Re: [Xen-devel] [PATCH 2/3] xen/vt-d: mask interrupt message generation

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 04.05.15 at 07:08, <tiejun.chen@xxxxxxxxx> wrote:
> At first I doubted this is issued by some improper cache behaviors.
> Because as you see, "root_entry[0] = 80f5001" indicates we already set 
> that present bit. But Caching Mode bit is zero in BDW so this means 
> remapping hardware doesn't own contest cache. And I also check xen 
> always calls clflush to write back memory on CPU side. (Even I also 
> tried to use wbinvd to replace clflush). And plus, you can see this 
> guest fault address is a weird zero, so I turned to concern if this is 
> just an unexpected fault which is pending because of some BIOS cleanup, 
> or undefined hardware behaviors. Here I mean clear_fault_bits() is 
> already not enough to clear this kind of pending interrupt before we 
> complete all VT-D initializations.

This last aspect in particular needs more explanation, but I'm
wary of the change in general (see Yang's response).

Jan


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