On Wed, 8 May 2013 10:57:29 +0800 Asias He <[email protected]> wrote:
> In commit a0f155e96 '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: Asias He <[email protected]> Acked-by: Cornelia Huck <[email protected]> > --- > virt/kvm/kvm_main.c | 18 +++++++++++++----- > 1 file changed, 13 insertions(+), 5 deletions(-) > > diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c > index 8fd325a..85b93d2 100644 > --- a/virt/kvm/kvm_main.c > +++ b/virt/kvm/kvm_main.c > @@ -3078,13 +3078,21 @@ int kvm_init(void *opaque, unsigned vcpu_size, > unsigned vcpu_align, > int r; > int cpu; > > - r = kvm_irqfd_init(); > - if (r) > - goto out_irqfd; > r = kvm_arch_init(opaque); > if (r) > goto out_fail; > > + /* > + * kvm_arch_init makes sure there's at most one caller > + * for architectures that support multiple implementations, > + * like intel and amd on x86. > + * kvm_arch_init must be called before kvm_irqfd_init to avoid creating > + * conflicts in case kvm is already setup for another implementation. > + */ > + r = kvm_irqfd_init(); > + if (r) > + goto out_irqfd; > + > if (!zalloc_cpumask_var(&cpus_hardware_enabled, GFP_KERNEL)) { > r = -ENOMEM; > goto out_free_0; > @@ -3159,10 +3167,10 @@ out_free_1: > out_free_0a: > free_cpumask_var(cpus_hardware_enabled); > out_free_0: > - kvm_arch_exit(); > -out_fail: > kvm_irqfd_exit(); > out_irqfd: > + kvm_arch_exit(); > +out_fail: > return r; > } > EXPORT_SYMBOL_GPL(kvm_init); _______________________________________________ Virtualization mailing list [email protected] https://lists.linuxfoundation.org/mailman/listinfo/virtualization
