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When adding support for the slightly wonky Apple M1, we had to populate ID_AA64PFR0_EL1.GIC==1 to present something to the guest, as the HW itself doesn't advertise the feature. However, we gated this on the in-kernel irqchip being created. This causes some trouble for QEMU, which snapshots the state of the registers before creating a virtual GIC, and then tries to restore these registers once the GIC has been created. Obviously, between the two stages, ID_AA64PFR0_EL1.GIC has changed value, and the write fails. The fix is to actually emulate the HW, and always populate the field if the HW is capable of it. Bug: 254441685 Fixes:562e530fd7("KVM: arm64: Force ID_AA64PFR0_EL1.GIC=1 when exposing a virtual GICv3") Cc: stable@vger.kernel.org Signed-off-by: Marc Zyngier <maz@kernel.org> Reported-by: Peter Maydell <peter.maydell@linaro.org> Reviewed-by: Oliver Upton <oupton@google.com> Link: https://lore.kernel.org/r/20220503211424.3375263-1-maz@kernel.org (cherry picked from commit5163373af1) Signed-off-by: Lee Jones <joneslee@google.com> Change-Id: I8126f08ac61896bb5b2982257ad3ecc7d1a1a423