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    Subject[59/80] KVM: VMX: Fix host GDT.LIMIT corruption
    2.6.35-stable review patch.  If anyone has any objections, please let us know.

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


    From: Avi Kivity <avi@redhat.com>

    commit 3444d7da1839b851eefedd372978d8a982316c36 upstream.

    vmx does not restore GDT.LIMIT to the host value, instead it sets it to 64KB.
    This means host userspace can learn a few bits of host memory.

    Fix by reloading GDTR when we load other host state.

    Signed-off-by: Avi Kivity <avi@redhat.com>
    Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
    Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
    ---
    arch/x86/kvm/vmx.c | 4 ++++
    1 file changed, 4 insertions(+)

    --- a/arch/x86/kvm/vmx.c
    +++ b/arch/x86/kvm/vmx.c
    @@ -177,6 +177,7 @@ static u64 construct_eptp(unsigned long
    static DEFINE_PER_CPU(struct vmcs *, vmxarea);
    static DEFINE_PER_CPU(struct vmcs *, current_vmcs);
    static DEFINE_PER_CPU(struct list_head, vcpus_on_cpu);
    +static DEFINE_PER_CPU(struct desc_ptr, host_gdt);

    static unsigned long *vmx_io_bitmap_a;
    static unsigned long *vmx_io_bitmap_b;
    @@ -812,6 +813,7 @@ static void __vmx_load_host_state(struct
    wrmsrl(MSR_KERNEL_GS_BASE, vmx->msr_host_kernel_gs_base);
    }
    #endif
    + load_gdt(&__get_cpu_var(host_gdt));
    }

    static void vmx_load_host_state(struct vcpu_vmx *vmx)
    @@ -1314,6 +1316,8 @@ static int hardware_enable(void *garbage

    ept_sync_global();

    + store_gdt(&__get_cpu_var(host_gdt));
    +
    return 0;
    }




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