[PATCH] kvm: do not handle APIC access page if in-kernel irqchip is not in use

From: Paolo Bonzini
Date: Thu Oct 02 2014 - 08:00:39 EST


This fixes the following OOPS:

loaded kvm module (v3.17-rc1-168-gcec26bc)
BUG: unable to handle kernel paging request at fffffffffffffffe
IP: [<ffffffff81168449>] put_page+0x9/0x30
PGD 1e15067 PUD 1e17067 PMD 0
Oops: 0000 [#1] PREEMPT SMP
[<ffffffffa063271d>] ? kvm_vcpu_reload_apic_access_page+0x5d/0x70 [kvm]
[<ffffffffa013b6db>] vmx_vcpu_reset+0x21b/0x470 [kvm_intel]
[<ffffffffa0658816>] ? kvm_pmu_reset+0x76/0xb0 [kvm]
[<ffffffffa064032a>] kvm_vcpu_reset+0x15a/0x1b0 [kvm]
[<ffffffffa06403ac>] kvm_arch_vcpu_setup+0x2c/0x50 [kvm]
[<ffffffffa062e540>] kvm_vm_ioctl+0x200/0x780 [kvm]
[<ffffffff81212170>] do_vfs_ioctl+0x2d0/0x4b0
[<ffffffff8108bd99>] ? __mmdrop+0x69/0xb0
[<ffffffff812123d1>] SyS_ioctl+0x81/0xa0
[<ffffffff8112a6f6>] ? __audit_syscall_exit+0x1f6/0x2a0
[<ffffffff817229e9>] system_call_fastpath+0x16/0x1b
Code: c6 78 ce a3 81 4c 89 e7 e8 d9 80 ff ff 0f 0b 4c 89 e7 e8 8f f6 ff ff e9 fa fe ff ff 66 2e 0f 1f 84 00 00 00 00 00 66 66 66 66 90 <48> f7 07 00 c0 00 00 55 48 89 e5 75 1e 8b 47 1c 85 c0 74 27 f0
RIP [<ffffffff81193045>] put_page+0x5/0x50

when not using the in-kernel irqchip ("-machine kernel_irqchip=off"
with QEMU).

Reported-by: Jan Kiszka <jan.kiszka@xxxxxxxxxxx>
Fixes: 4256f43f9fab91e1c17b5846a240cf4b66a768a8
Signed-off-by: Paolo Bonzini <pbonzini@xxxxxxxxxx>
---
arch/x86/kvm/x86.c | 3 +++
1 file changed, 3 insertions(+)

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 6857257f3810..5430e4b0af29 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -6030,6 +6030,9 @@ void kvm_vcpu_reload_apic_access_page(struct kvm_vcpu *vcpu)
{
struct page *page = NULL;

+ if (!irqchip_in_kernel(vcpu->kvm))
+ return;
+
if (!kvm_x86_ops->set_apic_access_page_addr)
return;

--
1.8.3.1

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