[Qemu-devel] [PATCH] 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>
---
I think this is the last of the EL3 traps we need to implement...

Alistair, now we have these two access functions can you check
that any new perf registers that are added in the patches you've
got pending use the right accessfn? (I'll probably catch it in
code review if you forget, but basing on top of this patch will
hopefully avoid unnecessary merge conflicts.)

thanks
-- PMM

 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 3d7fda1..e7dbc02 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