diff mbox series

[PULL,2/8] hw/intc/arm_gicv3: ICC_PMR_EL1 high bits should be RAZ

Message ID 20231121102441.3872902-3-peter.maydell@linaro.org
State Accepted
Commit 70726a15bc7e61d16f3efe5bfd9b061ca077f533
Headers show
Series [PULL,1/8] target/arm: enable FEAT_RNG on Neoverse-N2 | expand

Commit Message

Peter Maydell Nov. 21, 2023, 10:24 a.m. UTC 
From: Ben Dooks <ben.dooks@codethink.co.uk>

The ICC_PMR_ELx and ICV_PMR_ELx bit masks returned from
ic{c,v}_fullprio_mask should technically also remove any
bit above 7 as these are marked reserved (read 0) and should
therefore should not be written as anything other than 0.

This was noted during a run of a proprietary test system and
discused on the mailing list [1] and initially thought not to
be an issue due to RES0 being technically allowed to be
written to and read back as long as the implementation does
not use the RES0 bits. It is very possible that the values
are used in comparison without masking, as pointed out by
Peter in [2], if (cs->hppi.prio >= cs->icc_pmr_el1) may well
do the wrong thing.

Masking these values in ic{c,v}_fullprio_mask() should fix
this and prevent any future problems with playing with the
values.

[1]: https://lists.nongnu.org/archive/html/qemu-arm/2023-11/msg00607.html
[2]: https://lists.nongnu.org/archive/html/qemu-arm/2023-11/msg00737.html

Signed-off-by: Ben Dooks <ben.dooks@codethink.co.uk>
Message-id: 20231116172818.792364-1-ben.dooks@codethink.co.uk
Suggested-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
---
 hw/intc/arm_gicv3_cpuif.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)
diff mbox series

Patch

diff --git a/hw/intc/arm_gicv3_cpuif.c b/hw/intc/arm_gicv3_cpuif.c
index d07b13eb270..ab1a00508e6 100644
--- a/hw/intc/arm_gicv3_cpuif.c
+++ b/hw/intc/arm_gicv3_cpuif.c
@@ -146,7 +146,7 @@  static uint32_t icv_fullprio_mask(GICv3CPUState *cs)
      * with the group priority, whose mask depends on the value of VBPR
      * for the interrupt group.)
      */
-    return ~0U << (8 - cs->vpribits);
+    return (~0U << (8 - cs->vpribits)) & 0xff;
 }
 
 static int ich_highest_active_virt_prio(GICv3CPUState *cs)
@@ -803,7 +803,7 @@  static uint32_t icc_fullprio_mask(GICv3CPUState *cs)
      * with the group priority, whose mask depends on the value of BPR
      * for the interrupt group.)
      */
-    return ~0U << (8 - cs->pribits);
+    return (~0U << (8 - cs->pribits)) & 0xff;
 }
 
 static inline int icc_min_bpr(GICv3CPUState *cs)