x86: read apic ID in the !acpi_lapic case

Ed found that on 32-bit, boot_cpu_physical_apicid is not read right,
when the mptable is broken.

Interestingly, actually three paths use/set it:

 1. acpi: at that time that is already read from reg
 2. mptable: only read from mptable
 3. no madt, and no mptable, that use default apic id 0 for 64-bit, -1 for 32-bit

so we could read the apic id for the 2/3 path. We trust the hardware
register more than we trust a BIOS data structure (the mptable).

We can also avoid the double set_fixmap() when acpi_lapic
is used, and also need to move cpu_has_apic earlier and
call apic_disable().

Also when need to update the apic id, we'd better read and
set the apic version as well - so that quirks are applied precisely.

v2: make path 3 with 64bit, use -1 as apic id, so could read it later.
v3: fix whitespace problem pointed out by Ed Swierk
v5: fix boot crash

[ Impact: get correct apic id for bsp other than acpi path ]

Reported-by: Ed Swierk <eswierk@aristanetworks.com>
Signed-off-by: Yinghai Lu <yinghai@kernel.org>
Acked-by: Cyrill Gorcunov <gorcunov@openvz.org>
LKML-Reference: <49FC85A9.2070702@kernel.org>
[ v4: sanity-check in the ACPI case too ]
Signed-off-by: Ingo Molnar <mingo@elte.hu>

diff --git a/arch/x86/include/asm/smp.h b/arch/x86/include/asm/smp.h
index 19e0d88..6a84ed1 100644 (file)
--- a/arch/x86/include/asm/smp.h
+++ b/arch/x86/include/asm/smp.h
@@ -180,7 +180,7 @@ extern int safe_smp_processor_id(void);
 static inline int logical_smp_processor_id(void)
 {
        /* we don't want to mark this access volatile - bad code generation */
-       return GET_APIC_LOGICAL_ID(*(u32 *)(APIC_BASE + APIC_LDR));
+       return GET_APIC_LOGICAL_ID(apic_read(APIC_LDR));
 }
 
 #endif

diff --git a/arch/x86/kernel/apic/apic.c b/arch/x86/kernel/apic/apic.c
index 07cffc1..b0fd264 100644 (file)
--- a/arch/x86/kernel/apic/apic.c
+++ b/arch/x86/kernel/apic/apic.c
@@ -242,17 +242,24 @@ static int modern_apic(void)
  * bare function to substitute write operation
  * and it's _that_ fast :)
  */
-void native_apic_write_dummy(u32 reg, u32 v)
+static void native_apic_write_dummy(u32 reg, u32 v)
 {
        WARN_ON_ONCE((cpu_has_apic || !disable_apic));
 }
 
+static u32 native_apic_read_dummy(u32 reg)
+{
+       WARN_ON_ONCE((cpu_has_apic || !disable_apic));
+       return 0;
+}
+
 /*
- * right after this call apic->write doesn't do anything
+ * right after this call apic->write/read doesn't do anything
  * note that there is no restore operation it works one way
  */
 void apic_disable(void)
 {
+       apic->read = native_apic_read_dummy;
        apic->write = native_apic_write_dummy;
 }
 
@@ -1576,32 +1583,23 @@ void __init init_apic_mappings(void)
                return;
        }
 
-       /*
-        * If no local APIC can be found then set up a fake all
-        * zeroes page to simulate the local APIC and another
-        * one for the IO-APIC.
-        */
+       /* If no local APIC can be found return early */
        if (!smp_found_config && detect_init_APIC()) {
-               apic_phys = (unsigned long) alloc_bootmem_pages(PAGE_SIZE);
-               apic_phys = __pa(apic_phys);
-       } else
+               /* lets NOP'ify apic operations */
+               pr_info("APIC: disable apic facility\n");
+               apic_disable();
+       } else {
                apic_phys = mp_lapic_addr;
 
-       /*
-        * acpi lapic path already maps that address in
-        * acpi_register_lapic_address()
-        */
-       if (!acpi_lapic)
-               set_fixmap_nocache(FIX_APIC_BASE, apic_phys);
-
-       apic_printk(APIC_VERBOSE, "mapped APIC to %08lx (%08lx)\n",
-                       APIC_BASE, apic_phys);
+               /*
+                * acpi lapic path already maps that address in
+                * acpi_register_lapic_address()
+                */
+               if (!acpi_lapic)
+                       set_fixmap_nocache(FIX_APIC_BASE, apic_phys);
 
-       /* lets check if we may NOP'ify apic operations */
-       if (!cpu_has_apic) {
-               pr_info("APIC: disable apic facility\n");
-               apic_disable();
-               return;
+               apic_printk(APIC_VERBOSE, "mapped APIC to %08lx (%08lx)\n",
+                                       APIC_BASE, apic_phys);
        }
 
        /*

diff --git a/arch/x86/kernel/apic/io_apic.c b/arch/x86/kernel/apic/io_apic.c
index 1f3d366..74d2b48 100644 (file)
--- a/arch/x86/kernel/apic/io_apic.c
+++ b/arch/x86/kernel/apic/io_apic.c
@@ -1878,6 +1878,11 @@ __apicdebuginit(void) print_PIC(void)
 __apicdebuginit(int) print_all_ICs(void)
 {
        print_PIC();
+
+       /* don't print out if apic is not there */
+       if (!cpu_has_apic || disable_apic)
+               return 0;
+
        print_all_local_APICs();
        print_IO_APIC();