From bdb860d01cac7bcbaebbdce29ae9e9c7e9582d03 Mon Sep 17 00:00:00 2001 From: Jan Beulich Date: Mon, 26 Sep 2016 17:27:34 +0200 Subject: [PATCH] x86/HVM: correct segment register loading during task switch Instead of #NP, #SS needs to be raised for a non-present %ss descriptor. Don't lose the low two selector bits on null selector loads. Signed-off-by: Jan Beulich Reviewed-by: Andrew Cooper --- xen/arch/x86/hvm/hvm.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/xen/arch/x86/hvm/hvm.c b/xen/arch/x86/hvm/hvm.c index 7bad845306..73730d1fe0 100644 --- a/xen/arch/x86/hvm/hvm.c +++ b/xen/arch/x86/hvm/hvm.c @@ -2723,6 +2723,7 @@ static int hvm_load_segment_selector( if ( (seg == x86_seg_cs) || (seg == x86_seg_ss) ) goto fail; memset(&segr, 0, sizeof(segr)); + segr.sel = sel; hvm_set_segment_register(v, seg, &segr); return 0; } @@ -2749,7 +2750,8 @@ static int hvm_load_segment_selector( /* Segment present in memory? */ if ( !(desc.b & _SEGMENT_P) ) { - fault_type = TRAP_no_segment; + fault_type = (seg != x86_seg_ss) ? TRAP_no_segment + : TRAP_stack_error; goto unmap_and_fail; } -- 2.30.2