From 0279d8951ead549fdebce93130a2f6c673081862 Mon Sep 17 00:00:00 2001 From: Benjamin Herrenschmidt Date: Sun, 24 Jul 2016 09:32:10 +1000 Subject: 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 [stewart@linux.vnet.ibm.com: hide behind nvram option, include Mambo fixes from Mikey] Signed-off-by: Stewart Smith --- hw/occ.c | 5 +++++ 1 file changed, 5 insertions(+) (limited to 'hw/occ.c') diff --git a/hw/occ.c b/hw/occ.c index 63e142cf..d5c590b1 100644 --- a/hw/occ.c +++ b/hw/occ.c @@ -517,10 +517,14 @@ void occ_pstates_init(void) struct proc_chip *chip; struct cpu_thread *c; s8 pstate_nom; + static bool occ_pstates_initialized; /* OCC is P8 only */ if (proc_gen != proc_gen_p8) return; + /* Handle fast reboots */ + if (occ_pstates_initialized) + return; chip = next_chip(NULL); if (!chip->homer_base) { @@ -558,6 +562,7 @@ void occ_pstates_init(void) for_each_chip(chip) chip->throttle = 0; opal_add_poller(occ_throttle_poll, NULL); + occ_pstates_initialized = true; } struct occ_load_req { -- cgit v1.2.1