Fast reboot for P8

This is an experimental patch that implements "Fast reboot" on P8
machines.

The basic idea is that when the OS calls OPAL reboot, we gather all
the threads in the system using a combination of patching the reset
vector and soft-resetting them, then cleanup a few bits of hardware
(we do re-probe PCIe for example), and reload & restart the bootloader.

For Trusted Boot, this means we *add* measurements to the TPM, so you
will get *different* PCR values as compared to a full IPL. This makes
sense as if you want to be sure you are running something known then,
well, do a full IPL as soft reset should never be trusted to clear any
malicious code.

This is very experimental and needs a lot of testing and also auditing
code for other bits of HW that might need to be cleaned up.

BenH TODO: I also need to check if we are properly PERST'ing PCI devices.

This is partially based on old code I had to do that on P7. I only
support it on P8 though as there are issues with the PSI interrupts
on P7 that cannot be reliably solved.

Even though this should be considered somewhat experimental, we've had
a lot of success on a variety of machines. Dozens/hundreds of reboots
across Tuleta, Garrison and Habanero.

Currently, we've hidden it behind a NVRAM config option, which *is*
liable to change in the future (to ensure that only those who know
what they're doing enable it)

You can enable the experimental support via nvram option:
 nvram -p ibm,skiboot --update-config experimental-fast-reset=feeling-lucky

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
[stewart@linux.vnet.ibm.com: hide behind nvram option, include Mambo fixes
from Mikey]
Signed-off-by: Stewart Smith <stewart@linux.vnet.ibm.com>

4 files changed, 10 insertions, 4 deletions

diff --git a/include/config.h b/include/config.h
index 2524570..f6572b0 100644
--- a/include/config.h
+++ b/include/config.h
@@ -72,9 +72,6 @@
  */
 //#define FORCE_DUMMY_CONSOLE 1
 
-/* Enable this to do fast resets. Currently unreliable... */
-//#define ENABLE_FAST_RESET	1
-
 /* Enable this to make fast reboot clear memory */
 //#define FAST_REBOOT_CLEARS_MEMORY	1
 
diff --git a/include/cpu.h b/include/cpu.h
index 341e73d..f649a13 100644
--- a/include/cpu.h
+++ b/include/cpu.h
@@ -66,6 +66,7 @@ struct cpu_thread {
 	bool				in_mcount;
 	bool				in_poller;
 	bool				in_reinit;
+	bool				in_fast_sleep;
 	bool				in_sleep;
 	bool				in_idle;
 	uint32_t			hbrt_spec_wakeup; /* primary only */
diff --git a/include/processor.h b/include/processor.h
index 4b11702..3942268 100644
--- a/include/processor.h
+++ b/include/processor.h
@@ -164,6 +164,7 @@
 /* Bits in HID0 */
 #define SPR_HID0_POWER8_4LPARMODE	PPC_BIT(2)
 #define SPR_HID0_POWER8_2LPARMODE	PPC_BIT(6)
+#define SPR_HID0_POWER8_DYNLPARDIS	PPC_BIT(15)
 #define SPR_HID0_POWER8_HILE		PPC_BIT(19)
 #define SPR_HID0_POWER9_HILE		PPC_BIT(4)
 #define SPR_HID0_POWER8_ENABLE_ATTN	PPC_BIT(31)
diff --git a/include/skiboot.h b/include/skiboot.h
index 2a9f5e2..2ef7677 100644
--- a/include/skiboot.h
+++ b/include/skiboot.h
@@ -190,12 +190,14 @@ extern unsigned long get_symbol(unsigned long addr,
 				char **sym, char **sym_end);
 
 /* Fast reboot support */
-extern void fast_reset(void);
+extern void fast_reboot(void);
 extern void __noreturn __secondary_cpu_entry(void);
 extern void __noreturn load_and_boot_kernel(bool is_reboot);
 extern void cleanup_tlb(void);
 extern void init_shared_sprs(void);
 extern void init_replicated_sprs(void);
+extern bool start_preload_kernel(void);
+extern void copy_exception_vectors(void);
 extern void setup_reset_vector(void);
 
 /* Various probe routines, to replace with an initcall system */
@@ -269,6 +271,11 @@ extern void slw_update_timer_expiry(uint64_t new_target);
 /* Is SLW timer available ? */
 extern bool slw_timer_ok(void);
 
+/* Patch SPR in SLW image */
+extern int64_t opal_slw_set_reg(uint64_t cpu_pir, uint64_t sprn, uint64_t val);
+
+extern void fast_sleep_exit(void);
+
 /* Fallback fake RTC */
 extern void fake_rtc_init(void);