[PATCH v2 2/4] hw/cxl/device: read from register values in mdev_reg_read()

[Hyeonggon Yoo <42.hyeyoo@gmail.com>]

In the current mdev_reg_read() implementation, it consistently returns
that the Media Status is Ready (01b). This was fine until commit
25a52959f99d ("hw/cxl: Add support for device sanitation") because the
media was presumed to be ready.

However, as per the CXL 3.0 spec "8.2.9.8.5.1 Sanitize (Opcode 4400h)",
during sanitation, the Media State should be set to Disabled (11b). The
mentioned commit correctly sets it to Disabled, but mdev_reg_read()
still returns Media Status as Ready.

To address this, update mdev_reg_read() to read register values instead
of returning dummy values.

Fixes: commit 25a52959f99d ("hw/cxl: Add support for device sanitation")
Reviewed-by: Davidlohr Bueso <dave@stgolabs.net>
Signed-off-by: Hyeonggon Yoo <42.hyeyoo@gmail.com>
---
 hw/cxl/cxl-device-utils.c   | 17 +++++++++++------
 include/hw/cxl/cxl_device.h |  4 +++-
 2 files changed, 14 insertions(+), 7 deletions(-)

diff --git a/hw/cxl/cxl-device-utils.c b/hw/cxl/cxl-device-utils.c
index 29de298117..ba3f80e6e7 100644
--- a/hw/cxl/cxl-device-utils.c
+++ b/hw/cxl/cxl-device-utils.c
@@ -229,12 +229,9 @@ static void mailbox_reg_write(void *opaque, hwaddr offset, uint64_t value,
 
 static uint64_t mdev_reg_read(void *opaque, hwaddr offset, unsigned size)
 {
-    uint64_t retval = 0;
-
-    retval = FIELD_DP64(retval, CXL_MEM_DEV_STS, MEDIA_STATUS, 1);
-    retval = FIELD_DP64(retval, CXL_MEM_DEV_STS, MBOX_READY, 1);
+    CXLDeviceState *cxl_dstate = opaque;
 
-    return retval;
+    return cxl_dstate->mbox_reg_state64[R_CXL_MEM_DEV_STS];
 }
 
 static void ro_reg_write(void *opaque, hwaddr offset, uint64_t value,
@@ -371,7 +368,15 @@ static void mailbox_reg_init_common(CXLDeviceState *cxl_dstate)
     cxl_dstate->mbox_msi_n = msi_n;
 }
 
-static void memdev_reg_init_common(CXLDeviceState *cxl_dstate) { }
+static void memdev_reg_init_common(CXLDeviceState *cxl_dstate)
+{
+    uint64_t memdev_status_reg;
+
+    memdev_status_reg = FIELD_DP64(0, CXL_MEM_DEV_STS, MEDIA_STATUS, 1);
+    memdev_status_reg = FIELD_DP64(memdev_status_reg, CXL_MEM_DEV_STS,
+                                   MBOX_READY, 1);
+    cxl_dstate->mbox_reg_state64[R_CXL_MEM_DEV_STS] = memdev_status_reg;
+}
 
 void cxl_device_register_init_t3(CXLType3Dev *ct3d)
 {
diff --git a/include/hw/cxl/cxl_device.h b/include/hw/cxl/cxl_device.h
index b2cb280e16..b318d94b36 100644
--- a/include/hw/cxl/cxl_device.h
+++ b/include/hw/cxl/cxl_device.h
@@ -408,7 +408,9 @@ static inline void __toggle_media(CXLDeviceState *cxl_dstate, int val)
 {
     uint64_t dev_status_reg;
 
-    dev_status_reg = FIELD_DP64(0, CXL_MEM_DEV_STS, MEDIA_STATUS, val);
+    dev_status_reg = cxl_dstate->mbox_reg_state64[R_CXL_MEM_DEV_STS];
+    dev_status_reg = FIELD_DP64(dev_status_reg, CXL_MEM_DEV_STS, MEDIA_STATUS,
+                                val);
     cxl_dstate->mbox_reg_state64[R_CXL_MEM_DEV_STS] = dev_status_reg;
 }
 #define cxl_dev_disable_media(cxlds)                    \
-- 
2.39.3