[PATCH 3/5] cxl/device: Handle Media Disabled state

[Davidlohr Bueso <dave@stgolabs.net>]

Ensure that both memory device read/writes and mailbox commands
can deal with the device media being disabled - per CXL 3.0 specs
8.2.9.8.5.1 - Sanitize. Disabled semantics here are strictly 11b,
however noting that if the media is not in the ready state (01b),
user data is not accessible.

Signed-off-by: Davidlohr Bueso <dave@stgolabs.net>
---
 hw/cxl/cxl-mailbox-utils.c  | 15 +++++++++++++++
 hw/mem/cxl_type3.c          | 10 ++++++++++
 include/hw/cxl/cxl_device.h | 33 +++++++++++++++++++++++++++++++++
 3 files changed, 58 insertions(+)

diff --git a/hw/cxl/cxl-mailbox-utils.c b/hw/cxl/cxl-mailbox-utils.c
index 224bfdb4bfca..e0e20bc3a2bb 100644
--- a/hw/cxl/cxl-mailbox-utils.c
+++ b/hw/cxl/cxl-mailbox-utils.c
@@ -891,6 +891,21 @@ void cxl_process_mailbox(CXLDeviceState *cxl_dstate)
         if (len == cxl_cmd->in || cxl_cmd->in == ~0) {
             cxl_cmd->payload = cxl_dstate->mbox_reg_state +
                 A_CXL_DEV_CMD_PAYLOAD;
+
+            if (cxl_dev_media_disabled(cxl_dstate)) {
+                if (h == cmd_events_get_records ||
+                    h == cmd_logs_get_log ||
+                    h == cmd_ccls_get_partition_info ||
+                    h == cmd_ccls_get_lsa ||
+                    h == cmd_ccls_set_lsa ||
+                    h == cmd_media_get_poison_list ||
+                    h == cmd_media_inject_poison ||
+                    h == cmd_media_clear_poison) {
+                        ret = CXL_MBOX_MEDIA_DISABLED;
+                        goto done;
+                }
+            }
+
             /* Only one bg command at a time */
             if ((cxl_cmd->effect & BACKGROUND_OPERATION) &&
                 cxl_dstate->bg.runtime > 0) {
diff --git a/hw/mem/cxl_type3.c b/hw/mem/cxl_type3.c
index 801f72c5fcae..707bdc263f03 100644
--- a/hw/mem/cxl_type3.c
+++ b/hw/mem/cxl_type3.c
@@ -12,6 +12,7 @@
 #include "qemu/pmem.h"
 #include "qemu/range.h"
 #include "qemu/rcu.h"
+#include "qemu/guest-random.h"
 #include "sysemu/hostmem.h"
 #include "sysemu/numa.h"
 #include "hw/cxl/cxl.h"
@@ -989,6 +990,11 @@ MemTxResult cxl_type3_read(PCIDevice *d, hwaddr host_addr, uint64_t *data,
     if (res) {
         return MEMTX_ERROR;
     }
+    /* all memory reads will return random values */
+    if (cxl_dev_media_disabled(&CXL_TYPE3(d)->cxl_dstate)) {
+        qemu_guest_getrandom_nofail(data, size);
+        return MEMTX_OK;
+    }
 
     return address_space_read(as, dpa_offset, attrs, data, size);
 }
@@ -1005,6 +1011,10 @@ MemTxResult cxl_type3_write(PCIDevice *d, hwaddr host_addr, uint64_t data,
     if (res) {
         return MEMTX_ERROR;
     }
+    /* memory writes to the device will have no effect */
+    if (cxl_dev_media_disabled(&CXL_TYPE3(d)->cxl_dstate)) {
+        return MEMTX_OK;
+    }
 
     return address_space_write(as, dpa_offset, attrs, &data, size);
 }
diff --git a/include/hw/cxl/cxl_device.h b/include/hw/cxl/cxl_device.h
index f986651b6ead..3ef7a7cded95 100644
--- a/include/hw/cxl/cxl_device.h
+++ b/include/hw/cxl/cxl_device.h
@@ -346,6 +346,39 @@ REG64(CXL_MEM_DEV_STS, 0)
     FIELD(CXL_MEM_DEV_STS, MBOX_READY, 4, 1)
     FIELD(CXL_MEM_DEV_STS, RESET_NEEDED, 5, 3)
 
+static inline void cxl_dev_media_toggle(CXLDeviceState *cxl_dstate, int val)
+{
+    uint64_t reg;
+
+    reg = ldq_le_p(cxl_dstate->mbox_reg_state64 + R_CXL_MEM_DEV_STS);
+    if (FIELD_EX64(reg, CXL_MEM_DEV_STS, MEDIA_STATUS) == val) {
+        return;
+    }
+
+    reg = FIELD_DP64(0, CXL_MEM_DEV_STS, MEDIA_STATUS, val);
+    reg = FIELD_DP64(reg, CXL_MEM_DEV_STS, MBOX_READY, 0x1);
+
+    stq_le_p(&cxl_dstate->mbox_reg_state64 + R_CXL_MEM_DEV_STS, reg);
+}
+
+static inline void cxl_dev_media_enable(CXLDeviceState *cxl_dstate)
+{
+    cxl_dev_media_toggle(cxl_dstate, 0x1);
+}
+
+static inline void cxl_dev_media_disable(CXLDeviceState *cxl_dstate)
+{
+    cxl_dev_media_toggle(cxl_dstate, 0x3);
+}
+
+static inline bool cxl_dev_media_disabled(CXLDeviceState *cxl_dstate)
+{
+    uint64_t reg;
+
+    reg = ldq_le_p(cxl_dstate->mbox_reg_state64 + R_CXL_MEM_DEV_STS);
+    return unlikely(FIELD_EX64(reg, CXL_MEM_DEV_STS, MEDIA_STATUS) == 0x3);
+}
+
 typedef struct CXLError {
     QTAILQ_ENTRY(CXLError) node;
     int type; /* Error code as per FE definition */
-- 
2.40.0