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Re: [Qemu-arm] [PATCH v4 0/3] Generic PCIe host bridge INTx determinatio


From: Peter Maydell
Subject: Re: [Qemu-arm] [PATCH v4 0/3] Generic PCIe host bridge INTx determination for INTx routing
Date: Thu, 14 Sep 2017 16:06:10 +0100

On 13 September 2017 at 10:46, Eric Auger <address@hidden> 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/v2.10.0-gpex-v4
>
> References:
> [1] Generic PCIe host bridge INTx determination for INTx routing
>    https://lists.gnu.org/archive/html/qemu-devel/2015-09/msg04975.html

Applied to target-arm.next, thanks.

-- PMM



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