path: root/arch
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authorKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>2012-03-20 15:04:18 -0400
committerKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>2012-04-06 12:13:06 -0400
commit2531d64b6fe2724dc432b67d8dc66bd45621da0b (patch)
tree337d0c030f8ac7f72dadb7dfdd9e8cbe314936fe /arch
parente95ae5a4939c52ccab02a49238d5d15d492b2598 (diff)
xen/x86: Workaround 'x86/ioapic: Add register level checks to detect bogus io-apic entries'
The above mentioned patch checks the IOAPIC and if it contains -1, then it unmaps said IOAPIC. But under Xen we get this: BUG: unable to handle kernel NULL pointer dereference at 0000000000000040 IP: [<ffffffff8134e51f>] xen_irq_init+0x1f/0xb0 PGD 0 Oops: 0002 [#1] SMP CPU 0 Modules linked in: Pid: 1, comm: swapper/0 Not tainted 3.2.10-3.fc16.x86_64 #1 Dell Inc. Inspiron 1525 /0U990C RIP: e030:[<ffffffff8134e51f>] [<ffffffff8134e51f>] xen_irq_init+0x1f/0xb0 RSP: e02b: ffff8800d42cbb70 EFLAGS: 00010202 RAX: 0000000000000000 RBX: 00000000ffffffef RCX: 0000000000000001 RDX: 0000000000000040 RSI: 00000000ffffffef RDI: 0000000000000001 RBP: ffff8800d42cbb80 R08: ffff8800d6400000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000000 R12: 00000000ffffffef R13: 0000000000000001 R14: 0000000000000001 R15: 0000000000000010 FS: 0000000000000000(0000) GS:ffff8800df5fe000(0000) knlGS:0000000000000000 CS: e033 DS: 0000 ES: 0000 CR0:000000008005003b CR2: 0000000000000040 CR3: 0000000001a05000 CR4: 0000000000002660 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400 Process swapper/0 (pid: 1, threadinfo ffff8800d42ca000, task ffff8800d42d0000) Stack: 00000000ffffffef 0000000000000010 ffff8800d42cbbe0 ffffffff8134f157 ffffffff8100a9b2 ffffffff8182ffd1 00000000000000a0 00000000829e7384 0000000000000002 0000000000000010 00000000ffffffff 0000000000000000 Call Trace: [<ffffffff8134f157>] xen_bind_pirq_gsi_to_irq+0x87/0x230 [<ffffffff8100a9b2>] ? check_events+0x12+0x20 [<ffffffff814bab42>] xen_register_pirq+0x82/0xe0 [<ffffffff814bac1a>] xen_register_gsi.part.2+0x4a/0xd0 [<ffffffff814bacc0>] acpi_register_gsi_xen+0x20/0x30 [<ffffffff8103036f>] acpi_register_gsi+0xf/0x20 [<ffffffff8131abdb>] acpi_pci_irq_enable+0x12e/0x202 [<ffffffff814bc849>] pcibios_enable_device+0x39/0x40 [<ffffffff812dc7ab>] do_pci_enable_device+0x4b/0x70 [<ffffffff812dc878>] __pci_enable_device_flags+0xa8/0xf0 [<ffffffff812dc8d3>] pci_enable_device+0x13/0x20 The reason we are dying is b/c the call acpi_get_override_irq() is used, which returns the polarity and trigger for the IRQs. That function calls mp_find_ioapics to get the 'struct ioapic' structure - which along with the mp_irq[x] is used to figure out the default values and the polarity/trigger overrides. Since the mp_find_ioapics now returns -1 [b/c the IOAPIC is filled with 0xffffffff], the acpi_get_override_irq() stops trying to lookup in the mp_irq[x] the proper INT_SRV_OVR and we can't install the SCI interrupt. The proper fix for this is going in v3.5 and adds an x86_io_apic_ops struct so that platforms can override it. But for v3.4 lets carry this work-around. This patch does that by providing a slightly different variant of the fake IOAPIC entries. Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Diffstat (limited to 'arch')
1 files changed, 3 insertions, 1 deletions
diff --git a/arch/x86/xen/mmu.c b/arch/x86/xen/mmu.c
index 1a309ee2331e..91dc2871e336 100644
--- a/arch/x86/xen/mmu.c
+++ b/arch/x86/xen/mmu.c
@@ -1859,6 +1859,7 @@ pgd_t * __init xen_setup_kernel_pagetable(pgd_t *pgd,
#endif /* CONFIG_X86_64 */
static unsigned char dummy_mapping[PAGE_SIZE] __page_aligned_bss;
+static unsigned char fake_ioapic_mapping[PAGE_SIZE] __page_aligned_bss;
static void xen_set_fixmap(unsigned idx, phys_addr_t phys, pgprot_t prot)
@@ -1899,7 +1900,7 @@ static void xen_set_fixmap(unsigned idx, phys_addr_t phys, pgprot_t prot)
* We just don't map the IO APIC - all access is via
* hypercalls. Keep the address in the pte for reference.
- pte = pfn_pte(PFN_DOWN(__pa(dummy_mapping)), PAGE_KERNEL);
+ pte = pfn_pte(PFN_DOWN(__pa(fake_ioapic_mapping)), PAGE_KERNEL);
@@ -2064,6 +2065,7 @@ void __init xen_init_mmu_ops(void)
pv_mmu_ops = xen_mmu_ops;
memset(dummy_mapping, 0xff, PAGE_SIZE);
+ memset(fake_ioapic_mapping, 0xfd, PAGE_SIZE);
/* Protected by xen_reservation_lock. */

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