diff --git a/hw/riscv/riscv-iommu-bits.h b/hw/riscv/riscv-iommu-bits.h
index b1c477f..96a994b 100644
--- a/hw/riscv/riscv-iommu-bits.h
+++ b/hw/riscv/riscv-iommu-bits.h
@@ -79,6 +79,7 @@
 #define RISCV_IOMMU_CAP_SV57X4          BIT_ULL(19)
 #define RISCV_IOMMU_CAP_MSI_FLAT        BIT_ULL(22)
 #define RISCV_IOMMU_CAP_MSI_MRIF        BIT_ULL(23)
+#define RISCV_IOMMU_CAP_ATS             BIT_ULL(25)
 #define RISCV_IOMMU_CAP_T2GPA           BIT_ULL(26)
 #define RISCV_IOMMU_CAP_IGS             GENMASK_ULL(29, 28)
 #define RISCV_IOMMU_CAP_PAS             GENMASK_ULL(37, 32)
@@ -212,6 +213,7 @@
 
 /* Translation control fields */
 #define RISCV_IOMMU_DC_TC_V             BIT_ULL(0)
+#define RISCV_IOMMU_DC_TC_EN_ATS        BIT_ULL(1)
 #define RISCV_IOMMU_DC_TC_EN_PRI        BIT_ULL(2)
 #define RISCV_IOMMU_DC_TC_T2GPA         BIT_ULL(3)
 #define RISCV_IOMMU_DC_TC_DTF           BIT_ULL(4)
@@ -273,6 +275,20 @@
 #define RISCV_IOMMU_CMD_IODIR_DV        BIT_ULL(33)
 #define RISCV_IOMMU_CMD_IODIR_DID       GENMASK_ULL(63, 40)
 
+/* 3.1.4 I/O MMU PCIe ATS */
+#define RISCV_IOMMU_CMD_ATS_OPCODE              4
+#define RISCV_IOMMU_CMD_ATS_FUNC_INVAL          0
+#define RISCV_IOMMU_CMD_ATS_FUNC_PRGR           1
+#define RISCV_IOMMU_CMD_ATS_PID         GENMASK_ULL(31, 12)
+#define RISCV_IOMMU_CMD_ATS_PV          BIT_ULL(32)
+#define RISCV_IOMMU_CMD_ATS_DSV         BIT_ULL(33)
+#define RISCV_IOMMU_CMD_ATS_RID         GENMASK_ULL(55, 40)
+#define RISCV_IOMMU_CMD_ATS_DSEG        GENMASK_ULL(63, 56)
+/* dword1 is the ATS payload, two different payload types for INVAL and PRGR */
+
+/* ATS.PRGR payload */
+#define RISCV_IOMMU_CMD_ATS_PRGR_RESP_CODE      GENMASK_ULL(47, 44)
+
 enum riscv_iommu_dc_fsc_atp_modes {
     RISCV_IOMMU_DC_FSC_MODE_BARE = 0,
     RISCV_IOMMU_DC_FSC_IOSATP_MODE_SV32 = 8,
@@ -339,7 +355,32 @@
     RISCV_IOMMU_FQ_TTYPE_TADDR_INST_FETCH = 5,
     RISCV_IOMMU_FQ_TTYPE_TADDR_RD = 6,
     RISCV_IOMMU_FQ_TTYPE_TADDR_WR = 7,
-    RISCV_IOMMU_FW_TTYPE_PCIE_MSG_REQ = 8,
+    RISCV_IOMMU_FQ_TTYPE_PCIE_ATS_REQ = 8,
+    RISCV_IOMMU_FW_TTYPE_PCIE_MSG_REQ = 9,
+};
+
+/* Header fields */
+#define RISCV_IOMMU_PREQ_HDR_PID        GENMASK_ULL(31, 12)
+#define RISCV_IOMMU_PREQ_HDR_PV         BIT_ULL(32)
+#define RISCV_IOMMU_PREQ_HDR_PRIV       BIT_ULL(33)
+#define RISCV_IOMMU_PREQ_HDR_EXEC       BIT_ULL(34)
+#define RISCV_IOMMU_PREQ_HDR_DID        GENMASK_ULL(63, 40)
+
+/* Payload fields */
+#define RISCV_IOMMU_PREQ_PAYLOAD_R      BIT_ULL(0)
+#define RISCV_IOMMU_PREQ_PAYLOAD_W      BIT_ULL(1)
+#define RISCV_IOMMU_PREQ_PAYLOAD_L      BIT_ULL(2)
+#define RISCV_IOMMU_PREQ_PAYLOAD_M      GENMASK_ULL(2, 0)
+#define RISCV_IOMMU_PREQ_PRG_INDEX      GENMASK_ULL(11, 3)
+#define RISCV_IOMMU_PREQ_UADDR          GENMASK_ULL(63, 12)
+
+
+/*
+ * struct riscv_iommu_msi_pte - MSI Page Table Entry
+ */
+struct riscv_iommu_msi_pte {
+      uint64_t pte;
+      uint64_t mrif_info;
 };
 
 /* Fields on pte */
diff --git a/hw/riscv/riscv-iommu.c b/hw/riscv/riscv-iommu.c
index 7d291fa..1a8da00 100644
--- a/hw/riscv/riscv-iommu.c
+++ b/hw/riscv/riscv-iommu.c
@@ -669,6 +669,20 @@
                                             RISCVIOMMUContext *ctx)
 {
     uint32_t fsc_mode, msi_mode;
+    uint64_t gatp;
+
+    if (!(s->cap & RISCV_IOMMU_CAP_ATS) &&
+        (ctx->tc & RISCV_IOMMU_DC_TC_EN_ATS ||
+         ctx->tc & RISCV_IOMMU_DC_TC_EN_PRI ||
+         ctx->tc & RISCV_IOMMU_DC_TC_PRPR)) {
+        return false;
+    }
+
+    if (!(ctx->tc & RISCV_IOMMU_DC_TC_EN_ATS) &&
+        (ctx->tc & RISCV_IOMMU_DC_TC_T2GPA ||
+         ctx->tc & RISCV_IOMMU_DC_TC_EN_PRI)) {
+        return false;
+    }
 
     if (!(ctx->tc & RISCV_IOMMU_DC_TC_EN_PRI) &&
         ctx->tc & RISCV_IOMMU_DC_TC_PRPR) {
@@ -689,6 +703,12 @@
         }
     }
 
+    gatp = get_field(ctx->gatp, RISCV_IOMMU_ATP_MODE_FIELD);
+    if (ctx->tc & RISCV_IOMMU_DC_TC_T2GPA &&
+        gatp == RISCV_IOMMU_DC_IOHGATP_MODE_BARE) {
+        return false;
+    }
+
     fsc_mode = get_field(ctx->satp, RISCV_IOMMU_DC_FSC_MODE);
 
     if (ctx->tc & RISCV_IOMMU_DC_TC_PDTV) {
@@ -839,7 +859,12 @@
             RISCV_IOMMU_DC_IOHGATP_MODE_BARE);
         ctx->satp = set_field(0, RISCV_IOMMU_ATP_MODE_FIELD,
             RISCV_IOMMU_DC_FSC_MODE_BARE);
+
         ctx->tc = RISCV_IOMMU_DC_TC_V;
+        if (s->enable_ats) {
+            ctx->tc |= RISCV_IOMMU_DC_TC_EN_ATS;
+        }
+
         ctx->ta = 0;
         ctx->msiptp = 0;
         return 0;
@@ -1296,6 +1321,16 @@
     enable_pri = (iotlb->perm == IOMMU_NONE) && (ctx->tc & BIT_ULL(32));
     enable_pid = (ctx->tc & RISCV_IOMMU_DC_TC_PDTV);
 
+    /* Check for ATS request. */
+    if (iotlb->perm == IOMMU_NONE) {
+        /* Check if ATS is disabled. */
+        if (!(ctx->tc & RISCV_IOMMU_DC_TC_EN_ATS)) {
+            enable_pri = false;
+            fault = RISCV_IOMMU_FQ_CAUSE_TTYPE_BLOCKED;
+            goto done;
+        }
+    }
+
     iot = riscv_iommu_iot_lookup(ctx, iot_cache, iotlb->iova);
     perm = iot ? iot->perm : IOMMU_NONE;
     if (perm != IOMMU_NONE) {
@@ -1347,11 +1382,11 @@
     }
 
     if (fault) {
-        unsigned ttype;
+        unsigned ttype = RISCV_IOMMU_FQ_TTYPE_PCIE_ATS_REQ;
 
         if (iotlb->perm & IOMMU_RW) {
             ttype = RISCV_IOMMU_FQ_TTYPE_UADDR_WR;
-        } else {
+        } else if (iotlb->perm & IOMMU_RO) {
             ttype = RISCV_IOMMU_FQ_TTYPE_UADDR_RD;
         }
 
@@ -1379,6 +1414,71 @@
         MEMTXATTRS_UNSPECIFIED);
 }
 
+static void riscv_iommu_ats(RISCVIOMMUState *s,
+    struct riscv_iommu_command *cmd, IOMMUNotifierFlag flag,
+    IOMMUAccessFlags perm,
+    void (*trace_fn)(const char *id))
+{
+    RISCVIOMMUSpace *as = NULL;
+    IOMMUNotifier *n;
+    IOMMUTLBEvent event;
+    uint32_t pid;
+    uint32_t devid;
+    const bool pv = cmd->dword0 & RISCV_IOMMU_CMD_ATS_PV;
+
+    if (cmd->dword0 & RISCV_IOMMU_CMD_ATS_DSV) {
+        /* Use device segment and requester id */
+        devid = get_field(cmd->dword0,
+            RISCV_IOMMU_CMD_ATS_DSEG | RISCV_IOMMU_CMD_ATS_RID);
+    } else {
+        devid = get_field(cmd->dword0, RISCV_IOMMU_CMD_ATS_RID);
+    }
+
+    pid = get_field(cmd->dword0, RISCV_IOMMU_CMD_ATS_PID);
+
+    QLIST_FOREACH(as, &s->spaces, list) {
+        if (as->devid == devid) {
+            break;
+        }
+    }
+
+    if (!as || !as->notifier) {
+        return;
+    }
+
+    event.type = flag;
+    event.entry.perm = perm;
+    event.entry.target_as = s->target_as;
+
+    IOMMU_NOTIFIER_FOREACH(n, &as->iova_mr) {
+        if (!pv || n->iommu_idx == pid) {
+            event.entry.iova = n->start;
+            event.entry.addr_mask = n->end - n->start;
+            trace_fn(as->iova_mr.parent_obj.name);
+            memory_region_notify_iommu_one(n, &event);
+        }
+    }
+}
+
+static void riscv_iommu_ats_inval(RISCVIOMMUState *s,
+    struct riscv_iommu_command *cmd)
+{
+    return riscv_iommu_ats(s, cmd, IOMMU_NOTIFIER_DEVIOTLB_UNMAP, IOMMU_NONE,
+                           trace_riscv_iommu_ats_inval);
+}
+
+static void riscv_iommu_ats_prgr(RISCVIOMMUState *s,
+    struct riscv_iommu_command *cmd)
+{
+    unsigned resp_code = get_field(cmd->dword1,
+                                   RISCV_IOMMU_CMD_ATS_PRGR_RESP_CODE);
+
+    /* Using the access flag to carry response code information */
+    IOMMUAccessFlags perm = resp_code ? IOMMU_NONE : IOMMU_RW;
+    return riscv_iommu_ats(s, cmd, IOMMU_NOTIFIER_MAP, perm,
+                           trace_riscv_iommu_ats_prgr);
+}
+
 static void riscv_iommu_process_ddtp(RISCVIOMMUState *s)
 {
     uint64_t old_ddtp = s->ddtp;
@@ -1534,6 +1634,25 @@
                 get_field(cmd.dword0, RISCV_IOMMU_CMD_IODIR_PID));
             break;
 
+        /* ATS commands */
+        case RISCV_IOMMU_CMD(RISCV_IOMMU_CMD_ATS_FUNC_INVAL,
+                             RISCV_IOMMU_CMD_ATS_OPCODE):
+            if (!s->enable_ats) {
+                goto cmd_ill;
+            }
+
+            riscv_iommu_ats_inval(s, &cmd);
+            break;
+
+        case RISCV_IOMMU_CMD(RISCV_IOMMU_CMD_ATS_FUNC_PRGR,
+                             RISCV_IOMMU_CMD_ATS_OPCODE):
+            if (!s->enable_ats) {
+                goto cmd_ill;
+            }
+
+            riscv_iommu_ats_prgr(s, &cmd);
+            break;
+
         default:
         cmd_ill:
             /* Invalid instruction, do not advance instruction index. */
@@ -1935,6 +2054,9 @@
     if (s->enable_msi) {
         s->cap |= RISCV_IOMMU_CAP_MSI_FLAT | RISCV_IOMMU_CAP_MSI_MRIF;
     }
+    if (s->enable_ats) {
+        s->cap |= RISCV_IOMMU_CAP_ATS;
+    }
     if (s->enable_s_stage) {
         s->cap |= RISCV_IOMMU_CAP_SV32 | RISCV_IOMMU_CAP_SV39 |
                   RISCV_IOMMU_CAP_SV48 | RISCV_IOMMU_CAP_SV57;
@@ -2044,6 +2166,7 @@
     DEFINE_PROP_UINT32("ioatc-limit", RISCVIOMMUState, iot_limit,
         LIMIT_CACHE_IOT),
     DEFINE_PROP_BOOL("intremap", RISCVIOMMUState, enable_msi, TRUE),
+    DEFINE_PROP_BOOL("ats", RISCVIOMMUState, enable_ats, 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),
diff --git a/hw/riscv/riscv-iommu.h b/hw/riscv/riscv-iommu.h
index 9f15f3b..da3f034 100644
--- a/hw/riscv/riscv-iommu.h
+++ b/hw/riscv/riscv-iommu.h
@@ -37,6 +37,7 @@
 
     bool enable_off;      /* Enable out-of-reset OFF mode (DMA disabled) */
     bool enable_msi;      /* Enable MSI remapping */
+    bool enable_ats;      /* Enable ATS support */
     bool enable_s_stage;  /* Enable S/VS-Stage translation */
     bool enable_g_stage;  /* Enable G-Stage translation */
 
diff --git a/hw/riscv/trace-events b/hw/riscv/trace-events
index 3d5c331..0527c56 100644
--- a/hw/riscv/trace-events
+++ b/hw/riscv/trace-events
@@ -12,3 +12,6 @@
 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"
+riscv_iommu_ats(const char *id, unsigned b, unsigned d, unsigned f, uint64_t iova) "%s: translate request %04x:%02x.%u iova: 0x%"PRIx64
+riscv_iommu_ats_inval(const char *id) "%s: dev-iotlb invalidate"
+riscv_iommu_ats_prgr(const char *id) "%s: dev-iotlb page request group response"