[PATCHv5 2/2] nvme: remove virtual boundary for sgl capable devices

Keith Busch
2025-10-14T15:05:16Z

From: Keith Busch <kbusch@kernel.org>

The nvme virtual boundary is only required for the PRP format. Devices
that can use SGL for DMA don't need it for IO queues. Drop reporting it
for such devices; rdma fabrics controllers will continue to use the
limit as they currently don't report any boundary requirements, but tcp
and fc never needed it in the first place so they get to report no
virtual boundary.

Applications may continue to align to the same virtual boundaries for
optimization purposes if they want, and the driver will continue to
decide whether to use the PRP format the same as before if the IO allows
it.

Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Keith Busch <kbusch@kernel.org>
---
drivers/nvme/host/apple.c | 1 +
drivers/nvme/host/core.c | 10 +++++-----
drivers/nvme/host/fabrics.h | 6 ++++++
drivers/nvme/host/fc.c | 1 +
drivers/nvme/host/nvme.h | 7 +++++++
drivers/nvme/host/pci.c | 28 +++++++++++++++++++++++++---
drivers/nvme/host/rdma.c | 1 +
drivers/nvme/host/tcp.c | 1 +
drivers/nvme/target/loop.c | 1 +
9 files changed, 48 insertions(+), 8 deletions(-)

diff --git a/drivers/nvme/host/apple.c b/drivers/nvme/host/apple.c
index f35d3f71d14f3..15b3d07f8ccdd 100644
--- a/drivers/nvme/host/apple.c
+++ b/drivers/nvme/host/apple.c
@@ -1283,6 +1283,7 @@ static const struct nvme_ctrl_ops nvme_ctrl_ops = {
.reg_read64 = apple_nvme_reg_read64,
.free_ctrl = apple_nvme_free_ctrl,
.get_address = apple_nvme_get_address,
+ .get_virt_boundary = nvme_get_virt_boundary,
};

static void apple_nvme_async_probe(void *data, async_cookie_t cookie)
diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c
index fa4181d7de736..63e15cce3699c 100644
--- a/drivers/nvme/host/core.c
+++ b/drivers/nvme/host/core.c
@@ -2069,13 +2069,13 @@ static u32 nvme_max_drv_segments(struct nvme_ctrl *ctrl)
}

static void nvme_set_ctrl_limits(struct nvme_ctrl *ctrl,
- struct queue_limits *lim)
+ struct queue_limits *lim, bool is_admin)
{
lim->max_hw_sectors = ctrl->max_hw_sectors;
lim->max_segments = min_t(u32, USHRT_MAX,
min_not_zero(nvme_max_drv_segments(ctrl), ctrl->max_segments));
lim->max_integrity_segments = ctrl->max_integrity_segments;
- lim->virt_boundary_mask = NVME_CTRL_PAGE_SIZE - 1;
+ lim->virt_boundary_mask = ctrl->ops->get_virt_boundary(ctrl, is_admin);
lim->max_segment_size = UINT_MAX;
lim->dma_alignment = 3;
}
@@ -2177,7 +2177,7 @@ static int nvme_update_ns_info_generic(struct nvme_ns *ns,
int ret;

lim = queue_limits_start_update(ns->disk->queue);
- nvme_set_ctrl_limits(ns->ctrl, &lim);
+ nvme_set_ctrl_limits(ns->ctrl, &lim, false);

memflags = blk_mq_freeze_queue(ns->disk->queue);
ret = queue_limits_commit_update(ns->disk->queue, &lim);
@@ -2381,7 +2381,7 @@ static int nvme_update_ns_info_block(struct nvme_ns *ns,
ns->head->lba_shift = id->lbaf[lbaf].ds;
ns->head->nuse = le64_to_cpu(id->nuse);
capacity = nvme_lba_to_sect(ns->head, le64_to_cpu(id->nsze));
- nvme_set_ctrl_limits(ns->ctrl, &lim);
+ nvme_set_ctrl_limits(ns->ctrl, &lim, false);
nvme_configure_metadata(ns->ctrl, ns->head, id, nvm, info);
nvme_set_chunk_sectors(ns, id, &lim);
if (!nvme_update_disk_info(ns, id, &lim))
@@ -3589,7 +3589,7 @@ static int nvme_init_identify(struct nvme_ctrl *ctrl)
min_not_zero(ctrl->max_hw_sectors, max_hw_sectors);

lim = queue_limits_start_update(ctrl->admin_q);
- nvme_set_ctrl_limits(ctrl, &lim);
+ nvme_set_ctrl_limits(ctrl, &lim, true);
ret = queue_limits_commit_update(ctrl->admin_q, &lim);
if (ret)
goto out_free;
diff --git a/drivers/nvme/host/fabrics.h b/drivers/nvme/host/fabrics.h
index 1b58ee7d0dcee..caf5503d08332 100644
--- a/drivers/nvme/host/fabrics.h
+++ b/drivers/nvme/host/fabrics.h
@@ -217,6 +217,12 @@ static inline unsigned int nvmf_nr_io_queues(struct nvmf_ctrl_options *opts)
min(opts->nr_poll_queues, num_online_cpus());
}

+static inline unsigned long nvmf_get_virt_boundary(struct nvme_ctrl *ctrl,
+ bool is_admin)
+{
+ return 0;
+}
+
int nvmf_reg_read32(struct nvme_ctrl *ctrl, u32 off, u32 *val);
int nvmf_reg_read64(struct nvme_ctrl *ctrl, u32 off, u64 *val);
int nvmf_reg_write32(struct nvme_ctrl *ctrl, u32 off, u32 val);
diff --git a/drivers/nvme/host/fc.c b/drivers/nvme/host/fc.c
index 03987f497a5b5..70c066c2e2d42 100644
--- a/drivers/nvme/host/fc.c
+++ b/drivers/nvme/host/fc.c
@@ -3360,6 +3360,7 @@ static const struct nvme_ctrl_ops nvme_fc_ctrl_ops = {
.submit_async_event = nvme_fc_submit_async_event,
.delete_ctrl = nvme_fc_delete_ctrl,
.get_address = nvmf_get_address,
+ .get_virt_boundary = nvmf_get_virt_boundary,
};

static void
diff --git a/drivers/nvme/host/nvme.h b/drivers/nvme/host/nvme.h
index 102fae6a231c5..7f7cb823d60d8 100644
--- a/drivers/nvme/host/nvme.h
+++ b/drivers/nvme/host/nvme.h
@@ -558,6 +558,12 @@ static inline bool nvme_ns_has_pi(struct nvme_ns_head *head)
return head->pi_type && head->ms == head->pi_size;
}

+static inline unsigned long nvme_get_virt_boundary(struct nvme_ctrl *ctrl,
+ bool is_admin)
+{
+ return NVME_CTRL_PAGE_SIZE - 1;
+}
+
struct nvme_ctrl_ops {
const char *name;
struct module *module;
@@ -578,6 +584,7 @@ struct nvme_ctrl_ops {
int (*get_address)(struct nvme_ctrl *ctrl, char *buf, int size);
void (*print_device_info)(struct nvme_ctrl *ctrl);
bool (*supports_pci_p2pdma)(struct nvme_ctrl *ctrl);
+ unsigned long (*get_virt_boundary)(struct nvme_ctrl *ctrl, bool is_admin);
};

/*
diff --git a/drivers/nvme/host/pci.c b/drivers/nvme/host/pci.c
index c916176bd9f05..3c1727df1e36f 100644
--- a/drivers/nvme/host/pci.c
+++ b/drivers/nvme/host/pci.c
@@ -613,9 +613,22 @@ static inline enum nvme_use_sgl nvme_pci_use_sgls(struct nvme_dev *dev,
struct nvme_queue *nvmeq = req->mq_hctx->driver_data;

if (nvmeq->qid && nvme_ctrl_sgl_supported(&dev->ctrl)) {
- if (nvme_req(req)->flags & NVME_REQ_USERCMD)
- return SGL_FORCED;
- if (req->nr_integrity_segments > 1)
+ /*
+ * When the controller is capable of using SGL, there are
+ * several conditions that we force to use it:
+ *
+ * 1. A request containing page gaps within the controller's
+ * mask can not use the PRP format.
+ *
+ * 2. User commands use SGL because that lets the device
+ * validate the requested transfer lengths.
+ *
+ * 3. Multiple integrity segments must use SGL as that's the
+ * only way to describe such a command in NVMe.
+ */
+ if (req_phys_gap_mask(req) & (NVME_CTRL_PAGE_SIZE - 1) ||
+ nvme_req(req)->flags & NVME_REQ_USERCMD ||
+ req->nr_integrity_segments > 1)
return SGL_FORCED;
return SGL_SUPPORTED;
}
@@ -3243,6 +3256,14 @@ static bool nvme_pci_supports_pci_p2pdma(struct nvme_ctrl *ctrl)
return dma_pci_p2pdma_supported(dev->dev);
}

+static unsigned long nvme_pci_get_virt_boundary(struct nvme_ctrl *ctrl,
+ bool is_admin)
+{
+ if (!nvme_ctrl_sgl_supported(ctrl) || is_admin)
+ return NVME_CTRL_PAGE_SIZE - 1;
+ return 0;
+}
+
static const struct nvme_ctrl_ops nvme_pci_ctrl_ops = {
.name = "pcie",
.module = THIS_MODULE,
@@ -3257,6 +3278,7 @@ static const struct nvme_ctrl_ops nvme_pci_ctrl_ops = {
.get_address = nvme_pci_get_address,
.print_device_info = nvme_pci_print_device_info,
.supports_pci_p2pdma = nvme_pci_supports_pci_p2pdma,
+ .get_virt_boundary = nvme_pci_get_virt_boundary,
};

static int nvme_dev_map(struct nvme_dev *dev)
diff --git a/drivers/nvme/host/rdma.c b/drivers/nvme/host/rdma.c
index 190a4cfa8a5ee..35c0822edb2d7 100644
--- a/drivers/nvme/host/rdma.c
+++ b/drivers/nvme/host/rdma.c
@@ -2202,6 +2202,7 @@ static const struct nvme_ctrl_ops nvme_rdma_ctrl_ops = {
.delete_ctrl = nvme_rdma_delete_ctrl,
.get_address = nvmf_get_address,
.stop_ctrl = nvme_rdma_stop_ctrl,
+ .get_virt_boundary = nvme_get_virt_boundary,
};

/*
diff --git a/drivers/nvme/host/tcp.c b/drivers/nvme/host/tcp.c
index 1413788ca7d52..82875351442a0 100644
--- a/drivers/nvme/host/tcp.c
+++ b/drivers/nvme/host/tcp.c
@@ -2862,6 +2862,7 @@ static const struct nvme_ctrl_ops nvme_tcp_ctrl_ops = {
.delete_ctrl = nvme_tcp_delete_ctrl,
.get_address = nvme_tcp_get_address,
.stop_ctrl = nvme_tcp_stop_ctrl,
+ .get_virt_boundary = nvmf_get_virt_boundary,
};

static bool
diff --git a/drivers/nvme/target/loop.c b/drivers/nvme/target/loop.c
index f85a8441bcc6e..9fe88a489eb71 100644
--- a/drivers/nvme/target/loop.c
+++ b/drivers/nvme/target/loop.c
@@ -511,6 +511,7 @@ static const struct nvme_ctrl_ops nvme_loop_ctrl_ops = {
.submit_async_event = nvme_loop_submit_async_event,
.delete_ctrl = nvme_loop_delete_ctrl_host,
.get_address = nvmf_get_address,
+ .get_virt_boundary = nvme_get_virt_boundary,
};

static int nvme_loop_create_io_queues(struct nvme_loop_ctrl *ctrl)
--
2.47.3