Re: [Qemu-devel] [PATCH RESEND v3 0/3] Generic PCIe host bridge INTx determination for INTx routing

[Auger Eric]

Hi,

On 09/07/2017 23:02, Eric Auger wrote:
> This series implements INTx to gsi routing for ARM VIRT/Gpex. This is
> a respin of [1] which was lost in limbo.
> 
> ARM virt uses GPEX PCIe bridge. This latter does not implement INTx
> to GSI routing. PCIe/INTx assignment works but the consequence is
> irqfd is not used along with INTx interrupts and VFIO INTx handlers
> are executed on userspace leading to an important performance degradation.
> 
> This issue is witnessed by the following messages;
> 
> qemu-system-aarch64: -device vfio-pci,host=0006:90:00.0: PCI: Bug -
> unimplemented PCI INTx routing (gpex-pcihost)
> qemu-system-aarch64: PCI: Bug - unimplemented PCI INTx routing (gpex-pcihost)
> qemu-system-aarch64: PCI: Bug - unimplemented PCI INTx routing (gpex-pcihost)
> 
> So with this series, irqfd is set up for PCIe/INTx passthrough and we get
> the optimal performance. Also we get rid of the above messages.

If I haven't missed anything, I have not received any comment on this
series despite ping and resend since mid June. Now most of the 2.10 rush
is behind, please can anyone have a look?

The BUG message hits when your assign a PF and performance is largely
decreased whenever INTx are used during passthrough.

Thanks

Eric
> 
> This series can be found at:
> https://github.com/eauger/qemu/tree/v2.9-gpex-intx-v3
> 
> References:
> [1] Generic PCIe host bridge INTx determination for INTx routing
>    https://lists.gnu.org/archive/html/qemu-devel/2015-09/msg04975.html
> 
> 
> Pranavkumar Sawargaonkar (3):
>   hw/pci-host/gpex: Set INTx index/gsi mapping
>   hw/arm/virt: Set INTx/gsi mapping
>   hw/pci-host/gpex: Implement PCI INTx routing
> 
>  hw/arm/virt.c              |  4 ++++
>  hw/pci-host/gpex.c         | 22 ++++++++++++++++++++++
>  include/hw/pci-host/gpex.h |  3 +++
>  3 files changed, 29 insertions(+)
>