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Date: Thu, 25 Jan 2024 10:33:19 -0500
From: Frank Li <Frank.li@nxp.com>
To: mani@kernel.org
Cc: allenbh@gmail.com, bhelgaas@google.com, dave.jiang@intel.com,
	imx@lists.linux.dev, jdmason@kudzu.us, kishon@kernel.org,
	kw@linux.com, linux-kernel@vger.kernel.org,
	linux-pci@vger.kernel.org, lpieralisi@kernel.org,
	ntb@lists.linux.dev
Subject: Re: [PATCH v4 1/1] PCI: endpoint: pci-epf-vntb: Fix transfer failure
 for fixed size BARs
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References: <20240108151015.2030469-1-Frank.Li@nxp.com>
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On Mon, Jan 08, 2024 at 10:10:15AM -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.
> 
> This only fixes doorbell (DB) BAR. A similar fix is needed for memory map
> windows(MW) BARs.
> 
> Fixes: e35f56bb0330 ("PCI: endpoint: Support NTB transfer between RC and EP")
> Cc: stable@vger.kernel.org
> Reviewed-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
> Signed-off-by: Frank Li <Frank.Li@nxp.com>
> ---

@lpieralisi:

	Could you please pick this fix patch?

Frank

> 
> Notes:
>     Change from v3 to v4
>     - add notes: fixing the issue only for DB BAR and a similar fix is needed
>     for other MW BARs
>     - Add Manivannan Sadhasivam's review tag
>     
>     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
>