[PATCH 17/18] ppc/pnv: Implement POWER10 PC xscom registers for direct controls

[Nicholas Piggin <npiggin@gmail.com>]

The PC unit in the processor core contains xscom registers that provide
low level status and control of the CPU.

This implements "direct controls" sufficient for OPAL (skiboot) firmware
use, which is to stop threads and send them non-maskable IPIs in the
form of SRESET interrupts.

POWER10 is sufficiently different (particularly QME and special wakeup)
from POWER9 that it is not trivial to implement by reusing the code.

Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
---
 include/hw/core/cpu.h     |  8 ++++
 include/hw/ppc/pnv.h      |  2 +
 include/hw/ppc/pnv_core.h |  3 ++
 hw/ppc/pnv.c              | 19 +++++++--
 hw/ppc/pnv_core.c         | 88 ++++++++++++++++++++++++++++++++++++---
 system/cpus.c             | 10 +++++
 6 files changed, 122 insertions(+), 8 deletions(-)

diff --git a/include/hw/core/cpu.h b/include/hw/core/cpu.h
index a2c8536943..410e7d6f03 100644
--- a/include/hw/core/cpu.h
+++ b/include/hw/core/cpu.h
@@ -984,6 +984,14 @@ void cpu_reset_interrupt(CPUState *cpu, int mask);
  */
 void cpu_exit(CPUState *cpu);
 
+/**
+ * cpu_pause:
+ * @cpu: The CPU to pause.
+ *
+ * Resumes CPU, i.e. puts CPU into stopped state.
+ */
+void cpu_pause(CPUState *cpu);
+
 /**
  * cpu_resume:
  * @cpu: The CPU to resume.
diff --git a/include/hw/ppc/pnv.h b/include/hw/ppc/pnv.h
index c56d152889..b7858d310d 100644
--- a/include/hw/ppc/pnv.h
+++ b/include/hw/ppc/pnv.h
@@ -112,6 +112,8 @@ PnvChip *pnv_chip_add_phb(PnvChip *chip, PnvPHB *phb);
 #define PNV_FDT_ADDR          0x01000000
 #define PNV_TIMEBASE_FREQ     512000000ULL
 
+void pnv_cpu_do_nmi_resume(CPUState *cs);
+
 /*
  * BMC helpers
  */
diff --git a/include/hw/ppc/pnv_core.h b/include/hw/ppc/pnv_core.h
index c8784777a4..1de79a818e 100644
--- a/include/hw/ppc/pnv_core.h
+++ b/include/hw/ppc/pnv_core.h
@@ -109,6 +109,9 @@ OBJECT_DECLARE_TYPE(PnvQuad, PnvQuadClass, PNV_QUAD)
 struct PnvQuad {
     DeviceState parent_obj;
 
+    bool special_wakeup_done;
+    bool special_wakeup[4];
+
     uint32_t quad_id;
     MemoryRegion xscom_regs;
     MemoryRegion xscom_qme_regs;
diff --git a/hw/ppc/pnv.c b/hw/ppc/pnv.c
index 575f18958d..71b2b3806c 100644
--- a/hw/ppc/pnv.c
+++ b/hw/ppc/pnv.c
@@ -2747,11 +2747,24 @@ static void pnv_cpu_do_nmi_on_cpu(CPUState *cs, run_on_cpu_data arg)
          */
         env->spr[SPR_SRR1] |= SRR1_WAKESCOM;
     }
+    if (arg.host_int) {
+        cpu_resume(cs);
+    }
+}
+
+static void pnv_cpu_do_nmi(CPUState *cs, int resume)
+{
+    async_run_on_cpu(cs, pnv_cpu_do_nmi_on_cpu, RUN_ON_CPU_HOST_INT(resume));
+}
+
+void pnv_cpu_do_nmi_resume(CPUState *cs)
+{
+    pnv_cpu_do_nmi(cs, 1);
 }
 
-static void pnv_cpu_do_nmi(PnvChip *chip, PowerPCCPU *cpu, void *opaque)
+static void do_pnv_cpu_do_nmi(PnvChip *chip, PowerPCCPU *cpu, void *opaque)
 {
-    async_run_on_cpu(CPU(cpu), pnv_cpu_do_nmi_on_cpu, RUN_ON_CPU_NULL);
+    pnv_cpu_do_nmi(CPU(cpu), 0);
 }
 
 static void pnv_nmi(NMIState *n, int cpu_index, Error **errp)
@@ -2760,7 +2773,7 @@ static void pnv_nmi(NMIState *n, int cpu_index, Error **errp)
     int i;
 
     for (i = 0; i < pnv->num_chips; i++) {
-        pnv_chip_foreach_cpu(pnv->chips[i], pnv_cpu_do_nmi, NULL);
+        pnv_chip_foreach_cpu(pnv->chips[i], do_pnv_cpu_do_nmi, NULL);
     }
 }
 
diff --git a/hw/ppc/pnv_core.c b/hw/ppc/pnv_core.c
index e03ac5441e..a685a5dc1b 100644
--- a/hw/ppc/pnv_core.c
+++ b/hw/ppc/pnv_core.c
@@ -185,16 +185,40 @@ static const MemoryRegionOps pnv_core_power9_xscom_ops = {
  */
 
 #define PNV10_XSCOM_EC_CORE_THREAD_STATE    0x412
+#define PNV10_XSCOM_EC_CORE_THREAD_INFO     0x413
+#define PNV10_XSCOM_EC_CORE_DIRECT_CONTROLS 0x449
+#define PNV10_XSCOM_EC_CORE_RAS_STATUS      0x454
 
 static uint64_t pnv_core_power10_xscom_read(void *opaque, hwaddr addr,
                                            unsigned int width)
 {
+    PnvCore *pc = PNV_CORE(opaque);
+    int nr_threads = CPU_CORE(pc)->nr_threads;
+    int i;
     uint32_t offset = addr >> 3;
     uint64_t val = 0;
 
     switch (offset) {
     case PNV10_XSCOM_EC_CORE_THREAD_STATE:
-        val = 0;
+        for (i = 0; i < nr_threads; i++) {
+            PowerPCCPU *cpu = pc->threads[i];
+            CPUState *cs = CPU(cpu);
+
+            if (cs->halted) {
+                val |= PPC_BIT(56 + i);
+            }
+        }
+        break;
+    case PNV10_XSCOM_EC_CORE_THREAD_INFO:
+        break;
+    case PNV10_XSCOM_EC_CORE_RAS_STATUS:
+        for (i = 0; i < nr_threads; i++) {
+            PowerPCCPU *cpu = pc->threads[i];
+            CPUState *cs = CPU(cpu);
+            if (cs->stopped) {
+                val |= PPC_BIT(0 + 8*i) | PPC_BIT(1 + 8*i);
+            }
+        }
         break;
     default:
         qemu_log_mask(LOG_UNIMP, "%s: unimp read 0x%08x\n", __func__,
@@ -207,9 +231,45 @@ static uint64_t pnv_core_power10_xscom_read(void *opaque, hwaddr addr,
 static void pnv_core_power10_xscom_write(void *opaque, hwaddr addr,
                                          uint64_t val, unsigned int width)
 {
+    PnvCore *pc = PNV_CORE(opaque);
+    int nr_threads = CPU_CORE(pc)->nr_threads;
+    int i;
     uint32_t offset = addr >> 3;
 
     switch (offset) {
+    case PNV10_XSCOM_EC_CORE_DIRECT_CONTROLS:
+        for (i = 0; i < nr_threads; i++) {
+            PowerPCCPU *cpu = pc->threads[i];
+            CPUState *cs = CPU(cpu);
+
+            if (val & PPC_BIT(7 + 8*i)) { /* stop */
+                val &= ~PPC_BIT(7 + 8*i);
+                cpu_pause(cs);
+            }
+            if (val & PPC_BIT(6 + 8*i)) { /* start */
+                val &= ~PPC_BIT(6 + 8*i);
+                cpu_resume(cs);
+            }
+            if (val & PPC_BIT(4 + 8*i)) { /* sreset */
+                val &= ~PPC_BIT(4 + 8*i);
+                pnv_cpu_do_nmi_resume(cs);
+            }
+            if (val & PPC_BIT(3 + 8*i)) { /* clear maint */
+                /*
+                 * Hardware has very particular cases for where clear maint
+                 * must be used and where start must be used to resume a
+                 * thread. These are not modelled exactly, just treat
+                 * this and start the same.
+                 */
+                val &= ~PPC_BIT(3 + 8*i);
+                cpu_resume(cs);
+            }
+        }
+        if (val) {
+            qemu_log_mask(LOG_UNIMP, "%s: unimp bits in DIRECT_CONTROLS 0x%016lx\n", __func__, val);
+        }
+        break;
+
     default:
         qemu_log_mask(LOG_UNIMP, "%s: unimp write 0x%08x\n", __func__,
                       offset);
@@ -528,6 +588,7 @@ static const MemoryRegionOps pnv_quad_power10_xscom_ops = {
 static uint64_t pnv_qme_power10_xscom_read(void *opaque, hwaddr addr,
                                             unsigned int width)
 {
+    PnvQuad *eq = PNV_QUAD(opaque);
     uint32_t offset = addr >> 3;
     uint64_t val = -1;
 
@@ -535,10 +596,14 @@ static uint64_t pnv_qme_power10_xscom_read(void *opaque, hwaddr addr,
      * Forth nibble selects the core within a quad, mask it to process read
      * for any core.
      */
-    switch (offset & ~0xf000) {
-    case P10_QME_SPWU_HYP:
+    switch (offset & ~PPC_BITMASK32(16, 19)) {
     case P10_QME_SSH_HYP:
-        return 0;
+        val = 0;
+        if (eq->special_wakeup_done) {
+            val |= PPC_BIT(1); /* SPWU DONE */
+            val |= PPC_BIT(4); /* SSH SPWU DONE */
+        }
+        break;
     default:
         qemu_log_mask(LOG_UNIMP, "%s: unimp read 0x%08x\n", __func__,
                       offset);
@@ -550,9 +615,22 @@ static uint64_t pnv_qme_power10_xscom_read(void *opaque, hwaddr addr,
 static void pnv_qme_power10_xscom_write(void *opaque, hwaddr addr,
                                          uint64_t val, unsigned int width)
 {
+    PnvQuad *eq = PNV_QUAD(opaque);
     uint32_t offset = addr >> 3;
+    bool set;
+    int i;
 
-    switch (offset) {
+    switch (offset & ~PPC_BITMASK32(16, 19)) {
+    case P10_QME_SPWU_HYP:
+        set = !!(val & PPC_BIT(0));
+        eq->special_wakeup_done = set;
+        for (i = 0; i < 4; i++) {
+            /* These bits select cores in the quad */
+            if (offset & PPC_BIT32(16 + i)) {
+                eq->special_wakeup[i] = set;
+            }
+        }
+        break;
     default:
         qemu_log_mask(LOG_UNIMP, "%s: unimp write 0x%08x\n", __func__,
                       offset);
diff --git a/system/cpus.c b/system/cpus.c
index d3640c9503..083abbc393 100644
--- a/system/cpus.c
+++ b/system/cpus.c
@@ -613,6 +613,16 @@ void pause_all_vcpus(void)
     bql_lock();
 }
 
+void cpu_pause(CPUState *cpu)
+{
+    if (qemu_cpu_is_self(cpu)) {
+        qemu_cpu_stop(cpu, true);
+    } else {
+        cpu->stop = true;
+        qemu_cpu_kick(cpu);
+    }
+}
+
 void cpu_resume(CPUState *cpu)
 {
     cpu->stop = false;
-- 
2.45.1