Re: [PATCH] KVM: arm64: nv: Return correct RES0 bits for FGT registers

On Wed, 21 Jan 2026 10:16:31 +0000,
Zenghui Yu [off-list ref] wrote:

From: "Zenghui Yu (Huawei)" <redacted>

We had extended the sysreg masking infrastructure to more general
registers, instead of restricting it to VNCR-backed registers, since
commit a0162020095e ("KVM: arm64: Extend masking facility to arbitrary
registers"). Fix kvm_get_sysreg_res0() to reflect this fact.

Huh, what a howler! Thanks a lot for spotting this!

Note that we're sure that we only deal with FGT registers in
kvm_get_sysreg_res0(), the

	if (sr < __VNCR_START__)

is actually a never false, which should probably be removed later.

I think the biggest mistake is to have several places where we perform
sysreg index to array index conversions. We should try to unify that.

Fixes: 69c19e047dfe ("KVM: arm64: Add TCR2_EL2 to the sysreg arrays")
Signed-off-by: Zenghui Yu (Huawei) <redacted>

Cc: stable@vger.kernel.org

Thanks again,

	M.

-- 
Without deviation from the norm, progress is not possible.