From d0af9eed5aa91b6b7b5049cae69e5ea956fd85c3 Mon Sep 17 00:00:00 2001 From: Suresh Siddha Date: Wed, 19 Aug 2009 18:05:36 -0700 Subject: x86, pat/mtrr: Rendezvous all the cpus for MTRR/PAT init SDM Vol 3a section titled "MTRR considerations in MP systems" specifies the need for synchronizing the logical cpu's while initializing/updating MTRR. Currently Linux kernel does the synchronization of all cpu's only when a single MTRR register is programmed/updated. During an AP online (during boot/cpu-online/resume) where we initialize all the MTRR/PAT registers, we don't follow this synchronization algorithm. This can lead to scenarios where during a dynamic cpu online, that logical cpu is initializing MTRR/PAT with cache disabled (cr0.cd=1) etc while other logical HT sibling continue to run (also with cache disabled because of cr0.cd=1 on its sibling). Starting from Westmere, VMX transitions with cr0.cd=1 don't work properly (because of some VMX performance optimizations) and the above scenario (with one logical cpu doing VMX activity and another logical cpu coming online) can result in system crash. Fix the MTRR initialization by doing rendezvous of all the cpus. During boot and resume, we delay the MTRR/PAT init for APs till all the logical cpu's come online and the rendezvous process at the end of AP's bringup, will initialize the MTRR/PAT for all AP's. For dynamic single cpu online, we synchronize all the logical cpus and do the MTRR/PAT init on the AP that is coming online. Signed-off-by: Suresh Siddha Signed-off-by: H. Peter Anvin --- arch/x86/power/cpu.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'arch/x86/power') diff --git a/arch/x86/power/cpu.c b/arch/x86/power/cpu.c index b3d20b9cac63..417c9f5b4afa 100644 --- a/arch/x86/power/cpu.c +++ b/arch/x86/power/cpu.c @@ -242,7 +242,7 @@ static void __restore_processor_state(struct saved_context *ctxt) fix_processor_context(); do_fpu_end(); - mtrr_ap_init(); + mtrr_bp_restore(); #ifdef CONFIG_X86_OLD_MCE mcheck_init(&boot_cpu_data); -- cgit v1.2.3-58-ga151