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    Subject[129/139] KVM: VMX: Update instruction length on intercepted BP
    2.6.33-stable review patch.  If anyone has any objections, please let us know.

    ------------------

    From: Jan Kiszka <jan.kiszka@siemens.com>

    (Cherry-picked from commit c573cd22939e54fc1b8e672054a505048987a7cb)

    We intercept #BP while in guest debugging mode. As VM exits due to
    intercepted exceptions do not necessarily come with valid
    idt_vectoring, we have to update event_exit_inst_len explicitly in such
    cases. At least in the absence of migration, this ensures that
    re-injections of #BP will find and use the correct instruction length.

    Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
    Signed-off-by: Avi Kivity <avi@redhat.com>
    Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

    ---
    arch/x86/kvm/vmx.c | 13 +++++++++++++
    1 file changed, 13 insertions(+)

    --- a/arch/x86/kvm/vmx.c
    +++ b/arch/x86/kvm/vmx.c
    @@ -2719,6 +2719,12 @@ static int handle_rmode_exception(struct
    kvm_queue_exception(vcpu, vec);
    return 1;
    case BP_VECTOR:
    + /*
    + * Update instruction length as we may reinject the exception
    + * from user space while in guest debugging mode.
    + */
    + to_vmx(vcpu)->vcpu.arch.event_exit_inst_len =
    + vmcs_read32(VM_EXIT_INSTRUCTION_LEN);
    if (vcpu->guest_debug & KVM_GUESTDBG_USE_SW_BP)
    return 0;
    /* fall through */
    @@ -2841,6 +2847,13 @@ static int handle_exception(struct kvm_v
    kvm_run->debug.arch.dr7 = vmcs_readl(GUEST_DR7);
    /* fall through */
    case BP_VECTOR:
    + /*
    + * Update instruction length as we may reinject #BP from
    + * user space while in guest debugging mode. Reading it for
    + * #DB as well causes no harm, it is not used in that case.
    + */
    + vmx->vcpu.arch.event_exit_inst_len =
    + vmcs_read32(VM_EXIT_INSTRUCTION_LEN);
    kvm_run->exit_reason = KVM_EXIT_DEBUG;
    kvm_run->debug.arch.pc = vmcs_readl(GUEST_CS_BASE) + rip;
    kvm_run->debug.arch.exception = ex_no;



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