[PATCH 2/4] hw/cxl: Add get scan media capabilities cmd support

[Davidlohr Bueso <dave@stgolabs.net>]

Use simple heuristics to determine the cost of scanning any given
chunk, assuming cost is equal across the whole device, without
differentiating between volatile or persistent partitions. This
is aligned to the fact that these constraints are not enforced
in respective poison query commands.

Signed-off-by: Davidlohr Bueso <dave@stgolabs.net>
---
 hw/cxl/cxl-mailbox-utils.c | 53 ++++++++++++++++++++++++++++++++++++++
 1 file changed, 53 insertions(+)

diff --git a/hw/cxl/cxl-mailbox-utils.c b/hw/cxl/cxl-mailbox-utils.c
index 4e8651ebe2e9..3073222060ab 100644
--- a/hw/cxl/cxl-mailbox-utils.c
+++ b/hw/cxl/cxl-mailbox-utils.c
@@ -80,6 +80,7 @@ enum {
         #define GET_POISON_LIST        0x0
         #define INJECT_POISON          0x1
         #define CLEAR_POISON           0x2
+        #define GET_SCAN_MEDIA_CAPABILITIES 0x3
     DCD_CONFIG  = 0x48,
         #define GET_DC_CONFIG          0x0
         #define GET_DYN_CAP_EXT_LIST   0x1
@@ -1174,6 +1175,56 @@ static CXLRetCode cmd_media_clear_poison(const struct cxl_cmd *cmd,
     return CXL_MBOX_SUCCESS;
 }
 
+/*
+ * CXL r3.0 section 8.2.9.8.4.4: Get Scan Media Capabilities
+ */
+static CXLRetCode
+cmd_media_get_scan_media_capabilities(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_capabilities_pl {
+        uint64_t pa;
+        uint64_t length;
+    } QEMU_PACKED;
+
+    struct get_scan_media_capabilities_out_pl {
+        uint32_t estimated_runtime_ms;
+    } QEMU_PACKED;
+
+    CXLType3Dev *ct3d = CXL_TYPE3(cci->d);
+    CXLDeviceState *cxl_dstate = &ct3d->cxl_dstate;
+    struct get_scan_media_capabilities_pl *in = (void *)payload_in;
+    struct get_scan_media_capabilities_out_pl *out = (void *)payload_out;
+    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) * CXL_CACHE_LINE_SIZE;
+
+    if (query_start + query_length > cxl_dstate->static_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.
+     */
+    stl_le_p(&out->estimated_runtime_ms,
+             MAX(1, query_length * (0.0005L/64)));
+
+    *len_out = sizeof(*out);
+    return CXL_MBOX_SUCCESS;
+}
+
 /*
  * CXL r3.0 section 8.2.9.8.9.1: Dynamic Capacity Configuration
  */
@@ -1602,6 +1653,8 @@ static const 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 const struct cxl_cmd cxl_cmd_set_dcd[256][256] = {
-- 
2.42.0