Re: [PATCH v3] arm64: mpam: Document when to set arm64.nompam

[Catalin Marinas]

On Tue, 08 Sep 2026 15:56:22 +0100, Fuad Tabba wrote:
> arm64.nompam skips the MPAM2_EL2 and MPAMHCR_EL2 writes in
> finalise_el2_state and leaves the ARM64_MPAM cpucap unset. Where EL3
> firmware has cleared MPAM3_EL3.TRAPLOWER, the EL2 trap controls are
> left unwritten, at reset values that are UNKNOWN, and KVM still hides
> MPAM from the guest but no longer enables the traps that stop a guest
> from using it. KVM never saves or restores MPAM0_EL1, MPAM1_EL1 and
> MPAMSM_EL1, so what one guest writes reaches the next guest and the
> host. Nor can the kernel make the EL2 writes unconditionally: they trap
> to EL3 on the firmware the option exists for, and TRAPLOWER cannot be
> read below EL3.
> 
> [...]

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

[1/1] arm64: mpam: Document when to set arm64.nompam
      https://git.kernel.org/arm64/c/eb0fde98fee4

(and this wasn't a pure mpam patch, should have picked it directly ;))