[Qemu-devel] [PATCH 15/24] target-arm: Implement AArch64 memory attribute registers

[Peter Maydell <peter.maydell@linaro.org>]

Implement the AArch64 memory attribute registers. Since QEMU doesn't
model caches it does not need to care about memory attributes at all,
and we can simply make these read-as-written.

We did not previously implement the AArch32 versions of the MAIR
registers, which went unnoticed because of the overbroad TLB_LOCKDOWN
reginfo definition; provide them now to keep the 64<->32 register
relationship clear.

We already provided AMAIR registers for 32 bit as simple RAZ/WI;
extend that to provide a 64 bit RAZ/WI AMAIR_EL1.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
---
 target-arm/cpu.h    |  3 +++
 target-arm/helper.c | 24 +++++++++++++++++++++++-
 2 files changed, 26 insertions(+), 1 deletion(-)

diff --git a/target-arm/cpu.h b/target-arm/cpu.h
index 2e04a6d..c8b6cdb 100644
--- a/target-arm/cpu.h
+++ b/target-arm/cpu.h
@@ -74,8 +74,10 @@
  */
 #ifdef HOST_WORDS_BIGENDIAN
 #define offsetoflow32(S, M) (offsetof(S, M) + sizeof(uint32_t))
+#define offsetofhigh32(S, M) offsetof(S, M)
 #else
 #define offsetoflow32(S, M) offsetof(S, M)
+#define offsetofhigh32(S, M) (offsetof(S, M) + sizeof(uint32_t))
 #endif
 
 /* Meanings of the ARMCPU object's two inbound GPIO lines */
@@ -197,6 +199,7 @@ typedef struct CPUARMState {
         uint32_t c9_pmxevtyper; /* perf monitor event type */
         uint32_t c9_pmuserenr; /* perf monitor user enable */
         uint32_t c9_pminten; /* perf monitor interrupt enables */
+        uint64_t mair_el1;
         uint32_t c12_vbar; /* vector base address register */
         uint32_t c13_fcse; /* FCSE PID.  */
         uint32_t c13_context; /* Context ID.  */
diff --git a/target-arm/helper.c b/target-arm/helper.c
index 69cce6f..d03c0cd 100644
--- a/target-arm/helper.c
+++ b/target-arm/helper.c
@@ -688,6 +688,26 @@ static const ARMCPRegInfo v7_cp_reginfo[] = {
      */
     { .name = "AIDR", .cp = 15, .crn = 0, .crm = 0, .opc1 = 1, .opc2 = 7,
       .access = PL1_R, .type = ARM_CP_CONST, .resetvalue = 0 },
+    /* MAIR can just read-as-written because we don't implement caches
+     * and so don't need to care about memory attributes.
+     */
+    { .name = "MAIR_EL1", .state = ARM_CP_STATE_AA64,
+      .opc0 = 3, .opc1 = 0, .crn = 10, .crm = 2, .opc2 = 0,
+      .access = PL1_RW, .fieldoffset = offsetof(CPUARMState, cp15.mair_el1),
+      .resetvalue = 0 },
+    /* For non-long-descriptor page tables these are PRRR and NMRR;
+     * regardless they still act as reads-as-written for QEMU.
+     * The override is necessary because of the overly-broad TLB_LOCKDOWN
+     * definition.
+     */
+    { .name = "MAIR0", .state = ARM_CP_STATE_AA32, .type = ARM_CP_OVERRIDE,
+      .cp = 15, .opc1 = 0, .crn = 10, .crm = 2, .opc2 = 0, .access = PL1_RW,
+      .fieldoffset = offsetoflow32(CPUARMState, cp15.mair_el1),
+      .resetfn = arm_cp_reset_ignore },
+    { .name = "MAIR1", .state = ARM_CP_STATE_AA32, .type = ARM_CP_OVERRIDE,
+      .cp = 15, .opc1 = 0, .crn = 10, .crm = 2, .opc2 = 1, .access = PL1_RW,
+      .fieldoffset = offsetofhigh32(CPUARMState, cp15.mair_el1),
+      .resetfn = arm_cp_reset_ignore },
     REGINFO_SENTINEL
 };
 
@@ -1538,9 +1558,11 @@ static const ARMCPRegInfo lpae_cp_reginfo[] = {
     /* NOP AMAIR0/1: the override is because these clash with the rather
      * broadly specified TLB_LOCKDOWN entry in the generic cp_reginfo.
      */
-    { .name = "AMAIR0", .cp = 15, .crn = 10, .crm = 3, .opc1 = 0, .opc2 = 0,
+    { .name = "AMAIR0", .state = ARM_CP_STATE_BOTH,
+      .opc0 = 3, .crn = 10, .crm = 3, .opc1 = 0, .opc2 = 0,
       .access = PL1_RW, .type = ARM_CP_CONST | ARM_CP_OVERRIDE,
       .resetvalue = 0 },
+    /* AMAIR1 is mapped to AMAIR_EL1[63:32] */
     { .name = "AMAIR1", .cp = 15, .crn = 10, .crm = 3, .opc1 = 0, .opc2 = 1,
       .access = PL1_RW, .type = ARM_CP_CONST | ARM_CP_OVERRIDE,
       .resetvalue = 0 },
-- 
1.8.5