[tip:x86/apic] x86, irq: Prefer assigned ID in APIC ID register for x86_64

tip-bot for Yinghai Lu
2014-12-19T14:04:34Z

Commit-ID: 5411dc4ccb25de133701774dd2a3cf3f7e246f17
Gitweb: http://git.kernel.org/tip/5411dc4ccb25de133701774dd2a3cf3f7e246f17
Author: Yinghai Lu <yinghai@kernel.org>
AuthorDate: Mon, 27 Oct 2014 13:21:40 +0800
Committer: Thomas Gleixner <tglx@linutronix.de>
CommitDate: Tue, 16 Dec 2014 14:08:15 +0100

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 <yinghai@kernel.org>
Signed-off-by: Jiang Liu <jiang.liu@linux.intel.com>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Joerg Roedel <joro@8bytes.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Sebastian Andrzej Siewior <sebastian@breakpoint.cc>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Rafael J. Wysocki <rjw@rjwysocki.net>
Cc: Bjorn Helgaas <bhelgaas@google.com>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Grant Likely <grant.likely@linaro.org>
Cc: Prarit Bhargava <prarit@redhat.com>
Link: http://lkml.kernel.org/r/1414387308-27148-11-git-send-email-jiang.liu@linux.intel.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

---
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 654b69b..86fd286 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);

/*