Hi Marc, > On 6 Mar 2023, at 13:32, Marc Zyngier <m...@kernel.org> wrote: > > On Mon, 06 Mar 2023 14:02:33 +0000, > Peter Maydell <peter.mayd...@linaro.org> wrote: >> >> On Mon, 27 Feb 2023 at 16:37, Miguel Luis <miguel.l...@oracle.com> wrote: >>> >>> From: Haibo Xu <haibo...@linaro.org> >>> >>> Use the VGIC maintenance IRQ if VHE is requested. As per the ARM GIC >>> Architecture Specification for GICv3 and GICv4 Arm strongly recommends that >>> maintenance interrupts are configured to use INTID 25 matching the >>> Server Base System Architecture (SBSA) recomendation. >> >> What does this mean for QEMU, though? If the issue is >> "KVM doesn't support the maintenance interrupt being anything >> other than INTID 25" then we should say so (and have our code >> error out if the board tries to use some other value). > > No, KVM doesn't give two hoots about the INTID, as long as this is a > PPI that is otherwise unused. > >> If the >> issue is "the *host* has to be using the right INTID" then I >> would hope that KVM simply doesn't expose the capability if >> the host h/w won't let it work correctly. > > No host maintenance interrupt, no NV. This is specially mandatory as > the L1 guest is in (almost) complete control of the ICH_*_EL2 > registers and expects MIs to be delivered. > >> If KVM can happily >> use any maintenance interrupt ID that the board model wants, >> then we should make that work, rather than hardcoding 25 into >> our gicv3 code. > > +1. > > I'd eliminate any reference to SBSA, as it has no bearing on either > KVM nor the QEMU GIC code. > > I also question the "if VHE is requested". Not having VHE doesn't > preclude virtualisation. Was that supposed to be "virtualisation > extension" instead? >
s/VHE/virtualization extension/ I’ve noted it has been a recurring confusion on my part. Will fix. :) Thank you, Miguel > Thanks, > > M. > > -- > Without deviation from the norm, progress is not possible.
