* [PATCH] x86/HVM: correct segment register loading during task switch
@ 2016-09-23 10:09 Jan Beulich
2016-09-26 14:09 ` Andrew Cooper
0 siblings, 1 reply; 2+ messages in thread
From: Jan Beulich @ 2016-09-23 10:09 UTC (permalink / raw)
To: xen-devel; +Cc: Andrew Cooper
[-- Attachment #1: Type: text/plain, Size: 1098 bytes --]
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 <jbeulich@suse.com>
---
This basically mirrors
https://lists.xenproject.org/archives/html/xen-devel/2016-09/msg02198.html
taking into account that there's no 64-bit mode case here.
--- 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;
}
[-- Attachment #2: x86-HVM-task-switch-seg.patch --]
[-- Type: text/plain, Size: 1155 bytes --]
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 <jbeulich@suse.com>
---
This basically mirrors
https://lists.xenproject.org/archives/html/xen-devel/2016-09/msg02198.html
taking into account that there's no 64-bit mode case here.
--- 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;
}
[-- Attachment #3: Type: text/plain, Size: 127 bytes --]
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^ permalink raw reply [flat|nested] 2+ messages in thread
* Re: [PATCH] x86/HVM: correct segment register loading during task switch
2016-09-23 10:09 [PATCH] x86/HVM: correct segment register loading during task switch Jan Beulich
@ 2016-09-26 14:09 ` Andrew Cooper
0 siblings, 0 replies; 2+ messages in thread
From: Andrew Cooper @ 2016-09-26 14:09 UTC (permalink / raw)
To: Jan Beulich, xen-devel
On 23/09/16 11:09, Jan Beulich wrote:
> 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 <jbeulich@suse.com>
Reviewed-by: Andrew Cooper <andrew.cooper3@citrix.com>
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