[PATCH RFC v2 2/3] cxl_type3: add MHD callbacks

[Svetly Todorov]

Introduce an API for validating DC adds, removes, and responses
against a multi-headed device.

mhd_reserve_extents() is called during a DC add request. This allows
a multi-headed device to check whether the requested extents belong
to another host. If not, then this function can claim those extents
in the MHD state and allow the cxl_type3 code to follow suit in the
host-local blk_bitmap.

mhd_reclaim_extents() is called during the DC add response. It allows
the MHD to reclaim extents that were preallocated to a host during the
request but rejected in the response.

mhd_release_extent() is called during the DC release response. It can
be invoked after a host frees an extent in its local bitmap, allowing
the MHD handler to release that same extent in the multi-host state.
---
 hw/cxl/cxl-mailbox-utils.c  | 28 +++++++++++++++++++++++++++-
 hw/mem/cxl_type3.c          | 17 +++++++++++++++++
 include/hw/cxl/cxl_device.h |  8 ++++++++
 3 files changed, 52 insertions(+), 1 deletion(-)

diff --git a/hw/cxl/cxl-mailbox-utils.c b/hw/cxl/cxl-mailbox-utils.c
index dc916f5bb3..0429bb4816 100644
--- a/hw/cxl/cxl-mailbox-utils.c
+++ b/hw/cxl/cxl-mailbox-utils.c
@@ -2283,6 +2283,7 @@ static CXLRetCode cmd_dcd_add_dyn_cap_rsp(const struct 
cxl_cmd *cmd,
 {
     CXLUpdateDCExtentListInPl *in = (void *)payload_in;
     CXLType3Dev *ct3d = CXL_TYPE3(cci->d);
+    CXLType3Class *cvc = CXL_TYPE3_GET_CLASS(ct3d);
     CXLDCExtentList *extent_list = &ct3d->dc.extents;
     uint32_t i;
     uint64_t dpa, len;
@@ -2317,6 +2318,11 @@ static CXLRetCode cmd_dcd_add_dyn_cap_rsp(const struct 
cxl_cmd *cmd,
         ct3d->dc.total_extent_count += 1;
         ct3_set_region_block_backed(ct3d, dpa, len);
     }
+
+    if (cvc->mhd_reclaim_extents)
+        cvc->mhd_reclaim_extents(&ct3d->parent_obj, &ct3d->dc.extents_pending,
+                in);
+
     /* Remove the first extent group in the pending list*/
     cxl_extent_group_list_delete_front(&ct3d->dc.extents_pending);
 
@@ -2350,6 +2356,7 @@ static CXLRetCode 
cxl_dc_extent_release_dry_run(CXLType3Dev *ct3d,
         uint32_t *updated_list_size)
 {
     CXLDCExtent *ent, *ent_next;
+    CXLType3Class *cvc = CXL_TYPE3_GET_CLASS(ct3d);
     uint64_t dpa, len;
     uint32_t i;
     int cnt_delta = 0;
@@ -2370,6 +2377,13 @@ static CXLRetCode 
cxl_dc_extent_release_dry_run(CXLType3Dev *ct3d,
             goto free_and_exit;
         }
 
+        /* In an MHD, check that this DPA range belongs to this host */
+        if (cvc->mhd_access_valid &&
+            !cvc->mhd_access_valid(&ct3d->parent_obj, dpa, len)) {
+            ret = CXL_MBOX_INVALID_PA;
+            goto free_and_exit;
+        }
+
         /* After this point, extent overflow is the only error can happen */
         while (len > 0) {
             QTAILQ_FOREACH(ent, updated_list, node) {
@@ -2442,9 +2456,11 @@ static CXLRetCode cmd_dcd_release_dyn_cap(const struct 
cxl_cmd *cmd,
 {
     CXLUpdateDCExtentListInPl *in = (void *)payload_in;
     CXLType3Dev *ct3d = CXL_TYPE3(cci->d);
+    CXLType3Class *cvc = CXL_TYPE3_GET_CLASS(ct3d);
     CXLDCExtentList updated_list;
     CXLDCExtent *ent, *ent_next;
-    uint32_t updated_list_size;
+    uint32_t updated_list_size, i;
+    uint64_t dpa, len;
     CXLRetCode ret;
 
     if (in->num_entries_updated == 0) {
@@ -2462,6 +2478,16 @@ static CXLRetCode cmd_dcd_release_dyn_cap(const struct 
cxl_cmd *cmd,
         return ret;
     }
 
+    /* Updated_entries contains the released extents. Free those in the MHD */
+    for (i = 0; cvc->mhd_release_extent && i < in->num_entries_updated; ++i) {
+        dpa = in->updated_entries[i].start_dpa;
+        len = in->updated_entries[i].len;
+
+        if (cvc->mhd_release_extent) {
+            cvc->mhd_release_extent(&ct3d->parent_obj, dpa, len);
+        }
+    }
+
     /*
      * If the dry run release passes, the returned updated_list will
      * be the updated extent list and we just need to clear the extents
diff --git a/hw/mem/cxl_type3.c b/hw/mem/cxl_type3.c
index 88facd49ed..e69cb6f7b7 100644
--- a/hw/mem/cxl_type3.c
+++ b/hw/mem/cxl_type3.c
@@ -799,6 +799,7 @@ static void cxl_destroy_dc_regions(CXLType3Dev *ct3d)
 {
     CXLDCExtent *ent, *ent_next;
     CXLDCExtentGroup *group, *group_next;
+    CXLType3Class *cvc = CXL_TYPE3_CLASS(ct3d);
     int i;
     CXLDCRegion *region;
 
@@ -817,6 +818,10 @@ static void cxl_destroy_dc_regions(CXLType3Dev *ct3d)
     for (i = 0; i < ct3d->dc.num_regions; i++) {
         region = &ct3d->dc.regions[i];
         g_free(region->blk_bitmap);
+        if (cvc->mhd_release_extent) {
+            cvc->mhd_release_extent(&ct3d->parent_obj, region->base,
+                    region->len);
+        }
     }
 }
 
@@ -2104,6 +2109,7 @@ static void 
qmp_cxl_process_dynamic_capacity_prescriptive(const char *path,
     CXLEventDynamicCapacity dCap = {};
     CXLEventRecordHdr *hdr = &dCap.hdr;
     CXLType3Dev *dcd;
+    CXLType3Class *cvc;
     uint8_t flags = 1 << CXL_EVENT_TYPE_INFO;
     uint32_t num_extents = 0;
     CXLDCExtentRecordList *list;
@@ -2121,6 +2127,7 @@ static void 
qmp_cxl_process_dynamic_capacity_prescriptive(const char *path,
     }
 
     dcd = CXL_TYPE3(obj);
+    cvc = CXL_TYPE3_GET_CLASS(dcd);
     if (!dcd->dc.num_regions) {
         error_setg(errp, "No dynamic capacity support from the device");
         return;
@@ -2193,6 +2200,13 @@ static void 
qmp_cxl_process_dynamic_capacity_prescriptive(const char *path,
         num_extents++;
     }
 
+    /* If this is an MHD, attempt to reserve the extents */
+    if (type == DC_EVENT_ADD_CAPACITY && cvc->mhd_reserve_extents &&
+       !cvc->mhd_reserve_extents(&dcd->parent_obj, records, rid)) {
+        error_setg(errp, "mhsld is enabled and extent reservation failed");
+        return;
+    }
+
     /* Create extent list for event being passed to host */
     i = 0;
     list = records;
@@ -2336,6 +2350,9 @@ static void ct3_class_init(ObjectClass *oc, void *data)
     cvc->set_cacheline = set_cacheline;
     cvc->mhd_get_info = NULL;
     cvc->mhd_access_valid = NULL;
+    cvc->mhd_reserve_extents = NULL;
+    cvc->mhd_reclaim_extents = NULL;
+    cvc->mhd_release_extent = NULL;
 }
 
 static const TypeInfo ct3d_info = {
diff --git a/include/hw/cxl/cxl_device.h b/include/hw/cxl/cxl_device.h
index 5c60342556..f7ac0c34d2 100644
--- a/include/hw/cxl/cxl_device.h
+++ b/include/hw/cxl/cxl_device.h
@@ -14,6 +14,7 @@
 #include "hw/pci/pci_device.h"
 #include "hw/register.h"
 #include "hw/cxl/cxl_events.h"
+#include "qapi/qapi-commands-cxl.h"
 
 #include "hw/cxl/cxl_cpmu.h"
 /*
@@ -651,6 +652,13 @@ struct CXLType3Class {
                                size_t *len_out,
                                CXLCCI *cci);
     bool (*mhd_access_valid)(PCIDevice *d, uint64_t addr, unsigned int size);
+    bool (*mhd_reserve_extents)(PCIDevice *d,
+                                CXLDCExtentRecordList *records,
+                                uint8_t rid);
+    bool (*mhd_reclaim_extents)(PCIDevice *d,
+                                CXLDCExtentGroupList *groups,
+                                CXLUpdateDCExtentListInPl *in);
+    bool (*mhd_release_extent)(PCIDevice *d, uint64_t dpa, uint64_t len);
 };
 
 struct CSWMBCCIDev {

-- 
2.34.1