From 93789b32dbf355e70f18b17a82e8661677a7f7fb Mon Sep 17 00:00:00 2001 From: Borislav Petkov Date: Thu, 20 Jan 2011 15:42:52 +0100 Subject: x86, hotplug: Fix powersavings with offlined cores on AMD ea53069231f9317062910d6e772cca4ce93de8c8 made a CPU use monitor/mwait when offline. This is not the optimal choice for AMD wrt to powersavings and we'd prefer our cores to halt (i.e. enter C1) instead. For this, the same selection whether to use monitor/mwait has to be used as when we select the idle routine for the machine. With this patch, offlining cores 1-5 on a X6 machine allows core0 to boost again. [ hpa: putting this in urgent since it is a (power) regression fix ] Reported-by: Andreas Herrmann Cc: stable@kernel.org # 37.x Cc: H. Peter Anvin Cc: Arjan van de Ven Cc: Len Brown Cc: Venkatesh Pallipadi Cc: Peter Zijlstra Signed-off-by: Borislav Petkov LKML-Reference: <1295534572-10730-1-git-send-email-bp@amd64.org> Signed-off-by: H. Peter Anvin --- arch/x86/kernel/smpboot.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) (limited to 'arch/x86/kernel/smpboot.c') diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c index 763df77343dd..0cbe8c0b35ed 100644 --- a/arch/x86/kernel/smpboot.c +++ b/arch/x86/kernel/smpboot.c @@ -1402,8 +1402,9 @@ static inline void mwait_play_dead(void) unsigned int highest_subcstate = 0; int i; void *mwait_ptr; + struct cpuinfo_x86 *c = __this_cpu_ptr(&cpu_info); - if (!cpu_has(__this_cpu_ptr(&cpu_info), X86_FEATURE_MWAIT)) + if (!(cpu_has(c, X86_FEATURE_MWAIT) && mwait_usable(c))) return; if (!cpu_has(__this_cpu_ptr(&cpu_info), X86_FEATURE_CLFLSH)) return; -- cgit v1.2.3 From 11d4c3f9b671720e80353dd7e433ff2bf65e9500 Mon Sep 17 00:00:00 2001 From: "H. Peter Anvin" Date: Fri, 4 Feb 2011 16:14:11 -0800 Subject: x86-32: Make sure the stack is set up before we use it Since checkin ebba638ae723d8a8fc2f7abce5ec18b688b791d7 we call verify_cpu even in 32-bit mode. Unfortunately, calling a function means using the stack, and the stack pointer was not initialized in the 32-bit setup code! This code initializes the stack pointer, and simplifies the interface slightly since it is easier to rely on just a pointer value rather than a descriptor; we need to have different values for the segment register anyway. This retains start_stack as a virtual address, even though a physical address would be more convenient for 32 bits; the 64-bit code wants the other way around... Reported-by: Matthieu Castet LKML-Reference: <4D41E86D.8060205@free.fr> Tested-by: Kees Cook Signed-off-by: H. Peter Anvin --- arch/x86/kernel/smpboot.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'arch/x86/kernel/smpboot.c') diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c index 0cbe8c0b35ed..03273b6c272c 100644 --- a/arch/x86/kernel/smpboot.c +++ b/arch/x86/kernel/smpboot.c @@ -638,7 +638,7 @@ wakeup_secondary_cpu_via_init(int phys_apicid, unsigned long start_eip) * target processor state. */ startup_ipi_hook(phys_apicid, (unsigned long) start_secondary, - (unsigned long)stack_start.sp); + stack_start); /* * Run STARTUP IPI loop. @@ -785,7 +785,7 @@ do_rest: #endif early_gdt_descr.address = (unsigned long)get_cpu_gdt_table(cpu); initial_code = (unsigned long)start_secondary; - stack_start.sp = (void *) c_idle.idle->thread.sp; + stack_start = c_idle.idle->thread.sp; /* start_ip had better be page-aligned! */ start_ip = setup_trampoline(); -- cgit v1.2.3