soc/power9/homer.c: additionaly enable HDEE in self-restore

Hypervisor Doorbell Exit Enable is required for waking threads with
doorbell messages.

Signed-off-by: Krystian Hebel <krystian.hebel@3mdeb.com>
Change-Id: I0cbbe2c5d029b3cae5337a6fd5fcf3dbd5321b1a

Author: krystian-hebel

src/include/cpu/power/spr.h

@@ -21,6 +21,7 @@
 #define SPR_LPCR				0x13E
 #define SPR_LPCR_HVEE				PPC_BIT(17)
 #define SPR_LPCR_LD				PPC_BIT(46)
+#define SPR_LPCR_HDEE				PPC_BIT(48)
 #define SPR_LPCR_EEE				PPC_BIT(49)
 #define SPR_LPCR_DEE				PPC_BIT(50)
 #define SPR_LPCR_OEE				PPC_BIT(51)

src/soc/ibm/power9/homer.c

@@ -343,11 +343,11 @@ static void build_self_restore(struct homer_st *homer,
 	size_t size;
 	uint32_t *ptr;
 	const uint64_t hrmor = read_spr(SPR_HRMOR);
-	/* See cpu_winkle() */
+	/* See cpu_winkle(), additionally set Hypervisor Doorbell Exit Enable */
 	const uint64_t lpcr =
 	   (read_spr(SPR_LPCR)
 	    & ~(SPR_LPCR_EEE | SPR_LPCR_DEE | SPR_LPCR_OEE | SPR_LPCR_HDICE))
-	   | (SPR_LPCR_HVICE | SPR_LPCR_HVEE);
+	   | (SPR_LPCR_HVICE | SPR_LPCR_HVEE | SPR_LPCR_HDEE);
 	/*
 	 * Timing facilities may be lost. During their restoration Large Decrementer
 	 * in LPCR may be initially turned off, which may result in a spurious