[PATCH v7 17/17] vfio/mlx5: Enable the DMA link API

Leon Romanovsky
2025-02-05T14:42:01Z

From: Leon Romanovsky <leonro@nvidia.com>

Remove intermediate scatter-gather table completely and
enable new DMA link API.

Signed-off-by: Leon Romanovsky <leonro@nvidia.com>
---
drivers/vfio/pci/mlx5/cmd.c | 298 ++++++++++++++++-------------------
drivers/vfio/pci/mlx5/cmd.h | 21 ++-
drivers/vfio/pci/mlx5/main.c | 31 ----
3 files changed, 147 insertions(+), 203 deletions(-)

diff --git a/drivers/vfio/pci/mlx5/cmd.c b/drivers/vfio/pci/mlx5/cmd.c
index 84dc3bc128c6..b162e44112fb 100644
--- a/drivers/vfio/pci/mlx5/cmd.c
+++ b/drivers/vfio/pci/mlx5/cmd.c
@@ -345,26 +345,82 @@ static u32 *alloc_mkey_in(u32 npages, u32 pdn)
return in;
}

-static int create_mkey(struct mlx5_core_dev *mdev, u32 npages,
- struct mlx5_vhca_data_buffer *buf, u32 *mkey_in,
+static int create_mkey(struct mlx5_core_dev *mdev, u32 npages, u32 *mkey_in,
u32 *mkey)
{
+ int inlen = MLX5_ST_SZ_BYTES(create_mkey_in) +
+ sizeof(__be64) * round_up(npages, 2);
+
+ return mlx5_core_create_mkey(mdev, mkey, mkey_in, inlen);
+}
+
+static void unregister_dma_pages(struct mlx5_core_dev *mdev, u32 npages,
+ u32 *mkey_in, struct dma_iova_state *state,
+ enum dma_data_direction dir)
+{
+ dma_addr_t addr;
__be64 *mtt;
- int inlen;
+ int i;

- mtt = (__be64 *)MLX5_ADDR_OF(create_mkey_in, mkey_in, klm_pas_mtt);
- if (buf) {
- struct sg_dma_page_iter dma_iter;
+ WARN_ON_ONCE(dir == DMA_NONE);

- for_each_sgtable_dma_page(&buf->table.sgt, &dma_iter, 0)
- *mtt++ = cpu_to_be64(
- sg_page_iter_dma_address(&dma_iter));
+ if (dma_use_iova(state)) {
+ dma_iova_destroy(mdev->device, state, npages * PAGE_SIZE, dir,
+ 0);
+ } else {
+ mtt = (__be64 *)MLX5_ADDR_OF(create_mkey_in, mkey_in,
+ klm_pas_mtt);
+ for (i = npages - 1; i >= 0; i--) {
+ addr = be64_to_cpu(mtt[i]);
+ dma_unmap_page(mdev->device, addr, PAGE_SIZE, dir);
+ }
}
+}

- inlen = MLX5_ST_SZ_BYTES(create_mkey_in) +
- sizeof(__be64) * round_up(npages, 2);
+static int register_dma_pages(struct mlx5_core_dev *mdev, u32 npages,
+ struct page **page_list, u32 *mkey_in,
+ struct dma_iova_state *state,
+ enum dma_data_direction dir)
+{
+ dma_addr_t addr;
+ size_t mapped = 0;
+ __be64 *mtt;
+ int i, err;

- return mlx5_core_create_mkey(mdev, mkey, mkey_in, inlen);
+ WARN_ON_ONCE(dir == DMA_NONE);
+
+ mtt = (__be64 *)MLX5_ADDR_OF(create_mkey_in, mkey_in, klm_pas_mtt);
+
+ if (dma_iova_try_alloc(mdev->device, state, 0, npages * PAGE_SIZE)) {
+ addr = state->addr;
+ for (i = 0; i < npages; i++) {
+ err = dma_iova_link(mdev->device, state,
+ page_to_phys(page_list[i]), mapped,
+ PAGE_SIZE, dir, 0);
+ if (err)
+ goto error;
+ *mtt++ = cpu_to_be64(addr);
+ addr += PAGE_SIZE;
+ mapped += PAGE_SIZE;
+ }
+ err = dma_iova_sync(mdev->device, state, 0, mapped);
+ if (err)
+ goto error;
+ } else {
+ for (i = 0; i < npages; i++) {
+ addr = dma_map_page(mdev->device, page_list[i], 0,
+ PAGE_SIZE, dir);
+ err = dma_mapping_error(mdev->device, addr);
+ if (err)
+ goto error;
+ *mtt++ = cpu_to_be64(addr);
+ }
+ }
+ return 0;
+
+error:
+ unregister_dma_pages(mdev, i, mkey_in, state, dir);
+ return err;
}

static int mlx5vf_dma_data_buffer(struct mlx5_vhca_data_buffer *buf)
@@ -380,98 +436,90 @@ static int mlx5vf_dma_data_buffer(struct mlx5_vhca_data_buffer *buf)
if (buf->mkey_in || !buf->npages)
return -EINVAL;

- ret = dma_map_sgtable(mdev->device, &buf->table.sgt, buf->dma_dir, 0);
- if (ret)
- return ret;
-
buf->mkey_in = alloc_mkey_in(buf->npages, buf->migf->pdn);
- if (!buf->mkey_in) {
- ret = -ENOMEM;
- goto err;
- }
+ if (!buf->mkey_in)
+ return -ENOMEM;

- ret = create_mkey(mdev, buf->npages, buf, buf->mkey_in, &buf->mkey);
+ ret = register_dma_pages(mdev, buf->npages, buf->page_list,
+ buf->mkey_in, &buf->state, buf->dma_dir);
+ if (ret)
+ goto err_register_dma;
+
+ ret = create_mkey(mdev, buf->npages, buf->mkey_in, &buf->mkey);
if (ret)
goto err_create_mkey;

return 0;

err_create_mkey:
+ unregister_dma_pages(mdev, buf->npages, buf->mkey_in, &buf->state,
+ buf->dma_dir);
+err_register_dma:
kvfree(buf->mkey_in);
buf->mkey_in = NULL;
-err:
- dma_unmap_sgtable(mdev->device, &buf->table.sgt, buf->dma_dir, 0);
return ret;
}

+static void free_page_list(u32 npages, struct page **page_list)
+{
+ int i;
+
+ /* Undo alloc_pages_bulk() */
+ for (i = npages - 1; i >= 0; i--)
+ __free_page(page_list[i]);
+
+ kvfree(page_list);
+}
+
void mlx5vf_free_data_buffer(struct mlx5_vhca_data_buffer *buf)
{
- struct mlx5_vf_migration_file *migf = buf->migf;
- struct sg_page_iter sg_iter;
+ struct mlx5vf_pci_core_device *mvdev = buf->migf->mvdev;
+ struct mlx5_core_dev *mdev = mvdev->mdev;

- lockdep_assert_held(&migf->mvdev->state_mutex);
- WARN_ON(migf->mvdev->mdev_detach);
+ lockdep_assert_held(&mvdev->state_mutex);
+ WARN_ON(mvdev->mdev_detach);

if (buf->mkey_in) {
- mlx5_core_destroy_mkey(migf->mvdev->mdev, buf->mkey);
+ mlx5_core_destroy_mkey(mdev, buf->mkey);
+ unregister_dma_pages(mdev, buf->npages, buf->mkey_in,
+ &buf->state, buf->dma_dir);
kvfree(buf->mkey_in);
- dma_unmap_sgtable(migf->mvdev->mdev->device, &buf->table.sgt,
- buf->dma_dir, 0);
}

- /* Undo alloc_pages_bulk() */
- for_each_sgtable_page(&buf->table.sgt, &sg_iter, 0)
- __free_page(sg_page_iter_page(&sg_iter));
- sg_free_append_table(&buf->table);
+ free_page_list(buf->npages, buf->page_list);
kfree(buf);
}

-static int mlx5vf_add_migration_pages(struct mlx5_vhca_data_buffer *buf,
- unsigned int npages)
+static int mlx5vf_add_pages(struct page ***page_list, unsigned int npages)
{
- unsigned int to_alloc = npages;
- struct page **page_list;
- unsigned long filled;
- unsigned int to_fill;
- int ret;
+ unsigned int filled, done = 0;
int i;

- to_fill = min_t(unsigned int, npages, PAGE_SIZE / sizeof(*page_list));
- page_list = kvzalloc(to_fill * sizeof(*page_list), GFP_KERNEL_ACCOUNT);
- if (!page_list)
+ *page_list =
+ kvcalloc(npages, sizeof(struct page *), GFP_KERNEL_ACCOUNT);
+ if (!*page_list)
return -ENOMEM;

- do {
- filled = alloc_pages_bulk(GFP_KERNEL_ACCOUNT, to_fill,
- page_list);
- if (!filled) {
- ret = -ENOMEM;
+ for (;;) {
+ filled = alloc_pages_bulk(GFP_KERNEL_ACCOUNT, npages - done,
+ *page_list + done);
+ if (!filled)
goto err;
- }
- to_alloc -= filled;
- ret = sg_alloc_append_table_from_pages(
- &buf->table, page_list, filled, 0,
- filled << PAGE_SHIFT, UINT_MAX, SG_MAX_SINGLE_ALLOC,
- GFP_KERNEL_ACCOUNT);

- if (ret)
- goto err_append;
- buf->npages += filled;
- /* clean input for another bulk allocation */
- memset(page_list, 0, filled * sizeof(*page_list));
- to_fill = min_t(unsigned int, to_alloc,
- PAGE_SIZE / sizeof(*page_list));
- } while (to_alloc > 0);
+ done += filled;
+ if (done == npages)
+ break;
+ }

- kvfree(page_list);
return 0;

-err_append:
- for (i = filled - 1; i >= 0; i--)
- __free_page(page_list[i]);
err:
- kvfree(page_list);
- return ret;
+ for (i = 0; i < done; i++)
+ __free_page(*page_list[i]);
+
+ kvfree(*page_list);
+ *page_list = NULL;
+ return -ENOMEM;
}

struct mlx5_vhca_data_buffer *
@@ -488,10 +536,12 @@ mlx5vf_alloc_data_buffer(struct mlx5_vf_migration_file *migf, u32 npages,
buf->dma_dir = dma_dir;
buf->migf = migf;
if (npages) {
- ret = mlx5vf_add_migration_pages(buf, npages);
+ ret = mlx5vf_add_pages(&buf->page_list, npages);
if (ret)
goto end;

+ buf->npages = npages;
+
if (dma_dir != DMA_NONE) {
ret = mlx5vf_dma_data_buffer(buf);
if (ret)
@@ -1350,101 +1400,16 @@ static void mlx5vf_destroy_qp(struct mlx5_core_dev *mdev,
kfree(qp);
}

-static void free_recv_pages(struct mlx5_vhca_recv_buf *recv_buf)
-{
- int i;
-
- /* Undo alloc_pages_bulk() */
- for (i = 0; i < recv_buf->npages; i++)
- __free_page(recv_buf->page_list[i]);
-
- kvfree(recv_buf->page_list);
-}
-
-static int alloc_recv_pages(struct mlx5_vhca_recv_buf *recv_buf,
- unsigned int npages)
-{
- unsigned int filled = 0, done = 0;
- int i;
-
- recv_buf->page_list = kvcalloc(npages, sizeof(*recv_buf->page_list),
- GFP_KERNEL_ACCOUNT);
- if (!recv_buf->page_list)
- return -ENOMEM;
-
- for (;;) {
- filled = alloc_pages_bulk(GFP_KERNEL_ACCOUNT,
- npages - done,
- recv_buf->page_list + done);
- if (!filled)
- goto err;
-
- done += filled;
- if (done == npages)
- break;
- }
-
- recv_buf->npages = npages;
- return 0;
-
-err:
- for (i = 0; i < npages; i++) {
- if (recv_buf->page_list[i])
- __free_page(recv_buf->page_list[i]);
- }
-
- kvfree(recv_buf->page_list);
- return -ENOMEM;
-}
-static void unregister_dma_pages(struct mlx5_core_dev *mdev, u32 npages,
- u32 *mkey_in)
-{
- dma_addr_t addr;
- __be64 *mtt;
- int i;
-
- mtt = (__be64 *)MLX5_ADDR_OF(create_mkey_in, mkey_in, klm_pas_mtt);
- for (i = npages - 1; i >= 0; i--) {
- addr = be64_to_cpu(mtt[i]);
- dma_unmap_single(mdev->device, addr, PAGE_SIZE,
- DMA_FROM_DEVICE);
- }
-}
-
-static int register_dma_pages(struct mlx5_core_dev *mdev, u32 npages,
- struct page **page_list, u32 *mkey_in)
-{
- dma_addr_t addr;
- __be64 *mtt;
- int i;
-
- mtt = (__be64 *)MLX5_ADDR_OF(create_mkey_in, mkey_in, klm_pas_mtt);
-
- for (i = 0; i < npages; i++) {
- addr = dma_map_page(mdev->device, page_list[i], 0, PAGE_SIZE,
- DMA_FROM_DEVICE);
- if (dma_mapping_error(mdev->device, addr))
- goto error;
-
- *mtt++ = cpu_to_be64(addr);
- }
-
- return 0;
-
-error:
- unregister_dma_pages(mdev, i, mkey_in);
- return -ENOMEM;
-}
-
static void mlx5vf_free_qp_recv_resources(struct mlx5_core_dev *mdev,
struct mlx5_vhca_qp *qp)
{
struct mlx5_vhca_recv_buf *recv_buf = &qp->recv_buf;

mlx5_core_destroy_mkey(mdev, recv_buf->mkey);
- unregister_dma_pages(mdev, recv_buf->npages, recv_buf->mkey_in);
+ unregister_dma_pages(mdev, recv_buf->npages, recv_buf->mkey_in,
+ &recv_buf->state, DMA_FROM_DEVICE);
kvfree(recv_buf->mkey_in);
- free_recv_pages(&qp->recv_buf);
+ free_page_list(recv_buf->npages, recv_buf->page_list);
}

static int mlx5vf_alloc_qp_recv_resources(struct mlx5_core_dev *mdev,
@@ -1455,10 +1420,12 @@ static int mlx5vf_alloc_qp_recv_resources(struct mlx5_core_dev *mdev,
struct mlx5_vhca_recv_buf *recv_buf = &qp->recv_buf;
int err;

- err = alloc_recv_pages(recv_buf, npages);
- if (err < 0)
+ err = mlx5vf_add_pages(&recv_buf->page_list, npages);
+ if (err)
return err;

+ recv_buf->npages = npages;
+
recv_buf->mkey_in = alloc_mkey_in(npages, pdn);
if (!recv_buf->mkey_in) {
err = -ENOMEM;
@@ -1466,24 +1433,25 @@ static int mlx5vf_alloc_qp_recv_resources(struct mlx5_core_dev *mdev,
}

err = register_dma_pages(mdev, npages, recv_buf->page_list,
- recv_buf->mkey_in);
+ recv_buf->mkey_in, &recv_buf->state,
+ DMA_FROM_DEVICE);
if (err)
goto err_register_dma;

- err = create_mkey(mdev, npages, NULL, recv_buf->mkey_in,
- &recv_buf->mkey);
+ err = create_mkey(mdev, npages, recv_buf->mkey_in, &recv_buf->mkey);
if (err)
goto err_create_mkey;

return 0;

err_create_mkey:
- unregister_dma_pages(mdev, npages, recv_buf->mkey_in);
+ unregister_dma_pages(mdev, npages, recv_buf->mkey_in, &recv_buf->state,
+ DMA_FROM_DEVICE);
err_register_dma:
kvfree(recv_buf->mkey_in);
recv_buf->mkey_in = NULL;
end:
- free_recv_pages(recv_buf);
+ free_page_list(npages, recv_buf->page_list);
return err;
}

diff --git a/drivers/vfio/pci/mlx5/cmd.h b/drivers/vfio/pci/mlx5/cmd.h
index 25dd6ff54591..d7821b5ca772 100644
--- a/drivers/vfio/pci/mlx5/cmd.h
+++ b/drivers/vfio/pci/mlx5/cmd.h
@@ -53,7 +53,8 @@ struct mlx5_vf_migration_header {
};

struct mlx5_vhca_data_buffer {
- struct sg_append_table table;
+ struct page **page_list;
+ struct dma_iova_state state;
loff_t start_pos;
u64 length;
u32 npages;
@@ -63,10 +64,6 @@ struct mlx5_vhca_data_buffer {
u8 stop_copy_chunk_num;
struct list_head buf_elm;
struct mlx5_vf_migration_file *migf;
- /* Optimize mlx5vf_get_migration_page() for sequential access */
- struct scatterlist *last_offset_sg;
- unsigned int sg_last_entry;
- unsigned long last_offset;
};

struct mlx5vf_async_data {
@@ -133,6 +130,7 @@ struct mlx5_vhca_cq {
struct mlx5_vhca_recv_buf {
u32 npages;
struct page **page_list;
+ struct dma_iova_state state;
u32 next_rq_offset;
u32 *mkey_in;
u32 mkey;
@@ -224,8 +222,17 @@ struct mlx5_vhca_data_buffer *
mlx5vf_get_data_buffer(struct mlx5_vf_migration_file *migf, u32 npages,
enum dma_data_direction dma_dir);
void mlx5vf_put_data_buffer(struct mlx5_vhca_data_buffer *buf);
-struct page *mlx5vf_get_migration_page(struct mlx5_vhca_data_buffer *buf,
- unsigned long offset);
+static inline struct page *
+mlx5vf_get_migration_page(struct mlx5_vhca_data_buffer *buf,
+ unsigned long offset)
+{
+ int page_entry = offset / PAGE_SIZE;
+
+ if (page_entry >= buf->npages)
+ return NULL;
+
+ return buf->page_list[page_entry];
+}
void mlx5vf_state_mutex_unlock(struct mlx5vf_pci_core_device *mvdev);
void mlx5vf_disable_fds(struct mlx5vf_pci_core_device *mvdev,
enum mlx5_vf_migf_state *last_save_state);
diff --git a/drivers/vfio/pci/mlx5/main.c b/drivers/vfio/pci/mlx5/main.c
index bc0f468f741b..93f894fe60d2 100644
--- a/drivers/vfio/pci/mlx5/main.c
+++ b/drivers/vfio/pci/mlx5/main.c
@@ -34,37 +34,6 @@ static struct mlx5vf_pci_core_device *mlx5vf_drvdata(struct pci_dev *pdev)
core_device);
}

-struct page *
-mlx5vf_get_migration_page(struct mlx5_vhca_data_buffer *buf,
- unsigned long offset)
-{
- unsigned long cur_offset = 0;
- struct scatterlist *sg;
- unsigned int i;
-
- /* All accesses are sequential */
- if (offset < buf->last_offset || !buf->last_offset_sg) {
- buf->last_offset = 0;
- buf->last_offset_sg = buf->table.sgt.sgl;
- buf->sg_last_entry = 0;
- }
-
- cur_offset = buf->last_offset;
-
- for_each_sg(buf->last_offset_sg, sg,
- buf->table.sgt.orig_nents - buf->sg_last_entry, i) {
- if (offset < sg->length + cur_offset) {
- buf->last_offset_sg = sg;
- buf->sg_last_entry += i;
- buf->last_offset = cur_offset;
- return nth_page(sg_page(sg),
- (offset - cur_offset) / PAGE_SIZE);
- }
- cur_offset += sg->length;
- }
- return NULL;
-}
-
static void mlx5vf_disable_fd(struct mlx5_vf_migration_file *migf)
{
mutex_lock(&migf->lock);
--
2.48.1