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SubjectRe: [PATCH 4/4] KVM: nVMX: Fix using __this_cpu_read() in preemptible context
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On 17/05/19 10:49, Wanpeng Li wrote:
> From: Wanpeng Li <wanpengli@tencent.com>
>
> BUG: using __this_cpu_read() in preemptible [00000000] code: qemu-system-x86/4590
> caller is nested_vmx_enter_non_root_mode+0xebd/0x1790 [kvm_intel]
> CPU: 4 PID: 4590 Comm: qemu-system-x86 Tainted: G OE 5.1.0-rc4+ #1
> Call Trace:
> dump_stack+0x67/0x95
> __this_cpu_preempt_check+0xd2/0xe0
> nested_vmx_enter_non_root_mode+0xebd/0x1790 [kvm_intel]
> nested_vmx_run+0xda/0x2b0 [kvm_intel]
> handle_vmlaunch+0x13/0x20 [kvm_intel]
> vmx_handle_exit+0xbd/0x660 [kvm_intel]
> kvm_arch_vcpu_ioctl_run+0xa2c/0x1e50 [kvm]
> kvm_vcpu_ioctl+0x3ad/0x6d0 [kvm]
> do_vfs_ioctl+0xa5/0x6e0
> ksys_ioctl+0x6d/0x80
> __x64_sys_ioctl+0x1a/0x20
> do_syscall_64+0x6f/0x6c0
> entry_SYSCALL_64_after_hwframe+0x49/0xbe
>
> Accessing per-cpu variable should disable preemption, this patch extends the
> preemption disable region for __this_cpu_read().
>
> Cc: Paolo Bonzini <pbonzini@redhat.com>
> Cc: Radim Krčmář <rkrcmar@redhat.com>
> Signed-off-by: Wanpeng Li <wanpengli@tencent.com>
> ---
> arch/x86/kvm/vmx/nested.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c
> index 0c601d0..8f6f69c 100644
> --- a/arch/x86/kvm/vmx/nested.c
> +++ b/arch/x86/kvm/vmx/nested.c
> @@ -2792,14 +2792,13 @@ static int nested_vmx_check_vmentry_hw(struct kvm_vcpu *vcpu)
> : "cc", "memory"
> );
>
> - preempt_enable();
> -
> if (vmx->msr_autoload.host.nr)
> vmcs_write32(VM_EXIT_MSR_LOAD_COUNT, vmx->msr_autoload.host.nr);
> if (vmx->msr_autoload.guest.nr)
> vmcs_write32(VM_ENTRY_MSR_LOAD_COUNT, vmx->msr_autoload.guest.nr);
>
> if (vm_fail) {
> + preempt_enable();
> WARN_ON_ONCE(vmcs_read32(VM_INSTRUCTION_ERROR) !=
> VMXERR_ENTRY_INVALID_CONTROL_FIELD);
> return 1;
> @@ -2811,6 +2810,7 @@ static int nested_vmx_check_vmentry_hw(struct kvm_vcpu *vcpu)
> local_irq_enable();
> if (hw_breakpoint_active())
> set_debugreg(__this_cpu_read(cpu_dr7), 7);
> + preempt_enable();
>
> /*
> * A non-failing VMEntry means we somehow entered guest mode with
>


Queued, thanks.

Paolo

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