Define yet another magic number. The definition was copied from:
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/tree/drivers/net/ethernet/intel/e1000e/defines.h?h=v6.0.9#n374

Signed-off-by: Akihiko Odaki <akihiko.odaki@daynix.com>
---
 hw/net/e1000_regs.h  | 7 +++++++
 hw/net/e1000e_core.c | 2 +-
 2 files changed, 8 insertions(+), 1 deletion(-)

diff --git a/hw/net/e1000_regs.h b/hw/net/e1000_regs.h
index 9d423f6c09..214ba0f6f2 100644
--- a/hw/net/e1000_regs.h
+++ b/hw/net/e1000_regs.h
@@ -571,6 +571,13 @@
 /* PHY Link Partner Ability Register */
 #define MII_LPAR_LPACK           0x4000 /* Acked by link partner */
 
+/* SW Semaphore Register */
+#define E1000_SWSM_SMBI         0x00000001 /* Driver Semaphore bit */
+#define E1000_SWSM_SWESMBI      0x00000002 /* FW Semaphore bit */
+#define E1000_SWSM_DRV_LOAD     0x00000008 /* Driver Loaded Bit */
+
+#define E1000_SWSM2_LOCK        0x00000002 /* Secondary driver semaphore bit */
+
 /* Interrupt Cause Read */
 #define E1000_ICR_TXDW          0x00000001 /* Transmit desc written back */
 #define E1000_ICR_TXQE          0x00000002 /* Transmit Queue empty */
diff --git a/hw/net/e1000e_core.c b/hw/net/e1000e_core.c
index fc9cdb4528..a560fcb580 100644
--- a/hw/net/e1000e_core.c
+++ b/hw/net/e1000e_core.c
@@ -2634,7 +2634,7 @@ static uint32_t
 e1000e_mac_swsm_read(E1000ECore *core, int index)
 {
     uint32_t val = core->mac[SWSM];
-    core->mac[SWSM] = val | 1;
+    core->mac[SWSM] = val | E1000_SWSM_SMBI;
     return val;
 }
 
-- 
2.38.1