On 10/16/24 12:37 AM, Jason Chien wrote:
Hi Daniel,

On 2024/10/4 下午 11:57, Daniel Henrique Barboza wrote:
From: Tomasz Jeznach <tjezn...@rivosinc.com>

The RISC-V IOMMU specification is now ratified as-per the RISC-V
international process. The latest frozen specifcation can be found at:

https://github.com/riscv-non-isa/riscv-iommu/releases/download/v1.0/riscv-iommu.pdf

Add the foundation of the device emulation for RISC-V IOMMU. It includes
support for s-stage (sv32, sv39, sv48, sv57 caps) and g-stage (sv32x4,
sv39x4, sv48x4, sv57x4 caps).

Other capabilities like ATS and DBG support will be added incrementally
in the next patches.

Co-developed-by: Sebastien Boeuf <s...@rivosinc.com>
Signed-off-by: Sebastien Boeuf <s...@rivosinc.com>
Signed-off-by: Tomasz Jeznach <tjezn...@rivosinc.com>
Signed-off-by: Daniel Henrique Barboza <dbarb...@ventanamicro.com>
Acked-by: Alistair Francis <alistair.fran...@wdc.com>
---

(...)

+
+static void riscv_iommu_process_cq_tail(RISCVIOMMUState *s)
+{
+    struct riscv_iommu_command cmd;
+    MemTxResult res;
+    dma_addr_t addr;
+    uint32_t tail, head, ctrl;
+    uint64_t cmd_opcode;
+    GHFunc func;
+
+    ctrl = riscv_iommu_reg_get32(s, RISCV_IOMMU_REG_CQCSR);
+    tail = riscv_iommu_reg_get32(s, RISCV_IOMMU_REG_CQT) & s->cq_mask;
+    head = riscv_iommu_reg_get32(s, RISCV_IOMMU_REG_CQH) & s->cq_mask;
+
+    /* Check for pending error or queue processing disabled */
+    if (!(ctrl & RISCV_IOMMU_CQCSR_CQON) ||
+        !!(ctrl & (RISCV_IOMMU_CQCSR_CMD_ILL | RISCV_IOMMU_CQCSR_CQMF))) {
+        return;
+    }
+
+    while (tail != head) {
+        addr = s->cq_addr  + head * sizeof(cmd);
+        res = dma_memory_read(s->target_as, addr, &cmd, sizeof(cmd),
+                              MEMTXATTRS_UNSPECIFIED);
+
+        if (res != MEMTX_OK) {
+            riscv_iommu_reg_mod32(s, RISCV_IOMMU_REG_CQCSR,
+                                  RISCV_IOMMU_CQCSR_CQMF, 0);
+            goto fault;
+        }
+
+        trace_riscv_iommu_cmd(s->parent_obj.id, cmd.dword0, cmd.dword1);
+
+        cmd_opcode = get_field(cmd.dword0,
+                               RISCV_IOMMU_CMD_OPCODE | RISCV_IOMMU_CMD_FUNC);
+
+        switch (cmd_opcode) {
+        case RISCV_IOMMU_CMD(RISCV_IOMMU_CMD_IOFENCE_FUNC_C,
+                             RISCV_IOMMU_CMD_IOFENCE_OPCODE):
+            res = riscv_iommu_iofence(s,
+                cmd.dword0 & RISCV_IOMMU_CMD_IOFENCE_AV, cmd.dword1,
The correct address is cmd.dword1 << 2.

You're right. In riscv-iommu spec, section 3.1.2 "IOMMU Command-queue Fence 
commands":

The AV command operand indicates if ADDR[63:2] operand and DATA operands are 
valid.
If AV=1, the IOMMU writes DATA to memory at a 4-byte aligned address ADDR[63:2] 
* 4 as
a 4-byte store when the command completes. When AV is 0, the ADDR[63:2] and DATA
operands are ignored.


I'll fix this instance and the other 2 instances you pointed out in patch 8.

Reviewed-by: Jason Chien <jason.ch...@sifive.com>

Thanks for the tag!


Daniel

+                get_field(cmd.dword0, RISCV_IOMMU_CMD_IOFENCE_DATA));
+
+            if (res != MEMTX_OK) {
+                riscv_iommu_reg_mod32(s, RISCV_IOMMU_REG_CQCSR,
+                                      RISCV_IOMMU_CQCSR_CQMF, 0);
+                goto fault;
+            }
+            break;
+
+        case RISCV_IOMMU_CMD(RISCV_IOMMU_CMD_IOTINVAL_FUNC_GVMA,
+                             RISCV_IOMMU_CMD_IOTINVAL_OPCODE):
+            if (cmd.dword0 & RISCV_IOMMU_CMD_IOTINVAL_PSCV) {
+                /* illegal command arguments IOTINVAL.GVMA & PSCV == 1 */
+                goto cmd_ill;
+            }
+            /* translation cache not implemented yet */
+            break;
+
+        case RISCV_IOMMU_CMD(RISCV_IOMMU_CMD_IOTINVAL_FUNC_VMA,
+                             RISCV_IOMMU_CMD_IOTINVAL_OPCODE):
+            /* translation cache not implemented yet */
+            break;
+
+        case RISCV_IOMMU_CMD(RISCV_IOMMU_CMD_IODIR_FUNC_INVAL_DDT,
+                             RISCV_IOMMU_CMD_IODIR_OPCODE):
+            if (!(cmd.dword0 & RISCV_IOMMU_CMD_IODIR_DV)) {
+                /* invalidate all device context cache mappings */
+                func = riscv_iommu_ctx_inval_all;
+            } else {
+                /* invalidate all device context matching DID */
+                func = riscv_iommu_ctx_inval_devid;
+            }
+            riscv_iommu_ctx_inval(s, func,
+                get_field(cmd.dword0, RISCV_IOMMU_CMD_IODIR_DID), 0);
+            break;
+
+        case RISCV_IOMMU_CMD(RISCV_IOMMU_CMD_IODIR_FUNC_INVAL_PDT,
+                             RISCV_IOMMU_CMD_IODIR_OPCODE):
+            if (!(cmd.dword0 & RISCV_IOMMU_CMD_IODIR_DV)) {
+                /* illegal command arguments IODIR_PDT & DV == 0 */
+                goto cmd_ill;
+            } else {
+                func = riscv_iommu_ctx_inval_devid_procid;
+            }
+            riscv_iommu_ctx_inval(s, func,
+                get_field(cmd.dword0, RISCV_IOMMU_CMD_IODIR_DID),
+                get_field(cmd.dword0, RISCV_IOMMU_CMD_IODIR_PID));
+            break;
+
+        default:
+        cmd_ill:
+            /* Invalid instruction, do not advance instruction index. */
+            riscv_iommu_reg_mod32(s, RISCV_IOMMU_REG_CQCSR,
+                RISCV_IOMMU_CQCSR_CMD_ILL, 0);
+            goto fault;
+        }
+
+        /* Advance and update head pointer after command completes. */
+        head = (head + 1) & s->cq_mask;
+        riscv_iommu_reg_set32(s, RISCV_IOMMU_REG_CQH, head);
+    }
+    return;
+
+fault:
+    if (ctrl & RISCV_IOMMU_CQCSR_CIE) {
+        riscv_iommu_notify(s, RISCV_IOMMU_INTR_CQ);
+    }
+}
+
+static void riscv_iommu_process_cq_control(RISCVIOMMUState *s)
+{
+    uint64_t base;
+    uint32_t ctrl_set = riscv_iommu_reg_get32(s, RISCV_IOMMU_REG_CQCSR);
+    uint32_t ctrl_clr;
+    bool enable = !!(ctrl_set & RISCV_IOMMU_CQCSR_CQEN);
+    bool active = !!(ctrl_set & RISCV_IOMMU_CQCSR_CQON);
+
+    if (enable && !active) {
+        base = riscv_iommu_reg_get64(s, RISCV_IOMMU_REG_CQB);
+        s->cq_mask = (2ULL << get_field(base, RISCV_IOMMU_CQB_LOG2SZ)) - 1;
+        s->cq_addr = PPN_PHYS(get_field(base, RISCV_IOMMU_CQB_PPN));
+        stl_le_p(&s->regs_ro[RISCV_IOMMU_REG_CQT], ~s->cq_mask);
+        stl_le_p(&s->regs_rw[RISCV_IOMMU_REG_CQH], 0);
+        stl_le_p(&s->regs_rw[RISCV_IOMMU_REG_CQT], 0);
+        ctrl_set = RISCV_IOMMU_CQCSR_CQON;
+        ctrl_clr = RISCV_IOMMU_CQCSR_BUSY | RISCV_IOMMU_CQCSR_CQMF |
+                   RISCV_IOMMU_CQCSR_CMD_ILL | RISCV_IOMMU_CQCSR_CMD_TO |
+                   RISCV_IOMMU_CQCSR_FENCE_W_IP;
+    } else if (!enable && active) {
+        stl_le_p(&s->regs_ro[RISCV_IOMMU_REG_CQT], ~0);
+        ctrl_set = 0;
+        ctrl_clr = RISCV_IOMMU_CQCSR_BUSY | RISCV_IOMMU_CQCSR_CQON;
+    } else {
+        ctrl_set = 0;
+        ctrl_clr = RISCV_IOMMU_CQCSR_BUSY;
+    }
+
+    riscv_iommu_reg_mod32(s, RISCV_IOMMU_REG_CQCSR, ctrl_set, ctrl_clr);
+}
+
+static void riscv_iommu_process_fq_control(RISCVIOMMUState *s)
+{
+    uint64_t base;
+    uint32_t ctrl_set = riscv_iommu_reg_get32(s, RISCV_IOMMU_REG_FQCSR);
+    uint32_t ctrl_clr;
+    bool enable = !!(ctrl_set & RISCV_IOMMU_FQCSR_FQEN);
+    bool active = !!(ctrl_set & RISCV_IOMMU_FQCSR_FQON);
+
+    if (enable && !active) {
+        base = riscv_iommu_reg_get64(s, RISCV_IOMMU_REG_FQB);
+        s->fq_mask = (2ULL << get_field(base, RISCV_IOMMU_FQB_LOG2SZ)) - 1;
+        s->fq_addr = PPN_PHYS(get_field(base, RISCV_IOMMU_FQB_PPN));
+        stl_le_p(&s->regs_ro[RISCV_IOMMU_REG_FQH], ~s->fq_mask);
+        stl_le_p(&s->regs_rw[RISCV_IOMMU_REG_FQH], 0);
+        stl_le_p(&s->regs_rw[RISCV_IOMMU_REG_FQT], 0);
+        ctrl_set = RISCV_IOMMU_FQCSR_FQON;
+        ctrl_clr = RISCV_IOMMU_FQCSR_BUSY | RISCV_IOMMU_FQCSR_FQMF |
+            RISCV_IOMMU_FQCSR_FQOF;
+    } else if (!enable && active) {
+        stl_le_p(&s->regs_ro[RISCV_IOMMU_REG_FQH], ~0);
+        ctrl_set = 0;
+        ctrl_clr = RISCV_IOMMU_FQCSR_BUSY | RISCV_IOMMU_FQCSR_FQON;
+    } else {
+        ctrl_set = 0;
+        ctrl_clr = RISCV_IOMMU_FQCSR_BUSY;
+    }
+
+    riscv_iommu_reg_mod32(s, RISCV_IOMMU_REG_FQCSR, ctrl_set, ctrl_clr);
+}
+
+static void riscv_iommu_process_pq_control(RISCVIOMMUState *s)
+{
+    uint64_t base;
+    uint32_t ctrl_set = riscv_iommu_reg_get32(s, RISCV_IOMMU_REG_PQCSR);
+    uint32_t ctrl_clr;
+    bool enable = !!(ctrl_set & RISCV_IOMMU_PQCSR_PQEN);
+    bool active = !!(ctrl_set & RISCV_IOMMU_PQCSR_PQON);
+
+    if (enable && !active) {
+        base = riscv_iommu_reg_get64(s, RISCV_IOMMU_REG_PQB);
+        s->pq_mask = (2ULL << get_field(base, RISCV_IOMMU_PQB_LOG2SZ)) - 1;
+        s->pq_addr = PPN_PHYS(get_field(base, RISCV_IOMMU_PQB_PPN));
+        stl_le_p(&s->regs_ro[RISCV_IOMMU_REG_PQH], ~s->pq_mask);
+        stl_le_p(&s->regs_rw[RISCV_IOMMU_REG_PQH], 0);
+        stl_le_p(&s->regs_rw[RISCV_IOMMU_REG_PQT], 0);
+        ctrl_set = RISCV_IOMMU_PQCSR_PQON;
+        ctrl_clr = RISCV_IOMMU_PQCSR_BUSY | RISCV_IOMMU_PQCSR_PQMF |
+            RISCV_IOMMU_PQCSR_PQOF;
+    } else if (!enable && active) {
+        stl_le_p(&s->regs_ro[RISCV_IOMMU_REG_PQH], ~0);
+        ctrl_set = 0;
+        ctrl_clr = RISCV_IOMMU_PQCSR_BUSY | RISCV_IOMMU_PQCSR_PQON;
+    } else {
+        ctrl_set = 0;
+        ctrl_clr = RISCV_IOMMU_PQCSR_BUSY;
+    }
+
+    riscv_iommu_reg_mod32(s, RISCV_IOMMU_REG_PQCSR, ctrl_set, ctrl_clr);
+}
+
+typedef void riscv_iommu_process_fn(RISCVIOMMUState *s);
+
+static void riscv_iommu_update_icvec(RISCVIOMMUState *s, uint64_t data)
+{
+    uint64_t icvec = 0;
+
+    icvec |= MIN(data & RISCV_IOMMU_ICVEC_CIV,
+                 s->icvec_avail_vectors & RISCV_IOMMU_ICVEC_CIV);
+
+    icvec |= MIN(data & RISCV_IOMMU_ICVEC_FIV,
+                 s->icvec_avail_vectors & RISCV_IOMMU_ICVEC_FIV);
+
+    icvec |= MIN(data & RISCV_IOMMU_ICVEC_PMIV,
+                 s->icvec_avail_vectors & RISCV_IOMMU_ICVEC_PMIV);
+
+    icvec |= MIN(data & RISCV_IOMMU_ICVEC_PIV,
+                 s->icvec_avail_vectors & RISCV_IOMMU_ICVEC_PIV);
+
+    trace_riscv_iommu_icvec_write(data, icvec);
+
+    riscv_iommu_reg_set64(s, RISCV_IOMMU_REG_ICVEC, icvec);
+}
+
+static void riscv_iommu_update_ipsr(RISCVIOMMUState *s, uint64_t data)
+{
+    uint32_t cqcsr, fqcsr, pqcsr;
+    uint32_t ipsr_set = 0;
+    uint32_t ipsr_clr = 0;
+
+    if (data & RISCV_IOMMU_IPSR_CIP) {
+        cqcsr = riscv_iommu_reg_get32(s, RISCV_IOMMU_REG_CQCSR);
+
+        if (cqcsr & RISCV_IOMMU_CQCSR_CIE &&
+            (cqcsr & RISCV_IOMMU_CQCSR_FENCE_W_IP ||
+             cqcsr & RISCV_IOMMU_CQCSR_CMD_ILL ||
+             cqcsr & RISCV_IOMMU_CQCSR_CMD_TO ||
+             cqcsr & RISCV_IOMMU_CQCSR_CQMF)) {
+            ipsr_set |= RISCV_IOMMU_IPSR_CIP;
+        } else {
+            ipsr_clr |= RISCV_IOMMU_IPSR_CIP;
+        }
+    } else {
+        ipsr_clr |= RISCV_IOMMU_IPSR_CIP;
+    }
+
+    if (data & RISCV_IOMMU_IPSR_FIP) {
+        fqcsr = riscv_iommu_reg_get32(s, RISCV_IOMMU_REG_FQCSR);
+
+        if (fqcsr & RISCV_IOMMU_FQCSR_FIE &&
+            (fqcsr & RISCV_IOMMU_FQCSR_FQOF ||
+             fqcsr & RISCV_IOMMU_FQCSR_FQMF)) {
+            ipsr_set |= RISCV_IOMMU_IPSR_FIP;
+        } else {
+            ipsr_clr |= RISCV_IOMMU_IPSR_FIP;
+        }
+    } else {
+        ipsr_clr |= RISCV_IOMMU_IPSR_FIP;
+    }
+
+    if (data & RISCV_IOMMU_IPSR_PIP) {
+        pqcsr = riscv_iommu_reg_get32(s, RISCV_IOMMU_REG_PQCSR);
+
+        if (pqcsr & RISCV_IOMMU_PQCSR_PIE &&
+            (pqcsr & RISCV_IOMMU_PQCSR_PQOF ||
+             pqcsr & RISCV_IOMMU_PQCSR_PQMF)) {
+            ipsr_set |= RISCV_IOMMU_IPSR_PIP;
+        } else {
+            ipsr_clr |= RISCV_IOMMU_IPSR_PIP;
+        }
+    } else {
+        ipsr_clr |= RISCV_IOMMU_IPSR_PIP;
+    }
+
+    riscv_iommu_reg_mod32(s, RISCV_IOMMU_REG_IPSR, ipsr_set, ipsr_clr);
+}
+
+/*
+ * Write the resulting value of 'data' for the reg specified
+ * by 'reg_addr', after considering read-only/read-write/write-clear
+ * bits, in the pointer 'dest'.
+ *
+ * The result is written in little-endian.
+ */
+static void riscv_iommu_write_reg_val(RISCVIOMMUState *s,
+                                      void *dest, hwaddr reg_addr,
+                                      int size, uint64_t data)
+{
+    uint64_t ro = ldn_le_p(&s->regs_ro[reg_addr], size);
+    uint64_t wc = ldn_le_p(&s->regs_wc[reg_addr], size);
+    uint64_t rw = ldn_le_p(&s->regs_rw[reg_addr], size);
+
+    stn_le_p(dest, size, ((rw & ro) | (data & ~ro)) & ~(data & wc));
+}
+
+static MemTxResult riscv_iommu_mmio_write(void *opaque, hwaddr addr,
+                                          uint64_t data, unsigned size,
+                                          MemTxAttrs attrs)
+{
+    riscv_iommu_process_fn *process_fn = NULL;
+    RISCVIOMMUState *s = opaque;
+    uint32_t regb = addr & ~3;
+    uint32_t busy = 0;
+    uint64_t val = 0;
+
+    if ((addr & (size - 1)) != 0) {
+        /* Unsupported MMIO alignment or access size */
+        return MEMTX_ERROR;
+    }
+
+    if (addr + size > RISCV_IOMMU_REG_MSI_CONFIG) {
+        /* Unsupported MMIO access location. */
+        return MEMTX_ACCESS_ERROR;
+    }
+
+    /* Track actionable MMIO write. */
+    switch (regb) {
+    case RISCV_IOMMU_REG_DDTP:
+    case RISCV_IOMMU_REG_DDTP + 4:
+        process_fn = riscv_iommu_process_ddtp;
+        regb = RISCV_IOMMU_REG_DDTP;
+        busy = RISCV_IOMMU_DDTP_BUSY;
+        break;
+
+    case RISCV_IOMMU_REG_CQT:
+        process_fn = riscv_iommu_process_cq_tail;
+        break;
+
+    case RISCV_IOMMU_REG_CQCSR:
+        process_fn = riscv_iommu_process_cq_control;
+        busy = RISCV_IOMMU_CQCSR_BUSY;
+        break;
+
+    case RISCV_IOMMU_REG_FQCSR:
+        process_fn = riscv_iommu_process_fq_control;
+        busy = RISCV_IOMMU_FQCSR_BUSY;
+        break;
+
+    case RISCV_IOMMU_REG_PQCSR:
+        process_fn = riscv_iommu_process_pq_control;
+        busy = RISCV_IOMMU_PQCSR_BUSY;
+        break;
+
+    case RISCV_IOMMU_REG_ICVEC:
+    case RISCV_IOMMU_REG_IPSR:
+        /*
+         * ICVEC and IPSR have special read/write procedures. We'll
+         * call their respective helpers and exit.
+         */
+        riscv_iommu_write_reg_val(s, &val, addr, size, data);
+
+        /*
+         * 'val' is stored as LE. Switch to host endianess
+         * before using it.
+         */
+        val = le64_to_cpu(val);
+
+        if (regb == RISCV_IOMMU_REG_ICVEC) {
+            riscv_iommu_update_icvec(s, val);
+        } else {
+            riscv_iommu_update_ipsr(s, val);
+        }
+
+        return MEMTX_OK;
+
+    default:
+        break;
+    }
+
+    /*
+     * Registers update might be not synchronized with core logic.
+     * If system software updates register when relevant BUSY bit
+     * is set IOMMU behavior of additional writes to the register
+     * is UNSPECIFIED.
+     */
+    riscv_iommu_write_reg_val(s, &s->regs_rw[addr], addr, size, data);
+
+    /* Busy flag update, MSB 4-byte register. */
+    if (busy) {
+        uint32_t rw = ldl_le_p(&s->regs_rw[regb]);
+        stl_le_p(&s->regs_rw[regb], rw | busy);
+    }
+
+    if (process_fn) {
+        process_fn(s);
+    }
+
+    return MEMTX_OK;
+}
+
+static MemTxResult riscv_iommu_mmio_read(void *opaque, hwaddr addr,
+    uint64_t *data, unsigned size, MemTxAttrs attrs)
+{
+    RISCVIOMMUState *s = opaque;
+    uint64_t val = -1;
+    uint8_t *ptr;
+
+    if ((addr & (size - 1)) != 0) {
+        /* Unsupported MMIO alignment. */
+        return MEMTX_ERROR;
+    }
+
+    if (addr + size > RISCV_IOMMU_REG_MSI_CONFIG) {
+        return MEMTX_ACCESS_ERROR;
+    }
+
+    ptr = &s->regs_rw[addr];
+    val = ldn_le_p(ptr, size);
+
+    *data = val;
+
+    return MEMTX_OK;
+}
+
+static const MemoryRegionOps riscv_iommu_mmio_ops = {
+    .read_with_attrs = riscv_iommu_mmio_read,
+    .write_with_attrs = riscv_iommu_mmio_write,
+    .endianness = DEVICE_NATIVE_ENDIAN,
+    .impl = {
+        .min_access_size = 4,
+        .max_access_size = 8,
+        .unaligned = false,
+    },
+    .valid = {
+        .min_access_size = 4,
+        .max_access_size = 8,
+    }
+};
+
+/*
+ * Translations matching MSI pattern check are redirected to "riscv-iommu-trap"
+ * memory region as untranslated address, for additional MSI/MRIF interception
+ * by IOMMU interrupt remapping implementation.
+ * Note: Device emulation code generating an MSI is expected to provide a valid
+ * memory transaction attributes with requested_id set.
+ */
+static MemTxResult riscv_iommu_trap_write(void *opaque, hwaddr addr,
+    uint64_t data, unsigned size, MemTxAttrs attrs)
+{
+    RISCVIOMMUState* s = (RISCVIOMMUState *)opaque;
+    RISCVIOMMUContext *ctx;
+    MemTxResult res;
+    void *ref;
+    uint32_t devid = attrs.requester_id;
+
+    if (attrs.unspecified) {
+        return MEMTX_ACCESS_ERROR;
+    }
+
+    /* FIXME: PCIe bus remapping for attached endpoints. */
+    devid |= s->bus << 8;
+
+    ctx = riscv_iommu_ctx(s, devid, 0, &ref);
+    if (ctx == NULL) {
+        res = MEMTX_ACCESS_ERROR;
+    } else {
+        res = riscv_iommu_msi_write(s, ctx, addr, data, size, attrs);
+    }
+    riscv_iommu_ctx_put(s, ref);
+    return res;
+}
+
+static MemTxResult riscv_iommu_trap_read(void *opaque, hwaddr addr,
+    uint64_t *data, unsigned size, MemTxAttrs attrs)
+{
+    return MEMTX_ACCESS_ERROR;
+}
+
+static const MemoryRegionOps riscv_iommu_trap_ops = {
+    .read_with_attrs = riscv_iommu_trap_read,
+    .write_with_attrs = riscv_iommu_trap_write,
+    .endianness = DEVICE_LITTLE_ENDIAN,
+    .impl = {
+        .min_access_size = 4,
+        .max_access_size = 8,
+        .unaligned = true,
+    },
+    .valid = {
+        .min_access_size = 4,
+        .max_access_size = 8,
+    }
+};
+
+static void riscv_iommu_realize(DeviceState *dev, Error **errp)
+{
+    RISCVIOMMUState *s = RISCV_IOMMU(dev);
+
+    s->cap = s->version & RISCV_IOMMU_CAP_VERSION;
+    if (s->enable_msi) {
+        s->cap |= RISCV_IOMMU_CAP_MSI_FLAT | RISCV_IOMMU_CAP_MSI_MRIF;
+    }
+    if (s->enable_s_stage) {
+        s->cap |= RISCV_IOMMU_CAP_SV32 | RISCV_IOMMU_CAP_SV39 |
+                  RISCV_IOMMU_CAP_SV48 | RISCV_IOMMU_CAP_SV57;
+    }
+    if (s->enable_g_stage) {
+        s->cap |= RISCV_IOMMU_CAP_SV32X4 | RISCV_IOMMU_CAP_SV39X4 |
+                  RISCV_IOMMU_CAP_SV48X4 | RISCV_IOMMU_CAP_SV57X4;
+    }
+    /* Report QEMU target physical address space limits */
+    s->cap = set_field(s->cap, RISCV_IOMMU_CAP_PAS,
+                       TARGET_PHYS_ADDR_SPACE_BITS);
+
+    /* TODO: method to report supported PID bits */
+    s->pid_bits = 8; /* restricted to size of MemTxAttrs.pid */
+    s->cap |= RISCV_IOMMU_CAP_PD8;
+
+    /* Out-of-reset translation mode: OFF (DMA disabled) BARE (passthrough) */
+    s->ddtp = set_field(0, RISCV_IOMMU_DDTP_MODE, s->enable_off ?
+                        RISCV_IOMMU_DDTP_MODE_OFF : 
RISCV_IOMMU_DDTP_MODE_BARE);
+
+    /* register storage */
+    s->regs_rw = g_new0(uint8_t, RISCV_IOMMU_REG_SIZE);
+    s->regs_ro = g_new0(uint8_t, RISCV_IOMMU_REG_SIZE);
+    s->regs_wc = g_new0(uint8_t, RISCV_IOMMU_REG_SIZE);
+
+     /* Mark all registers read-only */
+    memset(s->regs_ro, 0xff, RISCV_IOMMU_REG_SIZE);
+
+    /*
+     * Register complete MMIO space, including MSI/PBA registers.
+     * Note, PCIDevice implementation will add overlapping MR for MSI/PBA,
+     * managed directly by the PCIDevice implementation.
+     */
+    memory_region_init_io(&s->regs_mr, OBJECT(dev), &riscv_iommu_mmio_ops, s,
+        "riscv-iommu-regs", RISCV_IOMMU_REG_SIZE);
+
+    /* Set power-on register state */
+    stq_le_p(&s->regs_rw[RISCV_IOMMU_REG_CAP], s->cap);
+    stq_le_p(&s->regs_rw[RISCV_IOMMU_REG_FCTL], 0);
+    stq_le_p(&s->regs_ro[RISCV_IOMMU_REG_FCTL],
+             ~(RISCV_IOMMU_FCTL_BE | RISCV_IOMMU_FCTL_WSI));
+    stq_le_p(&s->regs_ro[RISCV_IOMMU_REG_DDTP],
+        ~(RISCV_IOMMU_DDTP_PPN | RISCV_IOMMU_DDTP_MODE));
+    stq_le_p(&s->regs_ro[RISCV_IOMMU_REG_CQB],
+        ~(RISCV_IOMMU_CQB_LOG2SZ | RISCV_IOMMU_CQB_PPN));
+    stq_le_p(&s->regs_ro[RISCV_IOMMU_REG_FQB],
+        ~(RISCV_IOMMU_FQB_LOG2SZ | RISCV_IOMMU_FQB_PPN));
+    stq_le_p(&s->regs_ro[RISCV_IOMMU_REG_PQB],
+        ~(RISCV_IOMMU_PQB_LOG2SZ | RISCV_IOMMU_PQB_PPN));
+    stl_le_p(&s->regs_wc[RISCV_IOMMU_REG_CQCSR], RISCV_IOMMU_CQCSR_CQMF |
+        RISCV_IOMMU_CQCSR_CMD_TO | RISCV_IOMMU_CQCSR_CMD_ILL);
+    stl_le_p(&s->regs_ro[RISCV_IOMMU_REG_CQCSR], RISCV_IOMMU_CQCSR_CQON |
+        RISCV_IOMMU_CQCSR_BUSY);
+    stl_le_p(&s->regs_wc[RISCV_IOMMU_REG_FQCSR], RISCV_IOMMU_FQCSR_FQMF |
+        RISCV_IOMMU_FQCSR_FQOF);
+    stl_le_p(&s->regs_ro[RISCV_IOMMU_REG_FQCSR], RISCV_IOMMU_FQCSR_FQON |
+        RISCV_IOMMU_FQCSR_BUSY);
+    stl_le_p(&s->regs_wc[RISCV_IOMMU_REG_PQCSR], RISCV_IOMMU_PQCSR_PQMF |
+        RISCV_IOMMU_PQCSR_PQOF);
+    stl_le_p(&s->regs_ro[RISCV_IOMMU_REG_PQCSR], RISCV_IOMMU_PQCSR_PQON |
+        RISCV_IOMMU_PQCSR_BUSY);
+    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);
+
+    /* Memory region for downstream access, if specified. */
+    if (s->target_mr) {
+        s->target_as = g_new0(AddressSpace, 1);
+        address_space_init(s->target_as, s->target_mr,
+            "riscv-iommu-downstream");
+    } else {
+        /* Fallback to global system memory. */
+        s->target_as = &address_space_memory;
+    }
+
+    /* Memory region for untranslated MRIF/MSI writes */
+    memory_region_init_io(&s->trap_mr, OBJECT(dev), &riscv_iommu_trap_ops, s,
+            "riscv-iommu-trap", ~0ULL);
+    address_space_init(&s->trap_as, &s->trap_mr, "riscv-iommu-trap-as");
+
+    /* Device translation context cache */
+    s->ctx_cache = g_hash_table_new_full(riscv_iommu_ctx_hash,
+                                         riscv_iommu_ctx_equal,
+                                         g_free, NULL);
+
+    s->iommus.le_next = NULL;
+    s->iommus.le_prev = NULL;
+    QLIST_INIT(&s->spaces);
+}
+
+static void riscv_iommu_unrealize(DeviceState *dev)
+{
+    RISCVIOMMUState *s = RISCV_IOMMU(dev);
+
+    g_hash_table_unref(s->ctx_cache);
+}
+
+static Property riscv_iommu_properties[] = {
+    DEFINE_PROP_UINT32("version", RISCVIOMMUState, version,
+        RISCV_IOMMU_SPEC_DOT_VER),
+    DEFINE_PROP_UINT32("bus", RISCVIOMMUState, bus, 0x0),
+    DEFINE_PROP_BOOL("intremap", RISCVIOMMUState, enable_msi, TRUE),
+    DEFINE_PROP_BOOL("off", RISCVIOMMUState, enable_off, TRUE),
+    DEFINE_PROP_BOOL("s-stage", RISCVIOMMUState, enable_s_stage, TRUE),
+    DEFINE_PROP_BOOL("g-stage", RISCVIOMMUState, enable_g_stage, TRUE),
+    DEFINE_PROP_LINK("downstream-mr", RISCVIOMMUState, target_mr,
+        TYPE_MEMORY_REGION, MemoryRegion *),
+    DEFINE_PROP_END_OF_LIST(),
+};
+
+static void riscv_iommu_class_init(ObjectClass *klass, void* data)
+{
+    DeviceClass *dc = DEVICE_CLASS(klass);
+
+    /* internal device for riscv-iommu-{pci/sys}, not user-creatable */
+    dc->user_creatable = false;
+    dc->realize = riscv_iommu_realize;
+    dc->unrealize = riscv_iommu_unrealize;
+    device_class_set_props(dc, riscv_iommu_properties);
+}
+
+static const TypeInfo riscv_iommu_info = {
+    .name = TYPE_RISCV_IOMMU,
+    .parent = TYPE_DEVICE,
+    .instance_size = sizeof(RISCVIOMMUState),
+    .class_init = riscv_iommu_class_init,
+};
+
+static const char *IOMMU_FLAG_STR[] = {
+    "NA",
+    "RO",
+    "WR",
+    "RW",
+};
+
+/* RISC-V IOMMU Memory Region - Address Translation Space */
+static IOMMUTLBEntry riscv_iommu_memory_region_translate(
+    IOMMUMemoryRegion *iommu_mr, hwaddr addr,
+    IOMMUAccessFlags flag, int iommu_idx)
+{
+    RISCVIOMMUSpace *as = container_of(iommu_mr, RISCVIOMMUSpace, iova_mr);
+    RISCVIOMMUContext *ctx;
+    void *ref;
+    IOMMUTLBEntry iotlb = {
+        .iova = addr,
+        .target_as = as->iommu->target_as,
+        .addr_mask = ~0ULL,
+        .perm = flag,
+    };
+
+    ctx = riscv_iommu_ctx(as->iommu, as->devid, iommu_idx, &ref);
+    if (ctx == NULL) {
+        /* Translation disabled or invalid. */
+        iotlb.addr_mask = 0;
+        iotlb.perm = IOMMU_NONE;
+    } else if (riscv_iommu_translate(as->iommu, ctx, &iotlb)) {
+        /* Translation disabled or fault reported. */
+        iotlb.addr_mask = 0;
+        iotlb.perm = IOMMU_NONE;
+    }
+
+    /* Trace all dma translations with original access flags. */
+    trace_riscv_iommu_dma(as->iommu->parent_obj.id, PCI_BUS_NUM(as->devid),
+                          PCI_SLOT(as->devid), PCI_FUNC(as->devid), iommu_idx,
+                          IOMMU_FLAG_STR[flag & IOMMU_RW], iotlb.iova,
+                          iotlb.translated_addr);
+
+    riscv_iommu_ctx_put(as->iommu, ref);
+
+    return iotlb;
+}
+
+static int riscv_iommu_memory_region_notify(
+    IOMMUMemoryRegion *iommu_mr, IOMMUNotifierFlag old,
+    IOMMUNotifierFlag new, Error **errp)
+{
+    RISCVIOMMUSpace *as = container_of(iommu_mr, RISCVIOMMUSpace, iova_mr);
+
+    if (old == IOMMU_NOTIFIER_NONE) {
+        as->notifier = true;
+        trace_riscv_iommu_notifier_add(iommu_mr->parent_obj.name);
+    } else if (new == IOMMU_NOTIFIER_NONE) {
+        as->notifier = false;
+        trace_riscv_iommu_notifier_del(iommu_mr->parent_obj.name);
+    }
+
+    return 0;
+}
+
+static inline bool pci_is_iommu(PCIDevice *pdev)
+{
+    return pci_get_word(pdev->config + PCI_CLASS_DEVICE) == 0x0806;
+}
+
+static AddressSpace *riscv_iommu_find_as(PCIBus *bus, void *opaque, int devfn)
+{
+    RISCVIOMMUState *s = (RISCVIOMMUState *) opaque;
+    PCIDevice *pdev = pci_find_device(bus, pci_bus_num(bus), devfn);
+    AddressSpace *as = NULL;
+
+    if (pdev && pci_is_iommu(pdev)) {
+        return s->target_as;
+    }
+
+    /* Find first registered IOMMU device */
+    while (s->iommus.le_prev) {
+        s = *(s->iommus.le_prev);
+    }
+
+    /* Find first matching IOMMU */
+    while (s != NULL && as == NULL) {
+        as = riscv_iommu_space(s, PCI_BUILD_BDF(pci_bus_num(bus), devfn));
+        s = s->iommus.le_next;
+    }
+
+    return as ? as : &address_space_memory;
+}
+
+static const PCIIOMMUOps riscv_iommu_ops = {
+    .get_address_space = riscv_iommu_find_as,
+};
+
+void riscv_iommu_pci_setup_iommu(RISCVIOMMUState *iommu, PCIBus *bus,
+        Error **errp)
+{
+    if (bus->iommu_ops &&
+        bus->iommu_ops->get_address_space == riscv_iommu_find_as) {
+        /* Allow multiple IOMMUs on the same PCIe bus, link known devices */
+        RISCVIOMMUState *last = (RISCVIOMMUState *)bus->iommu_opaque;
+        QLIST_INSERT_AFTER(last, iommu, iommus);
+    } else if (!bus->iommu_ops && !bus->iommu_opaque) {
+        pci_setup_iommu(bus, &riscv_iommu_ops, iommu);
+    } else {
+        error_setg(errp, "can't register secondary IOMMU for PCI bus #%d",
+            pci_bus_num(bus));
+    }
+}
+
+static int riscv_iommu_memory_region_index(IOMMUMemoryRegion *iommu_mr,
+    MemTxAttrs attrs)
+{
+    return attrs.unspecified ? RISCV_IOMMU_NOPROCID : (int)attrs.pid;
+}
+
+static int riscv_iommu_memory_region_index_len(IOMMUMemoryRegion *iommu_mr)
+{
+    RISCVIOMMUSpace *as = container_of(iommu_mr, RISCVIOMMUSpace, iova_mr);
+    return 1 << as->iommu->pid_bits;
+}
+
+static void riscv_iommu_memory_region_init(ObjectClass *klass, void *data)
+{
+    IOMMUMemoryRegionClass *imrc = IOMMU_MEMORY_REGION_CLASS(klass);
+
+    imrc->translate = riscv_iommu_memory_region_translate;
+    imrc->notify_flag_changed = riscv_iommu_memory_region_notify;
+    imrc->attrs_to_index = riscv_iommu_memory_region_index;
+    imrc->num_indexes = riscv_iommu_memory_region_index_len;
+}
+
+static const TypeInfo riscv_iommu_memory_region_info = {
+    .parent = TYPE_IOMMU_MEMORY_REGION,
+    .name = TYPE_RISCV_IOMMU_MEMORY_REGION,
+    .class_init = riscv_iommu_memory_region_init,
+};
+
+static void riscv_iommu_register_mr_types(void)
+{
+    type_register_static(&riscv_iommu_memory_region_info);
+    type_register_static(&riscv_iommu_info);
+}
+
+type_init(riscv_iommu_register_mr_types);
diff --git a/hw/riscv/riscv-iommu.h b/hw/riscv/riscv-iommu.h
new file mode 100644
index 0000000000..af3fcafc19
--- /dev/null
+++ b/hw/riscv/riscv-iommu.h
@@ -0,0 +1,126 @@
+/*
+ * QEMU emulation of an RISC-V IOMMU
+ *
+ * Copyright (C) 2022-2023 Rivos Inc.
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU General Public License,
+ * version 2 or later, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, see <http://www.gnu.org/licenses/>.
+ */
+
+#ifndef HW_RISCV_IOMMU_STATE_H
+#define HW_RISCV_IOMMU_STATE_H
+
+#include "qom/object.h"
+#include "hw/riscv/iommu.h"
+
+struct RISCVIOMMUState {
+    /*< private >*/
+    DeviceState parent_obj;
+
+    /*< public >*/
+    uint32_t version;     /* Reported interface version number */
+    uint32_t pid_bits;    /* process identifier width */
+    uint32_t bus;         /* PCI bus mapping for non-root endpoints */
+
+    uint64_t cap;         /* IOMMU supported capabilities */
+    uint64_t fctl;        /* IOMMU enabled features */
+    uint64_t icvec_avail_vectors;  /* Available interrupt vectors in ICVEC */
+
+    bool enable_off;      /* Enable out-of-reset OFF mode (DMA disabled) */
+    bool enable_msi;      /* Enable MSI remapping */
+    bool enable_s_stage;  /* Enable S/VS-Stage translation */
+    bool enable_g_stage;  /* Enable G-Stage translation */
+
+    /* IOMMU Internal State */
+    uint64_t ddtp;        /* Validated Device Directory Tree Root Pointer */
+
+    dma_addr_t cq_addr;   /* Command queue base physical address */
+    dma_addr_t fq_addr;   /* Fault/event queue base physical address */
+    dma_addr_t pq_addr;   /* Page request queue base physical address */
+
+    uint32_t cq_mask;     /* Command queue index bit mask */
+    uint32_t fq_mask;     /* Fault/event queue index bit mask */
+    uint32_t pq_mask;     /* Page request queue index bit mask */
+
+    /* interrupt notifier */
+    void (*notify)(RISCVIOMMUState *iommu, unsigned vector);
+
+    /* IOMMU State Machine */
+    QemuThread core_proc; /* Background processing thread */
+    QemuCond core_cond;   /* Background processing wake up signal */
+    unsigned core_exec;   /* Processing thread execution actions */
+
+    /* IOMMU target address space */
+    AddressSpace *target_as;
+    MemoryRegion *target_mr;
+
+    /* MSI / MRIF access trap */
+    AddressSpace trap_as;
+    MemoryRegion trap_mr;
+
+    GHashTable *ctx_cache;          /* Device translation Context Cache */
+
+    /* MMIO Hardware Interface */
+    MemoryRegion regs_mr;
+    uint8_t *regs_rw;  /* register state (user write) */
+    uint8_t *regs_wc;  /* write-1-to-clear mask */
+    uint8_t *regs_ro;  /* read-only mask */
+
+    QLIST_ENTRY(RISCVIOMMUState) iommus;
+    QLIST_HEAD(, RISCVIOMMUSpace) spaces;
+};
+
+void riscv_iommu_pci_setup_iommu(RISCVIOMMUState *iommu, PCIBus *bus,
+         Error **errp);
+
+/* private helpers */
+
+/* Register helper functions */
+static inline uint32_t riscv_iommu_reg_mod32(RISCVIOMMUState *s,
+    unsigned idx, uint32_t set, uint32_t clr)
+{
+    uint32_t val = ldl_le_p(s->regs_rw + idx);
+    stl_le_p(s->regs_rw + idx, (val & ~clr) | set);
+    return val;
+}
+
+static inline void riscv_iommu_reg_set32(RISCVIOMMUState *s, unsigned idx,
+                                         uint32_t set)
+{
+    stl_le_p(s->regs_rw + idx, set);
+}
+
+static inline uint32_t riscv_iommu_reg_get32(RISCVIOMMUState *s, unsigned idx)
+{
+    return ldl_le_p(s->regs_rw + idx);
+}
+
+static inline uint64_t riscv_iommu_reg_mod64(RISCVIOMMUState *s, unsigned idx,
+                                             uint64_t set, uint64_t clr)
+{
+    uint64_t val = ldq_le_p(s->regs_rw + idx);
+    stq_le_p(s->regs_rw + idx, (val & ~clr) | set);
+    return val;
+}
+
+static inline void riscv_iommu_reg_set64(RISCVIOMMUState *s, unsigned idx,
+                                         uint64_t set)
+{
+    stq_le_p(s->regs_rw + idx, set);
+}
+
+static inline uint64_t riscv_iommu_reg_get64(RISCVIOMMUState *s,
+    unsigned idx)
+{
+    return ldq_le_p(s->regs_rw + idx);
+}
+#endif
diff --git a/hw/riscv/trace-events b/hw/riscv/trace-events
new file mode 100644
index 0000000000..3d5c33102d
--- /dev/null
+++ b/hw/riscv/trace-events
@@ -0,0 +1,14 @@
+# See documentation at docs/devel/tracing.rst
+
+# riscv-iommu.c
+riscv_iommu_new(const char *id, unsigned b, unsigned d, unsigned f) "%s: device 
attached %04x:%02x.%d"
+riscv_iommu_flt(const char *id, unsigned b, unsigned d, unsigned f, uint64_t reason, uint64_t 
iova) "%s: fault %04x:%02x.%u reason: 0x%"PRIx64" iova: 0x%"PRIx64
+riscv_iommu_pri(const char *id, unsigned b, unsigned d, unsigned f, uint64_t iova) 
"%s: page request %04x:%02x.%u iova: 0x%"PRIx64
+riscv_iommu_dma(const char *id, unsigned b, unsigned d, unsigned f, unsigned pasid, const char *dir, 
uint64_t iova, uint64_t phys) "%s: translate %04x:%02x.%u #%u %s 0x%"PRIx64" -> 
0x%"PRIx64
+riscv_iommu_msi(const char *id, unsigned b, unsigned d, unsigned f, uint64_t iova, uint64_t phys) 
"%s: translate %04x:%02x.%u MSI 0x%"PRIx64" -> 0x%"PRIx64
+riscv_iommu_mrif_notification(const char *id, uint32_t nid, uint64_t phys) "%s: 
sent MRIF notification 0x%x to 0x%"PRIx64
+riscv_iommu_cmd(const char *id, uint64_t l, uint64_t u) "%s: command 0x%"PRIx64" 
0x%"PRIx64
+riscv_iommu_notifier_add(const char *id) "%s: dev-iotlb notifier added"
+riscv_iommu_notifier_del(const char *id) "%s: dev-iotlb notifier removed"
+riscv_iommu_notify_int_vector(uint32_t cause, uint32_t vector) "Interrupt cause 
0x%x sent via vector 0x%x"
+riscv_iommu_icvec_write(uint32_t orig, uint32_t actual) "ICVEC write: incoming 0x%x 
actual 0x%x"
diff --git a/hw/riscv/trace.h b/hw/riscv/trace.h
new file mode 100644
index 0000000000..8c0e3ca1f3
--- /dev/null
+++ b/hw/riscv/trace.h
@@ -0,0 +1 @@
+#include "trace/trace-hw_riscv.h"
diff --git a/include/hw/riscv/iommu.h b/include/hw/riscv/iommu.h
new file mode 100644
index 0000000000..80769a1400
--- /dev/null
+++ b/include/hw/riscv/iommu.h
@@ -0,0 +1,36 @@
+/*
+ * QEMU emulation of an RISC-V IOMMU
+ *
+ * Copyright (C) 2022-2023 Rivos Inc.
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU General Public License,
+ * version 2 or later, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, see <http://www.gnu.org/licenses/>.
+ */
+
+#ifndef HW_RISCV_IOMMU_H
+#define HW_RISCV_IOMMU_H
+
+#include "qemu/osdep.h"
+#include "qom/object.h"
+
+#define TYPE_RISCV_IOMMU "riscv-iommu"
+OBJECT_DECLARE_SIMPLE_TYPE(RISCVIOMMUState, RISCV_IOMMU)
+typedef struct RISCVIOMMUState RISCVIOMMUState;
+
+#define TYPE_RISCV_IOMMU_MEMORY_REGION "riscv-iommu-mr"
+typedef struct RISCVIOMMUSpace RISCVIOMMUSpace;
+
+#define TYPE_RISCV_IOMMU_PCI "riscv-iommu-pci"
+OBJECT_DECLARE_SIMPLE_TYPE(RISCVIOMMUStatePci, RISCV_IOMMU_PCI)
+typedef struct RISCVIOMMUStatePci RISCVIOMMUStatePci;
+
+#endif
diff --git a/meson.build b/meson.build
index 10464466ff..71de8a5cd1 100644
--- a/meson.build
+++ b/meson.build
@@ -3439,6 +3439,7 @@ if have_system
      'hw/pci-host',
      'hw/ppc',
      'hw/rtc',
+    'hw/riscv',
      'hw/s390x',
      'hw/scsi',
      'hw/sd',

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