GIT: unionfs2-2.6.35.y: [PATCH] x86/apic: Map the local apic when parsing the MP table.

[Erez Zadok]

commit 52b6c3654eff73bc0d57634c068e15f88ba40506
Author: ebiederm at xxxxxxxxxxxx (Eric W. Biederman) <>
Date:   Tue Aug 10 23:14:00 2010 -0400

    [PATCH] x86/apic: Map the local apic when parsing the MP table.
    
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    Subject: [PATCH] x86/apic: Map the local apic when parsing the MP table.
    Date: Wed, 04 Aug 2010 13:30:27 -0700
    Cc: Tvrtko Ursulin <tvrtko.ursulin at xxxxxxxxxx>, Gleb Natapov <gleb at xxxxxxxxxx>, Yinghai Lu <yinghai at xxxxxxxxxx>, Avi Kivity <avi at xxxxxxxxxx>, "linux-kernel\@vger.kernel.org" <linux-kernel at xxxxxxxxxxxxxxx>, KVM list <kvm at xxxxxxxxxxxxxxx>, "Rafael J. Wysocki" <rjw at xxxxxxx>, David Hill <hilld at xxxxxxxxxxxxxxx>
    In-reply-to: <201008041146.56406.tvrtko.ursulin at xxxxxxxxxx> (Tvrtko Ursulin's message of "Wed\, 4 Aug 2010 11\:46\:55 +0100")
    References: <201008031028.57263.tvrtko.ursulin at xxxxxxxxxx>	<20100804093623.GE10499 at xxxxxxxxxx> <m1fwyuacjs.fsf at xxxxxxxxxxxxxxxxx>	<201008041146.56406.tvrtko.ursulin at xxxxxxxxxx>
    User-agent: Gnus/5.11 (Gnus v5.11) Emacs/22.2 (gnu/linux)
    This fixes a regression in 2.6.35 from 2.6.34, that is
    present for select models of Intel cpus when people are
    using an MP table.
    The commit cf7500c0ea133d66f8449d86392d83f840102632
    "x86, ioapic: In mpparse use mp_register_ioapic" started
    calling mp_register_ioapic from MP_ioapic_info.  An extremely
    simple change that was obviously correct.  Unfortunately
    mp_register_ioapic did just a little more than the previous
    hand crafted code and so we gained this call path.
    
    The problem call path is:
    MP_ioapic_info()
      mp_register_ioapic()
       io_apic_unique_id()
         io_apic_get_unique_id()
           get_physical_broadcast()
             modern_apic()
               lapic_get_version()
                 apic_read(APIC_LVR)
    
    Which turned out to be a problem because the local apic
    was not mapped, at that point, unlike the similar point
    in the ACPI parsing code.
    
    This problem is fixed by mapping the local apic when
    parsing the mptable as soon as we reasonably can.
    
    Looking at the number of places we setup the fixmap for
    the local apic, I see some serious simplification opportunities.
    For the moment except for not duplicating the setting up of the
    fixmap in init_apic_mappings, I have not acted on them.
    
    The regression from 2.6.34 is tracked in bug
    https://bugzilla.kernel.org/show_bug.cgi?id=16173
    
    Cc: stable at xxxxxxxxxx
    Reported-by: David Hill <hilld at xxxxxxxxxxxxxxx>
    Reported-by: Tvrtko Ursulin <tvrtko.ursulin at xxxxxxxxxx>
    Tested-by: Tvrtko Ursulin <tvrtko.ursulin at xxxxxxxxxx>
    Signed-off-by: Eric W. Biederman <ebiederm at xxxxxxxxxxxx>

diff --git a/arch/x86/kernel/apic/apic.c b/arch/x86/kernel/apic/apic.c
index a96489e..c07e513 100644
--- a/arch/x86/kernel/apic/apic.c
+++ b/arch/x86/kernel/apic/apic.c
@@ -1606,7 +1606,7 @@ void __init init_apic_mappings(void)
 		 * acpi lapic path already maps that address in
 		 * acpi_register_lapic_address()
 		 */
-		if (!acpi_lapic)
+		if (!acpi_lapic && !smp_found_config)
 			set_fixmap_nocache(FIX_APIC_BASE, apic_phys);
 
 		apic_printk(APIC_VERBOSE, "mapped APIC to %08lx (%08lx)\n",
diff --git a/arch/x86/kernel/mpparse.c b/arch/x86/kernel/mpparse.c
index d86dbf7..d7b6f7f 100644
--- a/arch/x86/kernel/mpparse.c
+++ b/arch/x86/kernel/mpparse.c
@@ -274,6 +274,18 @@ static void __init smp_dump_mptable(struct mpc_table *mpc, unsigned char *mpt)
 
 void __init default_smp_read_mpc_oem(struct mpc_table *mpc) { }
 
+static void __init smp_register_lapic_address(unsigned long address)
+{
+	mp_lapic_addr = address;
+
+	set_fixmap_nocache(FIX_APIC_BASE, address);
+	if (boot_cpu_physical_apicid == -1U) {
+		boot_cpu_physical_apicid  = read_apic_id();
+		apic_version[boot_cpu_physical_apicid] =
+			 GET_APIC_VERSION(apic_read(APIC_LVR));
+	}
+}
+
 static int __init smp_read_mpc(struct mpc_table *mpc, unsigned early)
 {
 	char str[16];
@@ -295,6 +307,10 @@ static int __init smp_read_mpc(struct mpc_table *mpc, unsigned early)
 	if (early)
 		return 1;
 
+	/* Initialize the lapic mapping */
+	if (!acpi_lapic)
+		smp_register_lapic_address(mpc->lapic);
+
 	if (mpc->oemptr)
 		x86_init.mpparse.smp_read_mpc_oem(mpc);