Re: [Qemu-devel] [PATCH] ahci: map memory via device's address space instead of address_space_memory

[John Snow]

On 02/26/2015 12:13 AM, Jordan Hargrave wrote:
> Referencing this old thread:
> https://lists.nongnu.org/archive/html/qemu-devel/2014-07/msg00606.html
>
> I've run into an issue recently with testing q35 DMAR/intel iommu with
> ahci driver.  My ahci driver writes the upper-32 bits (PORT_FIS_ADDR_HI)
> first then the lower 32-bits (PORT_FIS_ADDR).
>
> The contents of PORT_FIS_ADDR therefore are stale when the
> PORT_FIS_ADDR_HI write calls map_page().  DMAR translation fails at this
> point as the old stale address (from SEABIOS initialization) is not in
> the DMAR page table.

Hi: I posted a fix, but do you mind elaborating on what the failure 
actually looked like?

Did QEMU abort, did the guest crash, etc? What exact behavior did you 
observe?

Do you have a command line to share with us?

--js