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

[Peter Xu]

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.

> 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.

> > > > > > > I'm using Knut Omang SRIOV patches rebased to QEMU v2.12.

[1]

Regards,

-- 
Peter Xu