hw/cxl: Add get scan media results cmd support

Iterate over the list keeping the output payload size into account,
returning the results from a previous scan media operation. The
scan media operation does not fail prematurely due to device being
out of storage, so this implementation does not deal with the
retry/restart functionality.

Signed-off-by: Davidlohr Bueso <dave@stgolabs.net>
Link: https://lore.kernel.org/r/20230908073152.4386-5-dave@stgolabs.net
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Message-Id: <20240705120643.959422-5-Jonathan.Cameron@huawei.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

hw/cxl/cxl-mailbox-utils.c

@@ -85,6 +85,7 @@ enum {
         #define CLEAR_POISON           0x2
         #define GET_SCAN_MEDIA_CAPABILITIES 0x3
         #define SCAN_MEDIA             0x4
+        #define GET_SCAN_MEDIA_RESULTS 0x5
     DCD_CONFIG  = 0x48,
         #define GET_DC_CONFIG          0x0
         #define GET_DYN_CAP_EXT_LIST   0x1
@@ -1339,6 +1340,8 @@ static void __do_scan_media(CXLType3Dev *ct3d)
         ct3d->poison_list_cnt == results_cnt) {
         cxl_clear_poison_list_overflowed(ct3d);
     }
+    /* scan media has run since last conventional reset */
+    ct3d->scan_media_hasrun = true;
 }
 
 /*
@@ -1443,6 +1446,85 @@ static CXLRetCode cmd_media_scan_media(const struct cxl_cmd *cmd,
     return CXL_MBOX_BG_STARTED;
 }
 
+/*
+ * CXL r3.1 section 8.2.9.9.4.6: Get Scan Media Results
+ */
+static CXLRetCode cmd_media_get_scan_media_results(const struct cxl_cmd *cmd,
+                                                   uint8_t *payload_in,
+                                                   size_t len_in,
+                                                   uint8_t *payload_out,
+                                                   size_t *len_out,
+                                                   CXLCCI *cci)
+{
+    struct get_scan_media_results_out_pl {
+        uint64_t dpa_restart;
+        uint64_t length;
+        uint8_t flags;
+        uint8_t rsvd1;
+        uint16_t count;
+        uint8_t rsvd2[0xc];
+        struct {
+            uint64_t addr;
+            uint32_t length;
+            uint32_t resv;
+        } QEMU_PACKED records[];
+    } QEMU_PACKED;
+
+    struct get_scan_media_results_out_pl *out = (void *)payload_out;
+    CXLType3Dev *ct3d = CXL_TYPE3(cci->d);
+    CXLPoisonList *scan_media_results = &ct3d->scan_media_results;
+    CXLPoison *ent, *next;
+    uint16_t total_count = 0, record_count = 0, i = 0;
+    uint16_t out_pl_len;
+
+    if (!ct3d->scan_media_hasrun) {
+        return CXL_MBOX_UNSUPPORTED;
+    }
+
+    /*
+     * Calculate limits, all entries are within the same address range of the
+     * last scan media call.
+     */
+    QLIST_FOREACH(ent, scan_media_results, node) {
+        size_t rec_size = record_count * sizeof(out->records[0]);
+
+        if (sizeof(*out) + rec_size < CXL_MAILBOX_MAX_PAYLOAD_SIZE) {
+            record_count++;
+        }
+        total_count++;
+    }
+
+    out_pl_len = sizeof(*out) + record_count * sizeof(out->records[0]);
+    assert(out_pl_len <= CXL_MAILBOX_MAX_PAYLOAD_SIZE);
+
+    memset(out, 0, out_pl_len);
+    QLIST_FOREACH_SAFE(ent, scan_media_results, node, next) {
+        uint64_t start, stop;
+
+        if (i == record_count) {
+            break;
+        }
+
+        start = ROUND_DOWN(ent->start, 64ull);
+        stop = ROUND_DOWN(ent->start, 64ull) + ent->length;
+        stq_le_p(&out->records[i].addr, start | (ent->type & 0x7));
+        stl_le_p(&out->records[i].length, (stop - start) / CXL_CACHE_LINE_SIZE);
+        i++;
+
+        /* consume the returning entry */
+        QLIST_REMOVE(ent, node);
+        g_free(ent);
+    }
+
+    stw_le_p(&out->count, record_count);
+    if (total_count > record_count) {
+        out->flags = (1 << 0); /* More Media Error Records */
+    }
+
+    *len_out = out_pl_len;
+    return CXL_MBOX_SUCCESS;
+}
+
 /*
  * CXL r3.1 section 8.2.9.9.9.1: Get Dynamic Capacity Configuration
  * (Opcode: 4800h)
@@ -2060,6 +2142,9 @@ static const struct cxl_cmd cxl_cmd_set[256][256] = {
         cmd_media_get_scan_media_capabilities, 16, 0 },
     [MEDIA_AND_POISON][SCAN_MEDIA] = { "MEDIA_AND_POISON_SCAN_MEDIA",
         cmd_media_scan_media, 17, BACKGROUND_OPERATION },
+    [MEDIA_AND_POISON][GET_SCAN_MEDIA_RESULTS] = {
+        "MEDIA_AND_POISON_GET_SCAN_MEDIA_RESULTS",
+        cmd_media_get_scan_media_results, 0, 0 },
 };
 
 static const struct cxl_cmd cxl_cmd_set_dcd[256][256] = {

include/hw/cxl/cxl_device.h

@@ -499,6 +499,7 @@ struct CXLType3Dev {
     /* Poison Injection - backup */
     CXLPoisonList poison_list_bkp;
     CXLPoisonList scan_media_results;
+    bool scan_media_hasrun;
 
     struct dynamic_capacity {
         HostMemoryBackend *host_dc;