3.10-stable review patch. If anyone has any objections, please let me know.
------------------ From: Gleb Natapov <[email protected]> commit 03617c188f41eeeb4223c919ee7e66e5a114f2c6 upstream. Some userspaces do not preserve unusable property. Since usable segment has to be present according to VMX spec we can use present property to amend userspace bug by making unusable segment always nonpresent. vmx_segment_access_rights() already marks nonpresent segment as unusable. Reported-by: Stefan Pietsch <[email protected]> Tested-by: Stefan Pietsch <[email protected]> Signed-off-by: Gleb Natapov <[email protected]> Signed-off-by: Paolo Bonzini <[email protected]> Signed-off-by: Greg Kroah-Hartman <[email protected]> --- arch/x86/kvm/vmx.c | 11 +++++++++-- 1 file changed, 9 insertions(+), 2 deletions(-) --- a/arch/x86/kvm/vmx.c +++ b/arch/x86/kvm/vmx.c @@ -3399,15 +3399,22 @@ static void vmx_get_segment(struct kvm_v var->limit = vmx_read_guest_seg_limit(vmx, seg); var->selector = vmx_read_guest_seg_selector(vmx, seg); ar = vmx_read_guest_seg_ar(vmx, seg); + var->unusable = (ar >> 16) & 1; var->type = ar & 15; var->s = (ar >> 4) & 1; var->dpl = (ar >> 5) & 3; - var->present = (ar >> 7) & 1; + /* + * Some userspaces do not preserve unusable property. Since usable + * segment has to be present according to VMX spec we can use present + * property to amend userspace bug by making unusable segment always + * nonpresent. vmx_segment_access_rights() already marks nonpresent + * segment as unusable. + */ + var->present = !var->unusable; var->avl = (ar >> 12) & 1; var->l = (ar >> 13) & 1; var->db = (ar >> 14) & 1; var->g = (ar >> 15) & 1; - var->unusable = (ar >> 16) & 1; } static u64 vmx_get_segment_base(struct kvm_vcpu *vcpu, int seg) -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
