hw/cxl/device: Implement get/set Label Storage Area (LSA)

Implement get and set handlers for the Label Storage Area
used to hold data describing persistent memory configuration
so that it can be ensured it is seen in the same configuration
after reboot.

Signed-off-by: Ben Widawsky <ben.widawsky@intel.com>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Message-Id: <20220429144110.25167-22-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

@@ -57,6 +57,8 @@ enum {
         #define MEMORY_DEVICE 0x0
     CCLS        = 0x41,
         #define GET_PARTITION_INFO     0x0
+        #define GET_LSA       0x2
+        #define SET_LSA       0x3
 };
 
 /* 8.2.8.4.5.1 Command Return Codes */
@@ -326,7 +328,62 @@ static ret_code cmd_ccls_get_partition_info(struct cxl_cmd *cmd,
     return CXL_MBOX_SUCCESS;
 }
 
+static ret_code cmd_ccls_get_lsa(struct cxl_cmd *cmd,
+                                 CXLDeviceState *cxl_dstate,
+                                 uint16_t *len)
+{
+    struct {
+        uint32_t offset;
+        uint32_t length;
+    } QEMU_PACKED *get_lsa;
+    CXLType3Dev *ct3d = container_of(cxl_dstate, CXLType3Dev, cxl_dstate);
+    CXLType3Class *cvc = CXL_TYPE3_GET_CLASS(ct3d);
+    uint32_t offset, length;
+
+    get_lsa = (void *)cmd->payload;
+    offset = get_lsa->offset;
+    length = get_lsa->length;
+
+    if (offset + length > cvc->get_lsa_size(ct3d)) {
+        *len = 0;
+        return CXL_MBOX_INVALID_INPUT;
+    }
+
+    *len = cvc->get_lsa(ct3d, get_lsa, length, offset);
+    return CXL_MBOX_SUCCESS;
+}
+
+static ret_code cmd_ccls_set_lsa(struct cxl_cmd *cmd,
+                                 CXLDeviceState *cxl_dstate,
+                                 uint16_t *len)
+{
+    struct set_lsa_pl {
+        uint32_t offset;
+        uint32_t rsvd;
+        uint8_t data[];
+    } QEMU_PACKED;
+    struct set_lsa_pl *set_lsa_payload = (void *)cmd->payload;
+    CXLType3Dev *ct3d = container_of(cxl_dstate, CXLType3Dev, cxl_dstate);
+    CXLType3Class *cvc = CXL_TYPE3_GET_CLASS(ct3d);
+    const size_t hdr_len = offsetof(struct set_lsa_pl, data);
+    uint16_t plen = *len;
+
+    *len = 0;
+    if (!plen) {
+        return CXL_MBOX_SUCCESS;
+    }
+
+    if (set_lsa_payload->offset + plen > cvc->get_lsa_size(ct3d) + hdr_len) {
+        return CXL_MBOX_INVALID_INPUT;
+    }
+    plen -= hdr_len;
+
+    cvc->set_lsa(ct3d, set_lsa_payload->data, plen, set_lsa_payload->offset);
+    return CXL_MBOX_SUCCESS;
+}
+
 #define IMMEDIATE_CONFIG_CHANGE (1 << 1)
+#define IMMEDIATE_DATA_CHANGE (1 << 2)
 #define IMMEDIATE_POLICY_CHANGE (1 << 3)
 #define IMMEDIATE_LOG_CHANGE (1 << 4)
 
@@ -349,6 +406,9 @@ static struct cxl_cmd cxl_cmd_set[256][256] = {
         cmd_identify_memory_device, 0, 0 },
     [CCLS][GET_PARTITION_INFO] = { "CCLS_GET_PARTITION_INFO",
         cmd_ccls_get_partition_info, 0, 0 },
+    [CCLS][GET_LSA] = { "CCLS_GET_LSA", cmd_ccls_get_lsa, 0, 0 },
+    [CCLS][SET_LSA] = { "CCLS_SET_LSA", cmd_ccls_set_lsa,
+        ~0, IMMEDIATE_CONFIG_CHANGE | IMMEDIATE_DATA_CHANGE },
 };
 
 void cxl_process_mailbox(CXLDeviceState *cxl_dstate)

hw/mem/cxl_type3.c

@@ -8,6 +8,7 @@
 #include "qapi/error.h"
 #include "qemu/log.h"
 #include "qemu/module.h"
+#include "qemu/pmem.h"
 #include "qemu/range.h"
 #include "qemu/rcu.h"
 #include "sysemu/hostmem.h"
@@ -113,6 +114,11 @@ static bool cxl_setup_memory(CXLType3Dev *ct3d, Error **errp)
     host_memory_backend_set_mapped(ct3d->hostmem, true);
     ct3d->cxl_dstate.pmem_size = ct3d->hostmem->size;
 
+    if (!ct3d->lsa) {
+        error_setg(errp, "lsa property must be set");
+        return false;
+    }
+
     return true;
 }
 
@@ -176,12 +182,58 @@ static void ct3d_reset(DeviceState *dev)
 static Property ct3_props[] = {
     DEFINE_PROP_LINK("memdev", CXLType3Dev, hostmem, TYPE_MEMORY_BACKEND,
                      HostMemoryBackend *),
+    DEFINE_PROP_LINK("lsa", CXLType3Dev, lsa, TYPE_MEMORY_BACKEND,
+                     HostMemoryBackend *),
     DEFINE_PROP_END_OF_LIST(),
 };
 
 static uint64_t get_lsa_size(CXLType3Dev *ct3d)
 {
-    return 0;
+    MemoryRegion *mr;
+
+    mr = host_memory_backend_get_memory(ct3d->lsa);
+    return memory_region_size(mr);
+}
+
+static void validate_lsa_access(MemoryRegion *mr, uint64_t size,
+                                uint64_t offset)
+{
+    assert(offset + size <= memory_region_size(mr));
+    assert(offset + size > offset);
+}
+
+static uint64_t get_lsa(CXLType3Dev *ct3d, void *buf, uint64_t size,
+                    uint64_t offset)
+{
+    MemoryRegion *mr;
+    void *lsa;
+
+    mr = host_memory_backend_get_memory(ct3d->lsa);
+    validate_lsa_access(mr, size, offset);
+
+    lsa = memory_region_get_ram_ptr(mr) + offset;
+    memcpy(buf, lsa, size);
+
+    return size;
+}
+
+static void set_lsa(CXLType3Dev *ct3d, const void *buf, uint64_t size,
+                    uint64_t offset)
+{
+    MemoryRegion *mr;
+    void *lsa;
+
+    mr = host_memory_backend_get_memory(ct3d->lsa);
+    validate_lsa_access(mr, size, offset);
+
+    lsa = memory_region_get_ram_ptr(mr) + offset;
+    memcpy(lsa, buf, size);
+    memory_region_set_dirty(mr, offset, size);
+
+    /*
+     * Just like the PMEM, if the guest is not allowed to exit gracefully, label
+     * updates will get lost.
+     */
 }
 
 static void ct3_class_init(ObjectClass *oc, void *data)
@@ -203,6 +255,8 @@ static void ct3_class_init(ObjectClass *oc, void *data)
     device_class_set_props(dc, ct3_props);
 
     cvc->get_lsa_size = get_lsa_size;
+    cvc->get_lsa = get_lsa;
+    cvc->set_lsa = set_lsa;
 }
 
 static const TypeInfo ct3d_info = {

include/hw/cxl/cxl_device.h

@@ -252,6 +252,11 @@ struct CXLType3Class {
 
     /* public */
     uint64_t (*get_lsa_size)(CXLType3Dev *ct3d);
+
+    uint64_t (*get_lsa)(CXLType3Dev *ct3d, void *buf, uint64_t size,
+                        uint64_t offset);
+    void (*set_lsa)(CXLType3Dev *ct3d, const void *buf, uint64_t size,
+                    uint64_t offset);
 };
 
 #endif