File 5abcf445-x86-pv-fix-handing-of-writes-to-dr7.patch of Package xen

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File 5abcf445-x86-pv-fix-handing-of-writes-to-dr7.patch of Package xen (Revision 6cbe517c7c315868bcdc6e0dba24b72f)

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# Commit adf8feba1afa040f3a84a82953e18af02060884a
# Date 2018-03-29 15:12:21 +0100
# Author Andrew Cooper <andrew.cooper3@citrix.com>
# Committer Andrew Cooper <andrew.cooper3@citrix.com>
x86/pv: Fix the handing of writes to %dr7

c/s 65e35549 "x86/PV: support data breakpoint extension registers"
accidentally broke the handing of writes.  The call to activate_debugregs()
doesn't write %dr7 as v->arch.debugreg[7] hasn't been updated yet, and the
break skips the intended write to %dr7.

Remove the break, causing execution to hit the write_debugreg(7, value); in
context at the bottom of the hunk, which in turn causes hardware to be updated
appropriately.

Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>

--- a/xen/arch/x86/traps.c
+++ b/xen/arch/x86/traps.c
@@ -4223,14 +4223,11 @@ long set_debugreg(struct vcpu *v, unsign
             /*
              * If DR7 was previously clear then we need to load all other
              * debug registers at this point as they were not restored during
-             * context switch.
+             * context switch.  Updating DR7 itself happens later.
              */
             if ( (v == curr) &&
                  !(v->arch.debugreg[7] & DR7_ACTIVE_MASK) )
-            {
                 activate_debugregs(v);
-                break;
-            }
         }
         if ( v == curr )
             write_debugreg(7, value);

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File 5abcf445-x86-pv-fix-handing-of-writes-to-dr7.patch of Package xen (Revision 6cbe517c7c315868bcdc6e0dba24b72f)

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