diff --git a/hw/cxl/cxl-mailbox-utils.c b/hw/cxl/cxl-mailbox-utils.c
index 0621f686f4..b752920ec8 100644
--- a/hw/cxl/cxl-mailbox-utils.c
+++ b/hw/cxl/cxl-mailbox-utils.c
@@ -63,6 +63,8 @@ enum {
         #define SET_INTERRUPT_POLICY   0x3
     FIRMWARE_UPDATE = 0x02,
         #define GET_INFO      0x0
+        #define TRANSFER      0x1
+        #define ACTIVATE      0x2
     TIMESTAMP   = 0x03,
         #define GET           0x0
         #define SET           0x1
@@ -622,6 +624,9 @@ static CXLRetCode cmd_infostat_bg_op_sts(const struct cxl_cmd *cmd,
     return CXL_MBOX_SUCCESS;
 }
 
+#define CXL_FW_SLOTS 2
+#define CXL_FW_SIZE  0x02000000 /* 32 mb */
+
 /* CXL r3.1 Section 8.2.9.3.1: Get FW Info (Opcode 0200h) */
 static CXLRetCode cmd_firmware_update_get_info(const struct cxl_cmd *cmd,
                                                uint8_t *payload_in,
@@ -652,15 +657,192 @@ static CXLRetCode cmd_firmware_update_get_info(const struct cxl_cmd *cmd,
 
     fw_info = (void *)payload_out;
 
-    fw_info->slots_supported = 2;
-    fw_info->slot_info = BIT(0) | BIT(3);
-    fw_info->caps = 0;
-    pstrcpy(fw_info->fw_rev1, sizeof(fw_info->fw_rev1), "BWFW VERSION 0");
+    fw_info->slots_supported = CXL_FW_SLOTS;
+    fw_info->slot_info = (cci->fw.active_slot & 0x7) |
+            ((cci->fw.staged_slot & 0x7) << 3);
+    fw_info->caps = BIT(0);  /* online update supported */
+
+    if (cci->fw.slot[0]) {
+        pstrcpy(fw_info->fw_rev1, sizeof(fw_info->fw_rev1), "BWFW VERSION 0");
+    }
+    if (cci->fw.slot[1]) {
+        pstrcpy(fw_info->fw_rev2, sizeof(fw_info->fw_rev2), "BWFW VERSION 1");
+    }
 
     *len_out = sizeof(*fw_info);
     return CXL_MBOX_SUCCESS;
 }
 
+/* CXL r3.1 section 8.2.9.3.2: Transfer FW (Opcode 0201h) */
+#define CXL_FW_XFER_ALIGNMENT   128
+
+#define CXL_FW_XFER_ACTION_FULL     0x0
+#define CXL_FW_XFER_ACTION_INIT     0x1
+#define CXL_FW_XFER_ACTION_CONTINUE 0x2
+#define CXL_FW_XFER_ACTION_END      0x3
+#define CXL_FW_XFER_ACTION_ABORT    0x4
+
+static CXLRetCode cmd_firmware_update_transfer(const struct cxl_cmd *cmd,
+                                               uint8_t *payload_in,
+                                               size_t len,
+                                               uint8_t *payload_out,
+                                               size_t *len_out,
+                                               CXLCCI *cci)
+{
+    struct {
+        uint8_t action;
+        uint8_t slot;
+        uint8_t rsvd1[2];
+        uint32_t offset;
+        uint8_t rsvd2[0x78];
+        uint8_t data[];
+    } QEMU_PACKED *fw_transfer = (void *)payload_in;
+    size_t offset, length;
+
+    if (fw_transfer->action == CXL_FW_XFER_ACTION_ABORT) {
+        /*
+         * At this point there aren't any on-going transfers
+         * running in the bg - this is serialized before this
+         * call altogether. Just mark the state machine and
+         * disregard any other input.
+         */
+        cci->fw.transferring = false;
+        return CXL_MBOX_SUCCESS;
+    }
+
+    offset = fw_transfer->offset * CXL_FW_XFER_ALIGNMENT;
+    length = len - sizeof(*fw_transfer);
+    if (offset + length > CXL_FW_SIZE) {
+        return CXL_MBOX_INVALID_INPUT;
+    }
+
+    if (cci->fw.transferring) {
+        if (fw_transfer->action == CXL_FW_XFER_ACTION_FULL ||
+            fw_transfer->action == CXL_FW_XFER_ACTION_INIT) {
+            return CXL_MBOX_FW_XFER_IN_PROGRESS;
+        }
+        /*
+         * Abort partitioned package transfer if over 30 secs
+         * between parts. As opposed to the explicit ABORT action,
+         * semantically treat this condition as an error - as
+         * if a part action were passed without a previous INIT.
+         */
+        if (difftime(time(NULL), cci->fw.last_partxfer) > 30.0) {
+            cci->fw.transferring = false;
+            return CXL_MBOX_INVALID_INPUT;
+        }
+    } else if (fw_transfer->action == CXL_FW_XFER_ACTION_CONTINUE ||
+               fw_transfer->action == CXL_FW_XFER_ACTION_END) {
+        return CXL_MBOX_INVALID_INPUT;
+    }
+
+    /* allow back-to-back retransmission */
+    if ((offset != cci->fw.prev_offset || length != cci->fw.prev_len) &&
+        (fw_transfer->action == CXL_FW_XFER_ACTION_CONTINUE ||
+         fw_transfer->action == CXL_FW_XFER_ACTION_END)) {
+        /* verify no overlaps */
+        if (offset < cci->fw.prev_offset + cci->fw.prev_len) {
+            return CXL_MBOX_FW_XFER_OUT_OF_ORDER;
+        }
+    }
+
+    switch (fw_transfer->action) {
+    case CXL_FW_XFER_ACTION_FULL: /* ignores offset */
+    case CXL_FW_XFER_ACTION_END:
+        if (fw_transfer->slot == 0 ||
+            fw_transfer->slot == cci->fw.active_slot ||
+            fw_transfer->slot > CXL_FW_SLOTS) {
+            return CXL_MBOX_FW_INVALID_SLOT;
+        }
+
+        /* mark the slot used upon bg completion */
+        break;
+    case CXL_FW_XFER_ACTION_INIT:
+        if (offset != 0) {
+            return CXL_MBOX_INVALID_INPUT;
+        }
+
+        cci->fw.transferring = true;
+        cci->fw.prev_offset = offset;
+        cci->fw.prev_len = length;
+        break;
+    case CXL_FW_XFER_ACTION_CONTINUE:
+        cci->fw.prev_offset = offset;
+        cci->fw.prev_len = length;
+        break;
+    default:
+        return CXL_MBOX_INVALID_INPUT;
+    }
+
+    if (fw_transfer->action == CXL_FW_XFER_ACTION_FULL) {
+        cci->bg.runtime = 10 * 1000UL;
+    } else {
+        cci->bg.runtime = 2 * 1000UL;
+    }
+    /* keep relevant context for bg completion */
+    cci->fw.curr_action = fw_transfer->action;
+    cci->fw.curr_slot = fw_transfer->slot;
+    *len_out = 0;
+
+    return CXL_MBOX_BG_STARTED;
+}
+
+static void __do_firmware_xfer(CXLCCI *cci)
+{
+    switch (cci->fw.curr_action) {
+    case CXL_FW_XFER_ACTION_FULL:
+    case CXL_FW_XFER_ACTION_END:
+        cci->fw.slot[cci->fw.curr_slot - 1] = true;
+        cci->fw.transferring = false;
+        break;
+    case CXL_FW_XFER_ACTION_INIT:
+    case CXL_FW_XFER_ACTION_CONTINUE:
+        time(&cci->fw.last_partxfer);
+        break;
+    default:
+        break;
+    }
+}
+
+/* CXL r3.1 section 8.2.9.3.3: Activate FW (Opcode 0202h) */
+static CXLRetCode cmd_firmware_update_activate(const struct cxl_cmd *cmd,
+                                               uint8_t *payload_in,
+                                               size_t len,
+                                               uint8_t *payload_out,
+                                               size_t *len_out,
+                                               CXLCCI *cci)
+{
+    struct {
+        uint8_t action;
+        uint8_t slot;
+    } QEMU_PACKED *fw_activate = (void *)payload_in;
+    QEMU_BUILD_BUG_ON(sizeof(*fw_activate) != 0x2);
+
+    if (fw_activate->slot == 0 ||
+        fw_activate->slot == cci->fw.active_slot ||
+        fw_activate->slot > CXL_FW_SLOTS) {
+        return CXL_MBOX_FW_INVALID_SLOT;
+    }
+
+    /* ensure that an actual fw package is there */
+    if (!cci->fw.slot[fw_activate->slot - 1]) {
+        return CXL_MBOX_FW_INVALID_SLOT;
+    }
+
+    switch (fw_activate->action) {
+    case 0: /* online */
+        cci->fw.active_slot = fw_activate->slot;
+        break;
+    case 1: /* reset */
+        cci->fw.staged_slot = fw_activate->slot;
+        break;
+    default:
+        return CXL_MBOX_INVALID_INPUT;
+    }
+
+    return CXL_MBOX_SUCCESS;
+}
+
 /* CXL r3.1 Section 8.2.9.4.1: Get Timestamp (Opcode 0300h) */
 static CXLRetCode cmd_timestamp_get(const struct cxl_cmd *cmd,
                                     uint8_t *payload_in,
@@ -2494,6 +2676,10 @@ static const struct cxl_cmd cxl_cmd_set[256][256] = {
                                       ~0, CXL_MBOX_IMMEDIATE_CONFIG_CHANGE },
     [FIRMWARE_UPDATE][GET_INFO] = { "FIRMWARE_UPDATE_GET_INFO",
         cmd_firmware_update_get_info, 0, 0 },
+    [FIRMWARE_UPDATE][TRANSFER] = { "FIRMWARE_UPDATE_TRANSFER",
+        cmd_firmware_update_transfer, ~0, CXL_MBOX_BACKGROUND_OPERATION },
+    [FIRMWARE_UPDATE][ACTIVATE] = { "FIRMWARE_UPDATE_ACTIVATE",
+        cmd_firmware_update_activate, 2, CXL_MBOX_BACKGROUND_OPERATION },
     [TIMESTAMP][GET] = { "TIMESTAMP_GET", cmd_timestamp_get, 0, 0 },
     [TIMESTAMP][SET] = { "TIMESTAMP_SET", cmd_timestamp_set,
                          8, CXL_MBOX_IMMEDIATE_POLICY_CHANGE },
@@ -2622,7 +2808,9 @@ int cxl_process_cci_message(CXLCCI *cci, uint8_t set, uint8_t cmd,
                 h == cmd_media_get_poison_list ||
                 h == cmd_media_inject_poison ||
                 h == cmd_media_clear_poison ||
-                h == cmd_sanitize_overwrite) {
+                h == cmd_sanitize_overwrite ||
+                h == cmd_firmware_update_transfer ||
+                h == cmd_firmware_update_activate) {
                 return CXL_MBOX_MEDIA_DISABLED;
             }
         }
@@ -2667,6 +2855,9 @@ static void bg_timercb(void *opaque)
         cci->bg.complete_pct = 100;
         cci->bg.ret_code = ret;
         switch (cci->bg.opcode) {
+        case 0x0201: /* fw transfer */
+            __do_firmware_xfer(cci);
+            break;
         case 0x4400: /* sanitize */
         {
             CXLType3Dev *ct3d = CXL_TYPE3(cci->d);
@@ -2738,6 +2929,10 @@ void cxl_init_cci(CXLCCI *cci, size_t payload_max)
     cci->bg.runtime = 0;
     cci->bg.timer = timer_new_ms(QEMU_CLOCK_VIRTUAL,
                                  bg_timercb, cci);
+
+    memset(&cci->fw, 0, sizeof(cci->fw));
+    cci->fw.active_slot = 1;
+    cci->fw.slot[cci->fw.active_slot - 1] = true;
 }
 
 static void cxl_copy_cci_commands(CXLCCI *cci, const struct cxl_cmd (*cxl_cmds)[256])
diff --git a/include/hw/cxl/cxl_device.h b/include/hw/cxl/cxl_device.h
index 5cae7159e6..fdd0f4e62b 100644
--- a/include/hw/cxl/cxl_device.h
+++ b/include/hw/cxl/cxl_device.h
@@ -181,6 +181,21 @@ typedef struct CXLCCI {
         uint64_t runtime;
         QEMUTimer *timer;
     } bg;
+
+    /* firmware update */
+    struct {
+        uint8_t active_slot;
+        uint8_t staged_slot;
+        bool slot[4];
+        uint8_t curr_action;
+        uint8_t curr_slot;
+        /* handle partial transfers */
+        bool transferring;
+        size_t prev_offset;
+        size_t prev_len;
+        time_t last_partxfer;
+    } fw;
+
     size_t payload_max;
     /* Pointer to device hosting the CCI */
     DeviceState *d;