On 2014/10/2 18:09, Joerg Roedel wrote:
> From: Joerg Roedel <[email protected]>
>
> The VT-d specification states that an RMRR entry in the DMAR
> table needs to specify the full path to the device. This is
> also how newer Linux kernels implement it.
>
> Unfortunatly older drivers just match for the target device
> and not the full path to the device, so that BIOS vendors
> implement that behavior into their BIOSes to make them work
> with older Linux kernels. But those RMRR entries break on
> newer Linux kernels.
>
> Work around this issue by adding a fall-back into the RMRR
> matching code to match those old RMRR entries too.
>
> Signed-off-by: Joerg Roedel <[email protected]>
> ---
> drivers/iommu/dmar.c | 22 +++++++++++++++++++---
> 1 file changed, 19 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/iommu/dmar.c b/drivers/iommu/dmar.c
> index 6ba28b0..371ff33 100644
> --- a/drivers/iommu/dmar.c
> +++ b/drivers/iommu/dmar.c
> @@ -178,17 +178,33 @@ static bool dmar_match_pci_path(struct
> dmar_pci_notify_info *info, int bus,
> int i;
>
> if (info->bus != bus)
> - return false;
> + goto fallback;
> if (info->level != count)
> - return false;
> + goto fallback;
>
> for (i = 0; i < count; i++) {
> if (path[i].device != info->path[i].device ||
> path[i].function != info->path[i].function)
> - return false;
> + goto fallback;
> }
>
> return true;
> +
> +fallback:
> +
> + if (count != 1)
> + return false;
> +
> + i = info->level - 1;
> + if (bus == info->path[i].bus &&
> + path[0].device == info->path[i].device &&
> + path[0].function == info->path[i].function) {
> + pr_info(FW_BUG "RMRR entry for device %02x:%02x.%x is broken -
> applying workaround\n",
> + bus, path[0].device, path[0].function);
> + return true;
> + }
> +
> + return false;
> }
>
> /* Return: > 0 if match found, 0 if no match found, < 0 if error happens */
>
Hi Joerg,
Thanks for fixing this:)
Reviewed-by: Jiang Liu <[email protected]>
Regards!
Gerry
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