[Qemu-devel] [PATCH v6 1/6] ARM: Factor out ARM on/off PSCI control functions

[Jean-Christophe Dubois <jcd@tribudubois.net>]

Split ARM on/off function from PSCI support code.

This will allow to reuse these functions in other code.

Signed-off-by: Jean-Christophe Dubois <jcd@tribudubois.net>
---

Changes since V1:
 * Not present on V1

Changes since V2:
 * Not present on V2

Changes since V3:
 * Move to a more generic/usefull API
 * Manage CPU level/mode change at startup
 * Allow PSCI to cope with EL2/HYP level.
 * Keep distinct errors for different causes.

Changes since V4:
 * Rework documentation in header file.
 * Rework exception level handling.
 * Added a TODO for mode handling.

Changes since V5:
 * Code reworked based on feedback
 * Don't try to support AArch64 CPU booting to AArch32 for now.

 target-arm/Makefile.objs  |   1 +
 target-arm/arm-powerctl.c | 224 ++++++++++++++++++++++++++++++++++++++++++++++
 target-arm/arm-powerctl.h |  75 ++++++++++++++++
 target-arm/psci.c         |  70 ++-------------
 4 files changed, 307 insertions(+), 63 deletions(-)
 create mode 100644 target-arm/arm-powerctl.c
 create mode 100644 target-arm/arm-powerctl.h

diff --git a/target-arm/Makefile.objs b/target-arm/Makefile.objs
index a80eb39..60fd1dd 100644
--- a/target-arm/Makefile.objs
+++ b/target-arm/Makefile.objs
@@ -9,3 +9,4 @@ obj-y += neon_helper.o iwmmxt_helper.o
 obj-y += gdbstub.o
 obj-$(TARGET_AARCH64) += cpu64.o translate-a64.o helper-a64.o gdbstub64.o
 obj-y += crypto_helper.o
+obj-y += arm-powerctl.o
diff --git a/target-arm/arm-powerctl.c b/target-arm/arm-powerctl.c
new file mode 100644
index 0000000..8840f87
--- /dev/null
+++ b/target-arm/arm-powerctl.c
@@ -0,0 +1,224 @@
+/*
+ * QEMU support -- ARM Power Control specific functions.
+ *
+ * Copyright (c) 2016 Jean-Christophe Dubois
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2 or later.
+ * See the COPYING file in the top-level directory.
+ *
+ */
+
+#include "qemu/osdep.h"
+#include <cpu.h>
+#include <cpu-qom.h>
+#include "internals.h"
+#include "arm-powerctl.h"
+
+#ifndef DEBUG_ARM_POWERCTL
+#define DEBUG_ARM_POWERCTL 0
+#endif
+
+#define DPRINTF(fmt, args...) \
+    do { \
+        if (DEBUG_ARM_POWERCTL) { \
+            fprintf(stderr, "[ARM]%s: " fmt , __func__, ##args); \
+        } \
+    } while (0)
+
+CPUState *arm_get_cpu_by_id(uint64_t id)
+{
+    CPUState *cpu;
+
+    DPRINTF("cpu %" PRId64 "\n", id);
+
+    CPU_FOREACH(cpu) {
+        ARMCPU *armcpu = ARM_CPU(cpu);
+
+        if (armcpu->mp_affinity == id) {
+            return cpu;
+        }
+    }
+
+    qemu_log_mask(LOG_GUEST_ERROR,
+                  "[ARM]%s: Requesting unknown CPU %" PRId64 "\n",
+                  __func__, id);
+
+    return NULL;
+}
+
+int arm_set_cpu_on(uint64_t cpuid, uint64_t entry, uint64_t context_id,
+                   uint32_t target_el, bool target_aa64)
+{
+    CPUState *target_cpu_state;
+    ARMCPU *target_cpu;
+
+    DPRINTF("cpu %" PRId64 " (EL %d, %s) @ 0x%" PRIx64 " with R0 = 0x%" PRIx64
+            "\n", cpuid, target_el, target_aa64 ? "aarch64" : "aarch32", entry,
+            context_id);
+
+    /* requested EL level need to be in the 1 to 3 range */
+    assert((target_el > 0) && (target_el < 4));
+
+    if (target_aa64 && (entry & 3)) {
+        /*
+         * if we are booting in AArch64 mode then "entry" needs to be 4 bytes
+         * aligned.
+         */
+        return QEMU_ARM_POWERCTL_INVALID_PARAM;
+    }
+
+    /* Retrieve the cpu we are powering up */
+    target_cpu_state = arm_get_cpu_by_id(cpuid);
+    if (!target_cpu_state) {
+        /* The cpu was not found */
+        return QEMU_ARM_POWERCTL_INVALID_PARAM;
+    }
+
+    target_cpu = ARM_CPU(target_cpu_state);
+    if (!target_cpu->powered_off) {
+        qemu_log_mask(LOG_GUEST_ERROR,
+                      "[ARM]%s: CPU %" PRId64 " is already on\n",
+                      __func__, cpuid);
+        return QEMU_ARM_POWERCTL_ALREADY_ON;
+    }
+
+    /*
+     * The newly brought CPU is requested to enter the exception level
+     * "target_el" and be in the requested mode (AArch64 or AArch32).
+     */
+
+    if (((target_el == 3) && !arm_feature(&target_cpu->env, ARM_FEATURE_EL3)) ||
+        ((target_el == 2) && !arm_feature(&target_cpu->env, ARM_FEATURE_EL2))) {
+        /*
+         * The CPU does not support requested level
+         */
+        return QEMU_ARM_POWERCTL_INVALID_PARAM;
+    }
+
+    if (!target_aa64 && arm_feature(&target_cpu->env, ARM_FEATURE_AARCH64)) {
+        /*
+         * For now we don't support booting an AArch64 CPU in AArch32 mode
+         * TODO: We should add this support later
+         */
+        qemu_log_mask(LOG_UNIMP,
+                      "[ARM]%s: Starting AArch64 CPU %" PRId64
+                      " in AArch32 mode is not supported yet\n",
+                      __func__, cpuid);
+        return QEMU_ARM_POWERCTL_INVALID_PARAM;
+    }
+
+    /* Initialize the cpu we are turning on */
+    cpu_reset(target_cpu_state);
+    target_cpu->powered_off = false;
+    target_cpu_state->halted = 0;
+
+    if (target_aa64) {
+        if ((target_el < 3) && arm_feature(&target_cpu->env, ARM_FEATURE_EL3)) {
+            /*
+             * As target mode is AArch64, we need to set lower
+             * exception level (the requested level 2) to AArch64
+             */
+            target_cpu->env.cp15.scr_el3 |= SCR_RW;
+        }
+
+        if ((target_el < 2) && arm_feature(&target_cpu->env, ARM_FEATURE_EL2)) {
+            /*
+             * As target mode is AArch64, we need to set lower
+             * exception level (the requested level 1) to AArch64
+             */
+            target_cpu->env.cp15.hcr_el2 |= HCR_RW;
+        }
+
+        target_cpu->env.pstate = aarch64_pstate_mode(target_el, true);
+    } else {
+        /* We are requested to boot in AArch32 mode */
+        static uint32_t mode_for_el[] = { 0,
+                                          ARM_CPU_MODE_SVC,
+                                          ARM_CPU_MODE_HYP,
+                                          ARM_CPU_MODE_SVC };
+
+        cpsr_write(&target_cpu->env, mode_for_el[target_el], CPSR_M,
+                   CPSRWriteRaw);
+    }
+
+    if (target_el == 3) {
+        /* Processor is in secure mode */
+        target_cpu->env.cp15.scr_el3 &= ~SCR_NS;
+    } else {
+        /* Processor is not in secure mode */
+        target_cpu->env.cp15.scr_el3 |= SCR_NS;
+    }
+
+    /* We check if the started CPU is now at the correct level */
+    assert(target_el == arm_current_el(&target_cpu->env));
+
+    if (target_aa64) {
+        target_cpu->env.xregs[0] = context_id;
+        target_cpu->env.thumb = false;
+    } else {
+        target_cpu->env.regs[0] = context_id;
+        target_cpu->env.thumb = entry & 1;
+        entry &= 0xfffffffe;
+    }
+
+    /* Start the new CPU at the requested address */
+    cpu_set_pc(target_cpu_state, entry);
+
+    /* We are good to go */
+    return QEMU_ARM_POWERCTL_RET_SUCCESS;
+}
+
+int arm_set_cpu_off(uint64_t cpuid)
+{
+    CPUState *target_cpu_state;
+    ARMCPU *target_cpu;
+
+    DPRINTF("cpu %" PRId64 "\n", cpuid);
+
+    /* change to the cpu we are powering up */
+    target_cpu_state = arm_get_cpu_by_id(cpuid);
+    if (!target_cpu_state) {
+        return QEMU_ARM_POWERCTL_INVALID_PARAM;
+    }
+    target_cpu = ARM_CPU(target_cpu_state);
+    if (target_cpu->powered_off) {
+        qemu_log_mask(LOG_GUEST_ERROR,
+                      "[ARM]%s: CPU %" PRId64 " is already off\n",
+                      __func__, cpuid);
+        return QEMU_ARM_POWERCTL_IS_OFF;
+    }
+
+    target_cpu->powered_off = true;
+    target_cpu_state->halted = 1;
+    target_cpu_state->exception_index = EXCP_HLT;
+    cpu_loop_exit(target_cpu_state);
+    /* notreached */
+
+    return QEMU_ARM_POWERCTL_RET_SUCCESS;
+}
+
+int arm_reset_cpu(uint64_t cpuid)
+{
+    CPUState *target_cpu_state;
+    ARMCPU *target_cpu;
+
+    DPRINTF("cpu %" PRId64 "\n", cpuid);
+
+    /* change to the cpu we are resetting */
+    target_cpu_state = arm_get_cpu_by_id(cpuid);
+    if (!target_cpu_state) {
+        return QEMU_ARM_POWERCTL_INVALID_PARAM;
+    }
+    target_cpu = ARM_CPU(target_cpu_state);
+    if (target_cpu->powered_off) {
+        qemu_log_mask(LOG_GUEST_ERROR,
+                      "[ARM]%s: CPU %" PRId64 " is off\n",
+                      __func__, cpuid);
+        return QEMU_ARM_POWERCTL_IS_OFF;
+    }
+
+    /* Reset the cpu */
+    cpu_reset(target_cpu_state);
+
+    return QEMU_ARM_POWERCTL_RET_SUCCESS;
+}
diff --git a/target-arm/arm-powerctl.h b/target-arm/arm-powerctl.h
new file mode 100644
index 0000000..98ee049
--- /dev/null
+++ b/target-arm/arm-powerctl.h
@@ -0,0 +1,75 @@
+/*
+ * QEMU support -- ARM Power Control specific functions.
+ *
+ * Copyright (c) 2016 Jean-Christophe Dubois
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2 or later.
+ * See the COPYING file in the top-level directory.
+ *
+ */
+
+#ifndef QEMU_ARM_POWERCTL_H
+#define QEMU_ARM_POWERCTL_H
+
+#include "kvm-consts.h"
+
+#define QEMU_ARM_POWERCTL_RET_SUCCESS QEMU_PSCI_RET_SUCCESS
+#define QEMU_ARM_POWERCTL_INVALID_PARAM QEMU_PSCI_RET_INVALID_PARAMS
+#define QEMU_ARM_POWERCTL_ALREADY_ON QEMU_PSCI_RET_ALREADY_ON
+#define QEMU_ARM_POWERCTL_IS_OFF QEMU_PSCI_RET_DENIED
+
+/*
+ * arm_get_cpu_by_id:
+ * @cpuid: the id of the CPU we want to retrieve the state
+ *
+ * Retrieve a CPUState object from its CPU ID provided in @cpuid.
+ *
+ * Returns: a pointer to the CPUState structure of the requested CPU.
+ */
+CPUState *arm_get_cpu_by_id(uint64_t cpuid);
+
+/*
+ * arm_set_cpu_on:
+ * @cpuid: the id of the CPU we want to start/wake up.
+ * @entry: the address the CPU shall start from.
+ * @context_id: the value to put in r0/x0.
+ * @target_el: The desired exception level.
+ * @target_aa64: 1 if the requested mode is AArch64. 0 otherwise.
+ *
+ * Start the cpu designated by @cpuid in @target_el exception level. The mode
+ * shall be AArch64 if @target_aa64 is set to 1. Otherwise the mode is
+ * AArch32. The CPU shall start at @entry with @context_id in r0/x0.
+ *
+ * Returns: QEMU_ARM_POWERCTL_RET_SUCCESS on success.
+ * QEMU_ARM_POWERCTL_INVALID_PARAM if bad parameters are provided.
+ * QEMU_ARM_POWERCTL_ALREADY_ON if the CPU was already started.
+ */
+int arm_set_cpu_on(uint64_t cpuid, uint64_t entry, uint64_t context_id,
+                   uint32_t target_el, bool target_aa64);
+
+/*
+ * arm_set_cpu_off:
+ * @cpuid: the id of the CPU we want to stop/shut down.
+ *
+ * Stop the cpu designated by @cpuid.
+ *
+ * Returns: QEMU_ARM_POWERCTL_RET_SUCCESS on success.
+ * QEMU_ARM_POWERCTL_INVALID_PARAM if bad parameters are provided.
+ * QEMU_ARM_POWERCTL_IS_OFF if CPU is already off
+ */
+
+int arm_set_cpu_off(uint64_t cpuid);
+
+/*
+ * arm_reset_cpu:
+ * @cpuid: the id of the CPU we want to reset.
+ *
+ * Reset the cpu designated by @cpuid.
+ *
+ * Returns: QEMU_ARM_POWERCTL_RET_SUCCESS on success.
+ * QEMU_ARM_POWERCTL_INVALID_PARAM if bad parameters are provided.
+ * QEMU_ARM_POWERCTL_IS_OFF if CPU is off
+ */
+int arm_reset_cpu(uint64_t cpuid);
+
+#endif
diff --git a/target-arm/psci.c b/target-arm/psci.c
index c55487f..ce2e0dc 100644
--- a/target-arm/psci.c
+++ b/target-arm/psci.c
@@ -22,6 +22,7 @@
 #include <kvm-consts.h>
 #include <sysemu/sysemu.h>
 #include "internals.h"
+#include "arm-powerctl.h"
 
 bool arm_is_psci_call(ARMCPU *cpu, int excp_type)
 {
@@ -73,21 +74,6 @@ bool arm_is_psci_call(ARMCPU *cpu, int excp_type)
     }
 }
 
-static CPUState *get_cpu_by_id(uint64_t id)
-{
-    CPUState *cpu;
-
-    CPU_FOREACH(cpu) {
-        ARMCPU *armcpu = ARM_CPU(cpu);
-
-        if (armcpu->mp_affinity == id) {
-            return cpu;
-        }
-    }
-
-    return NULL;
-}
-
 void arm_handle_psci_call(ARMCPU *cpu)
 {
     /*
@@ -98,7 +84,6 @@ void arm_handle_psci_call(ARMCPU *cpu)
      * 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;
@@ -123,7 +108,6 @@ void arm_handle_psci_call(ARMCPU *cpu)
     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;
@@ -137,7 +121,7 @@ void arm_handle_psci_call(ARMCPU *cpu)
 
         switch (param[2]) {
         case 0:
-            target_cpu_state = get_cpu_by_id(mpidr);
+            target_cpu_state = arm_get_cpu_by_id(mpidr);
             if (!target_cpu_state) {
                 ret = QEMU_PSCI_RET_INVALID_PARAMS;
                 break;
@@ -167,52 +151,13 @@ void arm_handle_psci_call(ARMCPU *cpu)
         mpidr = param[1];
         entry = param[2];
         context_id = param[3];
-
-        /* change to the cpu we are powering up */
-        target_cpu_state = get_cpu_by_id(mpidr);
-        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;
+        ret = arm_set_cpu_on(mpidr, entry, context_id, arm_current_el(env),
+                             is_a64(env));
         break;
     case QEMU_PSCI_0_1_FN_CPU_OFF:
     case QEMU_PSCI_0_2_FN_CPU_OFF:
@@ -250,9 +195,8 @@ err:
     return;
 
 cpu_off:
-    cpu->powered_off = true;
-    cs->halted = 1;
-    cs->exception_index = EXCP_HLT;
-    cpu_loop_exit(cs);
+    ret = arm_set_cpu_off(cpu->mp_affinity);
     /* notreached */
+    /* sanity check in case something failed */
+    assert(ret == QEMU_ARM_POWERCTL_RET_SUCCESS);
 }
-- 
2.5.0