Re: [Qemu-devel] [PATCH qemu] memory: Fix IOMMU replay base address

[David Gibson <david@gibson.dropbear.id.au>]

[-- Attachment #1: Type: text/plain, Size: 2281 bytes --]

On Mon, Feb 22, 2016 at 10:36:19PM +1100, Alexey Kardashevskiy wrote:
> On 02/22/2016 05:26 PM, David Gibson wrote:
> >On Mon, Feb 22, 2016 at 05:09:39PM +1100, Alexey Kardashevskiy wrote:
> >>Since a788f227 "memory: Allow replay of IOMMU mapping notifications"
> >>when new VFIO listener is added, all existing IOMMU mappings are replayed.
> >>However there is a problem that the base address of an IOMMU memory region
> >>(IOMMU MR) is ignored which is not a problem for the existing user (which is
> >>pseries) with its default 32bit DMA window starting at 0 but it is if there is
> >>another DMA window.
> >>
> >>This adjusts the replaying address by mr->addr.
> >
> >Uh.. this doesn't look right to me.  AFAICT from the existing
> >implementations the 'addr' parameter to the translate function is an
> >offset within the memory region, which would make the original version
> >correct.
> 
> Ok, then spapr_tce_translate_iommu() needs to be fixed. Or I am missing
> something here? The @addr field is definitely ignored now.

I think at least one of us is missing something.  In the normal AS
translation path, IIUC, it will subtract the mr->addr value to give
offsets which are passed to translate.  It uses those offsets to find
the TCE and returns a translated address.  Where else the @addr be
used?


> 
> 
> >
> >>Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
> >>---
> >>  memory.c | 2 +-
> >>  1 file changed, 1 insertion(+), 1 deletion(-)
> >>
> >>diff --git a/memory.c b/memory.c
> >>index 09041ed..377269b 100644
> >>--- a/memory.c
> >>+++ b/memory.c
> >>@@ -1436,7 +1436,7 @@ void memory_region_iommu_replay(MemoryRegion *mr, Notifier *n,
> >>      IOMMUTLBEntry iotlb;
> >>
> >>      for (addr = 0; addr < memory_region_size(mr); addr += granularity) {
> >>-        iotlb = mr->iommu_ops->translate(mr, addr, is_write);
> >>+        iotlb = mr->iommu_ops->translate(mr, mr->addr + addr, is_write);
> >>          if (iotlb.perm != IOMMU_NONE) {
> >>              n->notify(n, &iotlb);
> >>          }
> >
> 
> 

-- 
David Gibson			| I'll have my music baroque, and my code
david AT gibson.dropbear.id.au	| minimalist, thank you.  NOT _the_ _other_
				| _way_ _around_!
http://www.ozlabs.org/~dgibson

[-- Attachment #2: signature.asc --]
[-- Type: application/pgp-signature, Size: 819 bytes --]