[PATCH v2 11/15] hw/riscv/riscv-iommu: add DBG support

[Daniel Henrique Barboza]

From: Tomasz Jeznach <tjeznach@rivosinc.com>

DBG support adds three additional registers: tr_req_iova, tr_req_ctl and
tr_response.

The DBG cap is always enabled. No on/off toggle is provided for it.

Signed-off-by: Tomasz Jeznach <tjeznach@rivosinc.com>
Signed-off-by: Daniel Henrique Barboza <dbarboza@ventanamicro.com>
---
 hw/riscv/riscv-iommu-bits.h | 20 +++++++++++++
 hw/riscv/riscv-iommu.c      | 57 ++++++++++++++++++++++++++++++++++++-
 2 files changed, 76 insertions(+), 1 deletion(-)

diff --git a/hw/riscv/riscv-iommu-bits.h b/hw/riscv/riscv-iommu-bits.h
index 0994f5ce48..b3f92411bb 100644
--- a/hw/riscv/riscv-iommu-bits.h
+++ b/hw/riscv/riscv-iommu-bits.h
@@ -83,6 +83,7 @@ struct riscv_iommu_pq_record {
 #define RISCV_IOMMU_CAP_MSI_MRIF        BIT_ULL(23)
 #define RISCV_IOMMU_CAP_ATS             BIT_ULL(25)
 #define RISCV_IOMMU_CAP_IGS             GENMASK_ULL(29, 28)
+#define RISCV_IOMMU_CAP_DBG             BIT_ULL(31)
 #define RISCV_IOMMU_CAP_PAS             GENMASK_ULL(37, 32)
 #define RISCV_IOMMU_CAP_PD8             BIT_ULL(38)
 
@@ -177,6 +178,25 @@ enum {
     RISCV_IOMMU_INTR_COUNT
 };
 
+#define RISCV_IOMMU_IPSR_CIP            BIT(RISCV_IOMMU_INTR_CQ)
+#define RISCV_IOMMU_IPSR_FIP            BIT(RISCV_IOMMU_INTR_FQ)
+#define RISCV_IOMMU_IPSR_PMIP           BIT(RISCV_IOMMU_INTR_PM)
+#define RISCV_IOMMU_IPSR_PIP            BIT(RISCV_IOMMU_INTR_PQ)
+
+/* 5.24 Translation request IOVA (64bits) */
+#define RISCV_IOMMU_REG_TR_REQ_IOVA     0x0258
+
+/* 5.25 Translation request control (64bits) */
+#define RISCV_IOMMU_REG_TR_REQ_CTL      0x0260
+#define RISCV_IOMMU_TR_REQ_CTL_GO_BUSY  BIT_ULL(0)
+#define RISCV_IOMMU_TR_REQ_CTL_PID      GENMASK_ULL(31, 12)
+#define RISCV_IOMMU_TR_REQ_CTL_DID      GENMASK_ULL(63, 40)
+
+/* 5.26 Translation request response (64bits) */
+#define RISCV_IOMMU_REG_TR_RESPONSE     0x0268
+#define RISCV_IOMMU_TR_RESPONSE_FAULT   BIT_ULL(0)
+#define RISCV_IOMMU_TR_RESPONSE_PPN     RISCV_IOMMU_PPN_FIELD
+
 /* 5.27 Interrupt cause to vector (64bits) */
 #define RISCV_IOMMU_REG_IVEC            0x02F8
 
diff --git a/hw/riscv/riscv-iommu.c b/hw/riscv/riscv-iommu.c
index 7af5929b10..1fa1286d07 100644
--- a/hw/riscv/riscv-iommu.c
+++ b/hw/riscv/riscv-iommu.c
@@ -1457,6 +1457,46 @@ static void 
riscv_iommu_process_pq_control(RISCVIOMMUState *s)
     riscv_iommu_reg_mod32(s, RISCV_IOMMU_REG_PQCSR, ctrl_set, ctrl_clr);
 }
 
+static void riscv_iommu_process_dbg(RISCVIOMMUState *s)
+{
+    uint64_t iova = riscv_iommu_reg_get64(s, RISCV_IOMMU_REG_TR_REQ_IOVA);
+    uint64_t ctrl = riscv_iommu_reg_get64(s, RISCV_IOMMU_REG_TR_REQ_CTL);
+    unsigned devid = get_field(ctrl, RISCV_IOMMU_TR_REQ_CTL_DID);
+    unsigned pid = get_field(ctrl, RISCV_IOMMU_TR_REQ_CTL_PID);
+    RISCVIOMMUContext *ctx;
+    void *ref;
+
+    if (!(ctrl & RISCV_IOMMU_TR_REQ_CTL_GO_BUSY)) {
+        return;
+    }
+
+    ctx = riscv_iommu_ctx(s, devid, pid, &ref);
+    if (ctx == NULL) {
+        riscv_iommu_reg_set64(s, RISCV_IOMMU_REG_TR_RESPONSE,
+                                 RISCV_IOMMU_TR_RESPONSE_FAULT |
+                                 (RISCV_IOMMU_FQ_CAUSE_DMA_DISABLED << 10));
+    } else {
+        IOMMUTLBEntry iotlb = {
+            .iova = iova,
+            .perm = IOMMU_NONE,
+            .addr_mask = ~0,
+            .target_as = NULL,
+        };
+        int fault = riscv_iommu_translate(s, ctx, &iotlb, false);
+        if (fault) {
+            iova = RISCV_IOMMU_TR_RESPONSE_FAULT | (((uint64_t) fault) << 10);
+        } else {
+            iova = ((iotlb.translated_addr & ~iotlb.addr_mask) >> 2) &
+                RISCV_IOMMU_TR_RESPONSE_PPN;
+        }
+        riscv_iommu_reg_set64(s, RISCV_IOMMU_REG_TR_RESPONSE, iova);
+    }
+
+    riscv_iommu_reg_mod64(s, RISCV_IOMMU_REG_TR_REQ_CTL, 0,
+        RISCV_IOMMU_TR_REQ_CTL_GO_BUSY);
+    riscv_iommu_ctx_put(s, ref);
+}
+
 /* Core IOMMU execution activation */
 enum {
     RISCV_IOMMU_EXEC_DDTP,
@@ -1502,7 +1542,7 @@ static void *riscv_iommu_core_proc(void* arg)
             /* NOP */
             break;
         case BIT(RISCV_IOMMU_EXEC_TR_REQUEST):
-            /* DBG support not implemented yet */
+            riscv_iommu_process_dbg(s);
             break;
         }
         exec &= ~mask;
@@ -1574,6 +1614,12 @@ static MemTxResult riscv_iommu_mmio_write(void *opaque, 
hwaddr addr,
         exec = BIT(RISCV_IOMMU_EXEC_PQCSR);
         busy = RISCV_IOMMU_PQCSR_BUSY;
         break;
+
+    case RISCV_IOMMU_REG_TR_REQ_CTL:
+        exec = BIT(RISCV_IOMMU_EXEC_TR_REQUEST);
+        regb = RISCV_IOMMU_REG_TR_REQ_CTL;
+        busy = RISCV_IOMMU_TR_REQ_CTL_GO_BUSY;
+        break;
     }
 
     /*
@@ -1746,6 +1792,9 @@ static void riscv_iommu_realize(DeviceState *dev, Error 
**errp)
         s->cap |= RISCV_IOMMU_CAP_SV32X4 | RISCV_IOMMU_CAP_SV39X4 |
                   RISCV_IOMMU_CAP_SV48X4 | RISCV_IOMMU_CAP_SV57X4;
     }
+    /* Enable translation debug interface */
+    s->cap |= RISCV_IOMMU_CAP_DBG;
+
     /* Report QEMU target physical address space limits */
     s->cap = set_field(s->cap, RISCV_IOMMU_CAP_PAS,
                        TARGET_PHYS_ADDR_SPACE_BITS);
@@ -1800,6 +1849,12 @@ static void riscv_iommu_realize(DeviceState *dev, Error 
**errp)
     stl_le_p(&s->regs_wc[RISCV_IOMMU_REG_IPSR], ~0);
     stl_le_p(&s->regs_ro[RISCV_IOMMU_REG_IVEC], 0);
     stq_le_p(&s->regs_rw[RISCV_IOMMU_REG_DDTP], s->ddtp);
+    /* If debug registers enabled. */
+    if (s->cap & RISCV_IOMMU_CAP_DBG) {
+        stq_le_p(&s->regs_ro[RISCV_IOMMU_REG_TR_REQ_IOVA], 0);
+        stq_le_p(&s->regs_ro[RISCV_IOMMU_REG_TR_REQ_CTL],
+            RISCV_IOMMU_TR_REQ_CTL_GO_BUSY);
+    }
 
     /* Memory region for downstream access, if specified. */
     if (s->target_mr) {
-- 
2.43.2