[PULL 34/96] ppc/pnv: Implement POWER10 PC xscom registers for direct controls

[Nicholas Piggin]

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 skiboot firmware,
which uses it to send NMI IPIs between CPUs.

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

Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
---
 hw/ppc/pnv_core.c         | 89 ++++++++++++++++++++++++++++++++++++---
 include/hw/ppc/pnv_core.h |  3 ++
 2 files changed, 87 insertions(+), 5 deletions(-)

diff --git a/hw/ppc/pnv_core.c b/hw/ppc/pnv_core.c
index 1783795b23..4484fe8c6a 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 +231,46 @@ 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%016" PRIx64 "\n", __func__, val);
+        }
+        break;
+
     default:
         qemu_log_mask(LOG_UNIMP, "%s: unimp write 0x%08x\n", __func__,
                       offset);
@@ -526,6 +587,7 @@ 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;
 
@@ -533,10 +595,14 @@ 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);
@@ -548,9 +614,22 @@ 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/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;
-- 
2.45.2