diff mbox series

[PULL,05/27] hw/intc/arm_gicv3_cpuif: Fix priority masking for NS BPR1

Message ID 1496337035-30213-6-git-send-email-peter.maydell@linaro.org
State Accepted
Commit a89ff39ee9016613356677941d8f70be40e06cc3
Headers show
Series target-arm queue | expand

Commit Message

Peter Maydell June 1, 2017, 5:10 p.m. UTC 
When we calculate the mask to use to get the group priority from
an interrupt priority, the way that NS BPR1 is handled differs
from how BPR0 and S BPR1 work -- a BPR1 value of 1 means
the group priority is in bits [7:1], whereas for BPR0 and S BPR1
this is indicated by a 0 BPR value.

Subtract 1 from the BPR value before creating the mask if
we're using the NS BPR value, for both hardware and virtual
interrupts, as the GICv3 pseudocode does, and fix the comments
accordingly.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>

Message-id: 1493226792-3237-4-git-send-email-peter.maydell@linaro.org
---
 hw/intc/arm_gicv3_cpuif.c | 42 ++++++++++++++++++++++++++++++++++++++----
 1 file changed, 38 insertions(+), 4 deletions(-)

-- 
2.7.4
diff mbox series

Patch

diff --git a/hw/intc/arm_gicv3_cpuif.c b/hw/intc/arm_gicv3_cpuif.c
index e660b3f..09d8ba0 100644
--- a/hw/intc/arm_gicv3_cpuif.c
+++ b/hw/intc/arm_gicv3_cpuif.c
@@ -216,18 +216,35 @@  static uint32_t icv_gprio_mask(GICv3CPUState *cs, int group)
 {
     /* Return a mask word which clears the subpriority bits from
      * a priority value for a virtual interrupt in the specified group.
-     * This depends on the VBPR value:
+     * This depends on the VBPR value.
+     * If using VBPR0 then:
      *  a BPR of 0 means the group priority bits are [7:1];
      *  a BPR of 1 means they are [7:2], and so on down to
      *  a BPR of 7 meaning no group priority bits at all.
+     * If using VBPR1 then:
+     *  a BPR of 0 is impossible (the minimum value is 1)
+     *  a BPR of 1 means the group priority bits are [7:1];
+     *  a BPR of 2 means they are [7:2], and so on down to
+     *  a BPR of 7 meaning the group priority is [7].
+     *
      * Which BPR to use depends on the group of the interrupt and
      * the current ICH_VMCR_EL2.VCBPR settings.
+     *
+     * This corresponds to the VGroupBits() pseudocode.
      */
+    int bpr;
+
     if (group == GICV3_G1NS && cs->ich_vmcr_el2 & ICH_VMCR_EL2_VCBPR) {
         group = GICV3_G0;
     }
 
-    return ~0U << (read_vbpr(cs, group) + 1);
+    bpr = read_vbpr(cs, group);
+    if (group == GICV3_G1NS) {
+        assert(bpr > 0);
+        bpr--;
+    }
+
+    return ~0U << (bpr + 1);
 }
 
 static bool icv_hppi_can_preempt(GICv3CPUState *cs, uint64_t lr)
@@ -674,20 +691,37 @@  static uint32_t icc_gprio_mask(GICv3CPUState *cs, int group)
 {
     /* Return a mask word which clears the subpriority bits from
      * a priority value for an interrupt in the specified group.
-     * This depends on the BPR value:
+     * This depends on the BPR value. For CBPR0 (S or NS):
      *  a BPR of 0 means the group priority bits are [7:1];
      *  a BPR of 1 means they are [7:2], and so on down to
      *  a BPR of 7 meaning no group priority bits at all.
+     * For CBPR1 NS:
+     *  a BPR of 0 is impossible (the minimum value is 1)
+     *  a BPR of 1 means the group priority bits are [7:1];
+     *  a BPR of 2 means they are [7:2], and so on down to
+     *  a BPR of 7 meaning the group priority is [7].
+     *
      * Which BPR to use depends on the group of the interrupt and
      * the current ICC_CTLR.CBPR settings.
+     *
+     * This corresponds to the GroupBits() pseudocode.
      */
+    int bpr;
+
     if ((group == GICV3_G1 && cs->icc_ctlr_el1[GICV3_S] & ICC_CTLR_EL1_CBPR) ||
         (group == GICV3_G1NS &&
          cs->icc_ctlr_el1[GICV3_NS] & ICC_CTLR_EL1_CBPR)) {
         group = GICV3_G0;
     }
 
-    return ~0U << ((cs->icc_bpr[group] & 7) + 1);
+    bpr = cs->icc_bpr[group] & 7;
+
+    if (group == GICV3_G1NS) {
+        assert(bpr > 0);
+        bpr--;
+    }
+
+    return ~0U << (bpr + 1);
 }
 
 static bool icc_no_enabled_hppi(GICv3CPUState *cs)