[PATCH v6 12/17] RDMA/umem: Store ODP access mask information in PFN

Leon Romanovsky
2025-01-17T11:17:53Z

As a preparation to remove dma_list, store access mask in PFN pointer
and not in dma_addr_t.

Signed-off-by: Leon Romanovsky <leonro@nvidia.com>
---
drivers/infiniband/core/umem_odp.c | 103 +++++++++++----------------
drivers/infiniband/hw/mlx5/mlx5_ib.h | 1 +
drivers/infiniband/hw/mlx5/odp.c | 37 +++++-----
include/rdma/ib_umem_odp.h | 14 +---
4 files changed, 64 insertions(+), 91 deletions(-)

diff --git a/drivers/infiniband/core/umem_odp.c b/drivers/infiniband/core/umem_odp.c
index e9fa22d31c23..e1a5a567efb3 100644
--- a/drivers/infiniband/core/umem_odp.c
+++ b/drivers/infiniband/core/umem_odp.c
@@ -296,22 +296,11 @@ EXPORT_SYMBOL(ib_umem_odp_release);
static int ib_umem_odp_map_dma_single_page(
struct ib_umem_odp *umem_odp,
unsigned int dma_index,
- struct page *page,
- u64 access_mask)
+ struct page *page)
{
struct ib_device *dev = umem_odp->umem.ibdev;
dma_addr_t *dma_addr = &umem_odp->dma_list[dma_index];

- if (*dma_addr) {
- /*
- * If the page is already dma mapped it means it went through
- * a non-invalidating trasition, like read-only to writable.
- * Resync the flags.
- */
- *dma_addr = (*dma_addr & ODP_DMA_ADDR_MASK) | access_mask;
- return 0;
- }
-
*dma_addr = ib_dma_map_page(dev, page, 0, 1 << umem_odp->page_shift,
DMA_BIDIRECTIONAL);
if (ib_dma_mapping_error(dev, *dma_addr)) {
@@ -319,7 +308,6 @@ static int ib_umem_odp_map_dma_single_page(
return -EFAULT;
}
umem_odp->npages++;
- *dma_addr |= access_mask;
return 0;
}

@@ -355,9 +343,6 @@ int ib_umem_odp_map_dma_and_lock(struct ib_umem_odp *umem_odp, u64 user_virt,
struct hmm_range range = {};
unsigned long timeout;

- if (access_mask == 0)
- return -EINVAL;
-
if (user_virt < ib_umem_start(umem_odp) ||
user_virt + bcnt > ib_umem_end(umem_odp))
return -EFAULT;
@@ -383,7 +368,7 @@ int ib_umem_odp_map_dma_and_lock(struct ib_umem_odp *umem_odp, u64 user_virt,
if (fault) {
range.default_flags = HMM_PFN_REQ_FAULT;

- if (access_mask & ODP_WRITE_ALLOWED_BIT)
+ if (access_mask & HMM_PFN_WRITE)
range.default_flags |= HMM_PFN_REQ_WRITE;
}

@@ -415,22 +400,17 @@ int ib_umem_odp_map_dma_and_lock(struct ib_umem_odp *umem_odp, u64 user_virt,
for (pfn_index = 0; pfn_index < num_pfns;
pfn_index += 1 << (page_shift - PAGE_SHIFT), dma_index++) {

- if (fault) {
- /*
- * Since we asked for hmm_range_fault() to populate
- * pages it shouldn't return an error entry on success.
- */
- WARN_ON(range.hmm_pfns[pfn_index] & HMM_PFN_ERROR);
- WARN_ON(!(range.hmm_pfns[pfn_index] & HMM_PFN_VALID));
- } else {
- if (!(range.hmm_pfns[pfn_index] & HMM_PFN_VALID)) {
- WARN_ON(umem_odp->dma_list[dma_index]);
- continue;
- }
- access_mask = ODP_READ_ALLOWED_BIT;
- if (range.hmm_pfns[pfn_index] & HMM_PFN_WRITE)
- access_mask |= ODP_WRITE_ALLOWED_BIT;
- }
+ /*
+ * Since we asked for hmm_range_fault() to populate
+ * pages it shouldn't return an error entry on success.
+ */
+ WARN_ON(fault && range.hmm_pfns[pfn_index] & HMM_PFN_ERROR);
+ WARN_ON(fault && !(range.hmm_pfns[pfn_index] & HMM_PFN_VALID));
+ if (!(range.hmm_pfns[pfn_index] & HMM_PFN_VALID))
+ continue;
+
+ if (range.hmm_pfns[pfn_index] & HMM_PFN_DMA_MAPPED)
+ continue;

hmm_order = hmm_pfn_to_map_order(range.hmm_pfns[pfn_index]);
/* If a hugepage was detected and ODP wasn't set for, the umem
@@ -445,13 +425,14 @@ int ib_umem_odp_map_dma_and_lock(struct ib_umem_odp *umem_odp, u64 user_virt,
}

ret = ib_umem_odp_map_dma_single_page(
- umem_odp, dma_index, hmm_pfn_to_page(range.hmm_pfns[pfn_index]),
- access_mask);
+ umem_odp, dma_index,
+ hmm_pfn_to_page(range.hmm_pfns[pfn_index]));
if (ret < 0) {
ibdev_dbg(umem_odp->umem.ibdev,
"ib_umem_odp_map_dma_single_page failed with error %d\n", ret);
break;
}
+ range.hmm_pfns[pfn_index] |= HMM_PFN_DMA_MAPPED;
}
/* upon success lock should stay on hold for the callee */
if (!ret)
@@ -471,7 +452,6 @@ EXPORT_SYMBOL(ib_umem_odp_map_dma_and_lock);
void ib_umem_odp_unmap_dma_pages(struct ib_umem_odp *umem_odp, u64 virt,
u64 bound)
{
- dma_addr_t dma_addr;
dma_addr_t dma;
int idx;
u64 addr;
@@ -482,34 +462,37 @@ void ib_umem_odp_unmap_dma_pages(struct ib_umem_odp *umem_odp, u64 virt,
virt = max_t(u64, virt, ib_umem_start(umem_odp));
bound = min_t(u64, bound, ib_umem_end(umem_odp));
for (addr = virt; addr < bound; addr += BIT(umem_odp->page_shift)) {
+ unsigned long pfn_idx = (addr - ib_umem_start(umem_odp)) >>
+ PAGE_SHIFT;
+ struct page *page =
+ hmm_pfn_to_page(umem_odp->pfn_list[pfn_idx]);
+
idx = (addr - ib_umem_start(umem_odp)) >> umem_odp->page_shift;
dma = umem_odp->dma_list[idx];

- /* The access flags guaranteed a valid DMA address in case was NULL */
- if (dma) {
- unsigned long pfn_idx = (addr - ib_umem_start(umem_odp)) >> PAGE_SHIFT;
- struct page *page = hmm_pfn_to_page(umem_odp->pfn_list[pfn_idx]);
-
- dma_addr = dma & ODP_DMA_ADDR_MASK;
- ib_dma_unmap_page(dev, dma_addr,
- BIT(umem_odp->page_shift),
- DMA_BIDIRECTIONAL);
- if (dma & ODP_WRITE_ALLOWED_BIT) {
- struct page *head_page = compound_head(page);
- /*
- * set_page_dirty prefers being called with
- * the page lock. However, MMU notifiers are
- * called sometimes with and sometimes without
- * the lock. We rely on the umem_mutex instead
- * to prevent other mmu notifiers from
- * continuing and allowing the page mapping to
- * be removed.
- */
- set_page_dirty(head_page);
- }
- umem_odp->dma_list[idx] = 0;
- umem_odp->npages--;
+ if (!(umem_odp->pfn_list[pfn_idx] & HMM_PFN_VALID))
+ goto clear;
+ if (!(umem_odp->pfn_list[pfn_idx] & HMM_PFN_DMA_MAPPED))
+ goto clear;
+
+ ib_dma_unmap_page(dev, dma, BIT(umem_odp->page_shift),
+ DMA_BIDIRECTIONAL);
+ if (umem_odp->pfn_list[pfn_idx] & HMM_PFN_WRITE) {
+ struct page *head_page = compound_head(page);
+ /*
+ * set_page_dirty prefers being called with
+ * the page lock. However, MMU notifiers are
+ * called sometimes with and sometimes without
+ * the lock. We rely on the umem_mutex instead
+ * to prevent other mmu notifiers from
+ * continuing and allowing the page mapping to
+ * be removed.
+ */
+ set_page_dirty(head_page);
}
+ umem_odp->npages--;
+clear:
+ umem_odp->pfn_list[pfn_idx] &= ~HMM_PFN_FLAGS;
}
}
EXPORT_SYMBOL(ib_umem_odp_unmap_dma_pages);
diff --git a/drivers/infiniband/hw/mlx5/mlx5_ib.h b/drivers/infiniband/hw/mlx5/mlx5_ib.h
index a01b592aa716..c4946d4f0ad7 100644
--- a/drivers/infiniband/hw/mlx5/mlx5_ib.h
+++ b/drivers/infiniband/hw/mlx5/mlx5_ib.h
@@ -336,6 +336,7 @@ struct mlx5_ib_flow_db {
#define MLX5_IB_UPD_XLT_PD BIT(4)
#define MLX5_IB_UPD_XLT_ACCESS BIT(5)
#define MLX5_IB_UPD_XLT_INDIRECT BIT(6)
+#define MLX5_IB_UPD_XLT_DOWNGRADE BIT(7)

/* Private QP creation flags to be passed in ib_qp_init_attr.create_flags.
*
diff --git a/drivers/infiniband/hw/mlx5/odp.c b/drivers/infiniband/hw/mlx5/odp.c
index 4b37446758fd..78887500ce15 100644
--- a/drivers/infiniband/hw/mlx5/odp.c
+++ b/drivers/infiniband/hw/mlx5/odp.c
@@ -34,6 +34,7 @@
#include <linux/kernel.h>
#include <linux/dma-buf.h>
#include <linux/dma-resv.h>
+#include <linux/hmm.h>

#include "mlx5_ib.h"
#include "cmd.h"
@@ -158,22 +159,12 @@ static void populate_klm(struct mlx5_klm *pklm, size_t idx, size_t nentries,
}
}

-static u64 umem_dma_to_mtt(dma_addr_t umem_dma)
-{
- u64 mtt_entry = umem_dma & ODP_DMA_ADDR_MASK;
-
- if (umem_dma & ODP_READ_ALLOWED_BIT)
- mtt_entry |= MLX5_IB_MTT_READ;
- if (umem_dma & ODP_WRITE_ALLOWED_BIT)
- mtt_entry |= MLX5_IB_MTT_WRITE;
-
- return mtt_entry;
-}
-
static void populate_mtt(__be64 *pas, size_t idx, size_t nentries,
struct mlx5_ib_mr *mr, int flags)
{
struct ib_umem_odp *odp = to_ib_umem_odp(mr->umem);
+ bool downgrade = flags & MLX5_IB_UPD_XLT_DOWNGRADE;
+ unsigned long pfn;
dma_addr_t pa;
size_t i;

@@ -181,8 +172,17 @@ static void populate_mtt(__be64 *pas, size_t idx, size_t nentries,
return;

for (i = 0; i < nentries; i++) {
+ pfn = odp->pfn_list[idx + i];
+ if (!(pfn & HMM_PFN_VALID))
+ /* ODP initialization */
+ continue;
+
pa = odp->dma_list[idx + i];
- pas[i] = cpu_to_be64(umem_dma_to_mtt(pa));
+ pa |= MLX5_IB_MTT_READ;
+ if ((pfn & HMM_PFN_WRITE) && !downgrade)
+ pa |= MLX5_IB_MTT_WRITE;
+
+ pas[i] = cpu_to_be64(pa);
}
}

@@ -286,8 +286,7 @@ static bool mlx5_ib_invalidate_range(struct mmu_interval_notifier *mni,
* estimate the cost of another UMR vs. the cost of bigger
* UMR.
*/
- if (umem_odp->dma_list[idx] &
- (ODP_READ_ALLOWED_BIT | ODP_WRITE_ALLOWED_BIT)) {
+ if (umem_odp->pfn_list[idx] & HMM_PFN_VALID) {
if (!in_block) {
blk_start_idx = idx;
in_block = 1;
@@ -668,7 +667,7 @@ static int pagefault_real_mr(struct mlx5_ib_mr *mr, struct ib_umem_odp *odp,
{
int page_shift, ret, np;
bool downgrade = flags & MLX5_PF_FLAGS_DOWNGRADE;
- u64 access_mask;
+ u64 access_mask = 0;
u64 start_idx;
bool fault = !(flags & MLX5_PF_FLAGS_SNAPSHOT);
u32 xlt_flags = MLX5_IB_UPD_XLT_ATOMIC;
@@ -676,12 +675,14 @@ static int pagefault_real_mr(struct mlx5_ib_mr *mr, struct ib_umem_odp *odp,
if (flags & MLX5_PF_FLAGS_ENABLE)
xlt_flags |= MLX5_IB_UPD_XLT_ENABLE;

+ if (flags & MLX5_PF_FLAGS_DOWNGRADE)
+ xlt_flags |= MLX5_IB_UPD_XLT_DOWNGRADE;
+
page_shift = odp->page_shift;
start_idx = (user_va - ib_umem_start(odp)) >> page_shift;
- access_mask = ODP_READ_ALLOWED_BIT;

if (odp->umem.writable && !downgrade)
- access_mask |= ODP_WRITE_ALLOWED_BIT;
+ access_mask |= HMM_PFN_WRITE;

np = ib_umem_odp_map_dma_and_lock(odp, user_va, bcnt, access_mask, fault);
if (np < 0)
diff --git a/include/rdma/ib_umem_odp.h b/include/rdma/ib_umem_odp.h
index 0844c1d05ac6..a345c26a745d 100644
--- a/include/rdma/ib_umem_odp.h
+++ b/include/rdma/ib_umem_odp.h
@@ -8,6 +8,7 @@

#include <rdma/ib_umem.h>
#include <rdma/ib_verbs.h>
+#include <linux/hmm.h>

struct ib_umem_odp {
struct ib_umem umem;
@@ -67,19 +68,6 @@ static inline size_t ib_umem_odp_num_pages(struct ib_umem_odp *umem_odp)
umem_odp->page_shift;
}

-/*
- * The lower 2 bits of the DMA address signal the R/W permissions for
- * the entry. To upgrade the permissions, provide the appropriate
- * bitmask to the map_dma_pages function.
- *
- * Be aware that upgrading a mapped address might result in change of
- * the DMA address for the page.
- */
-#define ODP_READ_ALLOWED_BIT (1<<0ULL)
-#define ODP_WRITE_ALLOWED_BIT (1<<1ULL)
-
-#define ODP_DMA_ADDR_MASK (~(ODP_READ_ALLOWED_BIT | ODP_WRITE_ALLOWED_BIT))
-
#ifdef CONFIG_INFINIBAND_ON_DEMAND_PAGING

struct ib_umem_odp *
--
2.47.1