[PATCH v5 06/43] hw/cxl/device: Implement basic mailbox (8.2.8.4)

[Jonathan Cameron via <qemu-devel@nongnu.org>]

From: Ben Widawsky <ben.widawsky@intel.com>

This is the beginning of implementing mailbox support for CXL 2.0
devices. The implementation recognizes when the doorbell is rung,
handles the command/payload, clears the doorbell while returning error
codes and data.

Generally the mailbox mechanism is designed to permit communication
between the host OS and the firmware running on the device. For our
purposes, we emulate both the firmware, implemented primarily in
cxl-mailbox-utils.c, and the hardware.

No commands are implemented yet.

Signed-off-by: Ben Widawsky <ben.widawsky@intel.com>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
---
v5: Responses to Alex Bennée review.

  - Fix the invalid write case Alex noted and return early.
  - Drop the RCU_READ_LOCK as it was pointless and I don't think
    we need to lock at all until we introduce other write paths
    (second mailbox or background commands).
  - Missing static on cel_uuid
  - Documentation of where cel_uuid value comes from (the CXL spec)
  - Drop a check that can't fail and hence get rid of a confusing
    LOG_UNIMP.
  - Move some small code rearrangement back to earlier patch.
  - Reorder the mailbox handler code and update the docs, as first
    part of removing many of the macros from this code.
  - Upper case remaining defines + drop the define_mailbox_handler_const()
    as it is never used.
    
 hw/cxl/cxl-device-utils.c   | 128 ++++++++++++++++++++++++++-
 hw/cxl/cxl-mailbox-utils.c  | 171 ++++++++++++++++++++++++++++++++++++
 hw/cxl/meson.build          |   1 +
 include/hw/cxl/cxl.h        |   3 +
 include/hw/cxl/cxl_device.h |  19 +++-
 5 files changed, 320 insertions(+), 2 deletions(-)
 create mode 100644 hw/cxl/cxl-mailbox-utils.c

diff --git a/hw/cxl/cxl-device-utils.c b/hw/cxl/cxl-device-utils.c
index 0895b9d78b..39011468ef 100644
--- a/hw/cxl/cxl-device-utils.c
+++ b/hw/cxl/cxl-device-utils.c
@@ -44,6 +44,114 @@ static uint64_t dev_reg_read(void *opaque, hwaddr offset, unsigned size)
     return 0;
 }
 
+static uint64_t mailbox_reg_read(void *opaque, hwaddr offset, unsigned size)
+{
+    CXLDeviceState *cxl_dstate = opaque;
+
+    switch (size) {
+    case 1:
+        return cxl_dstate->mbox_reg_state[offset];
+    case 2:
+        return cxl_dstate->mbox_reg_state16[offset / 2];
+    case 4:
+        return cxl_dstate->mbox_reg_state32[offset / 4];
+    case 8:
+        return cxl_dstate->mbox_reg_state64[offset / 8];
+    default:
+        g_assert_not_reached();
+    }
+}
+
+static void mailbox_mem_writel(uint32_t *reg_state, hwaddr offset,
+                               uint64_t value)
+{
+    switch (offset) {
+    case A_CXL_DEV_MAILBOX_CTRL:
+        /* fallthrough */
+    case A_CXL_DEV_MAILBOX_CAP:
+        /* RO register */
+        break;
+    default:
+        qemu_log_mask(LOG_UNIMP,
+                      "%s Unexpected 32-bit access to 0x%" PRIx64 " (WI)\n",
+                      __func__, offset);
+        return;
+    }
+
+    reg_state[offset / 4] = value;
+}
+
+static void mailbox_mem_writeq(uint64_t *reg_state, hwaddr offset,
+                               uint64_t value)
+{
+    switch (offset) {
+    case A_CXL_DEV_MAILBOX_CMD:
+        break;
+    case A_CXL_DEV_BG_CMD_STS:
+        /* BG not supported */
+        /* fallthrough */
+    case A_CXL_DEV_MAILBOX_STS:
+        /* Read only register, will get updated by the state machine */
+        return;
+    default:
+        qemu_log_mask(LOG_UNIMP,
+                      "%s Unexpected 64-bit access to 0x%" PRIx64 " (WI)\n",
+                      __func__, offset);
+        return;
+    }
+
+
+    reg_state[offset / 8] = value;
+}
+
+static void mailbox_reg_write(void *opaque, hwaddr offset, uint64_t value,
+                              unsigned size)
+{
+    CXLDeviceState *cxl_dstate = opaque;
+
+    if (offset >= A_CXL_DEV_CMD_PAYLOAD) {
+        memcpy(cxl_dstate->mbox_reg_state + offset, &value, size);
+        return;
+    }
+
+    /*
+     * Lock is needed to prevent concurrent writes as well as to
+     * prevent writes coming in while the firmware is processing.
+     * Until background commands or the second mailbox are implemented
+     * memory access is synchronized at a higher level (per memory region).
+     */
+
+    switch (size) {
+    case 4:
+        mailbox_mem_writel(cxl_dstate->mbox_reg_state32, offset, value);
+        break;
+    case 8:
+        mailbox_mem_writeq(cxl_dstate->mbox_reg_state64, offset, value);
+        break;
+    default:
+        g_assert_not_reached();
+    }
+
+    if (ARRAY_FIELD_EX32(cxl_dstate->mbox_reg_state32, CXL_DEV_MAILBOX_CTRL,
+                         DOORBELL))
+        cxl_process_mailbox(cxl_dstate);
+}
+
+static const MemoryRegionOps mailbox_ops = {
+    .read = mailbox_reg_read,
+    .write = mailbox_reg_write,
+    .endianness = DEVICE_LITTLE_ENDIAN,
+    .valid = {
+        .min_access_size = 1,
+        .max_access_size = 8,
+        .unaligned = false,
+    },
+    .impl = {
+        .min_access_size = 1,
+        .max_access_size = 8,
+    },
+};
+
 static const MemoryRegionOps dev_ops = {
     .read = dev_reg_read,
     .write = NULL, /* status register is read only */
@@ -84,20 +192,33 @@ void cxl_device_register_block_init(Object *obj, CXLDeviceState *cxl_dstate)
                           "cap-array", CXL_CAPS_SIZE);
     memory_region_init_io(&cxl_dstate->device, obj, &dev_ops, cxl_dstate,
                           "device-status", CXL_DEVICE_REGISTERS_LENGTH);
+    memory_region_init_io(&cxl_dstate->mailbox, obj, &mailbox_ops, cxl_dstate,
+                          "mailbox", CXL_MAILBOX_REGISTERS_LENGTH);
 
     memory_region_add_subregion(&cxl_dstate->device_registers, 0,
                                 &cxl_dstate->caps);
     memory_region_add_subregion(&cxl_dstate->device_registers,
                                 CXL_DEVICE_REGISTERS_OFFSET,
                                 &cxl_dstate->device);
+    memory_region_add_subregion(&cxl_dstate->device_registers,
+                                CXL_MAILBOX_REGISTERS_OFFSET,
+                                &cxl_dstate->mailbox);
 }
 
 static void device_reg_init_common(CXLDeviceState *cxl_dstate) { }
 
+static void mailbox_reg_init_common(CXLDeviceState *cxl_dstate)
+{
+    /* 2048 payload size, with no interrupt or background support */
+    ARRAY_FIELD_DP32(cxl_dstate->mbox_reg_state32, CXL_DEV_MAILBOX_CAP,
+                     PAYLOAD_SIZE, CXL_MAILBOX_PAYLOAD_SHIFT);
+    cxl_dstate->payload_size = CXL_MAILBOX_MAX_PAYLOAD_SIZE;
+}
+
 void cxl_device_register_init_common(CXLDeviceState *cxl_dstate)
 {
     uint64_t *cap_hdrs = cxl_dstate->caps_reg_state64;
-    const int cap_count = 1;
+    const int cap_count = 2;
 
     /* CXL Device Capabilities Array Register */
     ARRAY_FIELD_DP64(cap_hdrs, CXL_DEV_CAP_ARRAY, CAP_ID, 0);
@@ -106,4 +227,9 @@ void cxl_device_register_init_common(CXLDeviceState *cxl_dstate)
 
     cxl_device_cap_init(cxl_dstate, DEVICE, 1);
     device_reg_init_common(cxl_dstate);
+
+    cxl_device_cap_init(cxl_dstate, MAILBOX, 2);
+    mailbox_reg_init_common(cxl_dstate);
+
+    assert(cxl_initialize_mailbox(cxl_dstate) == 0);
 }
diff --git a/hw/cxl/cxl-mailbox-utils.c b/hw/cxl/cxl-mailbox-utils.c
new file mode 100644
index 0000000000..d497ec50a6
--- /dev/null
+++ b/hw/cxl/cxl-mailbox-utils.c
@@ -0,0 +1,171 @@
+/*
+ * CXL Utility library for mailbox interface
+ *
+ * Copyright(C) 2020 Intel Corporation.
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2. See the
+ * COPYING file in the top-level directory.
+ */
+
+#include "qemu/osdep.h"
+#include "hw/cxl/cxl.h"
+#include "hw/pci/pci.h"
+#include "qemu/log.h"
+#include "qemu/uuid.h"
+
+/*
+ * How to add a new command, example. The command set FOO, with cmd BAR.
+ *  1. Add the command set and cmd to the enum.
+ *     FOO    = 0x7f,
+ *          #define BAR 0
+ *  2. Implement the handler
+ *    static ret_code cmd_foo_bar(struct cxl_cmd *cmd,
+ *                                  CXLDeviceState *cxl_dstate, uint16_t *len)
+ *  3. Add the command to the cxl_cmd_set[][]
+ *    [FOO][BAR] = { "FOO_BAR", cmd_foo_bar, x, y },
+ *  4. Implement your handler
+ *     define_mailbox_handler(FOO_BAR) { ... return CXL_MBOX_SUCCESS; }
+ *
+ *
+ *  Writing the handler:
+ *    The handler will provide the &struct cxl_cmd, the &CXLDeviceState, and the
+ *    in/out length of the payload. The handler is responsible for consuming the
+ *    payload from cmd->payload and operating upon it as necessary. It must then
+ *    fill the output data into cmd->payload (overwriting what was there),
+ *    setting the length, and returning a valid return code.
+ *
+ *  XXX: The handler need not worry about endianess. The payload is read out of
+ *  a register interface that already deals with it.
+ */
+
+/* 8.2.8.4.5.1 Command Return Codes */
+typedef enum {
+    CXL_MBOX_SUCCESS = 0x0,
+    CXL_MBOX_BG_STARTED = 0x1,
+    CXL_MBOX_INVALID_INPUT = 0x2,
+    CXL_MBOX_UNSUPPORTED = 0x3,
+    CXL_MBOX_INTERNAL_ERROR = 0x4,
+    CXL_MBOX_RETRY_REQUIRED = 0x5,
+    CXL_MBOX_BUSY = 0x6,
+    CXL_MBOX_MEDIA_DISABLED = 0x7,
+    CXL_MBOX_FW_XFER_IN_PROGRESS = 0x8,
+    CXL_MBOX_FW_XFER_OUT_OF_ORDER = 0x9,
+    CXL_MBOX_FW_AUTH_FAILED = 0xa,
+    CXL_MBOX_FW_INVALID_SLOT = 0xb,
+    CXL_MBOX_FW_ROLLEDBACK = 0xc,
+    CXL_MBOX_FW_REST_REQD = 0xd,
+    CXL_MBOX_INVALID_HANDLE = 0xe,
+    CXL_MBOX_INVALID_PA = 0xf,
+    CXL_MBOX_INJECT_POISON_LIMIT = 0x10,
+    CXL_MBOX_PERMANENT_MEDIA_FAILURE = 0x11,
+    CXL_MBOX_ABORTED = 0x12,
+    CXL_MBOX_INVALID_SECURITY_STATE = 0x13,
+    CXL_MBOX_INCORRECT_PASSPHRASE = 0x14,
+    CXL_MBOX_UNSUPPORTED_MAILBOX = 0x15,
+    CXL_MBOX_INVALID_PAYLOAD_LENGTH = 0x16,
+    CXL_MBOX_MAX = 0x17
+} ret_code;
+
+struct cxl_cmd;
+typedef ret_code (*opcode_handler)(struct cxl_cmd *cmd,
+                                   CXLDeviceState *cxl_dstate, uint16_t *len);
+struct cxl_cmd {
+    const char *name;
+    opcode_handler handler;
+    ssize_t in;
+    uint16_t effect; /* Reported in CEL */
+    uint8_t *payload;
+};
+
+#define DEFINE_MAILBOX_HANDLER_ZEROED(name, size)                         \
+    uint16_t __zero##name = size;                                         \
+    static ret_code cmd_##name(struct cxl_cmd *cmd,                       \
+                               CXLDeviceState *cxl_dstate, uint16_t *len) \
+    {                                                                     \
+        *len = __zero##name;                                              \
+        memset(cmd->payload, 0, *len);                                    \
+        return CXL_MBOX_SUCCESS;                                          \
+    }
+#define DEFINE_MAILBOX_HANDLER_NOP(name)                                  \
+    static ret_code cmd_##name(struct cxl_cmd *cmd,                       \
+                               CXLDeviceState *cxl_dstate, uint16_t *len) \
+    {                                                                     \
+        return CXL_MBOX_SUCCESS;                                          \
+    }
+
+static QemuUUID cel_uuid;
+
+static struct cxl_cmd cxl_cmd_set[256][256] = {};
+
+void cxl_process_mailbox(CXLDeviceState *cxl_dstate)
+{
+    uint16_t ret = CXL_MBOX_SUCCESS;
+    struct cxl_cmd *cxl_cmd;
+    uint64_t status_reg;
+    opcode_handler h;
+
+    /*
+     * current state of mailbox interface
+     *  mbox_cap_reg = cxl_dstate->reg_state32[R_CXL_DEV_MAILBOX_CAP];
+     *  mbox_ctrl_reg = cxl_dstate->reg_state32[R_CXL_DEV_MAILBOX_CTRL];
+     *  status_reg = *(uint64_t *)&cxl_dstate->reg_state[A_CXL_DEV_MAILBOX_STS];
+     */
+    uint64_t command_reg = cxl_dstate->mbox_reg_state64[R_CXL_DEV_MAILBOX_CMD];
+
+    uint8_t set = FIELD_EX64(command_reg, CXL_DEV_MAILBOX_CMD, COMMAND_SET);
+    uint8_t cmd = FIELD_EX64(command_reg, CXL_DEV_MAILBOX_CMD, COMMAND);
+    uint16_t len = FIELD_EX64(command_reg, CXL_DEV_MAILBOX_CMD, LENGTH);
+    cxl_cmd = &cxl_cmd_set[set][cmd];
+    h = cxl_cmd->handler;
+    if (!h) {
+        qemu_log_mask(LOG_UNIMP, "Command %04xh not implemented\n",
+                                 set << 8 | cmd);
+        goto handled;
+    }
+
+    if (len != cxl_cmd->in) {
+        ret = CXL_MBOX_INVALID_PAYLOAD_LENGTH;
+    }
+
+    cxl_cmd->payload = cxl_dstate->mbox_reg_state + A_CXL_DEV_CMD_PAYLOAD;
+    ret = (*h)(cxl_cmd, cxl_dstate, &len);
+    assert(len <= cxl_dstate->payload_size);
+
+handled:
+    /* Set the return code */
+    status_reg = FIELD_DP64(0, CXL_DEV_MAILBOX_STS, ERRNO, ret);
+
+    /* Set the return length */
+    command_reg = FIELD_DP64(command_reg, CXL_DEV_MAILBOX_CMD, COMMAND_SET, 0);
+    command_reg = FIELD_DP64(command_reg, CXL_DEV_MAILBOX_CMD, COMMAND, 0);
+    command_reg = FIELD_DP64(command_reg, CXL_DEV_MAILBOX_CMD, LENGTH, len);
+
+    cxl_dstate->mbox_reg_state64[R_CXL_DEV_MAILBOX_CMD] = command_reg;
+    cxl_dstate->mbox_reg_state64[R_CXL_DEV_MAILBOX_STS] = status_reg;
+
+    /* Tell the host we're done */
+    ARRAY_FIELD_DP32(cxl_dstate->mbox_reg_state32, CXL_DEV_MAILBOX_CTRL,
+                     DOORBELL, 0);
+}
+
+int cxl_initialize_mailbox(CXLDeviceState *cxl_dstate)
+{
+    /* CXL 2.0: Table 169 Get Supported Logs Log Entry */
+    const char *cel_uuidstr = "0da9c0b5-bf41-4b78-8f79-96b1623b3f17";
+
+    for (int set = 0; set < 256; set++) {
+        for (int cmd = 0; cmd < 256; cmd++) {
+            if (cxl_cmd_set[set][cmd].handler) {
+                struct cxl_cmd *c = &cxl_cmd_set[set][cmd];
+                struct cel_log *log =
+                    &cxl_dstate->cel_log[cxl_dstate->cel_size];
+
+                log->opcode = (set << 8) | cmd;
+                log->effect = c->effect;
+                cxl_dstate->cel_size++;
+            }
+        }
+    }
+
+    return qemu_uuid_parse(cel_uuidstr, &cel_uuid);
+}
diff --git a/hw/cxl/meson.build b/hw/cxl/meson.build
index dd7c6f8e5a..e68eea2358 100644
--- a/hw/cxl/meson.build
+++ b/hw/cxl/meson.build
@@ -2,4 +2,5 @@ softmmu_ss.add(when: 'CONFIG_CXL',
                if_true: files(
                    'cxl-component-utils.c',
                    'cxl-device-utils.c',
+                   'cxl-mailbox-utils.c',
                ))
diff --git a/include/hw/cxl/cxl.h b/include/hw/cxl/cxl.h
index b9d1ac3fad..554ad93b6b 100644
--- a/include/hw/cxl/cxl.h
+++ b/include/hw/cxl/cxl.h
@@ -14,4 +14,7 @@
 #include "cxl_component.h"
 #include "cxl_device.h"
 
+#define CXL_COMPONENT_REG_BAR_IDX 0
+#define CXL_DEVICE_REG_BAR_IDX 2
+
 #endif
diff --git a/include/hw/cxl/cxl_device.h b/include/hw/cxl/cxl_device.h
index 1ac0dcd97e..49dcca7e44 100644
--- a/include/hw/cxl/cxl_device.h
+++ b/include/hw/cxl/cxl_device.h
@@ -95,7 +95,21 @@ typedef struct cxl_device_state {
     };
 
     /* mmio for the mailbox registers 8.2.8.4 */
-    MemoryRegion mailbox;
+    struct {
+        MemoryRegion mailbox;
+        uint16_t payload_size;
+        union {
+            uint8_t mbox_reg_state[CXL_MAILBOX_REGISTERS_LENGTH];
+            uint16_t mbox_reg_state16[CXL_MAILBOX_REGISTERS_LENGTH / 2];
+            uint32_t mbox_reg_state32[CXL_MAILBOX_REGISTERS_LENGTH / 4];
+            uint64_t mbox_reg_state64[CXL_MAILBOX_REGISTERS_LENGTH / 8];
+        };
+        struct cel_log {
+            uint16_t opcode;
+            uint16_t effect;
+        } cel_log[1 << 16];
+        size_t cel_size;
+    };
 
     /* memory region for persistent memory, HDM */
     uint64_t pmem_size;
@@ -145,6 +159,9 @@ CXL_DEVICE_CAPABILITY_HEADER_REGISTER(DEVICE, CXL_DEVICE_CAP_HDR1_OFFSET)
 CXL_DEVICE_CAPABILITY_HEADER_REGISTER(MAILBOX, CXL_DEVICE_CAP_HDR1_OFFSET + \
                                                CXL_DEVICE_CAP_REG_SIZE)
 
+int cxl_initialize_mailbox(CXLDeviceState *cxl_dstate);
+void cxl_process_mailbox(CXLDeviceState *cxl_dstate);
+
 #define cxl_device_cap_init(dstate, reg, cap_id)                           \
     do {                                                                   \
         uint32_t *cap_hdrs = dstate->caps_reg_state32;                     \
-- 
2.32.0