[Skiboot] [RFC PATCH 1/2] head: POWER9 initialise MMU registers to boot state for fast-reboot

[Nicholas Piggin]

When fast-rebooting, secondaries are sreset into OPAL with their
MMU registers (PTCR, PID, etc) still set up by the host OS. Clear
them at fastr-reboot time, before loading a new kernel.

Signed-off-by: Nicholas Piggin <npiggin at gmail.com>
---
 asm/head.S          | 11 ++++++++++-
 include/processor.h |  3 +++
 2 files changed, 13 insertions(+), 1 deletion(-)

diff --git a/asm/head.S b/asm/head.S
index eccf0702c..a96c5e4aa 100644
--- a/asm/head.S
+++ b/asm/head.S
@@ -810,13 +810,22 @@ init_replicated_sprs:
 4:	/* P9 */
 	/* LPCR: sane value */
 	LOAD_IMM64(%r3,0x0040000000000000)
+	isync
 	mtspr	SPR_LPCR, %r3
 	sync
 	isync
+	/* Zero out MMU registers */
+	li	%r3,0
+	ptesync
+	mtspr	SPR_PTCR,%r3
+	isync
+	mtspr	SPR_LPID,%r3
+	isync
+	mtspr	SPR_PID,%r3
+	isync
 	/* DSCR: Stride-N Stream Enable */
 	LOAD_IMM64(%r3,0x0000000000000010)
 	mtspr	SPR_DSCR,%r3
-
 9:	blr
 
 	.global enter_nap
diff --git a/include/processor.h b/include/processor.h
index 77110d011..bc02a0f09 100644
--- a/include/processor.h
+++ b/include/processor.h
@@ -53,6 +53,7 @@
 #define SPR_SRR1	0x01b	/* RW: Exception save/restore reg 1 */
 #define SPR_CFAR	0x01c	/* RW: Come From Address Register */
 #define SPR_AMR		0x01d	/* RW: Authority Mask Register */
+#define SPR_PID		0x030	/* RW: Process ID */
 #define SPR_IAMR	0x03d	/* RW: Instruction Authority Mask Register */
 #define SPR_RPR		0x0ba   /* RW: Relative Priority Register */
 #define SPR_TBRL	0x10c	/* RO: Timebase low */
@@ -75,9 +76,11 @@
 #define SPR_HSRR1	0x13b	/* RW: HV Exception save/restore reg 1 */
 #define SPR_TFMR	0x13d
 #define SPR_LPCR	0x13e
+#define SPR_LPID	0x13f	/* RW: Logical Partition Identifier */
 #define SPR_HMER	0x150	/* Hypervisor Maintenance Exception */
 #define SPR_HMEER	0x151	/* HMER interrupt enable mask */
 #define SPR_AMOR	0x15d
+#define SPR_PTCR	0x1d0	/* RW: Partition table control Register */
 #define SPR_PSSCR	0x357   /* RW: Stop status and control (ISA 3) */
 #define SPR_TSCR	0x399
 #define SPR_HID0	0x3f0
-- 
2.15.0