[RFC PATCH v2] nvme: enable PCI P2PDMA support for RDMA transport

[RFC PATCH v2] nvme: enable PCI P2PDMA support for RDMA transport

[Shivaji Kant]

Enable BLK_FEAT_PCI_P2PDMA on the NVMe when the underlying
RDMA controller supports it.

This patch depends on the PCI P2PDMA support added in this
patch [1].

Suggested-by: Pranjal Shrivastava <praan@google.com>
Signed-off-by: Shivaji Kant <shivajikant@google.com>
---
[1] https://lore.kernel.org/all/20260323234416.46944-3-kch@nvidia.com/
---
 drivers/nvme/host/rdma.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/drivers/nvme/host/rdma.c b/drivers/nvme/host/rdma.c
index 35c0822edb2d..09eefd7c3ff4 100644
--- a/drivers/nvme/host/rdma.c
+++ b/drivers/nvme/host/rdma.c
@@ -2189,6 +2189,13 @@ static void nvme_rdma_reset_ctrl_work(struct work_struct *work)
 	nvme_rdma_reconnect_or_remove(ctrl, ret);
 }
 
+static bool nvme_rdma_supports_pci_p2pdma(struct nvme_ctrl *ctrl)
+{
+	struct nvme_rdma_ctrl *r_ctrl = to_rdma_ctrl(ctrl);
+
+	return ib_dma_pci_p2p_dma_supported(r_ctrl->device->dev);
+}
+
 static const struct nvme_ctrl_ops nvme_rdma_ctrl_ops = {
 	.name			= "rdma",
 	.module			= THIS_MODULE,
@@ -2203,6 +2210,7 @@ static const struct nvme_ctrl_ops nvme_rdma_ctrl_ops = {
 	.get_address		= nvmf_get_address,
 	.stop_ctrl		= nvme_rdma_stop_ctrl,
 	.get_virt_boundary	= nvme_get_virt_boundary,
+	.supports_pci_p2pdma	= nvme_rdma_supports_pci_p2pdma,
 };
 
 /*
-- 
2.53.0.1185.g05d4b7b318-goog

Re: [RFC PATCH v2] nvme: enable PCI P2PDMA support for RDMA transport

[Pranjal Shrivastava]

On Thu, Apr 02, 2026 at 07:30:01AM +0000, Shivaji Kant wrote:
> Enable BLK_FEAT_PCI_P2PDMA on the NVMe when the underlying
> RDMA controller supports it.
> 
> This patch depends on the PCI P2PDMA support added in this
> patch [1].
> 
> Suggested-by: Pranjal Shrivastava <praan@google.com>
> Signed-off-by: Shivaji Kant <shivajikant@google.com>
> ---
> [1] https://lore.kernel.org/all/20260323234416.46944-3-kch@nvidia.com/
> ---
>  drivers/nvme/host/rdma.c | 8 ++++++++
>  1 file changed, 8 insertions(+)
> 
> diff --git a/drivers/nvme/host/rdma.c b/drivers/nvme/host/rdma.c
> index 35c0822edb2d..09eefd7c3ff4 100644
> --- a/drivers/nvme/host/rdma.c
> +++ b/drivers/nvme/host/rdma.c
> @@ -2189,6 +2189,13 @@ static void nvme_rdma_reset_ctrl_work(struct work_struct *work)
>  	nvme_rdma_reconnect_or_remove(ctrl, ret);
>  }
>  
> +static bool nvme_rdma_supports_pci_p2pdma(struct nvme_ctrl *ctrl)
> +{
> +	struct nvme_rdma_ctrl *r_ctrl = to_rdma_ctrl(ctrl);
> +
> +	return ib_dma_pci_p2p_dma_supported(r_ctrl->device->dev);
> +}
> +
>  static const struct nvme_ctrl_ops nvme_rdma_ctrl_ops = {
>  	.name			= "rdma",
>  	.module			= THIS_MODULE,
> @@ -2203,6 +2210,7 @@ static const struct nvme_ctrl_ops nvme_rdma_ctrl_ops = {
>  	.get_address		= nvmf_get_address,
>  	.stop_ctrl		= nvme_rdma_stop_ctrl,
>  	.get_virt_boundary	= nvme_get_virt_boundary,
> +	.supports_pci_p2pdma	= nvme_rdma_supports_pci_p2pdma,
>  };
>  

+Chaitanya.

Hi Chaitanya, would you like to pick this up with your v2 for the
multipath p2p enablement series [1] ?

For the changes (with Chaitanya's mpath patch):
Reviewed-by: Pranjal Shrivastava <praan@google.com>

Thanks,
Praan

[1] https://lore.kernel.org/all/20260323234416.46944-3-kch@nvidia.com/

Re: [RFC PATCH v2] nvme: enable PCI P2PDMA support for RDMA transport

[Shivaji Kant]

On Thu, Apr 2, 2026 at 1:00 PM Shivaji Kant <shivajikant@google.com> wrote:
>
> Enable BLK_FEAT_PCI_P2PDMA on the NVMe when the underlying
> RDMA controller supports it.
>
> This patch depends on the PCI P2PDMA support added in this
> patch [1].
>
> Suggested-by: Pranjal Shrivastava <praan@google.com>
> Signed-off-by: Shivaji Kant <shivajikant@google.com>
> ---
> [1] https://lore.kernel.org/all/20260323234416.46944-3-kch@nvidia.com/
> ---
>  drivers/nvme/host/rdma.c | 8 ++++++++
>  1 file changed, 8 insertions(+)
>
> diff --git a/drivers/nvme/host/rdma.c b/drivers/nvme/host/rdma.c
> index 35c0822edb2d..09eefd7c3ff4 100644
> --- a/drivers/nvme/host/rdma.c
> +++ b/drivers/nvme/host/rdma.c
> @@ -2189,6 +2189,13 @@ static void nvme_rdma_reset_ctrl_work(struct work_struct *work)
>         nvme_rdma_reconnect_or_remove(ctrl, ret);
>  }
>
> +static bool nvme_rdma_supports_pci_p2pdma(struct nvme_ctrl *ctrl)
> +{
> +       struct nvme_rdma_ctrl *r_ctrl = to_rdma_ctrl(ctrl);
> +
> +       return ib_dma_pci_p2p_dma_supported(r_ctrl->device->dev);
> +}
> +
>  static const struct nvme_ctrl_ops nvme_rdma_ctrl_ops = {
>         .name                   = "rdma",
>         .module                 = THIS_MODULE,
> @@ -2203,6 +2210,7 @@ static const struct nvme_ctrl_ops nvme_rdma_ctrl_ops = {
>         .get_address            = nvmf_get_address,
>         .stop_ctrl              = nvme_rdma_stop_ctrl,
>         .get_virt_boundary      = nvme_get_virt_boundary,
> +       .supports_pci_p2pdma    = nvme_rdma_supports_pci_p2pdma,
>  };
>
>  /*
> --
> 2.53.0.1185.g05d4b7b318-goog
>
JFYI the link to v1 patch:
https://lore.kernel.org/all/20260401103441.1229964-1-shivajikant@google.com/

Thanks
Shivaji

Re: [RFC PATCH v2] nvme: enable PCI P2PDMA support for RDMA transport

[Christoph Hellwig]

On Thu, Apr 02, 2026 at 07:30:01AM +0000, Shivaji Kant wrote:
> Enable BLK_FEAT_PCI_P2PDMA on the NVMe when the underlying
> RDMA controller supports it.

You can use up to 73 characters per line.
> 
> This patch depends on the PCI P2PDMA support added in this
> patch [1].

I don't think it actually does.  To support multi-path capable RDMA
controllers, and those the vast majority, you need the multipath
support.  But for non-multipath capable controllers your patch
just works.  So I'd suggest to drop this paragraph and reference
from the commit log.

Otherwise looks good.

Re: [RFC PATCH v2] nvme: enable PCI P2PDMA support for RDMA transport

[Shivaji Kant]

Thanks for reviewing.

On Sun, Apr 5, 2026 at 9:59 PM Henrique Carvalho
<henrique.carvalho@suse.com> wrote:
>
> Reviewed-by: Henrique Carvalho <henrique.carvalho@suse.com>