[PATCH 6/8] KVM: arm64: Remove dead PMU sysreg decoding code
Marc Zyngier
maz at kernel.org
Thu Nov 26 10:34:14 EST 2020
Hi Alex,
On 2020-11-26 15:18, Alexandru Elisei wrote:
> Hi Marc,
>
> I checked and indeed the remaining cases cover all registers that use
> this accessor.
>
> However, I'm a bit torn here. The warning that I got when trying to run
> a guest
> with the PMU feature flag set, but not initialized (reported at [1])
> was also not
> supposed to ever be reached:
>
> static u32 kvm_pmu_event_mask(struct kvm *kvm)
> {
> switch (kvm->arch.pmuver) {
> case 1: /* ARMv8.0 */
> return GENMASK(9, 0);
> case 4: /* ARMv8.1 */
> case 5: /* ARMv8.4 */
> case 6: /* ARMv8.5 */
> return GENMASK(15, 0);
> default: /* Shouldn't be here, just for sanity */
> WARN_ONCE(1, "Unknown PMU version %d\n", kvm->arch.pmuver);
> return 0;
> }
> }
>
> I realize it's not exactly the same thing and I'll leave it up to you
> if you want
> to add a warning for the cases that should never happen. I'm fine
> either way:
I already have queued such a warning[1]. It turns out that LLVM warns
idx can be left uninitialized, and shouts. Let me know if that works
for you.
Thanks,
M.
[1]
https://git.kernel.org/pub/scm/linux/kernel/git/maz/arm-platforms.git/commit/?h=kvm-arm64/pmu-undef&id=af7eff70eaf8f28179334f5aeabb70a306242c83
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