[Xen-changelog] [xen master] x86/PVH: only set accessed/busy bits for present segments

[patchbot@xxxxxxx]

commit 7d953e82632229ca1de8df5ede76d391b04645f8
Author:     Jan Beulich <jbeulich@xxxxxxxx>
AuthorDate: Tue Jan 24 12:36:30 2017 +0100
Commit:     Jan Beulich <jbeulich@xxxxxxxx>
CommitDate: Tue Jan 24 12:36:30 2017 +0100

    x86/PVH: only set accessed/busy bits for present segments
    
    Commit 366ff5f1b3 ("x86: segment attribute handling adjustments" went a
    little too far: We must not do such adjustments for non-present segments.
    
    Reported-by: Roger Pau Monné <roger.pau@xxxxxxxxxx>
    Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
    Reviewed-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
    Reviewed-by: Roger Pau Monné <roger.pau@xxxxxxxxxx>
    Tested-by: Roger Pau Monné <roger.pau@xxxxxxxxxx>
---
 xen/arch/x86/domain.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/xen/arch/x86/domain.c b/xen/arch/x86/domain.c
index 5a4e7f9..71c0e3c 100644
--- a/xen/arch/x86/domain.c
+++ b/xen/arch/x86/domain.c
@@ -1374,8 +1374,10 @@ int arch_set_info_hvm_guest(struct vcpu *v, const 
vcpu_hvm_context_t *ctx)
 #define SEG(s, r) ({                                                        \
     s = (struct segment_register){ .base = (r)->s ## _base,                 \
                                    .limit = (r)->s ## _limit,               \
-                                   .attr.bytes = (r)->s ## _ar |            \
-                                       (x86_seg_##s != x86_seg_tr ? 1 : 2) }; \
+                                   .attr.bytes = (r)->s ## _ar };           \
+    /* Set accessed / busy bit for present segments. */                     \
+    if ( s.attr.fields.p )                                                  \
+        s.attr.fields.type |= (x86_seg_##s != x86_seg_tr ? 1 : 2);          \
     check_segment(&s, x86_seg_ ## s); })
 
         rc = SEG(cs, regs);
--
generated by git-patchbot for /home/xen/git/xen.git#master

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