[PATCH v3 1/1] PCI: endpoint: pci-epf-vntb: Fix transfer failure for fixed size BARs

[PATCH v3 1/1] PCI: endpoint: pci-epf-vntb: Fix transfer failure for fixed size BARs

[Frank Li]

For the inbound MEM/IO TLPs, iATU on the endpoint expects the target
address to be aligned to the size of the BAR. For configurable BARs, there
is no issue because both host and endpoint will know the exact size of the
BAR region. But for fixed size BARs available in some controllers, if the
BAR size advertised by the endpoint is not same as of the actual BAR size
used in the controller, then the MEM/IO TLPs generated by the host will not
be translated properly by the endpoint iATU.

So if the fixed size BARs are available in endpoint controllers, always use
the actual BAR size.

Fixes: e35f56bb0330 ("PCI: endpoint: Support NTB transfer between RC and EP")
Cc: stable@vger.kernel.org
Signed-off-by: Frank Li <Frank.Li@nxp.com>
---

Notes:
    Change from v2 to v3
    - rework commti message
    - add fixes and cc stable
    - return -ENOMEN when request size > fix bar size
    Change from v1 to v2
    - Remove unnessary set align when fix_bar_size.

 drivers/pci/endpoint/functions/pci-epf-vntb.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/drivers/pci/endpoint/functions/pci-epf-vntb.c b/drivers/pci/endpoint/functions/pci-epf-vntb.c
index 3f60128560ed0..85120978fb8c9 100644
--- a/drivers/pci/endpoint/functions/pci-epf-vntb.c
+++ b/drivers/pci/endpoint/functions/pci-epf-vntb.c
@@ -550,6 +550,14 @@ static int epf_ntb_db_bar_init(struct epf_ntb *ntb)
 
 	barno = ntb->epf_ntb_bar[BAR_DB];
 
+	if (epc_features->bar_fixed_size[barno]) {
+		if (size > epc_features->bar_fixed_size[barno]) {
+			dev_err(dev, "Fixed BAR%d is too small for doorbell\n", barno);
+			return -ENOMEM;
+		}
+		size = epc_features->bar_fixed_size[barno];
+	}
+
 	mw_addr = pci_epf_alloc_space(ntb->epf, size, barno, align, 0);
 	if (!mw_addr) {
 		dev_err(dev, "Failed to allocate OB address\n");
-- 
2.34.1

Re: [PATCH v3 1/1] PCI: endpoint: pci-epf-vntb: Fix transfer failure for fixed size BARs

[Manivannan Sadhasivam]

On Wed, Dec 20, 2023 at 02:24:27PM -0500, Frank Li wrote:
> For the inbound MEM/IO TLPs, iATU on the endpoint expects the target
> address to be aligned to the size of the BAR. For configurable BARs, there
> is no issue because both host and endpoint will know the exact size of the
> BAR region. But for fixed size BARs available in some controllers, if the
> BAR size advertised by the endpoint is not same as of the actual BAR size
> used in the controller, then the MEM/IO TLPs generated by the host will not
> be translated properly by the endpoint iATU.
> 
> So if the fixed size BARs are available in endpoint controllers, always use
> the actual BAR size.
> 

You should add a note saying that you are fixing the issue only for DB BAR and a
similar fix is needed for other MW BARs.

> Fixes: e35f56bb0330 ("PCI: endpoint: Support NTB transfer between RC and EP")
> Cc: stable@vger.kernel.org
> Signed-off-by: Frank Li <Frank.Li@nxp.com>

With that,

Reviewed-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>

- Mani

> ---
> 
> Notes:
>     Change from v2 to v3
>     - rework commti message
>     - add fixes and cc stable
>     - return -ENOMEN when request size > fix bar size
>     Change from v1 to v2
>     - Remove unnessary set align when fix_bar_size.
> 
>  drivers/pci/endpoint/functions/pci-epf-vntb.c | 8 ++++++++
>  1 file changed, 8 insertions(+)
> 
> diff --git a/drivers/pci/endpoint/functions/pci-epf-vntb.c b/drivers/pci/endpoint/functions/pci-epf-vntb.c
> index 3f60128560ed0..85120978fb8c9 100644
> --- a/drivers/pci/endpoint/functions/pci-epf-vntb.c
> +++ b/drivers/pci/endpoint/functions/pci-epf-vntb.c
> @@ -550,6 +550,14 @@ static int epf_ntb_db_bar_init(struct epf_ntb *ntb)
>  
>  	barno = ntb->epf_ntb_bar[BAR_DB];
>  
> +	if (epc_features->bar_fixed_size[barno]) {
> +		if (size > epc_features->bar_fixed_size[barno]) {
> +			dev_err(dev, "Fixed BAR%d is too small for doorbell\n", barno);
> +			return -ENOMEM;
> +		}
> +		size = epc_features->bar_fixed_size[barno];
> +	}
> +
>  	mw_addr = pci_epf_alloc_space(ntb->epf, size, barno, align, 0);
>  	if (!mw_addr) {
>  		dev_err(dev, "Failed to allocate OB address\n");
> -- 
> 2.34.1
> 
> 

-- 
மணிவண்ணன் சதாசிவம்