Re: [Qemu-devel] QEMU and vIOMMU support for emulated VF passthrough to nested (L2) VM

[Elijah Shakkour]

> -----Original Message-----
> From: Peter Xu <address@hidden>
> Sent: Monday, April 1, 2019 5:47 AM
> To: Elijah Shakkour <address@hidden>
> Cc: Knut Omang <address@hidden>; Michael S. Tsirkin
> <address@hidden>; Alex Williamson <address@hidden>;
> Marcel Apfelbaum <address@hidden>; Stefan Hajnoczi
> <address@hidden>; address@hidden
> Subject: Re: QEMU and vIOMMU support for emulated VF passthrough to
> nested (L2) VM
> 
> On Sun, Mar 31, 2019 at 11:15:00AM +0000, Elijah Shakkour wrote:
> 
> [...]
> 
> > I didn't have DMA nor MMIO read/write working with my old command
> line.
> > But, when I removed all CPU flags and only provided "-cpu host", I see that
> MMIO works.
> > Still, DMA read/write from emulated device doesn't work for VF. For
> example:
> > Driver provides me a buffer pointer through MMIO write, this address
> (pointer) is GPA of L2, and when I try to call pci_dma_read() with this 
> address
> I get:
> > "
> > Unassigned mem read 0000000000000000
> > "
> 
> I don't know where this error log was dumped but if it's during DMA then I
> agree it can probably be related to vIOMMU.
> 

This log is dumped from:
memory.c: unassigned_mem_read()

> > As I said, my problem now is in translation of L2 GPA provided by driver,
> when I call DMA read/write for this address from VF.
> > Any insights?
> 
> I just noticed that you were using QEMU 2.12 [1].  If that's the case, please
> rebase to the latest QEMU, at least >=3.0 because there's major refactor of
> the shadow logic during 3.0 devel cycle AFAICT.
> 

Rebased to QEMU 3.1
Now I see the address I'm trying to read from in log but still same error:
"
Unassigned mem read 00000000f0481000
"
What do you suggest?

> > > > > > > > I'm using Knut Omang SRIOV patches rebased to QEMU v2.12.
> 
> [1]
> 
> Regards,
> 
> --
> Peter Xu