[Qemu-devel] [PULL 13/20] target-arm: Implement MDCR_EL3.TPM and MDCR_EL2.TPM traps

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

Implement the performance monitor register traps controlled
by MDCR_EL3.TPM and MDCR_EL2.TPM. Most of the performance
registers already have an access function to deal with the
user-enable bit, and the TPM checks can be added there. We
also need a new access function which only implements the
TPM checks for use by the few not-EL0-accessible registers
and by PMUSERENR_EL0 (which is always EL0-readable).

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Message-id: 1455892784-11328-3-git-send-email-peter.maydell@linaro.org
Reviewed-by: Sergey Fedorov <serge.fdrv@gmail.com>
Acked-by: Alistair Francis <alistair.francis@xilinx.com>
---
 target-arm/helper.c | 43 ++++++++++++++++++++++++++++++++++++-------
 1 file changed, 36 insertions(+), 7 deletions(-)

diff --git a/target-arm/helper.c b/target-arm/helper.c
index e9b89e6..ef3f1ce 100644
--- a/target-arm/helper.c
+++ b/target-arm/helper.c
@@ -439,6 +439,24 @@ static CPAccessResult access_tda(CPUARMState *env, const ARMCPRegInfo *ri,
     return CP_ACCESS_OK;
 }
 
+/* Check for traps to performance monitor registers, which are controlled
+ * by MDCR_EL2.TPM for EL2 and MDCR_EL3.TPM for EL3.
+ */
+static CPAccessResult access_tpm(CPUARMState *env, const ARMCPRegInfo *ri,
+                                 bool isread)
+{
+    int el = arm_current_el(env);
+
+    if (el < 2 && (env->cp15.mdcr_el2 & MDCR_TPM)
+        && !arm_is_secure_below_el3(env)) {
+        return CP_ACCESS_TRAP_EL2;
+    }
+    if (el < 3 && (env->cp15.mdcr_el3 & MDCR_TPM)) {
+        return CP_ACCESS_TRAP_EL3;
+    }
+    return CP_ACCESS_OK;
+}
+
 static void dacr_write(CPUARMState *env, const ARMCPRegInfo *ri, uint64_t value)
 {
     ARMCPU *cpu = arm_env_get_cpu(env);
@@ -774,11 +792,22 @@ static CPAccessResult pmreg_access(CPUARMState *env, const ARMCPRegInfo *ri,
                                    bool isread)
 {
     /* Performance monitor registers user accessibility is controlled
-     * by PMUSERENR.
+     * by PMUSERENR. MDCR_EL2.TPM and MDCR_EL3.TPM allow configurable
+     * trapping to EL2 or EL3 for other accesses.
      */
-    if (arm_current_el(env) == 0 && !env->cp15.c9_pmuserenr) {
+    int el = arm_current_el(env);
+
+    if (el == 0 && !env->cp15.c9_pmuserenr) {
         return CP_ACCESS_TRAP;
     }
+    if (el < 2 && (env->cp15.mdcr_el2 & MDCR_TPM)
+        && !arm_is_secure_below_el3(env)) {
+        return CP_ACCESS_TRAP_EL2;
+    }
+    if (el < 3 && (env->cp15.mdcr_el3 & MDCR_TPM)) {
+        return CP_ACCESS_TRAP_EL3;
+    }
+
     return CP_ACCESS_OK;
 }
 
@@ -1101,28 +1130,28 @@ static const ARMCPRegInfo v7_cp_reginfo[] = {
       .access = PL0_RW, .type = ARM_CP_CONST, .resetvalue = 0,
       .accessfn = pmreg_access },
     { .name = "PMUSERENR", .cp = 15, .crn = 9, .crm = 14, .opc1 = 0, .opc2 = 0,
-      .access = PL0_R | PL1_RW,
+      .access = PL0_R | PL1_RW, .accessfn = access_tpm,
       .fieldoffset = offsetof(CPUARMState, cp15.c9_pmuserenr),
       .resetvalue = 0,
       .writefn = pmuserenr_write, .raw_writefn = raw_write },
     { .name = "PMUSERENR_EL0", .state = ARM_CP_STATE_AA64,
       .opc0 = 3, .opc1 = 3, .crn = 9, .crm = 14, .opc2 = 0,
-      .access = PL0_R | PL1_RW, .type = ARM_CP_ALIAS,
+      .access = PL0_R | PL1_RW, .accessfn = access_tpm, .type = ARM_CP_ALIAS,
       .fieldoffset = offsetof(CPUARMState, cp15.c9_pmuserenr),
       .resetvalue = 0,
       .writefn = pmuserenr_write, .raw_writefn = raw_write },
     { .name = "PMINTENSET", .cp = 15, .crn = 9, .crm = 14, .opc1 = 0, .opc2 = 1,
-      .access = PL1_RW,
+      .access = PL1_RW, .accessfn = access_tpm,
       .fieldoffset = offsetof(CPUARMState, cp15.c9_pminten),
       .resetvalue = 0,
       .writefn = pmintenset_write, .raw_writefn = raw_write },
     { .name = "PMINTENCLR", .cp = 15, .crn = 9, .crm = 14, .opc1 = 0, .opc2 = 2,
-      .access = PL1_RW, .type = ARM_CP_ALIAS,
+      .access = PL1_RW, .accessfn = access_tpm, .type = ARM_CP_ALIAS,
       .fieldoffset = offsetof(CPUARMState, cp15.c9_pminten),
       .writefn = pmintenclr_write, },
     { .name = "PMINTENCLR_EL1", .state = ARM_CP_STATE_AA64,
       .opc0 = 3, .opc1 = 0, .crn = 9, .crm = 14, .opc2 = 2,
-      .access = PL1_RW, .type = ARM_CP_ALIAS,
+      .access = PL1_RW, .accessfn = access_tpm, .type = ARM_CP_ALIAS,
       .fieldoffset = offsetof(CPUARMState, cp15.c9_pminten),
       .writefn = pmintenclr_write },
     { .name = "VBAR", .state = ARM_CP_STATE_BOTH,
-- 
1.9.1