On Tue, May 03, 2022 at 10:14:24PM +0100, Marc Zyngier wrote:
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.
Fixes: 562e530fd770 ("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