From 5411dc4ccb25de133701774dd2a3cf3f7e246f17 Mon Sep 17 00:00:00 2001 From: Yinghai Lu Date: Mon, 27 Oct 2014 13:21:40 +0800 Subject: [PATCH] x86, irq: Prefer assigned ID in APIC ID register for x86_64 Perfer the assigned ID in APIC ID register for x86_64 if it's still available. [ tglx: Added comments ] Signed-off-by: Yinghai Lu Signed-off-by: Jiang Liu Cc: Konrad Rzeszutek Wilk Cc: Tony Luck Cc: Joerg Roedel Cc: Greg Kroah-Hartman Cc: Sebastian Andrzej Siewior Cc: Benjamin Herrenschmidt Cc: Rafael J. Wysocki Cc: Bjorn Helgaas Cc: Randy Dunlap Cc: Borislav Petkov Cc: Grant Likely Cc: Prarit Bhargava Link: http://lkml.kernel.org/r/1414387308-27148-11-git-send-email-jiang.liu@linux.intel.com Signed-off-by: Thomas Gleixner --- arch/x86/kernel/apic/io_apic.c | 45 +++++++++++++++++++++++++++++----- 1 file changed, 39 insertions(+), 6 deletions(-) diff --git a/arch/x86/kernel/apic/io_apic.c b/arch/x86/kernel/apic/io_apic.c index 654b69b836b6..86fd2865ff69 100644 --- a/arch/x86/kernel/apic/io_apic.c +++ b/arch/x86/kernel/apic/io_apic.c @@ -3580,26 +3580,59 @@ static int __init io_apic_get_unique_id(int ioapic, int apic_id) return apic_id; } -static u8 __init io_apic_unique_id(u8 id) +static u8 __init io_apic_unique_id(int idx, u8 id) { if ((boot_cpu_data.x86_vendor == X86_VENDOR_INTEL) && !APIC_XAPIC(apic_version[boot_cpu_physical_apicid])) - return io_apic_get_unique_id(nr_ioapics, id); + return io_apic_get_unique_id(idx, id); else return id; } #else -static u8 __init io_apic_unique_id(u8 id) +static u8 __init io_apic_unique_id(int idx, u8 id) { - int i; + union IO_APIC_reg_00 reg_00; DECLARE_BITMAP(used, 256); + unsigned long flags; + u8 new_id; + int i; bitmap_zero(used, 256); for_each_ioapic(i) __set_bit(mpc_ioapic_id(i), used); + + /* Hand out the requested id if available */ if (!test_bit(id, used)) return id; - return find_first_zero_bit(used, 256); + + /* + * Read the current id from the ioapic and keep it if + * available. + */ + raw_spin_lock_irqsave(&ioapic_lock, flags); + reg_00.raw = io_apic_read(idx, 0); + raw_spin_unlock_irqrestore(&ioapic_lock, flags); + new_id = reg_00.bits.ID; + if (!test_bit(new_id, used)) { + apic_printk(APIC_VERBOSE, KERN_INFO + "IOAPIC[%d]: Using reg apic_id %d instead of %d\n", + idx, new_id, id); + return new_id; + } + + /* + * Get the next free id and write it to the ioapic. + */ + new_id = find_first_zero_bit(used, 256); + reg_00.bits.ID = new_id; + raw_spin_lock_irqsave(&ioapic_lock, flags); + io_apic_write(idx, 0, reg_00.raw); + reg_00.raw = io_apic_read(idx, 0); + raw_spin_unlock_irqrestore(&ioapic_lock, flags); + /* Sanity check */ + BUG_ON(reg_00.bits.ID != new_id); + + return new_id; } #endif @@ -3865,7 +3898,7 @@ void __init mp_register_ioapic(int id, u32 address, u32 gsi_base, return; } - ioapics[idx].mp_config.apicid = io_apic_unique_id(id); + ioapics[idx].mp_config.apicid = io_apic_unique_id(idx, id); ioapics[idx].mp_config.apicver = io_apic_get_version(idx); /* -- 2.39.2