Re: [PATCH 0/7] arm64/boot: Enable EL2 requirements for FEAT_PMUv3p9

[Catalin Marinas <catalin.marinas@arm.com>]

On Tue, Jan 28, 2025 at 02:41:17PM +0530, Anshuman Khandual wrote:
> On 1/18/25 03:37, Rob Herring wrote:
> > On Thu, Jan 16, 2025 at 9:32 AM Catalin Marinas <catalin.marinas@arm.com> wrote:
> >>
> >> On Wed, Jan 08, 2025 at 07:47:16AM -0600, Rob Herring wrote:
> >>> On Wed, Jan 8, 2025 at 5:15 AM Marc Zyngier <maz@kernel.org> wrote:
> >>>> On Tue, 07 Jan 2025 22:13:47 +0000,
> >>>> Rob Herring <robh@kernel.org> wrote:
> >>>>> On Tue, Jan 7, 2025 at 6:13 AM Catalin Marinas <catalin.marinas@arm.com> wrote:
> >>>>>> But does KVM actually expose the feature to EL1 in ID_AA64DFR1_EL1 and
> >>>>>> than traps it at EL2?
> >>>>>
> >>>>> As Marc pointed out KVM only advertises PMUv3.8. Regardless, guest
> >>>>> accesses to these registers are trapped with or without this series.
> >>>>
> >>>> And most probably generates a nice splat in the kernel log, as nobody
> >>>> updated KVM to handle *correctly* PMICNTR_EL0 traps, let alone deal
> >>>> with the FGT2 registers.
> >>>
> >>> Isn't that this series[1]? Should that have come first, I guess I know
> >>> that *now*.
> >> [...]
> >>> [1] https://lore.kernel.org/all/20241210055311.780688-1-anshuman.khandual@arm.com/
> >>
> >> It's not any clearer to me. Does this series depend on the 46-patch one?
> >> Or, if we had the other, is this no longer needed? Or none of these,
> >> they are independent.
> > 
> > They are independent. I think ideally we'd want everything landing at
> > the same time, but we're past ideal at this point. Without this
> > series, if someone uses PMU on v8.9 and firmware enabled FGT2, then
> > the kernel will crash. Without the above series, KVM will have
> > warnings in the kernel log, but otherwise function.
> 
> Right, they are independent. Just that Rob had observed this PMU v3.8 boot
> requirement while reviewing the HW breakpoint series earlier. I should just
> respin this series after the upcoming v6.14-rc1 release is out ?

They may apply cleanly but please do rebase and repost at -rc1. Thanks.

-- 
Catalin