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Re: PCI devices passthrough on Arm design proposal


On 17/07/2020 17:05, Roger Pau Monné wrote:
IIRC Julien even said that Arm was likely to require much less traps
than x86 for accesses to MSI and MSI-X since you could allow untrusted
guests to write directly to the registers as there's another piece of
hardware that would already translate the interrupts?

This is correct in the case of the ITS. This is because the hardware will tag the message with the deviceÌD. So there is no way to spoof it.

However, this may not be the case of other MSI controllers. For instance, in the case of the GICv2m, I think we will need to trap and sanitize the MSI message (see [1]).

[1] https://www.linaro.org/blog/kvm-pciemsi-passthrough-armarm64/

Julien Grall



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