The GIC_MIN_BPR constant defines the minimum BPR value that the TCG
emulated GICv3 supports. We're currently using this also as the
value we reset the KVM GICv3 ICC_BPR registers to, but this is only
right by accident.
We want to make the emulated GICv3 use a configurable number of
priority bits, which means that GIC_MIN_BPR will no longer be a
constant. Replace the uses in the KVM reset code with literal 0,
plus a constant explaining why this is reasonable.
Signed-off-by: Peter Maydell <peter.mayd...@linaro.org>
---
hw/intc/arm_gicv3_kvm.c | 16 +++++++++++++---
1 file changed, 13 insertions(+), 3 deletions(-)
diff --git a/hw/intc/arm_gicv3_kvm.c b/hw/intc/arm_gicv3_kvm.c
index 2922c516e56..3ca643ecba4 100644
--- a/hw/intc/arm_gicv3_kvm.c
+++ b/hw/intc/arm_gicv3_kvm.c
@@ -673,9 +673,19 @@ static void arm_gicv3_icc_reset(CPUARMState *env, const
ARMCPRegInfo *ri)
s = c->gic;
c->icc_pmr_el1 = 0;
- c->icc_bpr[GICV3_G0] = GIC_MIN_BPR;
- c->icc_bpr[GICV3_G1] = GIC_MIN_BPR;
- c->icc_bpr[GICV3_G1NS] = GIC_MIN_BPR;
+ /*
+ * Architecturally the reset value of the ICC_BPR registers
+ * is UNKNOWN. We set them all to 0 here; when the kernel
+ * uses these values to program the ICH_VMCR_EL2 fields that
+ * determine the guest-visible ICC_BPR register values, the
+ * hardware's "writing a value less than the minimum sets
+ * the field to the minimum value" behaviour will result in
+ * them effectively resetting to the correct minimum value
+ * for the host GIC.
+ */
+ c->icc_bpr[GICV3_G0] = 0;
+ c->icc_bpr[GICV3_G1] = 0;
+ c->icc_bpr[GICV3_G1NS] = 0;
c->icc_sre_el1 = 0x7;
memset(c->icc_apr, 0, sizeof(c->icc_apr));
--
2.25.1
