[Patch v7 10/18] x86, irq: Prefer assigned ID in APIC ID register for x86_64

Jiang Liu
2014-10-27T05:20:53Z

From: Yinghai Lu <yinghai@kernel.org>

Perfer the assigned ID in APIC ID register for x86_64 if it's still
available.

Signed-off-by: Yinghai Lu <yinghai@kernel.org>
Cc: Joerg Roedel <joro@8bytes.org>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: Sebastian Andrzej Siewior <sebastian@breakpoint.cc>
Signed-off-by: Jiang Liu <jiang.liu@linux.intel.com>
---
arch/x86/kernel/apic/io_apic.c | 35 ++++++++++++++++++++++++++++++-----
1 file changed, 30 insertions(+), 5 deletions(-)

diff --git a/arch/x86/kernel/apic/io_apic.c b/arch/x86/kernel/apic/io_apic.c
index acaee90fc9cc..eaa7ea385600 100644
--- a/arch/x86/kernel/apic/io_apic.c
+++ b/arch/x86/kernel/apic/io_apic.c
@@ -3580,26 +3580,51 @@ 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;
+ u8 new_id;
+ unsigned long flags;
DECLARE_BITMAP(used, 256);
+ union IO_APIC_reg_00 reg_00;

bitmap_zero(used, 256);
for_each_ioapic(i)
__set_bit(mpc_ioapic_id(i), used);
if (!test_bit(id, used))
return id;
- return find_first_zero_bit(used, 256);
+
+ /* check register at first */
+ 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;
+ }
+
+ 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 +3890,7 @@ 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);

/*
--
1.7.10.4