[v3] Generic PCIe host bridge INTx determination for INTx routing

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

Posted by Eric Auger 8 years, 3 months ago

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.

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(+)

-- 
2.5.5

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

Posted by Auger Eric 8 years, 2 months ago

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(+)
>

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

Posted by Feng Kan via Qemu-devel 8 years, 2 months ago

On Jul 9, 2017 2:04 PM, "Eric Auger" <eric.auger@redhat.com> 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.

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(+)

--
2.5.5

Tested-by: Feng Kan <fkan@apm.com>

Works for APM XGene systems.
Thanks!