Re: [Qemu-devel] [Xen-devel] [PATCH][XSA-126] xen: limit guest control of PCI command register

[Jan Beulich]

>>> On 13.04.15 at 14:47, <address@hidden> wrote:
> On Mon, Apr 13, 2015 at 01:40:59PM +0100, Jan Beulich wrote:
>> Quite possible. Looking at the ITP log we were provided, the UR
>> severity bit is clear (non-fatal), yet the error got surfaced to the
>> OS as a fatal one (I would guess because it validly gets flagged as
>> uncorrectable at the same time).
> 
> No, that's not valid.
> Can you check device capabilities register, offset 0x4 within
> pci express capability structure?
> Bit 15 is 15 Role-Based Error Reporting.
> Is it set?
> 
> The spec says:
> 
>       15
>       On platforms where robust error handling and PC-compatible 
> Configuration 
> Space probing is
>       required, it is suggested that software or firmware have the 
> Unsupported 
> Request Reporting Enable
>       bit Set for Role-Based Error Reporting Functions, but clear for 1.0a 
> Functions. Software or
>       firmware can distinguish the two classes of Functions by examining the 
> Role-Based Error Reporting
>       bit in the Device Capabilities register.

Yes, that bit is set.

Jan