[PATCH] KVM: arm64: Check cpu_has_spe() before initializing PMSCR_EL1 in VHE

[Mukesh Ojha]

On Wed, Oct 08, 2025 at 01:40:40PM +0100, Leo Yan wrote:
> On Wed, Oct 08, 2025 at 11:46:55AM +0100, Marc Zyngier wrote:
> 
> [...]
> 
> > > > Lets guard the change with cpu_has_spe() check so that it only affects
> > > > the cpu which has SPE feature supported.
> > > 
> > > This could benefit from being spelled out a bit more. In both cases we
> > > check for the presence of FEAT_SPE, however I believe the issue you
> > > observe is EL3 hasn't delegated ownership of the Profiling Buffer to
> > > Non-secure nor does it reinject an UNDEF in response to the sysreg trap.
> > > 
> > > I agree that the change is correct but the rationale needs to be clear.
> > 
> > To me, this smells a lot more like some sort of papering over a
> > firmware bug. Why isn't SPE available the first place?
> 
> TF-a grants permission to non-secure world [1], only access from secure
> world or realm will trap to EL3.
> 
> So yes, it would be good to check if any issue in firmware.

We have our own implementation of EL3 and not using TF-A.

I believe, we should check in a similar way as we are doing for nVHE
case.

if (host_data_test_flag(HAS_SPE))
	write_sysreg_el1(0, SYS_PMSCR);

> 
> Thanks,
> Leo
> 
> [1] https://git.trustedfirmware.org/plugins/gitiles/TF-A/trusted-firmware-a.git/+/refs/heads/master/lib/extensions/spe/spe.c#52

-- 
-Mukesh Ojha