfio_dma_bitmap_free_all(struct vfio_iommu *iommu)
>>> +{
>>> +	struct rb_node *n = rb_first(&iommu->dma_list);
>>> +
>>> +	for (; n; n = rb_next(n)) {
>>> +		struct vfio_dma *dma = rb_entry(n, struct vfio_dma, node);
>>> +
>>> +		vfio_dma_bitmap_free(dma);
>>> +	}
>>> +}
>>> +
>>>   /*
>>>    * Helper Functions for host iova-pfn list
>>>    */
>>> @@ -567,6 +654,18 @@ static int vfio_iommu_type1_pin_pages(void *iommu_data,
>>>   			vfio_unpin_page_external(dma, iova, do_accounting);
>>>   			goto pin_unwind;
>>>   		}
>>> +
>>> +		if (iommu->dirty_page_tracking) {
>>> +			unsigned long pgshift =
>>> +					 __ffs(vfio_pgsize_bitmap(iommu));
>>> +
>>> +			/*
>>> +			 * Bitmap populated with the smallest supported page
>>> +			 * size
>>> +			 */
>>> +			bitmap_set(dma->bitmap,
>>> +				   (vpfn->iova - dma->iova) >> pgshift, 1);
>>> +		}
>>>   	}
>>>   
>>>   	ret = i;
>>> @@ -801,6 +900,7 @@ static void vfio_remove_dma(struct vfio_iommu *iommu, struct vfio_dma *dma)
>>>   	vfio_unmap_unpin(iommu, dma, true);
>>>   	vfio_unlink_dma(iommu, dma);
>>>   	put_task_struct(dma->task);
>>> +	vfio_dma_bitmap_free(dma);
>>>   	kfree(dma);
>>>   	iommu->dma_avail++;
>>>   }
>>> @@ -831,6 +931,56 @@ static unsigned long vfio_pgsize_bitmap(struct vfio_iommu *iommu)
>>>   	return bitmap;
>>>   }
>>>   
>>> +static int vfio_iova_dirty_bitmap(struct vfio_iommu *iommu, dma_addr_t iova,
>>> +				  size_t size, uint64_t pgsize,
>>> +				  u64 __user *bitmap)
>>> +{
>>> +	struct vfio_dma *dma;
>>> +	unsigned long pgshift = __ffs(pgsize);
>>> +	unsigned int npages, bitmap_size;
>>> +
>>> +	dma = vfio_find_dma(iommu, iova, 1);
>>> +
>>> +	if (!dma)
>>> +		return -EINVAL;
>>> +
>>> +	if (dma->iova != iova || dma->size != size)
>>> +		return -EINVAL;
>>> +
>>> +	npages = dma->size >> pgshift;
>>> +	bitmap_size = DIRTY_BITMAP_BYTES(npages);
>>> +
>>> +	/* mark all pages dirty if all pages are pinned and mapped. */
>>> +	if (dma->iommu_mapped)
>>> +		bitmap_set(dma->bitmap, 0, npages);
>>> +
>>> +	if (copy_to_user((void __user *)bitmap, dma->bitmap, bitmap_size))
>>> +		return -EFAULT;
>>> +
>>> +	/*
>>> +	 * Re-populate bitmap to include all pinned pages which are considered
>>> +	 * as dirty but exclude pages which are unpinned and pages which are
>>> +	 * marked dirty by vfio_dma_rw()
>>> +	 */
>>> +	vfio_dma_populate_bitmap(dma, pgsize);
>>
>> vfio_dma_populate_bitmap() only sets bits, it doesn't clear them.
>> Shouldn't we do a memset() zero before calling this?  Thanks,
> 
> Or a bitmap_clear() would be better given we use bitmap_set() above.
> Thanks,
> 

Oh, I missed clearing bitmap. Resending only this patch again.

Thanks,
Kirti

Re: [PATCH v16 Kernel 5/7] vfio iommu: Update UNMAP_DMA ioctl to get dirty bitmap before unmap

[Yan Zhao]

On Wed, Mar 25, 2020 at 03:32:37AM +0800, Kirti Wankhede wrote:
> DMA mapped pages, including those pinned by mdev vendor drivers, might
> get unpinned and unmapped while migration is active and device is still
> running. For example, in pre-copy phase while guest driver could access
> those pages, host device or vendor driver can dirty these mapped pages.
> Such pages should be marked dirty so as to maintain memory consistency
> for a user making use of dirty page tracking.
> 
> To get bitmap during unmap, user should allocate memory for bitmap, set
> size of allocated memory, set page size to be considered for bitmap and
> set flag VFIO_DMA_UNMAP_FLAG_GET_DIRTY_BITMAP.
> 
> Signed-off-by: Kirti Wankhede <kwankhede@nvidia.com>
> Reviewed-by: Neo Jia <cjia@nvidia.com>
> ---
>  drivers/vfio/vfio_iommu_type1.c | 54 ++++++++++++++++++++++++++++++++++++++---
>  include/uapi/linux/vfio.h       | 10 ++++++++
>  2 files changed, 60 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c
> index 27ed069c5053..b98a8d79e13a 100644
> --- a/drivers/vfio/vfio_iommu_type1.c
> +++ b/drivers/vfio/vfio_iommu_type1.c
> @@ -982,7 +982,8 @@ static int verify_bitmap_size(uint64_t npages, uint64_t bitmap_size)
>  }
>  
>  static int vfio_dma_do_unmap(struct vfio_iommu *iommu,
> -			     struct vfio_iommu_type1_dma_unmap *unmap)
> +			     struct vfio_iommu_type1_dma_unmap *unmap,
> +			     struct vfio_bitmap *bitmap)
>  {
>  	uint64_t mask;
>  	struct vfio_dma *dma, *dma_last = NULL;
> @@ -1033,6 +1034,10 @@ static int vfio_dma_do_unmap(struct vfio_iommu *iommu,
>  	 * will be returned if these conditions are not met.  The v2 interface
>  	 * will only return success and a size of zero if there were no
>  	 * mappings within the range.
> +	 *
> +	 * When VFIO_DMA_UNMAP_FLAG_GET_DIRTY_BITMAP flag is set, unmap request
> +	 * must be for single mapping. Multiple mappings with this flag set is
> +	 * not supported.
>  	 */
>  	if (iommu->v2) {
>  		dma = vfio_find_dma(iommu, unmap->iova, 1);
> @@ -1040,6 +1045,13 @@ static int vfio_dma_do_unmap(struct vfio_iommu *iommu,
>  			ret = -EINVAL;
>  			goto unlock;
>  		}
> +
> +		if ((unmap->flags & VFIO_DMA_UNMAP_FLAG_GET_DIRTY_BITMAP) &&
> +		    (dma->iova != unmap->iova || dma->size != unmap->size)) {
potential NULL pointer!

And could you address the comments in v14?
How to handle DSI unmaps in vIOMMU
(https://lore.kernel.org/kvm/20200323011041.GB5456@joy-OptiPlex-7040/)

> +			ret = -EINVAL;
> +			goto unlock;
> +		}
> +
>  		dma = vfio_find_dma(iommu, unmap->iova + unmap->size - 1, 0);
>  		if (dma && dma->iova + dma->size != unmap->iova + unmap->size) {
>  			ret = -EINVAL;
> @@ -1057,6 +1069,11 @@ static int vfio_dma_do_unmap(struct vfio_iommu *iommu,
>  		if (dma->task->mm != current->mm)
>  			break;
>  
> +		if ((unmap->flags & VFIO_DMA_UNMAP_FLAG_GET_DIRTY_BITMAP) &&
> +		     iommu->dirty_page_tracking)
> +			vfio_iova_dirty_bitmap(iommu, dma->iova, dma->size,
> +						bitmap->pgsize, bitmap->data);
> +
>  		if (!RB_EMPTY_ROOT(&dma->pfn_list)) {
>  			struct vfio_iommu_type1_dma_unmap nb_unmap;
>  
> @@ -2418,17 +2435,46 @@ static long vfio_iommu_type1_ioctl(void *iommu_data,
>  
>  	} else if (cmd == VFIO_IOMMU_UNMAP_DMA) {
>  		struct vfio_iommu_type1_dma_unmap unmap;
> -		long ret;
> +		struct vfio_bitmap bitmap = { 0 };
> +		int ret;
>  
>  		minsz = offsetofend(struct vfio_iommu_type1_dma_unmap, size);
>  
>  		if (copy_from_user(&unmap, (void __user *)arg, minsz))
>  			return -EFAULT;
>  
> -		if (unmap.argsz < minsz || unmap.flags)
> +		if (unmap.argsz < minsz ||
> +		    unmap.flags & ~VFIO_DMA_UNMAP_FLAG_GET_DIRTY_BITMAP)
>  			return -EINVAL;
>  
> -		ret = vfio_dma_do_unmap(iommu, &unmap);
> +		if (unmap.flags & VFIO_DMA_UNMAP_FLAG_GET_DIRTY_BITMAP) {
> +			unsigned long pgshift;
> +			uint64_t iommu_pgsize =
> +					 1 << __ffs(vfio_pgsize_bitmap(iommu));
> +
> +			if (unmap.argsz < (minsz + sizeof(bitmap)))
> +				return -EINVAL;
> +
> +			if (copy_from_user(&bitmap,
> +					   (void __user *)(arg + minsz),
> +					   sizeof(bitmap)))
> +				return -EFAULT;
> +
> +			/* allow only min supported pgsize */
> +			if (bitmap.pgsize != iommu_pgsize)
> +				return -EINVAL;
> +			if (!access_ok((void __user *)bitmap.data, bitmap.size))
> +				return -EINVAL;
> +
> +			pgshift = __ffs(bitmap.pgsize);
> +			ret = verify_bitmap_size(unmap.size >> pgshift,
> +						 bitmap.size);
> +			if (ret)
> +				return ret;
> +
> +		}
> +
> +		ret = vfio_dma_do_unmap(iommu, &unmap, &bitmap);
>  		if (ret)
>  			return ret;
>  
> diff --git a/include/uapi/linux/vfio.h b/include/uapi/linux/vfio.h
> index 0018721fb744..7c888041136f 100644
> --- a/include/uapi/linux/vfio.h
> +++ b/include/uapi/linux/vfio.h
> @@ -1011,12 +1011,22 @@ struct vfio_bitmap {
>   * field.  No guarantee is made to the user that arbitrary unmaps of iova
>   * or size different from those used in the original mapping call will
>   * succeed.
> + * VFIO_DMA_UNMAP_FLAG_GET_DIRTY_BITMAP should be set to get dirty bitmap
> + * before unmapping IO virtual addresses. When this flag is set, user must
> + * provide data[] as structure vfio_bitmap. User must allocate memory to get
> + * bitmap and must set size of allocated memory in vfio_bitmap.size field.
> + * A bit in bitmap represents one page of user provided page size in 'pgsize',
> + * consecutively starting from iova offset. Bit set indicates page at that
> + * offset from iova is dirty. Bitmap of pages in the range of unmapped size is
> + * returned in vfio_bitmap.data
>   */
>  struct vfio_iommu_type1_dma_unmap {
>  	__u32	argsz;
>  	__u32	flags;
> +#define VFIO_DMA_UNMAP_FLAG_GET_DIRTY_BITMAP (1 << 0)
>  	__u64	iova;				/* IO virtual address */
>  	__u64	size;				/* Size of mapping (bytes) */
> +	__u8    data[];
>  };
>  
>  #define VFIO_IOMMU_UNMAP_DMA _IO(VFIO_TYPE, VFIO_BASE + 14)
> -- 
> 2.7.0
> 

Re: [PATCH v16 Kernel 1/7] vfio: KABI for migration interface for device state

[Cornelia Huck]

On Wed, 25 Mar 2020 01:02:33 +0530
Kirti Wankhede <kwankhede@nvidia.com> wrote:

> - Defined MIGRATION region type and sub-type.
> 
> - Defined vfio_device_migration_info structure which will be placed at the
>   0th offset of migration region to get/set VFIO device related
>   information. Defined members of structure and usage on read/write access.
> 
> - Defined device states and state transition details.
> 
> - Defined sequence to be followed while saving and resuming VFIO device.
> 
> Signed-off-by: Kirti Wankhede <kwankhede@nvidia.com>
> Reviewed-by: Neo Jia <cjia@nvidia.com>
> ---
>  include/uapi/linux/vfio.h | 228 ++++++++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 228 insertions(+)

(...)

> +struct vfio_device_migration_info {
> +	__u32 device_state;         /* VFIO device state */
> +#define VFIO_DEVICE_STATE_STOP      (0)
> +#define VFIO_DEVICE_STATE_RUNNING   (1 << 0)
> +#define VFIO_DEVICE_STATE_SAVING    (1 << 1)
> +#define VFIO_DEVICE_STATE_RESUMING  (1 << 2)
> +#define VFIO_DEVICE_STATE_MASK      (VFIO_DEVICE_STATE_RUNNING | \
> +				     VFIO_DEVICE_STATE_SAVING |  \
> +				     VFIO_DEVICE_STATE_RESUMING)
> +
> +#define VFIO_DEVICE_STATE_VALID(state) \
> +	(state & VFIO_DEVICE_STATE_RESUMING ? \
> +	(state & VFIO_DEVICE_STATE_MASK) == VFIO_DEVICE_STATE_RESUMING : 1)
> +
> +#define VFIO_DEVICE_STATE_IS_ERROR(state) \
> +	((state & VFIO_DEVICE_STATE_MASK) == (VFIO_DEVICE_STATE_SAVING | \
> +					      VFIO_DEVICE_STATE_RESUMING))
> +
> +#define VFIO_DEVICE_STATE_SET_ERROR(state) \
> +	((state & ~VFIO_DEVICE_STATE_MASK) | VFIO_DEVICE_SATE_SAVING | \
> +					     VFIO_DEVICE_STATE_RESUMING)
> +
> +	__u32 reserved;
> +	__u64 pending_bytes;
> +	__u64 data_offset;
> +	__u64 data_size;
> +} __attribute__((packed));

The 'packed' should not even be needed, I think?

> +
>  /*
>   * The MSIX mappable capability informs that MSIX data of a BAR can be mmapped
>   * which allows direct access to non-MSIX registers which happened to be within

Generally, this looks sane to me; however, we should really have
something under Documentation/ in the long run that describes how this
works, so that you can find out about the protocol without having to
dig through headers.

Re: [PATCH v16 Kernel 2/7] vfio iommu: Remove atomicity of ref_count of pinned pages

[Cornelia Huck]

On Wed, 25 Mar 2020 01:02:34 +0530
Kirti Wankhede <kwankhede@nvidia.com> wrote:

> vfio_pfn.ref_count is always updated by holding iommu->lock, using atomic

s/by/while/

> variable is overkill.
> 
> Signed-off-by: Kirti Wankhede <kwankhede@nvidia.com>
> Reviewed-by: Neo Jia <cjia@nvidia.com>
> Reviewed-by: Eric Auger <eric.auger@redhat.com>
> ---
>  drivers/vfio/vfio_iommu_type1.c | 9 +++++----
>  1 file changed, 5 insertions(+), 4 deletions(-)
> 

Reviewed-by: Cornelia Huck <cohuck@redhat.com>

Re: [PATCH v16 Kernel 5/7] vfio iommu: Update UNMAP_DMA ioctl to get dirty bitmap before unmap

[Kirti Wankhede]

On 3/25/2020 7:48 AM, Yan Zhao wrote:
> On Wed, Mar 25, 2020 at 03:32:37AM +0800, Kirti Wankhede wrote:
>> DMA mapped pages, including those pinned by mdev vendor drivers, might
>> get unpinned and unmapped while migration is active and device is still
>> running. For example, in pre-copy phase while guest driver could access
>> those pages, host device or vendor driver can dirty these mapped pages.
>> Such pages should be marked dirty so as to maintain memory consistency
>> for a user making use of dirty page tracking.
>>
>> To get bitmap during unmap, user should allocate memory for bitmap, set
>> size of allocated memory, set page size to be considered for bitmap and
>> set flag VFIO_DMA_UNMAP_FLAG_GET_DIRTY_BITMAP.
>>
>> Signed-off-by: Kirti Wankhede <kwankhede@nvidia.com>
>> Reviewed-by: Neo Jia <cjia@nvidia.com>
>> ---
>>   drivers/vfio/vfio_iommu_type1.c | 54 ++++++++++++++++++++++++++++++++++++++---
>>   include/uapi/linux/vfio.h       | 10 ++++++++
>>   2 files changed, 60 insertions(+), 4 deletions(-)
>>
>> diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c
>> index 27ed069c5053..b98a8d79e13a 100644
>> --- a/drivers/vfio/vfio_iommu_type1.c
>> +++ b/drivers/vfio/vfio_iommu_type1.c
>> @@ -982,7 +982,8 @@ static int verify_bitmap_size(uint64_t npages, uint64_t bitmap_size)
>>   }
>>   
>>   static int vfio_dma_do_unmap(struct vfio_iommu *iommu,
>> -			     struct vfio_iommu_type1_dma_unmap *unmap)
>> +			     struct vfio_iommu_type1_dma_unmap *unmap,
>> +			     struct vfio_bitmap *bitmap)
>>   {
>>   	uint64_t mask;
>>   	struct vfio_dma *dma, *dma_last = NULL;
>> @@ -1033,6 +1034,10 @@ static int vfio_dma_do_unmap(struct vfio_iommu *iommu,
>>   	 * will be returned if these conditions are not met.  The v2 interface
>>   	 * will only return success and a size of zero if there were no
>>   	 * mappings within the range.
>> +	 *
>> +	 * When VFIO_DMA_UNMAP_FLAG_GET_DIRTY_BITMAP flag is set, unmap request
>> +	 * must be for single mapping. Multiple mappings with this flag set is
>> +	 * not supported.
>>   	 */
>>   	if (iommu->v2) {
>>   		dma = vfio_find_dma(iommu, unmap->iova, 1);
>> @@ -1040,6 +1045,13 @@ static int vfio_dma_do_unmap(struct vfio_iommu *iommu,
>>   			ret = -EINVAL;
>>   			goto unlock;
>>   		}
>> +
>> +		if ((unmap->flags & VFIO_DMA_UNMAP_FLAG_GET_DIRTY_BITMAP) &&
>> +		    (dma->iova != unmap->iova || dma->size != unmap->size)) {
> potential NULL pointer!
> 
> And could you address the comments in v14?
> How to handle DSI unmaps in vIOMMU
> (https://lore.kernel.org/kvm/20200323011041.GB5456@joy-OptiPlex-7040/)
> 

Sorry, I drafted reply to it, but I missed to send, it remained in my drafts

 >
 > it happens in vIOMMU Domain level invalidation of IOTLB
 > (domain-selective invalidation, see vtd_iotlb_domain_invalidate() in 
qemu).
 > common in VTD lazy mode, and NOT just happening once at boot time.
 > rather than invalidate page by page, it batches the page invalidation.
 > so, when this invalidation takes place, even higher level page tables
 > have been invalid and therefore it has to invalidate a bigger 
combined range.
 > That's why we see IOVAs are mapped in 4k pages, but are unmapped in 2M
 > pages.
 >
 > I think those UNMAPs should also have GET_DIRTY_BIMTAP flag on, right?


vtd_iotlb_domain_invalidate()
   vtd_sync_shadow_page_table()
     vtd_sync_shadow_page_table_range(vtd_as, &ce, 0, UINT64_MAX)
       vtd_page_walk()
         vtd_page_walk_level() - walk over specific level for IOVA range
           vtd_page_walk_one()
             memory_region_notify_iommu()
             ...
               vfio_iommu_map_notify()

In the above trace, isn't page walk will take care of creating proper 
IOTLB entry which should be same as created during mapping for that 
IOTLB entry?


 >>>
 >>> Such unmap would callback vfio_iommu_map_notify() in QEMU. In
 >>> vfio_iommu_map_notify(), unmap is called on same range <iova,
 >>> iotlb->addr_mask + 1> which was used for map. Secondly unmap with 
bitmap
 >>> will be called only when device state has _SAVING flag set.
 >>
 > in this case, iotlb->addr_mask in unmap is 0x200000 -1.
 > different than 0x1000 -1 used for map.
 >> It might be helpful for Yan, and everyone else, to see the latest QEMU
 >> patch series.  Thanks,
 >>
 > yes, please. also curious of log_sync part for vIOMMU. given most 
IOVAs in
 > address space are unmapped and therefore no IOTLBs are able to be found.
 >
	
Qemu patches compatible with v16 version are at:
https://www.mail-archive.com/qemu-devel@nongnu.org/msg691806.html

Hope that helps.

Thanks,
Kirti

Re: [PATCH v16 Kernel 1/7] vfio: KABI for migration interface for device state

[Kirti Wankhede]

On 3/26/2020 4:11 PM, Cornelia Huck wrote:
> On Wed, 25 Mar 2020 01:02:33 +0530
> Kirti Wankhede <kwankhede@nvidia.com> wrote:
> 
>> - Defined MIGRATION region type and sub-type.
>>
>> - Defined vfio_device_migration_info structure which will be placed at the
>>    0th offset of migration region to get/set VFIO device related
>>    information. Defined members of structure and usage on read/write access.
>>
>> - Defined device states and state transition details.
>>
>> - Defined sequence to be followed while saving and resuming VFIO device.
>>
>> Signed-off-by: Kirti Wankhede <kwankhede@nvidia.com>
>> Reviewed-by: Neo Jia <cjia@nvidia.com>
>> ---
>>   include/uapi/linux/vfio.h | 228 ++++++++++++++++++++++++++++++++++++++++++++++
>>   1 file changed, 228 insertions(+)
> 
> (...)
> 
>> +struct vfio_device_migration_info {
>> +	__u32 device_state;         /* VFIO device state */
>> +#define VFIO_DEVICE_STATE_STOP      (0)
>> +#define VFIO_DEVICE_STATE_RUNNING   (1 << 0)
>> +#define VFIO_DEVICE_STATE_SAVING    (1 << 1)
>> +#define VFIO_DEVICE_STATE_RESUMING  (1 << 2)
>> +#define VFIO_DEVICE_STATE_MASK      (VFIO_DEVICE_STATE_RUNNING | \
>> +				     VFIO_DEVICE_STATE_SAVING |  \
>> +				     VFIO_DEVICE_STATE_RESUMING)
>> +
>> +#define VFIO_DEVICE_STATE_VALID(state) \
>> +	(state & VFIO_DEVICE_STATE_RESUMING ? \
>> +	(state & VFIO_DEVICE_STATE_MASK) == VFIO_DEVICE_STATE_RESUMING : 1)
>> +
>> +#define VFIO_DEVICE_STATE_IS_ERROR(state) \
>> +	((state & VFIO_DEVICE_STATE_MASK) == (VFIO_DEVICE_STATE_SAVING | \
>> +					      VFIO_DEVICE_STATE_RESUMING))
>> +
>> +#define VFIO_DEVICE_STATE_SET_ERROR(state) \
>> +	((state & ~VFIO_DEVICE_STATE_MASK) | VFIO_DEVICE_SATE_SAVING | \
>> +					     VFIO_DEVICE_STATE_RESUMING)
>> +
>> +	__u32 reserved;
>> +	__u64 pending_bytes;
>> +	__u64 data_offset;
>> +	__u64 data_size;
>> +} __attribute__((packed));
> 
> The 'packed' should not even be needed, I think?
> 

Right, Above structure is padded properly. Removing it.

>> +
>>   /*
>>    * The MSIX mappable capability informs that MSIX data of a BAR can be mmapped
>>    * which allows direct access to non-MSIX registers which happened to be within
> 
> Generally, this looks sane to me; however, we should really have
> something under Documentation/ in the long run that describes how this
> works, so that you can find out about the protocol without having to
> dig through headers.
> 

But the documentation will have almost the same text as in this comment. 
Should we replicate it?

Thanks,
Kirti

Re: [PATCH v16 Kernel 2/7] vfio iommu: Remove atomicity of ref_count of pinned pages

[Kirti Wankhede]

On 3/26/2020 4:19 PM, Cornelia Huck wrote:
> On Wed, 25 Mar 2020 01:02:34 +0530
> Kirti Wankhede <kwankhede@nvidia.com> wrote:
> 
>> vfio_pfn.ref_count is always updated by holding iommu->lock, using atomic
> 
> s/by/while/
> 

Ok.

>> variable is overkill.
>>
>> Signed-off-by: Kirti Wankhede <kwankhede@nvidia.com>
>> Reviewed-by: Neo Jia <cjia@nvidia.com>
>> Reviewed-by: Eric Auger <eric.auger@redhat.com>
>> ---
>>   drivers/vfio/vfio_iommu_type1.c | 9 +++++----
>>   1 file changed, 5 insertions(+), 4 deletions(-)
>>
> 
> Reviewed-by: Cornelia Huck <cohuck@redhat.com>
> 

Thanks,
Kirti

Re: [PATCH v16 Kernel 5/7] vfio iommu: Update UNMAP_DMA ioctl to get dirty bitmap before unmap

[Yan Zhao]

On Fri, Mar 27, 2020 at 05:39:44AM +0800, Kirti Wankhede wrote:
> 
> 
> On 3/25/2020 7:48 AM, Yan Zhao wrote:
> > On Wed, Mar 25, 2020 at 03:32:37AM +0800, Kirti Wankhede wrote:
> >> DMA mapped pages, including those pinned by mdev vendor drivers, might
> >> get unpinned and unmapped while migration is active and device is still
> >> running. For example, in pre-copy phase while guest driver could access
> >> those pages, host device or vendor driver can dirty these mapped pages.
> >> Such pages should be marked dirty so as to maintain memory consistency
> >> for a user making use of dirty page tracking.
> >>
> >> To get bitmap during unmap, user should allocate memory for bitmap, set
> >> size of allocated memory, set page size to be considered for bitmap and
> >> set flag VFIO_DMA_UNMAP_FLAG_GET_DIRTY_BITMAP.
> >>
> >> Signed-off-by: Kirti Wankhede <kwankhede@nvidia.com>
> >> Reviewed-by: Neo Jia <cjia@nvidia.com>
> >> ---
> >>   drivers/vfio/vfio_iommu_type1.c | 54 ++++++++++++++++++++++++++++++++++++++---
> >>   include/uapi/linux/vfio.h       | 10 ++++++++
> >>   2 files changed, 60 insertions(+), 4 deletions(-)
> >>
> >> diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c
> >> index 27ed069c5053..b98a8d79e13a 100644
> >> --- a/drivers/vfio/vfio_iommu_type1.c
> >> +++ b/drivers/vfio/vfio_iommu_type1.c
> >> @@ -982,7 +982,8 @@ static int verify_bitmap_size(uint64_t npages, uint64_t bitmap_size)
> >>   }
> >>   
> >>   static int vfio_dma_do_unmap(struct vfio_iommu *iommu,
> >> -			     struct vfio_iommu_type1_dma_unmap *unmap)
> >> +			     struct vfio_iommu_type1_dma_unmap *unmap,
> >> +			     struct vfio_bitmap *bitmap)
> >>   {
> >>   	uint64_t mask;
> >>   	struct vfio_dma *dma, *dma_last = NULL;
> >> @@ -1033,6 +1034,10 @@ static int vfio_dma_do_unmap(struct vfio_iommu *iommu,
> >>   	 * will be returned if these conditions are not met.  The v2 interface
> >>   	 * will only return success and a size of zero if there were no
> >>   	 * mappings within the range.
> >> +	 *
> >> +	 * When VFIO_DMA_UNMAP_FLAG_GET_DIRTY_BITMAP flag is set, unmap request
> >> +	 * must be for single mapping. Multiple mappings with this flag set is
> >> +	 * not supported.
> >>   	 */
> >>   	if (iommu->v2) {
> >>   		dma = vfio_find_dma(iommu, unmap->iova, 1);
> >> @@ -1040,6 +1045,13 @@ static int vfio_dma_do_unmap(struct vfio_iommu *iommu,
> >>   			ret = -EINVAL;
> >>   			goto unlock;
> >>   		}
> >> +
> >> +		if ((unmap->flags & VFIO_DMA_UNMAP_FLAG_GET_DIRTY_BITMAP) &&
> >> +		    (dma->iova != unmap->iova || dma->size != unmap->size)) {
> > potential NULL pointer!
> > 
> > And could you address the comments in v14?
> > How to handle DSI unmaps in vIOMMU
> > (https://lore.kernel.org/kvm/20200323011041.GB5456@joy-OptiPlex-7040/)
> > 
> 
> Sorry, I drafted reply to it, but I missed to send, it remained in my drafts
> 
>  >
>  > it happens in vIOMMU Domain level invalidation of IOTLB
>  > (domain-selective invalidation, see vtd_iotlb_domain_invalidate() in 
> qemu).
>  > common in VTD lazy mode, and NOT just happening once at boot time.
>  > rather than invalidate page by page, it batches the page invalidation.
>  > so, when this invalidation takes place, even higher level page tables
>  > have been invalid and therefore it has to invalidate a bigger 
> combined range.
>  > That's why we see IOVAs are mapped in 4k pages, but are unmapped in 2M
>  > pages.
>  >
>  > I think those UNMAPs should also have GET_DIRTY_BIMTAP flag on, right?
> 
> 
> vtd_iotlb_domain_invalidate()
>    vtd_sync_shadow_page_table()
>      vtd_sync_shadow_page_table_range(vtd_as, &ce, 0, UINT64_MAX)
>        vtd_page_walk()
>          vtd_page_walk_level() - walk over specific level for IOVA range
>            vtd_page_walk_one()
>              memory_region_notify_iommu()
>              ...
>                vfio_iommu_map_notify()
> 
> In the above trace, isn't page walk will take care of creating proper 
> IOTLB entry which should be same as created during mapping for that 
> IOTLB entry?
>
No. It does walk the page table, but as it's dsi (delay & batched unmap),
pages table entry for a whole 2M (the higher level, not last level for 4K)
range is invalid, so the iotlb->addr_mask what vfio_iommu_map_notify()
receives is (2M - 1), not the same as the size for map.

> 
>  >>>
>  >>> Such unmap would callback vfio_iommu_map_notify() in QEMU. In
>  >>> vfio_iommu_map_notify(), unmap is called on same range <iova,
>  >>> iotlb->addr_mask + 1> which was used for map. Secondly unmap with 
> bitmap
>  >>> will be called only when device state has _SAVING flag set.
>  >>
>  > in this case, iotlb->addr_mask in unmap is 0x200000 -1.
>  > different than 0x1000 -1 used for map.
>  >> It might be helpful for Yan, and everyone else, to see the latest QEMU
>  >> patch series.  Thanks,
>  >>
>  > yes, please. also curious of log_sync part for vIOMMU. given most 
> IOVAs in
>  > address space are unmapped and therefore no IOTLBs are able to be found.
>  >
> 	
> Qemu patches compatible with v16 version are at:
> https://www.mail-archive.com/qemu-devel@nongnu.org/msg691806.html
> 
> 

Re: [PATCH v16 Kernel 5/7] vfio iommu: Update UNMAP_DMA ioctl to get dirty bitmap before unmap

[Kirti Wankhede]

On 3/27/2020 5:34 AM, Yan Zhao wrote:
> On Fri, Mar 27, 2020 at 05:39:44AM +0800, Kirti Wankhede wrote:
>>
>>
>> On 3/25/2020 7:48 AM, Yan Zhao wrote:
>>> On Wed, Mar 25, 2020 at 03:32:37AM +0800, Kirti Wankhede wrote:
>>>> DMA mapped pages, including those pinned by mdev vendor drivers, might
>>>> get unpinned and unmapped while migration is active and device is still
>>>> running. For example, in pre-copy phase while guest driver could access
>>>> those pages, host device or vendor driver can dirty these mapped pages.
>>>> Such pages should be marked dirty so as to maintain memory consistency
>>>> for a user making use of dirty page tracking.
>>>>
>>>> To get bitmap during unmap, user should allocate memory for bitmap, set
>>>> size of allocated memory, set page size to be considered for bitmap and
>>>> set flag VFIO_DMA_UNMAP_FLAG_GET_DIRTY_BITMAP.
>>>>
>>>> Signed-off-by: Kirti Wankhede <kwankhede@nvidia.com>
>>>> Reviewed-by: Neo Jia <cjia@nvidia.com>
>>>> ---
>>>>    drivers/vfio/vfio_iommu_type1.c | 54 ++++++++++++++++++++++++++++++++++++++---
>>>>    include/uapi/linux/vfio.h       | 10 ++++++++
>>>>    2 files changed, 60 insertions(+), 4 deletions(-)
>>>>
>>>> diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c
>>>> index 27ed069c5053..b98a8d79e13a 100644
>>>> --- a/drivers/vfio/vfio_iommu_type1.c
>>>> +++ b/drivers/vfio/vfio_iommu_type1.c
>>>> @@ -982,7 +982,8 @@ static int verify_bitmap_size(uint64_t npages, uint64_t bitmap_size)
>>>>    }
>>>>    
>>>>    static int vfio_dma_do_unmap(struct vfio_iommu *iommu,
>>>> -			     struct vfio_iommu_type1_dma_unmap *unmap)
>>>> +			     struct vfio_iommu_type1_dma_unmap *unmap,
>>>> +			     struct vfio_bitmap *bitmap)
>>>>    {
>>>>    	uint64_t mask;
>>>>    	struct vfio_dma *dma, *dma_last = NULL;
>>>> @@ -1033,6 +1034,10 @@ static int vfio_dma_do_unmap(struct vfio_iommu *iommu,
>>>>    	 * will be returned if these conditions are not met.  The v2 interface
>>>>    	 * will only return success and a size of zero if there were no
>>>>    	 * mappings within the range.
>>>> +	 *
>>>> +	 * When VFIO_DMA_UNMAP_FLAG_GET_DIRTY_BITMAP flag is set, unmap request
>>>> +	 * must be for single mapping. Multiple mappings with this flag set is
>>>> +	 * not supported.
>>>>    	 */
>>>>    	if (iommu->v2) {
>>>>    		dma = vfio_find_dma(iommu, unmap->iova, 1);
>>>> @@ -1040,6 +1045,13 @@ static int vfio_dma_do_unmap(struct vfio_iommu *iommu,
>>>>    			ret = -EINVAL;
>>>>    			goto unlock;
>>>>    		}
>>>> +
>>>> +		if ((unmap->flags & VFIO_DMA_UNMAP_FLAG_GET_DIRTY_BITMAP) &&
>>>> +		    (dma->iova != unmap->iova || dma->size != unmap->size)) {
>>> potential NULL pointer!
>>>
>>> And could you address the comments in v14?
>>> How to handle DSI unmaps in vIOMMU
>>> (https://lore.kernel.org/kvm/20200323011041.GB5456@joy-OptiPlex-7040/)
>>>
>>
>> Sorry, I drafted reply to it, but I missed to send, it remained in my drafts
>>
>>   >
>>   > it happens in vIOMMU Domain level invalidation of IOTLB
>>   > (domain-selective invalidation, see vtd_iotlb_domain_invalidate() in
>> qemu).
>>   > common in VTD lazy mode, and NOT just happening once at boot time.
>>   > rather than invalidate page by page, it batches the page invalidation.
>>   > so, when this invalidation takes place, even higher level page tables
>>   > have been invalid and therefore it has to invalidate a bigger
>> combined range.
>>   > That's why we see IOVAs are mapped in 4k pages, but are unmapped in 2M
>>   > pages.
>>   >
>>   > I think those UNMAPs should also have GET_DIRTY_BIMTAP flag on, right?
>>
>>
>> vtd_iotlb_domain_invalidate()
>>     vtd_sync_shadow_page_table()
>>       vtd_sync_shadow_page_table_range(vtd_as, &ce, 0, UINT64_MAX)
>>         vtd_page_walk()
>>           vtd_page_walk_level() - walk over specific level for IOVA range
>>             vtd_page_walk_one()
>>               memory_region_notify_iommu()
>>               ...
>>                 vfio_iommu_map_notify()
>>
>> In the above trace, isn't page walk will take care of creating proper
>> IOTLB entry which should be same as created during mapping for that
>> IOTLB entry?
>>
> No. It does walk the page table, but as it's dsi (delay & batched unmap),
> pages table entry for a whole 2M (the higher level, not last level for 4K)
> range is invalid, so the iotlb->addr_mask what vfio_iommu_map_notify()
> receives is (2M - 1), not the same as the size for map.
> 

When do this happen? during my testing I never hit this case. How can I 
hit this case?

In this case, will adjacent whole vfio_dmas will be clubbed together or 
will there be any intersection of vfio_dmas?

Thanks,
Kirti

Re: [PATCH v16 Kernel 5/7] vfio iommu: Update UNMAP_DMA ioctl to get dirty bitmap before unmap

[Yan Zhao]

On Fri, Mar 27, 2020 at 12:42:43PM +0800, Kirti Wankhede wrote:
> 
> 
> On 3/27/2020 5:34 AM, Yan Zhao wrote:
> > On Fri, Mar 27, 2020 at 05:39:44AM +0800, Kirti Wankhede wrote:
> >>
> >>
> >> On 3/25/2020 7:48 AM, Yan Zhao wrote:
> >>> On Wed, Mar 25, 2020 at 03:32:37AM +0800, Kirti Wankhede wrote:
> >>>> DMA mapped pages, including those pinned by mdev vendor drivers, might
> >>>> get unpinned and unmapped while migration is active and device is still
> >>>> running. For example, in pre-copy phase while guest driver could access
> >>>> those pages, host device or vendor driver can dirty these mapped pages.
> >>>> Such pages should be marked dirty so as to maintain memory consistency
> >>>> for a user making use of dirty page tracking.
> >>>>
> >>>> To get bitmap during unmap, user should allocate memory for bitmap, set
> >>>> size of allocated memory, set page size to be considered for bitmap and
> >>>> set flag VFIO_DMA_UNMAP_FLAG_GET_DIRTY_BITMAP.
> >>>>
> >>>> Signed-off-by: Kirti Wankhede <kwankhede@nvidia.com>
> >>>> Reviewed-by: Neo Jia <cjia@nvidia.com>
> >>>> ---
> >>>>    drivers/vfio/vfio_iommu_type1.c | 54 ++++++++++++++++++++++++++++++++++++++---
> >>>>    include/uapi/linux/vfio.h       | 10 ++++++++
> >>>>    2 files changed, 60 insertions(+), 4 deletions(-)
> >>>>
> >>>> diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c
> >>>> index 27ed069c5053..b98a8d79e13a 100644
> >>>> --- a/drivers/vfio/vfio_iommu_type1.c
> >>>> +++ b/drivers/vfio/vfio_iommu_type1.c
> >>>> @@ -982,7 +982,8 @@ static int verify_bitmap_size(uint64_t npages, uint64_t bitmap_size)
> >>>>    }
> >>>>    
> >>>>    static int vfio_dma_do_unmap(struct vfio_iommu *iommu,
> >>>> -			     struct vfio_iommu_type1_dma_unmap *unmap)
> >>>> +			     struct vfio_iommu_type1_dma_unmap *unmap,
> >>>> +			     struct vfio_bitmap *bitmap)
> >>>>    {
> >>>>    	uint64_t mask;
> >>>>    	struct vfio_dma *dma, *dma_last = NULL;
> >>>> @@ -1033,6 +1034,10 @@ static int vfio_dma_do_unmap(struct vfio_iommu *iommu,
> >>>>    	 * will be returned if these conditions are not met.  The v2 interface
> >>>>    	 * will only return success and a size of zero if there were no
> >>>>    	 * mappings within the range.
> >>>> +	 *
> >>>> +	 * When VFIO_DMA_UNMAP_FLAG_GET_DIRTY_BITMAP flag is set, unmap request
> >>>> +	 * must be for single mapping. Multiple mappings with this flag set is
> >>>> +	 * not supported.
> >>>>    	 */
> >>>>    	if (iommu->v2) {
> >>>>    		dma = vfio_find_dma(iommu, unmap->iova, 1);
> >>>> @@ -1040,6 +1045,13 @@ static int vfio_dma_do_unmap(struct vfio_iommu *iommu,
> >>>>    			ret = -EINVAL;
> >>>>    			goto unlock;
> >>>>    		}
> >>>> +
> >>>> +		if ((unmap->flags & VFIO_DMA_UNMAP_FLAG_GET_DIRTY_BITMAP) &&
> >>>> +		    (dma->iova != unmap->iova || dma->size != unmap->size)) {
> >>> potential NULL pointer!
> >>>
> >>> And could you address the comments in v14?
> >>> How to handle DSI unmaps in vIOMMU
> >>> (https://lore.kernel.org/kvm/20200323011041.GB5456@joy-OptiPlex-7040/)
> >>>
> >>
> >> Sorry, I drafted reply to it, but I missed to send, it remained in my drafts
> >>
> >>   >
> >>   > it happens in vIOMMU Domain level invalidation of IOTLB
> >>   > (domain-selective invalidation, see vtd_iotlb_domain_invalidate() in
> >> qemu).
> >>   > common in VTD lazy mode, and NOT just happening once at boot time.
> >>   > rather than invalidate page by page, it batches the page invalidation.
> >>   > so, when this invalidation takes place, even higher level page tables
> >>   > have been invalid and therefore it has to invalidate a bigger
> >> combined range.
> >>   > That's why we see IOVAs are mapped in 4k pages, but are unmapped in 2M
> >>   > pages.
> >>   >
> >>   > I think those UNMAPs should also have GET_DIRTY_BIMTAP flag on, right?
> >>
> >>
> >> vtd_iotlb_domain_invalidate()
> >>     vtd_sync_shadow_page_table()
> >>       vtd_sync_shadow_page_table_range(vtd_as, &ce, 0, UINT64_MAX)
> >>         vtd_page_walk()
> >>           vtd_page_walk_level() - walk over specific level for IOVA range
> >>             vtd_page_walk_one()
> >>               memory_region_notify_iommu()
> >>               ...
> >>                 vfio_iommu_map_notify()
> >>
> >> In the above trace, isn't page walk will take care of creating proper
> >> IOTLB entry which should be same as created during mapping for that
> >> IOTLB entry?
> >>
> > No. It does walk the page table, but as it's dsi (delay & batched unmap),
> > pages table entry for a whole 2M (the higher level, not last level for 4K)
> > range is invalid, so the iotlb->addr_mask what vfio_iommu_map_notify()
> > receives is (2M - 1), not the same as the size for map.
> > 
> 
> When do this happen? during my testing I never hit this case. How can I 
> hit this case?

Just common settings to enable vIOMMU:
Qemu: -device intel-iommu,caching-mode=true
guest kernel parameter: intel_iommu=on

(intel_iommu=on turns on lazy mode by default)

In lazy mode, guest notifies DMA MAP on page level, but notifies DMA UNMAPs
in batch.
with a pass-through NVMe, there are 89 DSI unmaps in 1 second for a typical fio.
With a pass-through GPU, there 22 DSI unmaps in total for benchmark openArena
(lasting around 55 secs)
> 
> In this case, will adjacent whole vfio_dmas will be clubbed together or 
> will there be any intersection of vfio_dmas?
>
clubbed together.

Re: [PATCH v16 Kernel 5/7] vfio iommu: Update UNMAP_DMA ioctl to get dirty bitmap before unmap

[Kirti Wankhede]

On 3/30/2020 7:45 AM, Yan Zhao wrote:
> On Fri, Mar 27, 2020 at 12:42:43PM +0800, Kirti Wankhede wrote:
>>
>>
>> On 3/27/2020 5:34 AM, Yan Zhao wrote:
>>> On Fri, Mar 27, 2020 at 05:39:44AM +0800, Kirti Wankhede wrote:
>>>>
>>>>
>>>> On 3/25/2020 7:48 AM, Yan Zhao wrote:
>>>>> On Wed, Mar 25, 2020 at 03:32:37AM +0800, Kirti Wankhede wrote:
>>>>>> DMA mapped pages, including those pinned by mdev vendor drivers, might
>>>>>> get unpinned and unmapped while migration is active and device is still
>>>>>> running. For example, in pre-copy phase while guest driver could access
>>>>>> those pages, host device or vendor driver can dirty these mapped pages.
>>>>>> Such pages should be marked dirty so as to maintain memory consistency
>>>>>> for a user making use of dirty page tracking.
>>>>>>
>>>>>> To get bitmap during unmap, user should allocate memory for bitmap, set
>>>>>> size of allocated memory, set page size to be considered for bitmap and
>>>>>> set flag VFIO_DMA_UNMAP_FLAG_GET_DIRTY_BITMAP.
>>>>>>
>>>>>> Signed-off-by: Kirti Wankhede <kwankhede@nvidia.com>
>>>>>> Reviewed-by: Neo Jia <cjia@nvidia.com>
>>>>>> ---
>>>>>>     drivers/vfio/vfio_iommu_type1.c | 54 ++++++++++++++++++++++++++++++++++++++---
>>>>>>     include/uapi/linux/vfio.h       | 10 ++++++++
>>>>>>     2 files changed, 60 insertions(+), 4 deletions(-)
>>>>>>
>>>>>> diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c
>>>>>> index 27ed069c5053..b98a8d79e13a 100644
>>>>>> --- a/drivers/vfio/vfio_iommu_type1.c
>>>>>> +++ b/drivers/vfio/vfio_iommu_type1.c
>>>>>> @@ -982,7 +982,8 @@ static int verify_bitmap_size(uint64_t npages, uint64_t bitmap_size)
>>>>>>     }
>>>>>>     
>>>>>>     static int vfio_dma_do_unmap(struct vfio_iommu *iommu,
>>>>>> -			     struct vfio_iommu_type1_dma_unmap *unmap)
>>>>>> +			     struct vfio_iommu_type1_dma_unmap *unmap,
>>>>>> +			     struct vfio_bitmap *bitmap)
>>>>>>     {
>>>>>>     	uint64_t mask;
>>>>>>     	struct vfio_dma *dma, *dma_last = NULL;
>>>>>> @@ -1033,6 +1034,10 @@ static int vfio_dma_do_unmap(struct vfio_iommu *iommu,
>>>>>>     	 * will be returned if these conditions are not met.  The v2 interface
>>>>>>     	 * will only return success and a size of zero if there were no
>>>>>>     	 * mappings within the range.
>>>>>> +	 *
>>>>>> +	 * When VFIO_DMA_UNMAP_FLAG_GET_DIRTY_BITMAP flag is set, unmap request
>>>>>> +	 * must be for single mapping. Multiple mappings with this flag set is
>>>>>> +	 * not supported.
>>>>>>     	 */
>>>>>>     	if (iommu->v2) {
>>>>>>     		dma = vfio_find_dma(iommu, unmap->iova, 1);
>>>>>> @@ -1040,6 +1045,13 @@ static int vfio_dma_do_unmap(struct vfio_iommu *iommu,
>>>>>>     			ret = -EINVAL;
>>>>>>     			goto unlock;
>>>>>>     		}
>>>>>> +
>>>>>> +		if ((unmap->flags & VFIO_DMA_UNMAP_FLAG_GET_DIRTY_BITMAP) &&
>>>>>> +		    (dma->iova != unmap->iova || dma->size != unmap->size)) {
>>>>> potential NULL pointer!
>>>>>
>>>>> And could you address the comments in v14?
>>>>> How to handle DSI unmaps in vIOMMU
>>>>> (https://lore.kernel.org/kvm/20200323011041.GB5456@joy-OptiPlex-7040/)
>>>>>
>>>>
>>>> Sorry, I drafted reply to it, but I missed to send, it remained in my drafts
>>>>
>>>>    >
>>>>    > it happens in vIOMMU Domain level invalidation of IOTLB
>>>>    > (domain-selective invalidation, see vtd_iotlb_domain_invalidate() in
>>>> qemu).
>>>>    > common in VTD lazy mode, and NOT just happening once at boot time.
>>>>    > rather than invalidate page by page, it batches the page invalidation.
>>>>    > so, when this invalidation takes place, even higher level page tables
>>>>    > have been invalid and therefore it has to invalidate a bigger
>>>> combined range.
>>>>    > That's why we see IOVAs are mapped in 4k pages, but are unmapped in 2M
>>>>    > pages.
>>>>    >
>>>>    > I think those UNMAPs should also have GET_DIRTY_BIMTAP flag on, right?
>>>>
>>>>
>>>> vtd_iotlb_domain_invalidate()
>>>>      vtd_sync_shadow_page_table()
>>>>        vtd_sync_shadow_page_table_range(vtd_as, &ce, 0, UINT64_MAX)
>>>>          vtd_page_walk()
>>>>            vtd_page_walk_level() - walk over specific level for IOVA range
>>>>              vtd_page_walk_one()
>>>>                memory_region_notify_iommu()
>>>>                ...
>>>>                  vfio_iommu_map_notify()
>>>>
>>>> In the above trace, isn't page walk will take care of creating proper
>>>> IOTLB entry which should be same as created during mapping for that
>>>> IOTLB entry?
>>>>
>>> No. It does walk the page table, but as it's dsi (delay & batched unmap),
>>> pages table entry for a whole 2M (the higher level, not last level for 4K)
>>> range is invalid, so the iotlb->addr_mask what vfio_iommu_map_notify()
>>> receives is (2M - 1), not the same as the size for map.
>>>
>>
>> When do this happen? during my testing I never hit this case. How can I
>> hit this case?
> 
> Just common settings to enable vIOMMU:
> Qemu: -device intel-iommu,caching-mode=true
> guest kernel parameter: intel_iommu=on
> 
> (intel_iommu=on turns on lazy mode by default)
> 
> In lazy mode, guest notifies DMA MAP on page level, but notifies DMA UNMAPs
> in batch.
> with a pass-through NVMe, there are 89 DSI unmaps in 1 second for a typical fio.
> With a pass-through GPU, there 22 DSI unmaps in total for benchmark openArena
> (lasting around 55 secs)
>>
>> In this case, will adjacent whole vfio_dmas will be clubbed together or
>> will there be any intersection of vfio_dmas?
>>
> clubbed together.
> 

Even if support for clubbing bitmap together is added, still there will 
be limitation that clubbed vfio_dmas size shouldn't exceed INT_MAX pages.

Thanks,
Kirti