powerpc/powernv/idle: Restore CIABR after idle for Power9

On Power9, CIABR is lost after idle. This means that instruction
breakpoints set by xmon which use CIABR do not work. Fix this by
restoring CIABR after idle.

Signed-off-by: Jordan Niethe <jniethe5@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20201207010519.15597-2-jniethe5@gmail.com

arch/powerpc/platforms/powernv/idle.c

@@ -589,6 +589,7 @@ struct p9_sprs {
 	u64 spurr;
 	u64 dscr;
 	u64 wort;
+	u64 ciabr;
 
 	u64 mmcra;
 	u32 mmcr0;
@@ -668,6 +669,7 @@ static unsigned long power9_idle_stop(unsigned long psscr, bool mmu_on)
 		sprs.spurr	= mfspr(SPRN_SPURR);
 		sprs.dscr	= mfspr(SPRN_DSCR);
 		sprs.wort	= mfspr(SPRN_WORT);
+		sprs.ciabr	= mfspr(SPRN_CIABR);
 
 		sprs.mmcra	= mfspr(SPRN_MMCRA);
 		sprs.mmcr0	= mfspr(SPRN_MMCR0);
@@ -785,6 +787,7 @@ static unsigned long power9_idle_stop(unsigned long psscr, bool mmu_on)
 	mtspr(SPRN_SPURR,	sprs.spurr);
 	mtspr(SPRN_DSCR,	sprs.dscr);
 	mtspr(SPRN_WORT,	sprs.wort);
+	mtspr(SPRN_CIABR,	sprs.ciabr);
 
 	mtspr(SPRN_MMCRA,	sprs.mmcra);
 	mtspr(SPRN_MMCR0,	sprs.mmcr0);