vfio/pds: Add support for dirty page tracking

In order to support dirty page tracking, the driver has to implement
the VFIO subsystem's vfio_log_ops. This includes log_start, log_stop,
and log_read_and_clear.

All of the tracker resources are allocated and dirty tracking on the
device is started during log_start. The resources are cleaned up and
dirty tracking on the device is stopped during log_stop. The dirty
pages are determined and reported during log_read_and_clear.

In order to support these callbacks admin queue commands are used.
All of the adminq queue command structures and implementations
are included as part of this patch.

PDS_LM_CMD_DIRTY_STATUS is added to query the current status of
dirty tracking on the device. This includes if it's enabled (i.e.
number of regions being tracked from the device's perspective) and
the maximum number of regions supported from the device's perspective.

PDS_LM_CMD_DIRTY_ENABLE is added to enable dirty tracking on the
specified number of regions and their iova ranges.

PDS_LM_CMD_DIRTY_DISABLE is added to disable dirty tracking for all
regions on the device.

PDS_LM_CMD_READ_SEQ and PDS_LM_CMD_DIRTY_WRITE_ACK are added to
support reading and acknowledging the currently dirtied pages.

Signed-off-by: Brett Creeley <brett.creeley@amd.com>
Signed-off-by: Shannon Nelson <shannon.nelson@amd.com>
Reviewed-by: Simon Horman <horms@kernel.org>
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Reviewed-by: Shameer Kolothum <shameerali.kolothum.thodi@huawei.com>
Link: https://lore.kernel.org/r/20230807205755.29579-7-brett.creeley@amd.com
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>

1 files changed, 564 insertions, 0 deletions

diff --git a/drivers/vfio/pci/pds/dirty.c b/drivers/vfio/pci/pds/dirty.c
new file mode 100644
index 000000000000..c937aa6f3954
--- /dev/null
+++ b/drivers/vfio/pci/pds/dirty.c
@@ -0,0 +1,564 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright(c) 2023 Advanced Micro Devices, Inc. */
+
+#include <linux/interval_tree.h>
+#include <linux/vfio.h>
+
+#include <linux/pds/pds_common.h>
+#include <linux/pds/pds_core_if.h>
+#include <linux/pds/pds_adminq.h>
+
+#include "vfio_dev.h"
+#include "cmds.h"
+#include "dirty.h"
+
+#define READ_SEQ true
+#define WRITE_ACK false
+
+bool pds_vfio_dirty_is_enabled(struct pds_vfio_pci_device *pds_vfio)
+{
+	return pds_vfio->dirty.is_enabled;
+}
+
+void pds_vfio_dirty_set_enabled(struct pds_vfio_pci_device *pds_vfio)
+{
+	pds_vfio->dirty.is_enabled = true;
+}
+
+void pds_vfio_dirty_set_disabled(struct pds_vfio_pci_device *pds_vfio)
+{
+	pds_vfio->dirty.is_enabled = false;
+}
+
+static void
+pds_vfio_print_guest_region_info(struct pds_vfio_pci_device *pds_vfio,
+				 u8 max_regions)
+{
+	int len = max_regions * sizeof(struct pds_lm_dirty_region_info);
+	struct pci_dev *pdev = pds_vfio->vfio_coredev.pdev;
+	struct device *pdsc_dev = &pci_physfn(pdev)->dev;
+	struct pds_lm_dirty_region_info *region_info;
+	dma_addr_t regions_dma;
+	u8 num_regions;
+	int err;
+
+	region_info = kcalloc(max_regions,
+			      sizeof(struct pds_lm_dirty_region_info),
+			      GFP_KERNEL);
+	if (!region_info)
+		return;
+
+	regions_dma =
+		dma_map_single(pdsc_dev, region_info, len, DMA_FROM_DEVICE);
+	if (dma_mapping_error(pdsc_dev, regions_dma))
+		goto out_free_region_info;
+
+	err = pds_vfio_dirty_status_cmd(pds_vfio, regions_dma, &max_regions,
+					&num_regions);
+	dma_unmap_single(pdsc_dev, regions_dma, len, DMA_FROM_DEVICE);
+	if (err)
+		goto out_free_region_info;
+
+	for (unsigned int i = 0; i < num_regions; i++)
+		dev_dbg(&pdev->dev,
+			"region_info[%d]: dma_base 0x%llx page_count %u page_size_log2 %u\n",
+			i, le64_to_cpu(region_info[i].dma_base),
+			le32_to_cpu(region_info[i].page_count),
+			region_info[i].page_size_log2);
+
+out_free_region_info:
+	kfree(region_info);
+}
+
+static int pds_vfio_dirty_alloc_bitmaps(struct pds_vfio_dirty *dirty,
+					unsigned long bytes)
+{
+	unsigned long *host_seq_bmp, *host_ack_bmp;
+
+	host_seq_bmp = vzalloc(bytes);
+	if (!host_seq_bmp)
+		return -ENOMEM;
+
+	host_ack_bmp = vzalloc(bytes);
+	if (!host_ack_bmp) {
+		bitmap_free(host_seq_bmp);
+		return -ENOMEM;
+	}
+
+	dirty->host_seq.bmp = host_seq_bmp;
+	dirty->host_ack.bmp = host_ack_bmp;
+
+	return 0;
+}
+
+static void pds_vfio_dirty_free_bitmaps(struct pds_vfio_dirty *dirty)
+{
+	vfree(dirty->host_seq.bmp);
+	vfree(dirty->host_ack.bmp);
+	dirty->host_seq.bmp = NULL;
+	dirty->host_ack.bmp = NULL;
+}
+
+static void __pds_vfio_dirty_free_sgl(struct pds_vfio_pci_device *pds_vfio,
+				      struct pds_vfio_bmp_info *bmp_info)
+{
+	struct pci_dev *pdev = pds_vfio->vfio_coredev.pdev;
+	struct device *pdsc_dev = &pci_physfn(pdev)->dev;
+
+	dma_unmap_single(pdsc_dev, bmp_info->sgl_addr,
+			 bmp_info->num_sge * sizeof(struct pds_lm_sg_elem),
+			 DMA_BIDIRECTIONAL);
+	kfree(bmp_info->sgl);
+
+	bmp_info->num_sge = 0;
+	bmp_info->sgl = NULL;
+	bmp_info->sgl_addr = 0;
+}
+
+static void pds_vfio_dirty_free_sgl(struct pds_vfio_pci_device *pds_vfio)
+{
+	if (pds_vfio->dirty.host_seq.sgl)
+		__pds_vfio_dirty_free_sgl(pds_vfio, &pds_vfio->dirty.host_seq);
+	if (pds_vfio->dirty.host_ack.sgl)
+		__pds_vfio_dirty_free_sgl(pds_vfio, &pds_vfio->dirty.host_ack);
+}
+
+static int __pds_vfio_dirty_alloc_sgl(struct pds_vfio_pci_device *pds_vfio,
+				      struct pds_vfio_bmp_info *bmp_info,
+				      u32 page_count)
+{
+	struct pci_dev *pdev = pds_vfio->vfio_coredev.pdev;
+	struct device *pdsc_dev = &pci_physfn(pdev)->dev;
+	struct pds_lm_sg_elem *sgl;
+	dma_addr_t sgl_addr;
+	size_t sgl_size;
+	u32 max_sge;
+
+	max_sge = DIV_ROUND_UP(page_count, PAGE_SIZE * 8);
+	sgl_size = max_sge * sizeof(struct pds_lm_sg_elem);
+
+	sgl = kzalloc(sgl_size, GFP_KERNEL);
+	if (!sgl)
+		return -ENOMEM;
+
+	sgl_addr = dma_map_single(pdsc_dev, sgl, sgl_size, DMA_BIDIRECTIONAL);
+	if (dma_mapping_error(pdsc_dev, sgl_addr)) {
+		kfree(sgl);
+		return -EIO;
+	}
+
+	bmp_info->sgl = sgl;
+	bmp_info->num_sge = max_sge;
+	bmp_info->sgl_addr = sgl_addr;
+
+	return 0;
+}
+
+static int pds_vfio_dirty_alloc_sgl(struct pds_vfio_pci_device *pds_vfio,
+				    u32 page_count)
+{
+	struct pds_vfio_dirty *dirty = &pds_vfio->dirty;
+	int err;
+
+	err = __pds_vfio_dirty_alloc_sgl(pds_vfio, &dirty->host_seq,
+					 page_count);
+	if (err)
+		return err;
+
+	err = __pds_vfio_dirty_alloc_sgl(pds_vfio, &dirty->host_ack,
+					 page_count);
+	if (err) {
+		__pds_vfio_dirty_free_sgl(pds_vfio, &dirty->host_seq);
+		return err;
+	}
+
+	return 0;
+}
+
+static int pds_vfio_dirty_enable(struct pds_vfio_pci_device *pds_vfio,
+				 struct rb_root_cached *ranges, u32 nnodes,
+				 u64 *page_size)
+{
+	struct pci_dev *pdev = pds_vfio->vfio_coredev.pdev;
+	struct device *pdsc_dev = &pci_physfn(pdev)->dev;
+	struct pds_vfio_dirty *dirty = &pds_vfio->dirty;
+	u64 region_start, region_size, region_page_size;
+	struct pds_lm_dirty_region_info *region_info;
+	struct interval_tree_node *node = NULL;
+	u8 max_regions = 0, num_regions;
+	dma_addr_t regions_dma = 0;
+	u32 num_ranges = nnodes;
+	u32 page_count;
+	u16 len;
+	int err;
+
+	dev_dbg(&pdev->dev, "vf%u: Start dirty page tracking\n",
+		pds_vfio->vf_id);
+
+	if (pds_vfio_dirty_is_enabled(pds_vfio))
+		return -EINVAL;
+
+	/* find if dirty tracking is disabled, i.e. num_regions == 0 */
+	err = pds_vfio_dirty_status_cmd(pds_vfio, 0, &max_regions,
+					&num_regions);
+	if (err < 0) {
+		dev_err(&pdev->dev, "Failed to get dirty status, err %pe\n",
+			ERR_PTR(err));
+		return err;
+	} else if (num_regions) {
+		dev_err(&pdev->dev,
+			"Dirty tracking already enabled for %d regions\n",
+			num_regions);
+		return -EEXIST;
+	} else if (!max_regions) {
+		dev_err(&pdev->dev,
+			"Device doesn't support dirty tracking, max_regions %d\n",
+			max_regions);
+		return -EOPNOTSUPP;
+	}
+
+	/*
+	 * Only support 1 region for now. If there are any large gaps in the
+	 * VM's address regions, then this would be a waste of memory as we are
+	 * generating 2 bitmaps (ack/seq) from the min address to the max
+	 * address of the VM's address regions. In the future, if we support
+	 * more than one region in the device/driver we can split the bitmaps
+	 * on the largest address region gaps. We can do this split up to the
+	 * max_regions times returned from the dirty_status command.
+	 */
+	max_regions = 1;
+	if (num_ranges > max_regions) {
+		vfio_combine_iova_ranges(ranges, nnodes, max_regions);
+		num_ranges = max_regions;
+	}
+
+	node = interval_tree_iter_first(ranges, 0, ULONG_MAX);
+	if (!node)
+		return -EINVAL;
+
+	region_size = node->last - node->start + 1;
+	region_start = node->start;
+	region_page_size = *page_size;
+
+	len = sizeof(*region_info);
+	region_info = kzalloc(len, GFP_KERNEL);
+	if (!region_info)
+		return -ENOMEM;
+
+	page_count = DIV_ROUND_UP(region_size, region_page_size);
+
+	region_info->dma_base = cpu_to_le64(region_start);
+	region_info->page_count = cpu_to_le32(page_count);
+	region_info->page_size_log2 = ilog2(region_page_size);
+
+	regions_dma = dma_map_single(pdsc_dev, (void *)region_info, len,
+				     DMA_BIDIRECTIONAL);
+	if (dma_mapping_error(pdsc_dev, regions_dma)) {
+		err = -ENOMEM;
+		goto out_free_region_info;
+	}
+
+	err = pds_vfio_dirty_enable_cmd(pds_vfio, regions_dma, max_regions);
+	dma_unmap_single(pdsc_dev, regions_dma, len, DMA_BIDIRECTIONAL);
+	if (err)
+		goto out_free_region_info;
+
+	/*
+	 * page_count might be adjusted by the device,
+	 * update it before freeing region_info DMA
+	 */
+	page_count = le32_to_cpu(region_info->page_count);
+
+	dev_dbg(&pdev->dev,
+		"region_info: regions_dma 0x%llx dma_base 0x%llx page_count %u page_size_log2 %u\n",
+		regions_dma, region_start, page_count,
+		(u8)ilog2(region_page_size));
+
+	err = pds_vfio_dirty_alloc_bitmaps(dirty, page_count / BITS_PER_BYTE);
+	if (err) {
+		dev_err(&pdev->dev, "Failed to alloc dirty bitmaps: %pe\n",
+			ERR_PTR(err));
+		goto out_free_region_info;
+	}
+
+	err = pds_vfio_dirty_alloc_sgl(pds_vfio, page_count);
+	if (err) {
+		dev_err(&pdev->dev, "Failed to alloc dirty sg lists: %pe\n",
+			ERR_PTR(err));
+		goto out_free_bitmaps;
+	}
+
+	dirty->region_start = region_start;
+	dirty->region_size = region_size;
+	dirty->region_page_size = region_page_size;
+	pds_vfio_dirty_set_enabled(pds_vfio);
+
+	pds_vfio_print_guest_region_info(pds_vfio, max_regions);
+
+	kfree(region_info);
+
+	return 0;
+
+out_free_bitmaps:
+	pds_vfio_dirty_free_bitmaps(dirty);
+out_free_region_info:
+	kfree(region_info);
+	return err;
+}
+
+void pds_vfio_dirty_disable(struct pds_vfio_pci_device *pds_vfio, bool send_cmd)
+{
+	if (pds_vfio_dirty_is_enabled(pds_vfio)) {
+		pds_vfio_dirty_set_disabled(pds_vfio);
+		if (send_cmd)
+			pds_vfio_dirty_disable_cmd(pds_vfio);
+		pds_vfio_dirty_free_sgl(pds_vfio);
+		pds_vfio_dirty_free_bitmaps(&pds_vfio->dirty);
+	}
+
+	if (send_cmd)
+		pds_vfio_send_host_vf_lm_status_cmd(pds_vfio, PDS_LM_STA_NONE);
+}
+
+static int pds_vfio_dirty_seq_ack(struct pds_vfio_pci_device *pds_vfio,
+				  struct pds_vfio_bmp_info *bmp_info,
+				  u32 offset, u32 bmp_bytes, bool read_seq)
+{
+	const char *bmp_type_str = read_seq ? "read_seq" : "write_ack";
+	u8 dma_dir = read_seq ? DMA_FROM_DEVICE : DMA_TO_DEVICE;
+	struct pci_dev *pdev = pds_vfio->vfio_coredev.pdev;
+	struct device *pdsc_dev = &pci_physfn(pdev)->dev;
+	unsigned long long npages;
+	struct sg_table sg_table;
+	struct scatterlist *sg;
+	struct page **pages;
+	u32 page_offset;
+	const void *bmp;
+	size_t size;
+	u16 num_sge;
+	int err;
+	int i;
+
+	bmp = (void *)((u64)bmp_info->bmp + offset);
+	page_offset = offset_in_page(bmp);
+	bmp -= page_offset;
+
+	/*
+	 * Start and end of bitmap section to seq/ack might not be page
+	 * aligned, so use the page_offset to account for that so there
+	 * will be enough pages to represent the bmp_bytes
+	 */
+	npages = DIV_ROUND_UP_ULL(bmp_bytes + page_offset, PAGE_SIZE);
+	pages = kmalloc_array(npages, sizeof(*pages), GFP_KERNEL);
+	if (!pages)
+		return -ENOMEM;
+
+	for (unsigned long long i = 0; i < npages; i++) {
+		struct page *page = vmalloc_to_page(bmp);
+
+		if (!page) {
+			err = -EFAULT;
+			goto out_free_pages;
+		}
+
+		pages[i] = page;
+		bmp += PAGE_SIZE;
+	}
+
+	err = sg_alloc_table_from_pages(&sg_table, pages, npages, page_offset,
+					bmp_bytes, GFP_KERNEL);
+	if (err)
+		goto out_free_pages;
+
+	err = dma_map_sgtable(pdsc_dev, &sg_table, dma_dir, 0);
+	if (err)
+		goto out_free_sg_table;
+
+	for_each_sgtable_dma_sg(&sg_table, sg, i) {
+		struct pds_lm_sg_elem *sg_elem = &bmp_info->sgl[i];
+
+		sg_elem->addr = cpu_to_le64(sg_dma_address(sg));
+		sg_elem->len = cpu_to_le32(sg_dma_len(sg));
+	}
+
+	num_sge = sg_table.nents;
+	size = num_sge * sizeof(struct pds_lm_sg_elem);
+	dma_sync_single_for_device(pdsc_dev, bmp_info->sgl_addr, size, dma_dir);
+	err = pds_vfio_dirty_seq_ack_cmd(pds_vfio, bmp_info->sgl_addr, num_sge,
+					 offset, bmp_bytes, read_seq);
+	if (err)
+		dev_err(&pdev->dev,
+			"Dirty bitmap %s failed offset %u bmp_bytes %u num_sge %u DMA 0x%llx: %pe\n",
+			bmp_type_str, offset, bmp_bytes,
+			num_sge, bmp_info->sgl_addr, ERR_PTR(err));
+	dma_sync_single_for_cpu(pdsc_dev, bmp_info->sgl_addr, size, dma_dir);
+
+	dma_unmap_sgtable(pdsc_dev, &sg_table, dma_dir, 0);
+out_free_sg_table:
+	sg_free_table(&sg_table);
+out_free_pages:
+	kfree(pages);
+
+	return err;
+}
+
+static int pds_vfio_dirty_write_ack(struct pds_vfio_pci_device *pds_vfio,
+				    u32 offset, u32 len)
+{
+	return pds_vfio_dirty_seq_ack(pds_vfio, &pds_vfio->dirty.host_ack,
+				      offset, len, WRITE_ACK);
+}
+
+static int pds_vfio_dirty_read_seq(struct pds_vfio_pci_device *pds_vfio,
+				   u32 offset, u32 len)
+{
+	return pds_vfio_dirty_seq_ack(pds_vfio, &pds_vfio->dirty.host_seq,
+				      offset, len, READ_SEQ);
+}
+
+static int pds_vfio_dirty_process_bitmaps(struct pds_vfio_pci_device *pds_vfio,
+					  struct iova_bitmap *dirty_bitmap,
+					  u32 bmp_offset, u32 len_bytes)
+{
+	u64 page_size = pds_vfio->dirty.region_page_size;
+	u64 region_start = pds_vfio->dirty.region_start;
+	u32 bmp_offset_bit;
+	__le64 *seq, *ack;
+	int dword_count;
+
+	dword_count = len_bytes / sizeof(u64);
+	seq = (__le64 *)((u64)pds_vfio->dirty.host_seq.bmp + bmp_offset);
+	ack = (__le64 *)((u64)pds_vfio->dirty.host_ack.bmp + bmp_offset);
+	bmp_offset_bit = bmp_offset * 8;
+
+	for (int i = 0; i < dword_count; i++) {
+		u64 xor = le64_to_cpu(seq[i]) ^ le64_to_cpu(ack[i]);
+
+		/* prepare for next write_ack call */
+		ack[i] = seq[i];
+
+		for (u8 bit_i = 0; bit_i < BITS_PER_TYPE(u64); ++bit_i) {
+			if (xor & BIT(bit_i)) {
+				u64 abs_bit_i = bmp_offset_bit +
+						i * BITS_PER_TYPE(u64) + bit_i;
+				u64 addr = abs_bit_i * page_size + region_start;
+
+				iova_bitmap_set(dirty_bitmap, addr, page_size);
+			}
+		}
+	}
+
+	return 0;
+}
+
+static int pds_vfio_dirty_sync(struct pds_vfio_pci_device *pds_vfio,
+			       struct iova_bitmap *dirty_bitmap,
+			       unsigned long iova, unsigned long length)
+{
+	struct device *dev = &pds_vfio->vfio_coredev.pdev->dev;
+	struct pds_vfio_dirty *dirty = &pds_vfio->dirty;
+	u64 bmp_offset, bmp_bytes;
+	u64 bitmap_size, pages;
+	int err;
+
+	dev_dbg(dev, "vf%u: Get dirty page bitmap\n", pds_vfio->vf_id);
+
+	if (!pds_vfio_dirty_is_enabled(pds_vfio)) {
+		dev_err(dev, "vf%u: Sync failed, dirty tracking is disabled\n",
+			pds_vfio->vf_id);
+		return -EINVAL;
+	}
+
+	pages = DIV_ROUND_UP(length, pds_vfio->dirty.region_page_size);
+	bitmap_size =
+		round_up(pages, sizeof(u64) * BITS_PER_BYTE) / BITS_PER_BYTE;
+
+	dev_dbg(dev,
+		"vf%u: iova 0x%lx length %lu page_size %llu pages %llu bitmap_size %llu\n",
+		pds_vfio->vf_id, iova, length, pds_vfio->dirty.region_page_size,
+		pages, bitmap_size);
+
+	if (!length || ((dirty->region_start + iova + length) >
+			(dirty->region_start + dirty->region_size))) {
+		dev_err(dev, "Invalid iova 0x%lx and/or length 0x%lx to sync\n",
+			iova, length);
+		return -EINVAL;
+	}
+
+	/* bitmap is modified in 64 bit chunks */
+	bmp_bytes = ALIGN(DIV_ROUND_UP(length / dirty->region_page_size,
+				       sizeof(u64)),
+			  sizeof(u64));
+	if (bmp_bytes != bitmap_size) {
+		dev_err(dev,
+			"Calculated bitmap bytes %llu not equal to bitmap size %llu\n",
+			bmp_bytes, bitmap_size);
+		return -EINVAL;
+	}
+
+	bmp_offset = DIV_ROUND_UP(iova / dirty->region_page_size, sizeof(u64));
+
+	dev_dbg(dev,
+		"Syncing dirty bitmap, iova 0x%lx length 0x%lx, bmp_offset %llu bmp_bytes %llu\n",
+		iova, length, bmp_offset, bmp_bytes);
+
+	err = pds_vfio_dirty_read_seq(pds_vfio, bmp_offset, bmp_bytes);
+	if (err)
+		return err;
+
+	err = pds_vfio_dirty_process_bitmaps(pds_vfio, dirty_bitmap, bmp_offset,
+					     bmp_bytes);
+	if (err)
+		return err;
+
+	err = pds_vfio_dirty_write_ack(pds_vfio, bmp_offset, bmp_bytes);
+	if (err)
+		return err;
+
+	return 0;
+}
+
+int pds_vfio_dma_logging_report(struct vfio_device *vdev, unsigned long iova,
+				unsigned long length, struct iova_bitmap *dirty)
+{
+	struct pds_vfio_pci_device *pds_vfio =
+		container_of(vdev, struct pds_vfio_pci_device,
+			     vfio_coredev.vdev);
+	int err;
+
+	mutex_lock(&pds_vfio->state_mutex);
+	err = pds_vfio_dirty_sync(pds_vfio, dirty, iova, length);
+	pds_vfio_state_mutex_unlock(pds_vfio);
+
+	return err;
+}
+
+int pds_vfio_dma_logging_start(struct vfio_device *vdev,
+			       struct rb_root_cached *ranges, u32 nnodes,
+			       u64 *page_size)
+{
+	struct pds_vfio_pci_device *pds_vfio =
+		container_of(vdev, struct pds_vfio_pci_device,
+			     vfio_coredev.vdev);
+	int err;
+
+	mutex_lock(&pds_vfio->state_mutex);
+	pds_vfio_send_host_vf_lm_status_cmd(pds_vfio, PDS_LM_STA_IN_PROGRESS);
+	err = pds_vfio_dirty_enable(pds_vfio, ranges, nnodes, page_size);
+	pds_vfio_state_mutex_unlock(pds_vfio);
+
+	return err;
+}
+
+int pds_vfio_dma_logging_stop(struct vfio_device *vdev)
+{
+	struct pds_vfio_pci_device *pds_vfio =
+		container_of(vdev, struct pds_vfio_pci_device,
+			     vfio_coredev.vdev);
+
+	mutex_lock(&pds_vfio->state_mutex);
+	pds_vfio_dirty_disable(pds_vfio, true);
+	pds_vfio_state_mutex_unlock(pds_vfio);
+
+	return 0;
+}