lkml.org 
[lkml]   [2018]   [Oct]   [22]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH] fpga: altera_cvp: restrict registration to CvP enabled devices
Hi Andreas,

Am 22.10.2018 15:15, schrieb Andreas Puhm:

> Hi Moritz,
>
> Thank you, for your fast response!
> Below you can find the updated patch.
>
> --------------------------------------------------------------------
> Full description:
> The altera_cvp probe function only checks,
> if the Altera/Intel PCI device configuration space contains a vendor
> specific entry (VSEC Capability Header 0x000b) at offset 0x200.
> But the probe function does not verify, if the PCI device (and further
> the FPGA),
> for which it has been called, actually supports the
> Configure-via-Protocol feature.
>
> The PCI device (FPGA) can explicitly disable the Configur-via-Protocol
> (CvP) feature by setting the CVP_EN bit, index 20 of CVP_STATUS
> register, to '0'.
> As the altera_cvp probe function does not check this it registers the
> device in any way.
> At this point, the altera_cvp module cannot be used to program this
> device via CvP.
> In addition no other module can use the device, as it is still
> registered by altera_cvp.
>
> Keywords: altera_cvp module, PCI, Configure-via-Protocol
>
> Kernel version: problem occured with v4.15, should occur from 4.14+
>
> Instructions to reproduce:
> Proper hardware is necessary to reproduce this, i.e., FPGA with
> instantiated Altera/Intel PCIe IP Core with disabled CvP feature.
>
> Workaround:
> It is possible to circumvent this problem by manually unloading or
> blacklisting the altera_cvp module.
> --------------------------------------------------------------------
> Suggested Patch:
> This patch was successfully build and tested for 4.15 and 4.18
>
> The patch is based on:
> git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tag/?h=v4.18
>
> Subject: [PATCH] fpga: altera_cvp: restrict registration to CvP enabled
> devices
>
> The altera-cvp probe function now verifies, that the PCI device
> supports
> the CvP feature, before it registers the device.
> This is done by reading the CVP_EN bit,
> Bit 20 of the CVP_STATUS register (@ PCI Config Address 0x21C).
>
> If this bit is '1' (CvP enabled), altera-cvp will register the device
> for further interaction.
> If this bit is '0' (CvP disabled), altera-cvp will not register the
> device.
>
> Signed-off-by: Andreas Puhm <puhm@oregano.at>
> ---
> drivers/fpga/altera-cvp.c | 9 +++++++++
> 1 file changed, 9 insertions(+)
>
> diff --git a/drivers/fpga/altera-cvp.c b/drivers/fpga/altera-cvp.c
> index 7fa793672a7a..838abcfca0fb 100644
> --- a/drivers/fpga/altera-cvp.c
> +++ b/drivers/fpga/altera-cvp.c
> @@ -403,6 +403,7 @@ static int altera_cvp_probe(struct pci_dev *pdev,
> struct altera_cvp_conf *conf;
> struct fpga_manager *mgr;
> u16 cmd, val;
> + u32 val32;

Please do not use variable size in variable name.

> int ret;
>
> /*
> @@ -416,6 +417,14 @@ static int altera_cvp_probe(struct pci_dev *pdev,
> return -ENODEV;
> }
>
> + pci_read_config_dword(pdev, VSE_CVP_STATUS, &val32);
> + if (!(val32 & VSE_CVP_STATUS_CVP_EN)) {
> + dev_err(&pdev->dev,
> + "CVP is disabled for this device: CVP_STATUS Reg 0x%x\n",
> + val32);
> + return -ENODEV;
> + }
> +
> conf = devm_kzalloc(&pdev->dev, sizeof(*conf), GFP_KERNEL);
> if (!conf)
> return -ENOMEM;
> --
>
> With best regards,
> Andreas Puhm <puhm@oregano.at>

Cheers
Eric

\
 
 \ /
  Last update: 2018-10-22 15:35    [W:0.089 / U:0.464 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site