hw/cxl: Support aborting background commands

As of 3.1 spec, background commands can be canceled with a new
abort command. Implement the support, which is advertised in
the CEL. No ad-hoc context undoing is necessary as all the
command logic of the running bg command is done upon completion.
Arbitrarily, the on-going background cmd will not be aborted if
already at least 85% done;

A mutex is introduced to stabilize mbox request cancel command vs
the timer callback being fired scenarios (as well as reading the
mbox registers). While some operations under critical regions
may be unnecessary (irq notifying, cmd callbacks), this is not
a path where performance is important, so simplicity is preferred.

Tested-by: Ajay Joshi <ajay.opensrc@micron.com>
Reviewed-by: Ajay Joshi <ajay.opensrc@micron.com>
Signed-off-by: Davidlohr Bueso <dave@stgolabs.net>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Message-Id: <20250305092501.191929-2-Jonathan.Cameron@huawei.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

1 files changed, 65 insertions, 7 deletions

diff --git a/hw/cxl/cxl-mailbox-utils.c b/hw/cxl/cxl-mailbox-utils.c
index 516c01d840..4401f446d9 100644
--- a/hw/cxl/cxl-mailbox-utils.c
+++ b/hw/cxl/cxl-mailbox-utils.c
@@ -56,6 +56,7 @@ enum {
     INFOSTAT    = 0x00,
         #define IS_IDENTIFY   0x1
         #define BACKGROUND_OPERATION_STATUS    0x2
+        #define BACKGROUND_OPERATION_ABORT     0x5
     EVENTS      = 0x01,
         #define GET_RECORDS   0x0
         #define CLEAR_RECORDS   0x1
@@ -636,6 +637,41 @@ static CXLRetCode cmd_infostat_bg_op_sts(const struct cxl_cmd *cmd,
     return CXL_MBOX_SUCCESS;
 }
 
+/*
+ * CXL r3.1 Section 8.2.9.1.5:
+ * Request Abort Background Operation (Opcode 0005h)
+ */
+static CXLRetCode cmd_infostat_bg_op_abort(const struct cxl_cmd *cmd,
+                                           uint8_t *payload_in,
+                                           size_t len_in,
+                                           uint8_t *payload_out,
+                                           size_t *len_out,
+                                           CXLCCI *cci)
+{
+    int bg_set = cci->bg.opcode >> 8;
+    int bg_cmd = cci->bg.opcode & 0xff;
+    const struct cxl_cmd *bg_c = &cci->cxl_cmd_set[bg_set][bg_cmd];
+
+    if (!(bg_c->effect & CXL_MBOX_BACKGROUND_OPERATION_ABORT)) {
+        return CXL_MBOX_REQUEST_ABORT_NOTSUP;
+    }
+
+    qemu_mutex_lock(&cci->bg.lock);
+    if (cci->bg.runtime) {
+        /* operation is near complete, let it finish */
+        if (cci->bg.complete_pct < 85) {
+            timer_del(cci->bg.timer);
+            cci->bg.ret_code = CXL_MBOX_ABORTED;
+            cci->bg.starttime = 0;
+            cci->bg.runtime = 0;
+            cci->bg.aborted = true;
+        }
+    }
+    qemu_mutex_unlock(&cci->bg.lock);
+
+    return CXL_MBOX_SUCCESS;
+}
+
 #define CXL_FW_SLOTS 2
 #define CXL_FW_SIZE  0x02000000 /* 32 mb */
 
@@ -2715,6 +2751,8 @@ static CXLRetCode cmd_dcd_release_dyn_cap(const struct cxl_cmd *cmd,
 }
 
 static const struct cxl_cmd cxl_cmd_set[256][256] = {
+    [INFOSTAT][BACKGROUND_OPERATION_ABORT] = { "BACKGROUND_OPERATION_ABORT",
+        cmd_infostat_bg_op_abort, 0, 0 },
     [EVENTS][GET_RECORDS] = { "EVENTS_GET_RECORDS",
         cmd_events_get_records, 1, 0 },
     [EVENTS][CLEAR_RECORDS] = { "EVENTS_CLEAR_RECORDS",
@@ -2727,9 +2765,11 @@ static const struct cxl_cmd cxl_cmd_set[256][256] = {
     [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 },
+        cmd_firmware_update_transfer, ~0,
+        CXL_MBOX_BACKGROUND_OPERATION | CXL_MBOX_BACKGROUND_OPERATION_ABORT },
     [FIRMWARE_UPDATE][ACTIVATE] = { "FIRMWARE_UPDATE_ACTIVATE",
-        cmd_firmware_update_activate, 2, CXL_MBOX_BACKGROUND_OPERATION },
+        cmd_firmware_update_activate, 2,
+        CXL_MBOX_BACKGROUND_OPERATION | CXL_MBOX_BACKGROUND_OPERATION_ABORT },
     [TIMESTAMP][GET] = { "TIMESTAMP_GET", cmd_timestamp_get, 0, 0 },
     [TIMESTAMP][SET] = { "TIMESTAMP_SET", cmd_timestamp_set,
                          8, CXL_MBOX_IMMEDIATE_POLICY_CHANGE },
@@ -2758,7 +2798,8 @@ static const struct cxl_cmd cxl_cmd_set[256][256] = {
     [SANITIZE][OVERWRITE] = { "SANITIZE_OVERWRITE", cmd_sanitize_overwrite, 0,
         (CXL_MBOX_IMMEDIATE_DATA_CHANGE |
          CXL_MBOX_SECURITY_STATE_CHANGE |
-         CXL_MBOX_BACKGROUND_OPERATION)},
+         CXL_MBOX_BACKGROUND_OPERATION |
+         CXL_MBOX_BACKGROUND_OPERATION_ABORT)},
     [PERSISTENT_MEM][GET_SECURITY_STATE] = { "GET_SECURITY_STATE",
         cmd_get_security_state, 0, 0 },
     [MEDIA_AND_POISON][GET_POISON_LIST] = { "MEDIA_AND_POISON_GET_POISON_LIST",
@@ -2771,7 +2812,8 @@ static const struct cxl_cmd cxl_cmd_set[256][256] = {
         "MEDIA_AND_POISON_GET_SCAN_MEDIA_CAPABILITIES",
         cmd_media_get_scan_media_capabilities, 16, 0 },
     [MEDIA_AND_POISON][SCAN_MEDIA] = { "MEDIA_AND_POISON_SCAN_MEDIA",
-        cmd_media_scan_media, 17, CXL_MBOX_BACKGROUND_OPERATION },
+        cmd_media_scan_media, 17,
+        (CXL_MBOX_BACKGROUND_OPERATION | CXL_MBOX_BACKGROUND_OPERATION_ABORT)},
     [MEDIA_AND_POISON][GET_SCAN_MEDIA_RESULTS] = {
         "MEDIA_AND_POISON_GET_SCAN_MEDIA_RESULTS",
         cmd_media_get_scan_media_results, 0, 0 },
@@ -2795,6 +2837,8 @@ static const struct cxl_cmd cxl_cmd_set_sw[256][256] = {
     [INFOSTAT][IS_IDENTIFY] = { "IDENTIFY", cmd_infostat_identify, 0, 0 },
     [INFOSTAT][BACKGROUND_OPERATION_STATUS] = { "BACKGROUND_OPERATION_STATUS",
         cmd_infostat_bg_op_sts, 0, 0 },
+    [INFOSTAT][BACKGROUND_OPERATION_ABORT] = { "BACKGROUND_OPERATION_ABORT",
+        cmd_infostat_bg_op_abort, 0, 0 },
     [TIMESTAMP][GET] = { "TIMESTAMP_GET", cmd_timestamp_get, 0, 0 },
     [TIMESTAMP][SET] = { "TIMESTAMP_SET", cmd_timestamp_set, 8,
                          CXL_MBOX_IMMEDIATE_POLICY_CHANGE },
@@ -2881,6 +2925,7 @@ int cxl_process_cci_message(CXLCCI *cci, uint8_t set, uint8_t cmd,
         cci->bg.opcode = (set << 8) | cmd;
 
         cci->bg.complete_pct = 0;
+        cci->bg.aborted = false;
         cci->bg.ret_code = 0;
 
         now = qemu_clock_get_ms(QEMU_CLOCK_VIRTUAL);
@@ -2894,10 +2939,12 @@ int cxl_process_cci_message(CXLCCI *cci, uint8_t set, uint8_t cmd,
 static void bg_timercb(void *opaque)
 {
     CXLCCI *cci = opaque;
-    uint64_t now = qemu_clock_get_ms(QEMU_CLOCK_VIRTUAL);
-    uint64_t total_time = cci->bg.starttime + cci->bg.runtime;
+    uint64_t now, total_time;
+
+    qemu_mutex_lock(&cci->bg.lock);
 
-    assert(cci->bg.runtime > 0);
+    now = qemu_clock_get_ms(QEMU_CLOCK_VIRTUAL);
+    total_time = cci->bg.starttime + cci->bg.runtime;
 
     if (now >= total_time) { /* we are done */
         uint16_t ret = CXL_MBOX_SUCCESS;
@@ -2950,6 +2997,8 @@ static void bg_timercb(void *opaque)
             msi_notify(pdev, cxl_dstate->mbox_msi_n);
         }
     }
+
+    qemu_mutex_unlock(&cci->bg.lock);
 }
 
 static void cxl_rebuild_cel(CXLCCI *cci)
@@ -2978,12 +3027,21 @@ void cxl_init_cci(CXLCCI *cci, size_t payload_max)
     cci->bg.complete_pct = 0;
     cci->bg.starttime = 0;
     cci->bg.runtime = 0;
+    cci->bg.aborted = false;
     cci->bg.timer = timer_new_ms(QEMU_CLOCK_VIRTUAL,
                                  bg_timercb, cci);
+    qemu_mutex_init(&cci->bg.lock);
 
     memset(&cci->fw, 0, sizeof(cci->fw));
     cci->fw.active_slot = 1;
     cci->fw.slot[cci->fw.active_slot - 1] = true;
+    cci->initialized = true;
+}
+
+void cxl_destroy_cci(CXLCCI *cci)
+{
+    qemu_mutex_destroy(&cci->bg.lock);
+    cci->initialized = false;
 }
 
 static void cxl_copy_cci_commands(CXLCCI *cci, const struct cxl_cmd (*cxl_cmds)[256])