[RFC -tip] x86,io-apic: Do not map IO-APIC direct registers twice
From: Cyrill Gorcunov
Date: Thu Nov 12 2009 - 15:49:11 EST
Please review, I didn't manage to test (emulate actually since I don't
have such a hardware) it yet (going to do so this weekend).
Meanwhile I would like to heard comments, complains and etc...
Perhaps I miss something obvious so don't hesitate to poke me.
-- Cyrill
---
x86,io-apic: Do not map IO-APIC direct registers twice
In case if IO-APIC address is not 4K aligned (which is pretty
established by MPS-1.4) we may not fixmap they twice and
should eliminate resourse overlap in this case.
An example of a such configureation is
http://marc.info/?l=linux-kernel&m=118114792006520
| Quoting the message
|
| IOAPIC[0]: apic_id 2, version 32, address 0xfec00000, GSI 0-23
| IOAPIC[1]: apic_id 3, version 32, address 0xfec80000, GSI 24-47
| IOAPIC[2]: apic_id 4, version 32, address 0xfec80400, GSI 48-71
| IOAPIC[3]: apic_id 5, version 32, address 0xfec84000, GSI 72-95
| IOAPIC[4]: apic_id 8, version 32, address 0xfec84400, GSI 96-119
Some io-apics are 4K aligned while others are -- 1K. We may have
the situation when next IO-APIC address (1K aligned) is following
previous 4K one. So instead of allocating new fixmap we may use already
done one.
To implement it ioapic_fixmap_shared is introduced which check if
new IO-APIC base address lays inside already mapped page.
Also insert_resourse will not fail anymore on 1K aligned io-apics.
CC: "Maciej W. Rozycki" <macro@xxxxxxxxxxxxxx>
CC: Yinghai Lu <yinghai@xxxxxxxxxx>
Signed-off-by: Cyrill Gorcunov <gorcunov@xxxxxxxxx>
---
arch/x86/include/asm/apicdef.h | 23 +++++++++++++++--
arch/x86/include/asm/mpspec_def.h | 9 +++---
arch/x86/kernel/apic/io_apic.c | 50 +++++++++++++++++++++++++++++++-------
arch/x86/kernel/mpparse.c | 2 -
4 files changed, 67 insertions(+), 17 deletions(-)
Index: linux-2.6.git/arch/x86/include/asm/apicdef.h
=====================================================================
--- linux-2.6.git.orig/arch/x86/include/asm/apicdef.h
+++ linux-2.6.git/arch/x86/include/asm/apicdef.h
@@ -1,6 +1,3 @@
-#ifndef _ASM_X86_APICDEF_H
-#define _ASM_X86_APICDEF_H
-
/*
* Constants for various Intel APICs. (local APIC, IOAPIC, etc.)
*
@@ -8,9 +5,29 @@
* Ingo Molnar <mingo@xxxxxxxxxx>, 1999, 2000
*/
+#ifndef _ASM_X86_APICDEF_H
+#define _ASM_X86_APICDEF_H
+
#define IO_APIC_DEFAULT_PHYS_BASE 0xfec00000
#define APIC_DEFAULT_PHYS_BASE 0xfee00000
+/*
+ * MP 1.4 specify that LAPIC must be aligned
+ * on 4K bound and IO-APIC on 1K
+ * (4K boud on IO-APIC is widely used too)
+ */
+#define APIC_PHYS_BASE_SHIFT (12)
+#define IO_APIC_PHYS_BASE_SHIFT (10)
+#define APIC_PHYS_BASE_MASK (~((1U << APIC_PHYS_BASE_SHIFT) - 1))
+#define IO_APIC_PHYS_BASE_MASK (~((1U << IO_APIC_PHYS_BASE_SHIFT) - 1))
+
+/*
+ * We assume that 1024 bytes will be more
+ * then enough in feasible feauture to cover
+ * all direct accessible IO-APIC registers
+ */
+#define IO_APIC_SLOT_SIZE (1 << IO_APIC_PHYS_BASE_SHIFT)
+
#define APIC_ID 0x20
#define APIC_LVR 0x30
Index: linux-2.6.git/arch/x86/include/asm/mpspec_def.h
=====================================================================
--- linux-2.6.git.orig/arch/x86/include/asm/mpspec_def.h
+++ linux-2.6.git/arch/x86/include/asm/mpspec_def.h
@@ -1,11 +1,11 @@
-#ifndef _ASM_X86_MPSPEC_DEF_H
-#define _ASM_X86_MPSPEC_DEF_H
-
/*
* Structure definitions for SMP machines following the
* Intel Multiprocessing Specification 1.1 and 1.4.
*/
+#ifndef _ASM_X86_MPSPEC_DEF_H
+#define _ASM_X86_MPSPEC_DEF_H
+
/*
* This tag identifies where the SMP configuration
* information is.
@@ -107,7 +107,8 @@ struct mpc_bus {
#define BUSTYPE_VME "VME"
#define BUSTYPE_XPRESS "XPRESS"
-#define MPC_APIC_USABLE 0x01
+#define MPC_IO_APIC_USABLE (1 << 0)
+#define MPC_IO_APIC_MAPPED (1 << 1)
struct mpc_ioapic {
unsigned char type;
Index: linux-2.6.git/arch/x86/kernel/apic/io_apic.c
=====================================================================
--- linux-2.6.git.orig/arch/x86/kernel/apic/io_apic.c
+++ linux-2.6.git/arch/x86/kernel/apic/io_apic.c
@@ -4108,6 +4108,38 @@ static struct resource * __init ioapic_s
return res;
}
+static __init int ioapic_fixmap_shared(unsigned long phys)
+{
+ unsigned long min, max;
+ int i;
+
+ /* if unpredictable change of PAGE_SHIFT happen */
+ BUILD_BUG_ON(APIC_PHYS_BASE_SHIFT != PAGE_SHIFT);
+
+ if (!(phys & ~APIC_PHYS_BASE_MASK))
+ return -1;
+
+ /*
+ * if this get "hot-path" status we would need
+ * more sophisticated/fast algorithm instead
+ *
+ * Note that we rely on BIOS that there is no
+ * *overlapped or same* base addresses
+ */
+ for (i = 0; i < nr_ioapics; i++) {
+ if (!(mp_ioapics[i].flags & MPC_IO_APIC_MAPPED)) {
+ pr_warning("IO-APIC: IO-APIC %d not mapped yet!\n", i);
+ break;
+ }
+ min = mp_ioapics[i].apicaddr & APIC_PHYS_BASE_MASK;
+ max = min + (PAGE_SIZE - IO_APIC_SLOT_SIZE);
+ if (phys >= min && phys <= max)
+ return i;
+ }
+
+ return -1;
+}
+
void __init ioapic_init_mappings(void)
{
unsigned long ioapic_phys, idx = FIX_IO_APIC_BASE_0;
@@ -4133,19 +4165,19 @@ void __init ioapic_init_mappings(void)
#ifdef CONFIG_X86_32
fake_ioapic_page:
#endif
- ioapic_phys = (unsigned long)
- alloc_bootmem_pages(PAGE_SIZE);
+ ioapic_phys = (unsigned long)alloc_bootmem_pages(PAGE_SIZE);
ioapic_phys = __pa(ioapic_phys);
}
- set_fixmap_nocache(idx, ioapic_phys);
- apic_printk(APIC_VERBOSE,
- "mapped IOAPIC to %08lx (%08lx)\n",
- __fix_to_virt(idx), ioapic_phys);
- idx++;
+ /* not mapped yet */
+ if (ioapic_fixmap_shared(ioapic_phys) == -1) {
+ set_fixmap_nocache(idx, ioapic_phys);
+ idx++;
+ }
ioapic_res->start = ioapic_phys;
- ioapic_res->end = ioapic_phys + PAGE_SIZE-1;
+ ioapic_res->end = ioapic_phys + IO_APIC_SLOT_SIZE - 1;
ioapic_res++;
+ mp_ioapics[i].flags |= MPC_IO_APIC_MAPPED;
}
}
@@ -4217,7 +4249,7 @@ void __init mp_register_ioapic(int id, u
idx = nr_ioapics;
mp_ioapics[idx].type = MP_IOAPIC;
- mp_ioapics[idx].flags = MPC_APIC_USABLE;
+ mp_ioapics[idx].flags = MPC_IO_APIC_USABLE;
mp_ioapics[idx].apicaddr = address;
set_fixmap_nocache(FIX_IO_APIC_BASE_0 + idx, address);
Index: linux-2.6.git/arch/x86/kernel/mpparse.c
=====================================================================
--- linux-2.6.git.orig/arch/x86/kernel/mpparse.c
+++ linux-2.6.git/arch/x86/kernel/mpparse.c
@@ -132,7 +132,7 @@ static int bad_ioapic(unsigned long addr
static void __init MP_ioapic_info(struct mpc_ioapic *m)
{
- if (!(m->flags & MPC_APIC_USABLE))
+ if (!(m->flags & MPC_IO_APIC_USABLE))
return;
printk(KERN_INFO "I/O APIC #%d Version %d at 0x%X.\n",
--
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