• Asias He's avatar
    KVM: Fix kvm_irqfd_init initialization · 7dac16c3
    Asias He authored
    In commit a0f155e9
    
     'KVM: Initialize irqfd from kvm_init()', when
    kvm_init() is called the second time (e.g kvm-amd.ko and kvm-intel.ko),
    kvm_arch_init() will fail with -EEXIST, then kvm_irqfd_exit() will be
    called on the error handling path. This way, the kvm_irqfd system will
    not be ready.
    
    This patch fix the following:
    
    BUG: unable to handle kernel NULL pointer dereference at           (null)
    IP: [<ffffffff81c0721e>] _raw_spin_lock+0xe/0x30
    PGD 0
    Oops: 0002 [#1] SMP
    Modules linked in: vhost_net
    CPU 6
    Pid: 4257, comm: qemu-system-x86 Not tainted 3.9.0-rc3+ #757 Dell Inc. OptiPlex 790/0V5HMK
    RIP: 0010:[<ffffffff81c0721e>]  [<ffffffff81c0721e>] _raw_spin_lock+0xe/0x30
    RSP: 0018:ffff880221721cc8  EFLAGS: 00010046
    RAX: 0000000000000100 RBX: ffff88022dcc003f RCX: ffff880221734950
    RDX: ffff8802208f6ca8 RSI: 000000007fffffff RDI: 0000000000000000
    RBP: ffff880221721cc8 R08: 0000000000000002 R09: 0000000000000002
    R10: 00007f7fd01087e0 R11: 0000000000000246 R12: ffff8802208f6ca8
    R13: 0000000000000080 R14: ffff880223e2a900 R15: 0000000000000000
    FS:  00007f7fd38488e0(0000) GS:ffff88022dcc0000(0000) knlGS:0000000000000000
    CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
    CR2: 0000000000000000 CR3: 000000022309f000 CR4: 00000000000427e0
    DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
    DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
    Process qemu-system-x86 (pid: 4257, threadinfo ffff880221720000, task ffff880222bd5640)
    Stack:
     ffff880221721d08 ffffffff810ac5c5 ffff88022431dc00 0000000000000086
     0000000000000080 ffff880223e2a900 ffff8802208f6ca8 0000000000000000
     ffff880221721d48 ffffffff810ac8fe 0000000000000000 ffff880221734000
    Call Trace:
     [<ffffffff810ac5c5>] __queue_work+0x45/0x2d0
     [<ffffffff810ac8fe>] queue_work_on+0x8e/0xa0
     [<ffffffff810ac949>] queue_work+0x19/0x20
     [<ffffffff81009b6b>] irqfd_deactivate+0x4b/0x60
     [<ffffffff8100a69d>] kvm_irqfd+0x39d/0x580
     [<ffffffff81007a27>] kvm_vm_ioctl+0x207/0x5b0
     [<ffffffff810c9545>] ? update_curr+0xf5/0x180
     [<ffffffff811b66e8>] do_vfs_ioctl+0x98/0x550
     [<ffffffff810c1f5e>] ? finish_task_switch+0x4e/0xe0
     [<ffffffff81c054aa>] ? __schedule+0x2ea/0x710
     [<ffffffff811b6bf7>] sys_ioctl+0x57/0x90
     [<ffffffff8140ae9e>] ? trace_hardirqs_on_thunk+0x3a/0x3c
     [<ffffffff81c0f602>] system_call_fastpath+0x16/0x1b
    Code: c1 ea 08 38 c2 74 0f 66 0f 1f 44 00 00 f3 90 0f b6 03 38 c2 75 f7 48 83 c4 08 5b c9 c3 55 48 89 e5 66 66 66 66 90 b8 00 01 00 00 <f0> 66 0f c1 07 89 c2 66 c1 ea 08 38 c2 74 0c 0f 1f 00 f3 90 0f
    RIP  [<ffffffff81c0721e>] _raw_spin_lock+0xe/0x30
    RSP <ffff880221721cc8>
    CR2: 0000000000000000
    ---[ end trace 13fb1e4b6e5ab21f ]---
    
    Signed-off-by: default avatarAsias He <asias@redhat.com>
    Acked-by: default avatarCornelia Huck <cornelia.huck@de.ibm.com>
    Signed-off-by: default avatarGleb Natapov <gleb@redhat.com>
    7dac16c3