https://bugzilla.kernel.org/show_bug.cgi?id=103141

Wanpeng Li <wanpeng...@hotmail.com> changed:

           What    |Removed                     |Added
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                 CC|                            |wanpeng...@hotmail.com

--- Comment #1 from Wanpeng Li <wanpeng...@hotmail.com> ---
The below commit can fix it.

commit 370777daab3f024f1645177039955088e2e9ae73
Author: Radim Krčmář <rkrc...@redhat.com>
Date:   Fri Jul 3 15:49:28 2015 +0200

    KVM: VMX: fix vmwrite to invalid VMCS

    fpu_activate is called outside of vcpu_load(), which means it should not
    touch VMCS, but fpu_activate needs to.  Avoid the call by moving it to a
    point where we know that the guest needs eager FPU and VMCS is loaded.

    This will get rid of the following trace

     vmwrite error: reg 6800 value 0 (err 1)
      [<ffffffff8162035b>] dump_stack+0x19/0x1b
      [<ffffffffa046c701>] vmwrite_error+0x2c/0x2e [kvm_intel]
      [<ffffffffa045f26f>] vmcs_writel+0x1f/0x30 [kvm_intel]
      [<ffffffffa04617e5>] vmx_fpu_activate.part.61+0x45/0xb0 [kvm_intel]
      [<ffffffffa0461865>] vmx_fpu_activate+0x15/0x20 [kvm_intel]
      [<ffffffffa0560b91>] kvm_arch_vcpu_create+0x51/0x70 [kvm]
      [<ffffffffa0548011>] kvm_vm_ioctl+0x1c1/0x760 [kvm]
      [<ffffffff8118b55a>] ? handle_mm_fault+0x49a/0xec0
      [<ffffffff811e47d5>] do_vfs_ioctl+0x2e5/0x4c0
      [<ffffffff8127abbe>] ? file_has_perm+0xae/0xc0
      [<ffffffff811e4a51>] SyS_ioctl+0xa1/0xc0
      [<ffffffff81630949>] system_call_fastpath+0x16/0x1b

    (Note: we also unconditionally activate FPU in vmx_vcpu_reset(), so the
     removed code added nothing.)

    Fixes: c447e76b4cab ("kvm/fpu: Enable eager restore kvm FPU for MPX")
    Cc: <sta...@vger.kernel.org>
    Reported-by: Vlastimil Holer <vlastimil.ho...@gmail.com>
    Signed-off-by: Radim Krčmář <rkrc...@redhat.com>
    Signed-off-by: Paolo Bonzini <pbonz...@redhat.com>

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