[PATCH 1/3] hw/cxl: Add get scan media capabilities mailbox command support

[Davidlohr Bueso <dave@stgolabs.net>]

Use simple heuristics to determine the cost of scanning any given chunk,
assuming cost is even across the whole device.

Signed-off-by: Davidlohr Bueso <dave@stgolabs.net>
---
 hw/cxl/cxl-mailbox-utils.c | 45 +++++++++++++++++++++++++++++++++++++-
 1 file changed, 44 insertions(+), 1 deletion(-)

diff --git a/hw/cxl/cxl-mailbox-utils.c b/hw/cxl/cxl-mailbox-utils.c
index 0849cfbc2a4c..f346aa8ce3b2 100644
--- a/hw/cxl/cxl-mailbox-utils.c
+++ b/hw/cxl/cxl-mailbox-utils.c
@@ -79,6 +79,7 @@ enum {
         #define GET_POISON_LIST        0x0
         #define INJECT_POISON          0x1
         #define CLEAR_POISON           0x2
+        #define GET_SCAN_MEDIA_CAPABILITIES 0x3
     PHYSICAL_SWITCH = 0x51
         #define IDENTIFY_SWITCH_DEVICE      0x0
 };
@@ -882,7 +883,7 @@ static CXLRetCode cmd_media_clear_poison(struct cxl_cmd *cmd,
             return CXL_MBOX_INTERNAL_ERROR;
         }
     }
-  
+
     QLIST_FOREACH(ent, poison_list, node) {
         /*
          * Test for contained in entry. Simpler than general case
@@ -934,6 +935,45 @@ static CXLRetCode cmd_media_clear_poison(struct cxl_cmd *cmd,
     return CXL_MBOX_SUCCESS;
 }
 
+static CXLRetCode
+cmd_media_get_scan_media_capabilities(struct cxl_cmd *cmd,
+                                      CXLDeviceState *cxl_dstate, uint16_t *len)
+{
+    struct get_scan_media_capabilities_pl {
+        uint64_t pa;
+        uint64_t length;
+    } QEMU_PACKED;
+    struct get_scan_media_capabilities_out_pl {
+        uint32_t estimated_runtime_ms;
+    } QEMU_PACKED;
+    struct get_scan_media_capabilities_pl *in = (void *)cmd->payload;
+    struct get_scan_media_capabilities_out_pl *out = (void *)cmd->payload;
+    uint64_t query_start;
+    uint64_t query_length;
+
+    query_start = ldq_le_p(&in->pa);
+    /* 64 byte alignment required */
+    if (query_start & 0x3f) {
+        return CXL_MBOX_INVALID_INPUT;
+    }
+    query_length = ldq_le_p(&in->length) * 64;
+
+    if (query_start + query_length > cxl_dstate->mem_size) {
+        return CXL_MBOX_INVALID_PA;
+    }
+
+    /*
+     * Just use 400 nanosecond access/read latency + 100 ns for
+     * the cost of updating the poison list. For small enough
+     * chunks return at least 1 ms.
+     */
+    stq_le_p(&out->estimated_runtime_ms,
+             MAX(1, query_length * (0.0005L/64)));
+
+    *len = sizeof(*out);
+    return CXL_MBOX_SUCCESS;
+}
+
 #define IMMEDIATE_CONFIG_CHANGE (1 << 1)
 #define IMMEDIATE_DATA_CHANGE (1 << 2)
 #define IMMEDIATE_POLICY_CHANGE (1 << 3)
@@ -972,6 +1012,9 @@ static struct cxl_cmd cxl_cmd_set[256][256] = {
         cmd_media_inject_poison, 8, 0 },
     [MEDIA_AND_POISON][CLEAR_POISON] = { "MEDIA_AND_POISON_CLEAR_POISON",
         cmd_media_clear_poison, 72, 0 },
+    [MEDIA_AND_POISON][GET_SCAN_MEDIA_CAPABILITIES] = { "MEDIA_AND_POISON_GET_SCAN_MEDIA_CAPABILITIES",
+        cmd_media_get_scan_media_capabilities, 16, 0 },
+
 };
 
 static struct cxl_cmd cxl_cmd_set_sw[256][256] = {
-- 
2.40.0