On 08/10/2025 1:08 pm, Jan Beulich wrote:
> In preparation to add support for the CMCI LVT, which is discontiguous to
> the other LVTs, add a level of indirection.

It's not the only extra LVT.

AMD have Extended LVTs, which are necessary if we want to get virt-PMU
working.

https://sandpile.org/x86/apic.htm is a recent addition which covers all
of this.

>  Rename the prior
> vlapic_lvt_mask[] while doing so (as subsequently a 2nd array will want
> adding, for use by guest_wrmsr_x2apic()).
>
> Signed-off-by: Jan Beulich <[email protected]>

I'm afraid this introduces a vulnerability.

APIC_LVR is a toolstack-provided value.  Nothing bounds checks the
MAX_LVT value in it AFAICT, and previously this did not matter (from a
security point of view at least) because the loop bounds were constant.

~Andrew

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