[PATCH v1] arm64/boot: Disable trapping of PMZR_EL0 writes to EL2

[Will Deacon]

On Tue, 22 Sep 2026 19:14:30 +0100, Fuad Tabba wrote:
> __init_el2_fgt2() writes one mask to both HDFGRTR2_EL2 and HDFGWTR2_EL2.
> PMZR_EL0 is write-only, so its trap bit, nPMZR_EL0, exists only in
> HDFGWTR2_EL2 and is therefore never set: a PMZR_EL0 write from the host
> traps to EL2, where the nVHE hypervisor has no handler and BUG()s. The
> kernel never writes PMZR_EL0, but kernel.perf_user_access=1 has the PMU
> driver set PMUSERENR_EL0.UEN for a task with a user-read event, so a
> write from EL0 reaches the trap and takes the host down without a panic
> message.
> 
> [...]

Applied to arm64 (for-next/fixes), thanks!

[1/1] arm64/boot: Disable trapping of PMZR_EL0 writes to EL2
      https://git.kernel.org/arm64/c/2bc6b218717b

Cheers,
-- 
Will

https://fixes.arm64.dev
https://next.arm64.dev
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