[Xen-changelog] [xen stable-4.6] x86/pv: Fix bugs with the handling of int80_bounce

[patchbot@xxxxxxx]

commit ff3f674fa25116f68f24ae43ed2f44ed86d8ca71
Author:     Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
AuthorDate: Fri Jun 9 13:56:40 2017 +0200
Commit:     Jan Beulich <jbeulich@xxxxxxxx>
CommitDate: Fri Jun 9 13:56:40 2017 +0200

    x86/pv: Fix bugs with the handling of int80_bounce
    
    Testing has revealed two issues:
    
     1) Passing a NULL handle to set_trap_table() is intended to flush the 
entire
        table.  The 64bit guest case (and 32bit guest on 32bit Xen, when it
        existed) called init_int80_direct_trap() to reset int80_bounce, but c/s
        cda335c279 which introduced the 32bit guest on 64bit Xen support omitted
        this step.  Previously therefore, it was impossible for a 32bit guest to
        reset its registered int80_bounce details.
    
     2) init_int80_direct_trap() doesn't honour the guests request to have
        interrupts disabled on entry.  PVops Linux requests that interrupts are
        disabled, but Xen currently leaves them enabled when following the int80
        fastpath.
    
    Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
    Reviewed-by: Jan Beulich <jbeulich@xxxxxxxx>
    master commit: 55ab172a1f286742d918947ecb9b257ce31cc253
    master date: 2017-05-09 19:00:04 +0100
---
 xen/arch/x86/x86_64/compat/traps.c | 1 +
 xen/arch/x86/x86_64/traps.c        | 3 ++-
 2 files changed, 3 insertions(+), 1 deletion(-)

diff --git a/xen/arch/x86/x86_64/compat/traps.c 
b/xen/arch/x86/x86_64/compat/traps.c
index 2dae0c7..5945f98 100644
--- a/xen/arch/x86/x86_64/compat/traps.c
+++ b/xen/arch/x86/x86_64/compat/traps.c
@@ -324,6 +324,7 @@ int 
compat_set_trap_table(XEN_GUEST_HANDLE(trap_info_compat_t) traps)
     if ( guest_handle_is_null(traps) )
     {
         memset(dst, 0, NR_VECTORS * sizeof(*dst));
+        init_int80_direct_trap(current);
         return 0;
     }
 
diff --git a/xen/arch/x86/x86_64/traps.c b/xen/arch/x86/x86_64/traps.c
index 0846a19..e8d3ba9 100644
--- a/xen/arch/x86/x86_64/traps.c
+++ b/xen/arch/x86/x86_64/traps.c
@@ -420,12 +420,13 @@ void init_int80_direct_trap(struct vcpu *v)
     struct trap_info *ti = &v->arch.pv_vcpu.trap_ctxt[0x80];
     struct trap_bounce *tb = &v->arch.pv_vcpu.int80_bounce;
 
-    tb->flags = TBF_EXCEPTION;
     tb->cs    = ti->cs;
     tb->eip   = ti->address;
 
     if ( null_trap_bounce(v, tb) )
         tb->flags = 0;
+    else
+        tb->flags = TBF_EXCEPTION | (TI_GET_IF(ti) ? TBF_INTERRUPT : 0);
 }
 
 static long register_guest_callback(struct callback_register *reg)
--
generated by git-patchbot for /home/xen/git/xen.git#stable-4.6

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