hw/riscv/riscv-iommu: add DBG support

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>
Reviewed-by: Frank Chang <frank.chang@sifive.com>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Message-ID: <20241016204038.649340-11-dbarboza@ventanamicro.com>
Signed-off-by: Alistair Francis <alistair.francis@wdc.com>

1 files changed, 59 insertions, 0 deletions

diff --git a/hw/riscv/riscv-iommu.c b/hw/riscv/riscv-iommu.c
index 1a8da005c0..feb650549a 100644
--- a/hw/riscv/riscv-iommu.c
+++ b/hw/riscv/riscv-iommu.c
@@ -1764,6 +1764,50 @@ 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 = ctrl & RISCV_IOMMU_TR_REQ_CTL_NW ? IOMMU_RO : IOMMU_RW,
+            .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;
+            iova >>= TARGET_PAGE_BITS;
+            iova &= RISCV_IOMMU_TR_RESPONSE_PPN;
+
+            /* We do not support superpages (> 4kbs) for now */
+            iova &= ~RISCV_IOMMU_TR_RESPONSE_S;
+        }
+        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);
+}
+
 typedef void riscv_iommu_process_fn(RISCVIOMMUState *s);
 
 static void riscv_iommu_update_icvec(RISCVIOMMUState *s, uint64_t data)
@@ -1928,6 +1972,12 @@ static MemTxResult riscv_iommu_mmio_write(void *opaque, hwaddr addr,
 
         return MEMTX_OK;
 
+    case RISCV_IOMMU_REG_TR_REQ_CTL:
+        process_fn = riscv_iommu_process_dbg;
+        regb = RISCV_IOMMU_REG_TR_REQ_CTL;
+        busy = RISCV_IOMMU_TR_REQ_CTL_GO_BUSY;
+        break;
+
     default:
         break;
     }
@@ -2065,6 +2115,9 @@ 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);
@@ -2121,6 +2174,12 @@ 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_ICVEC], 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) {