Re: [Xen-devel] [PATCH] VT-d: fix mask applied to DMIBAR in desktop chipset XSA-59 workaround

["Zhang, Yang Z" <yang.z.zhang@xxxxxxxxx>]

Jan Beulich wrote on 2014-05-23:
> In commit  ("VT-d: suppress UR signaling for desktop chipsets") the 
> mask applied to the value read from DMIBAR is to narrow, only the 
> comment accompanying it was correct. Fix that and tag the literal 
> number as "long" at once to avoid eventual compiler warnings.
> 
> The widest possible value so far is 39 bits; all chipsets covered here 
> but having less than this number of bits have the remaining bits 
> marked reserved (zero), and hence there's no need for making the mask chipset 
> specific.
> 
> Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>

Acked-by: Yang Zhang <yang.z.zhang@xxxxxxxxx>

> 
> --- a/xen/drivers/passthrough/vtd/quirks.c
> +++ b/xen/drivers/passthrough/vtd/quirks.c
> @@ -467,7 +467,7 @@ void pci_vtd_quirk(const struct pci_dev
>      case 0xc00: case 0xc04: case 0xc08: /* Haswell */
>          bar = pci_conf_read32(seg, bus, dev, func, 0x6c);
>          bar = (bar << 32) | pci_conf_read32(seg, bus, dev, func, 0x68);
> -        pa = bar & 0x7fffff000; /* bits 12...38 */
> +        pa = bar & 0x7ffffff000UL; /* bits 12...38 */
>          if ( (bar & 1) && pa &&
>               page_is_ram_type(paddr_to_pfn(pa),
> RAM_TYPE_RESERVED) )
>          {
>


Best regards,
Yang



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