target-arm: add emulation of PSCI calls for system emulation

Add support for handling PSCI calls in system emulation. Both version
0.1 and 0.2 of the PSCI spec are supported. Platforms can enable support
by setting the "psci-conduit" QOM property on the cpus to SMC or HVC
emulation and having a PSCI binding in their dtb.

Signed-off-by: Rob Herring <rob.herring@linaro.org>
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Message-id: 1412865028-17725-7-git-send-email-peter.maydell@linaro.org
[PMM: made system reset/off PSCI functions power down the CPU so
 we obey the PSCI API requirement never to return from them;
 rearranged how the code is plumbed into the exception system,
 so that we split "is this a valid call?" from "do the call"]
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

9 files changed, 301 insertions, 3 deletions

diff --git a/target-arm/Makefile.objs b/target-arm/Makefile.objs
index dcd167e..9460b40 100644
--- a/target-arm/Makefile.objs
+++ b/target-arm/Makefile.objs
@@ -7,5 +7,6 @@ obj-$(call lnot,$(CONFIG_KVM)) += kvm-stub.o
 obj-y += translate.o op_helper.o helper.o cpu.o
 obj-y += neon_helper.o iwmmxt_helper.o
 obj-y += gdbstub.o
+obj-$(CONFIG_SOFTMMU) += psci.o
 obj-$(TARGET_AARCH64) += cpu64.o translate-a64.o helper-a64.o gdbstub64.o
 obj-y += crypto_helper.o
diff --git a/target-arm/cpu-qom.h b/target-arm/cpu-qom.h
index aeb7e1d..dcfda7d 100644
--- a/target-arm/cpu-qom.h
+++ b/target-arm/cpu-qom.h
@@ -101,6 +101,11 @@ typedef struct ARMCPU {
     /* CPU currently in PSCI powered-off state */
     bool powered_off;
 
+    /* PSCI conduit used to invoke PSCI methods
+     * 0 - disabled, 1 - smc, 2 - hvc
+     */
+    uint32_t psci_conduit;
+
     /* [QEMU_]KVM_ARM_TARGET_* constant for this CPU, or
      * QEMU_KVM_ARM_TARGET_NONE if the kernel doesn't support this CPU type.
      */
diff --git a/target-arm/cpu.c b/target-arm/cpu.c
index 2061cb7..e837f64 100644
--- a/target-arm/cpu.c
+++ b/target-arm/cpu.c
@@ -334,9 +334,12 @@ static void arm_cpu_initfn(Object *obj)
     cpu->psci_version = 1; /* By default assume PSCI v0.1 */
     cpu->kvm_target = QEMU_KVM_ARM_TARGET_NONE;
 
-    if (tcg_enabled() && !inited) {
-        inited = true;
-        arm_translate_init();
+    if (tcg_enabled()) {
+        cpu->psci_version = 2; /* TCG implements PSCI 0.2 */
+        if (!inited) {
+            inited = true;
+            arm_translate_init();
+        }
     }
 }
 
@@ -1090,6 +1093,7 @@ static const ARMCPUInfo arm_cpus[] = {
 
 static Property arm_cpu_properties[] = {
     DEFINE_PROP_BOOL("start-powered-off", ARMCPU, start_powered_off, false),
+    DEFINE_PROP_UINT32("psci-conduit", ARMCPU, psci_conduit, 0),
     DEFINE_PROP_UINT32("midr", ARMCPU, midr, 0),
     DEFINE_PROP_END_OF_LIST()
 };
diff --git a/target-arm/cpu.h b/target-arm/cpu.h
index 65a3417..690686c 100644
--- a/target-arm/cpu.h
+++ b/target-arm/cpu.h
@@ -1484,4 +1484,10 @@ static inline void cpu_pc_from_tb(CPUARMState *env, TranslationBlock *tb)
     }
 }
 
+enum {
+    QEMU_PSCI_CONDUIT_DISABLED = 0,
+    QEMU_PSCI_CONDUIT_SMC = 1,
+    QEMU_PSCI_CONDUIT_HVC = 2,
+};
+
 #endif
diff --git a/target-arm/helper-a64.c b/target-arm/helper-a64.c
index 7ae84f6..daf5adc 100644
--- a/target-arm/helper-a64.c
+++ b/target-arm/helper-a64.c
@@ -468,6 +468,12 @@ void aarch64_cpu_do_interrupt(CPUState *cs)
                       env->exception.syndrome);
     }
 
+    if (arm_is_psci_call(cpu, cs->exception_index)) {
+        arm_handle_psci_call(cpu);
+        qemu_log_mask(CPU_LOG_INT, "...handled as PSCI call\n");
+        return;
+    }
+
     switch (cs->exception_index) {
     case EXCP_PREFETCH_ABORT:
     case EXCP_DATA_ABORT:
diff --git a/target-arm/helper.c b/target-arm/helper.c
index 497178a..d837820 100644
--- a/target-arm/helper.c
+++ b/target-arm/helper.c
@@ -3970,6 +3970,12 @@ void arm_cpu_do_interrupt(CPUState *cs)
 
     arm_log_exception(cs->exception_index);
 
+    if (arm_is_psci_call(cpu, cs->exception_index)) {
+        arm_handle_psci_call(cpu);
+        qemu_log_mask(CPU_LOG_INT, "...handled as PSCI call\n");
+        return;
+    }
+
     /* If this is a debug exception we must update the DBGDSCR.MOE bits */
     switch (env->exception.syndrome >> ARM_EL_EC_SHIFT) {
     case EC_BREAKPOINT:
diff --git a/target-arm/internals.h b/target-arm/internals.h
index e46de71..51c5c16 100644
--- a/target-arm/internals.h
+++ b/target-arm/internals.h
@@ -366,4 +366,16 @@ void hw_breakpoint_update_all(ARMCPU *cpu);
 /* Callback function for when a watchpoint or breakpoint triggers. */
 void arm_debug_excp_handler(CPUState *cs);
 
+#ifdef CONFIG_USER_ONLY
+static inline bool arm_is_psci_call(ARMCPU *cpu, int excp_type)
+{
+    return false;
+}
+#else
+/* Return true if the r0/x0 value indicates that this SMC/HVC is a PSCI call. */
+bool arm_is_psci_call(ARMCPU *cpu, int excp_type);
+/* Actually handle a PSCI call */
+void arm_handle_psci_call(ARMCPU *cpu);
+#endif
+
 #endif
diff --git a/target-arm/op_helper.c b/target-arm/op_helper.c
index 5652096..464a5ce 100644
--- a/target-arm/op_helper.c
+++ b/target-arm/op_helper.c
@@ -387,11 +387,19 @@ void HELPER(clear_pstate_ss)(CPUARMState *env)
 
 void HELPER(pre_hvc)(CPUARMState *env)
 {
+    ARMCPU *cpu = arm_env_get_cpu(env);
     int cur_el = arm_current_pl(env);
     /* FIXME: Use actual secure state.  */
     bool secure = false;
     bool undef;
 
+    if (arm_is_psci_call(cpu, EXCP_HVC)) {
+        /* If PSCI is enabled and this looks like a valid PSCI call then
+         * that overrides the architecturally mandated HVC behaviour.
+         */
+        return;
+    }
+
     if (!arm_feature(env, ARM_FEATURE_EL2)) {
         /* If EL2 doesn't exist, HVC always UNDEFs */
         undef = true;
@@ -419,6 +427,7 @@ void HELPER(pre_hvc)(CPUARMState *env)
 
 void HELPER(pre_smc)(CPUARMState *env, uint32_t syndrome)
 {
+    ARMCPU *cpu = arm_env_get_cpu(env);
     int cur_el = arm_current_pl(env);
     /* FIXME: Use real secure state.  */
     bool secure = false;
@@ -430,6 +439,13 @@ void HELPER(pre_smc)(CPUARMState *env, uint32_t syndrome)
      */
     bool undef = is_a64(env) ? smd : (!secure && smd);
 
+    if (arm_is_psci_call(cpu, EXCP_SMC)) {
+        /* If PSCI is enabled and this looks like a valid PSCI call then
+         * that overrides the architecturally mandated SMC behaviour.
+         */
+        return;
+    }
+
     if (!arm_feature(env, ARM_FEATURE_EL3)) {
         /* If we have no EL3 then SMC always UNDEFs */
         undef = true;
diff --git a/target-arm/psci.c b/target-arm/psci.c
new file mode 100644
index 0000000..d8fafab
--- /dev/null
+++ b/target-arm/psci.c
@@ -0,0 +1,242 @@
+/*
+ * Copyright (C) 2014 - Linaro
+ * Author: Rob Herring <rob.herring@linaro.org>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation; either version 2 of the License, or
+ *  (at your option) any later version.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with this program; if not, see <http://www.gnu.org/licenses/>.
+ */
+#include <cpu.h>
+#include <cpu-qom.h>
+#include <exec/helper-proto.h>
+#include <kvm-consts.h>
+#include <sysemu/sysemu.h>
+#include "internals.h"
+
+bool arm_is_psci_call(ARMCPU *cpu, int excp_type)
+{
+    /* Return true if the r0/x0 value indicates a PSCI call and
+     * the exception type matches the configured PSCI conduit. This is
+     * called before the SMC/HVC instruction is executed, to decide whether
+     * we should treat it as a PSCI call or with the architecturally
+     * defined behaviour for an SMC or HVC (which might be UNDEF or trap
+     * to EL2 or to EL3).
+     */
+    CPUARMState *env = &cpu->env;
+    uint64_t param = is_a64(env) ? env->xregs[0] : env->regs[0];
+
+    switch (excp_type) {
+    case EXCP_HVC:
+        if (cpu->psci_conduit != QEMU_PSCI_CONDUIT_HVC) {
+            return false;
+        }
+        break;
+    case EXCP_SMC:
+        if (cpu->psci_conduit != QEMU_PSCI_CONDUIT_SMC) {
+            return false;
+        }
+        break;
+    default:
+        return false;
+    }
+
+    switch (param) {
+    case QEMU_PSCI_0_2_FN_PSCI_VERSION:
+    case QEMU_PSCI_0_2_FN_MIGRATE_INFO_TYPE:
+    case QEMU_PSCI_0_2_FN_AFFINITY_INFO:
+    case QEMU_PSCI_0_2_FN64_AFFINITY_INFO:
+    case QEMU_PSCI_0_2_FN_SYSTEM_RESET:
+    case QEMU_PSCI_0_2_FN_SYSTEM_OFF:
+    case QEMU_PSCI_0_1_FN_CPU_ON:
+    case QEMU_PSCI_0_2_FN_CPU_ON:
+    case QEMU_PSCI_0_2_FN64_CPU_ON:
+    case QEMU_PSCI_0_1_FN_CPU_OFF:
+    case QEMU_PSCI_0_2_FN_CPU_OFF:
+    case QEMU_PSCI_0_1_FN_CPU_SUSPEND:
+    case QEMU_PSCI_0_2_FN_CPU_SUSPEND:
+    case QEMU_PSCI_0_2_FN64_CPU_SUSPEND:
+    case QEMU_PSCI_0_1_FN_MIGRATE:
+    case QEMU_PSCI_0_2_FN_MIGRATE:
+        return true;
+    default:
+        return false;
+    }
+}
+
+void arm_handle_psci_call(ARMCPU *cpu)
+{
+    /*
+     * This function partially implements the logic for dispatching Power State
+     * Coordination Interface (PSCI) calls (as described in ARM DEN 0022B.b),
+     * to the extent required for bringing up and taking down secondary cores,
+     * and for handling reset and poweroff requests.
+     * Additional information about the calling convention used is available in
+     * the document 'SMC Calling Convention' (ARM DEN 0028)
+     */
+    CPUState *cs = CPU(cpu);
+    CPUARMState *env = &cpu->env;
+    uint64_t param[4];
+    uint64_t context_id, mpidr;
+    target_ulong entry;
+    int32_t ret = 0;
+    int i;
+
+    for (i = 0; i < 4; i++) {
+        /*
+         * All PSCI functions take explicit 32-bit or native int sized
+         * arguments so we can simply zero-extend all arguments regardless
+         * of which exact function we are about to call.
+         */
+        param[i] = is_a64(env) ? env->xregs[i] : env->regs[i];
+    }
+
+    if ((param[0] & QEMU_PSCI_0_2_64BIT) && !is_a64(env)) {
+        ret = QEMU_PSCI_RET_INVALID_PARAMS;
+        goto err;
+    }
+
+    switch (param[0]) {
+        CPUState *target_cpu_state;
+        ARMCPU *target_cpu;
+        CPUClass *target_cpu_class;
+
+    case QEMU_PSCI_0_2_FN_PSCI_VERSION:
+        ret = QEMU_PSCI_0_2_RET_VERSION_0_2;
+        break;
+    case QEMU_PSCI_0_2_FN_MIGRATE_INFO_TYPE:
+        ret = QEMU_PSCI_0_2_RET_TOS_MIGRATION_NOT_REQUIRED; /* No trusted OS */
+        break;
+    case QEMU_PSCI_0_2_FN_AFFINITY_INFO:
+    case QEMU_PSCI_0_2_FN64_AFFINITY_INFO:
+        mpidr = param[1];
+
+        switch (param[2]) {
+        case 0:
+            target_cpu_state = qemu_get_cpu(mpidr & 0xff);
+            if (!target_cpu_state) {
+                ret = QEMU_PSCI_RET_INVALID_PARAMS;
+                break;
+            }
+            target_cpu = ARM_CPU(target_cpu_state);
+            ret = target_cpu->powered_off ? 1 : 0;
+            break;
+        default:
+            /* Everything above affinity level 0 is always on. */
+            ret = 0;
+        }
+        break;
+    case QEMU_PSCI_0_2_FN_SYSTEM_RESET:
+        qemu_system_reset_request();
+        /* QEMU reset and shutdown are async requests, but PSCI
+         * mandates that we never return from the reset/shutdown
+         * call, so power the CPU off now so it doesn't execute
+         * anything further.
+         */
+        goto cpu_off;
+    case QEMU_PSCI_0_2_FN_SYSTEM_OFF:
+        qemu_system_shutdown_request();
+        goto cpu_off;
+    case QEMU_PSCI_0_1_FN_CPU_ON:
+    case QEMU_PSCI_0_2_FN_CPU_ON:
+    case QEMU_PSCI_0_2_FN64_CPU_ON:
+        mpidr = param[1];
+        entry = param[2];
+        context_id = param[3];
+
+        /* change to the cpu we are powering up */
+        target_cpu_state = qemu_get_cpu(mpidr & 0xff);
+        if (!target_cpu_state) {
+            ret = QEMU_PSCI_RET_INVALID_PARAMS;
+            break;
+        }
+        target_cpu = ARM_CPU(target_cpu_state);
+        if (!target_cpu->powered_off) {
+            ret = QEMU_PSCI_RET_ALREADY_ON;
+            break;
+        }
+        target_cpu_class = CPU_GET_CLASS(target_cpu);
+
+        /* Initialize the cpu we are turning on */
+        cpu_reset(target_cpu_state);
+        target_cpu->powered_off = false;
+        target_cpu_state->halted = 0;
+
+        /*
+         * The PSCI spec mandates that newly brought up CPUs enter the
+         * exception level of the caller in the same execution mode as
+         * the caller, with context_id in x0/r0, respectively.
+         *
+         * For now, it is sufficient to assert() that CPUs come out of
+         * reset in the same mode as the calling CPU, since we only
+         * implement EL1, which means that
+         * (a) there is no EL2 for the calling CPU to trap into to change
+         *     its state
+         * (b) the newly brought up CPU enters EL1 immediately after coming
+         *     out of reset in the default state
+         */
+        assert(is_a64(env) == is_a64(&target_cpu->env));
+        if (is_a64(env)) {
+            if (entry & 1) {
+                ret = QEMU_PSCI_RET_INVALID_PARAMS;
+                break;
+            }
+            target_cpu->env.xregs[0] = context_id;
+        } else {
+            target_cpu->env.regs[0] = context_id;
+            target_cpu->env.thumb = entry & 1;
+        }
+        target_cpu_class->set_pc(target_cpu_state, entry);
+
+        ret = 0;
+        break;
+    case QEMU_PSCI_0_1_FN_CPU_OFF:
+    case QEMU_PSCI_0_2_FN_CPU_OFF:
+        goto cpu_off;
+    case QEMU_PSCI_0_1_FN_CPU_SUSPEND:
+    case QEMU_PSCI_0_2_FN_CPU_SUSPEND:
+    case QEMU_PSCI_0_2_FN64_CPU_SUSPEND:
+        /* Affinity levels are not supported in QEMU */
+        if (param[1] & 0xfffe0000) {
+            ret = QEMU_PSCI_RET_INVALID_PARAMS;
+            break;
+        }
+        /* Powerdown is not supported, we always go into WFI */
+        if (is_a64(env)) {
+            env->xregs[0] = 0;
+        } else {
+            env->regs[0] = 0;
+        }
+        helper_wfi(env);
+        break;
+    case QEMU_PSCI_0_1_FN_MIGRATE:
+    case QEMU_PSCI_0_2_FN_MIGRATE:
+        ret = QEMU_PSCI_RET_NOT_SUPPORTED;
+        break;
+    default:
+        g_assert_not_reached();
+    }
+
+err:
+    if (is_a64(env)) {
+        env->xregs[0] = ret;
+    } else {
+        env->regs[0] = ret;
+    }
+    return;
+
+cpu_off:
+    cpu->powered_off = true;
+    cs->halted = 1;
+    cs->exception_index = EXCP_HLT;
+    cpu_loop_exit(cs);
+    /* notreached */
+}