From: Xiao Guangrong Date: Tue, 8 Jun 2010 02:15:51 +0000 (+0800) Subject: KVM: VMX: fix rcu usage warning in init_rmode() X-Git-Tag: firefly_0821_release~9833^2~1315^2~101 X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=4b9d3a04519fb508ad3b7ce8a7962929b2614185;p=firefly-linux-kernel-4.4.55.git KVM: VMX: fix rcu usage warning in init_rmode() fix: [ INFO: suspicious rcu_dereference_check() usage. ] --------------------------------------------------- include/linux/kvm_host.h:258 invoked rcu_dereference_check() without protection! other info that might help us debug this: rcu_scheduler_active = 1, debug_locks = 1 1 lock held by qemu-system-x86/3796: #0: (&vcpu->mutex){+.+.+.}, at: [] vcpu_load+0x1a/0x66 [kvm] stack backtrace: Pid: 3796, comm: qemu-system-x86 Not tainted 2.6.34 #25 Call Trace: [] lockdep_rcu_dereference+0x9d/0xa5 [] gfn_to_memslot_unaliased+0x65/0xa0 [kvm] [] gfn_to_hva+0x22/0x4c [kvm] [] kvm_write_guest_page+0x2a/0x7f [kvm] [] kvm_clear_guest_page+0x1a/0x1c [kvm] [] init_rmode+0x3b/0x180 [kvm_intel] [] vmx_set_cr0+0x350/0x4d3 [kvm_intel] [] kvm_arch_vcpu_ioctl_set_sregs+0x122/0x31a [kvm] [] kvm_vcpu_ioctl+0x578/0xa3d [kvm] [] ? cpu_clock+0x2d/0x40 [] ? fget_light+0x244/0x28e [] ? trace_hardirqs_off_caller+0x1f/0x10e [] vfs_ioctl+0x32/0xa6 [] do_vfs_ioctl+0x47f/0x4b8 [] ? sub_preempt_count+0xa3/0xb7 [] ? fget_light+0x266/0x28e [] ? fget_light+0x111/0x28e [] sys_ioctl+0x47/0x6a [] system_call_fastpath+0x16/0x1b Signed-off-by: Xiao Guangrong Signed-off-by: Avi Kivity --- diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c index 7d7361750bf2..01b054c98139 100644 --- a/arch/x86/kvm/vmx.c +++ b/arch/x86/kvm/vmx.c @@ -2659,21 +2659,27 @@ static int vmx_vcpu_setup(struct vcpu_vmx *vmx) static int init_rmode(struct kvm *kvm) { + int idx, ret = 0; + + idx = srcu_read_lock(&kvm->srcu); if (!init_rmode_tss(kvm)) - return 0; + goto exit; if (!init_rmode_identity_map(kvm)) - return 0; - return 1; + goto exit; + + ret = 1; +exit: + srcu_read_unlock(&kvm->srcu, idx); + return ret; } static int vmx_vcpu_reset(struct kvm_vcpu *vcpu) { struct vcpu_vmx *vmx = to_vmx(vcpu); u64 msr; - int ret, idx; + int ret; vcpu->arch.regs_avail = ~((1 << VCPU_REGS_RIP) | (1 << VCPU_REGS_RSP)); - idx = srcu_read_lock(&vcpu->kvm->srcu); if (!init_rmode(vmx->vcpu.kvm)) { ret = -ENOMEM; goto out; @@ -2783,7 +2789,6 @@ static int vmx_vcpu_reset(struct kvm_vcpu *vcpu) vmx->emulation_required = 0; out: - srcu_read_unlock(&vcpu->kvm->srcu, idx); return ret; }