linux-kernel - Re: [PATCH] scsi: smartpqi: properly set both the DMA mask and the coherent DMA mask in pqi_pci

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Message-ID: <c5d45523-43f5-d2fd-01ac-85f285146ecd@amd.com>
Date:   Thu, 23 May 2019 14:45:12 +0000
From:   "Lendacky, Thomas" <Thomas.Lendacky@....com>
To:     Lianbo Jiang <lijiang@...hat.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
CC:     "don.brace@...rosemi.com" <don.brace@...rosemi.com>,
        "jejb@...ux.ibm.com" <jejb@...ux.ibm.com>,
        "martin.petersen@...cle.com" <martin.petersen@...cle.com>,
        "linux-scsi@...r.kernel.org" <linux-scsi@...r.kernel.org>,
        "esc.storagedev@...rosemi.com" <esc.storagedev@...rosemi.com>,
        "dyoung@...hat.com" <dyoung@...hat.com>
Subject: Re: [PATCH] scsi: smartpqi: properly set both the DMA mask and the
 coherent DMA mask in pqi_pci_init()

On 5/23/19 12:52 AM, Lianbo Jiang wrote:
> When SME is enabled, the smartpqi driver won't work on the HP DL385
> G10 machine, which causes the failure of kernel boot because it fails
> to allocate pqi error buffer. Please refer to the kernel log:
> ....
> [    9.431749] usbcore: registered new interface driver uas
> [    9.441524] Microsemi PQI Driver (v1.1.4-130)
> [    9.442956] i40e 0000:04:00.0: fw 6.70.48768 api 1.7 nvm 10.2.5
> [    9.447237] smartpqi 0000:23:00.0: Microsemi Smart Family Controller found
>          Starting dracut initqueue hook...
> [  OK  ] Started Show Plymouth Boot Scre[    9.471654] Broadcom NetXtreme-C/E driver bnxt_en v1.9.1
> en.
> [  OK  ] Started Forward Password Requests to Plymouth Directory Watch.
> [[0;[    9.487108] smartpqi 0000:23:00.0: failed to allocate PQI error buffer
> ....
> [  139.050544] dracut-initqueue[949]: Warning: dracut-initqueue timeout - starting timeout scripts
> [  139.589779] dracut-initqueue[949]: Warning: dracut-initqueue timeout - starting timeout scripts
> 
> For correct operation, lets call the dma_set_mask_and_coherent() to
> properly set the mask for both streaming and coherent, in order to
> inform the kernel about the devices DMA addressing capabilities.

You should probably expand on this a bit...  Basically, the fact that
the coherent DMA mask value wasn't set caused the driver to fall back
to SWIOTLB when SME is active. I'm not sure if the failure was from
running out of SWIOTLB or exceeding the maximum allocation size for
SWIOTLB.

I believe the fix is proper, but I'll let the driver owner comment on
that.

Thanks,
Tom

> 
> Signed-off-by: Lianbo Jiang <lijiang@...hat.com>
> ---
>  drivers/scsi/smartpqi/smartpqi_init.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/scsi/smartpqi/smartpqi_init.c b/drivers/scsi/smartpqi/smartpqi_init.c
> index c26cac819f9e..8b1fde6c7dab 100644
> --- a/drivers/scsi/smartpqi/smartpqi_init.c
> +++ b/drivers/scsi/smartpqi/smartpqi_init.c
> @@ -7282,7 +7282,7 @@ static int pqi_pci_init(struct pqi_ctrl_info *ctrl_info)
>         else
>                 mask = DMA_BIT_MASK(32);
> 
> -       rc = dma_set_mask(&ctrl_info->pci_dev->dev, mask);
> +       rc = dma_set_mask_and_coherent(&ctrl_info->pci_dev->dev, mask);
>         if (rc) {
>                 dev_err(&ctrl_info->pci_dev->dev, "failed to set DMA mask\n");
>                 goto disable_device;
> --
> 2.17.1
>