On Fri, 06 Apr 2018 15:12:21 +0200,
Stuart Hayes wrote:
> 
> The dell_rbu driver takes firmware update payloads and puts them in memory so
> the system BIOS can find them after a reboot.  This sometimes fails (though
> rarely), because the memory containing the payload is in the CPU cache but
> never gets written back to main memory before the system is rebooted (CPU
> cache contents are lost on reboot).
> 
> With this patch, the payload memory will be changed to uncachable to ensure
> that the payload is actually in main memory before the system is rebooted.
> 
> Signed-off-by: Stuart Hayes <stuart.w.ha...@gmail.com>

Looks good to me.

Reviewed-by: Takashi Iwai <ti...@suse.de>

Andrew, could you pick this one?  The driver seems to have no
maintainer.


thanks,

Takashi

> ---
> v2 Added include, removed extra parentheses
> v3 Corrected formatting and include line
> v4 Moved set_memory_uc() outside the while loop so that the memory is
>    definitely allocated before it is set to uncachable
> 
> This driver has no maintainer.
> 
> 
> diff --git a/drivers/firmware/dell_rbu.c b/drivers/firmware/dell_rbu.c
> index 2f452f1f7c8a..53f27a6e2d76 100644
> --- a/drivers/firmware/dell_rbu.c
> +++ b/drivers/firmware/dell_rbu.c
> @@ -45,6 +45,7 @@
>  #include <linux/moduleparam.h>
>  #include <linux/firmware.h>
>  #include <linux/dma-mapping.h>
> +#include <asm/set_memory.h>
>  
>  MODULE_AUTHOR("Abhay Salunke <abhay_salu...@dell.com>");
>  MODULE_DESCRIPTION("Driver for updating BIOS image on DELL systems");
> @@ -181,6 +182,11 @@ static int create_packet(void *data, size_t length)
>                       packet_data_temp_buf = NULL;
>               }
>       }
> +     /*
> +      * set to uncachable or it may never get written back before reboot
> +      */
> +     set_memory_uc((unsigned long)packet_data_temp_buf, 1 << ordernum);
> +
>       spin_lock(&rbu_data.lock);
>  
>       newpacket->data = packet_data_temp_buf;
> @@ -349,6 +355,8 @@ static void packet_empty_list(void)
>                * to make sure there are no stale RBU packets left in memory
>                */
>               memset(newpacket->data, 0, rbu_data.packetsize);
> +             set_memory_wb((unsigned long)newpacket->data,
> +                     1 << newpacket->ordernum);
>               free_pages((unsigned long) newpacket->data,
>                       newpacket->ordernum);
>               kfree(newpacket);
> 

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