[Xen-changelog] [xen stable-4.5] x86: don't clear high 32 bits of RAX on sub-word guest I/O port reads

[patchbot@xxxxxxx]

commit bf30232bf17ad2cdf55d50a98759ee45c0ad00e0
Author:     Jan Beulich <jbeulich@xxxxxxxx>
AuthorDate: Tue May 19 11:47:13 2015 +0200
Commit:     Jan Beulich <jbeulich@xxxxxxxx>
CommitDate: Tue May 19 11:47:13 2015 +0200

    x86: don't clear high 32 bits of RAX on sub-word guest I/O port reads
    
    1- or 2-byte operations never alter the high halves of registers.
    
    Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
    Reviewed-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
    master commit: 1191aa9d1988c469844eb4545689617a8b13eae1
    master date: 2015-05-11 10:37:58 +0200
---
 xen/arch/x86/traps.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/xen/arch/x86/traps.c b/xen/arch/x86/traps.c
index 61316ba..c037b00 100644
--- a/xen/arch/x86/traps.c
+++ b/xen/arch/x86/traps.c
@@ -2174,7 +2174,7 @@ static int emulate_privileged_op(struct cpu_user_regs 
*regs)
             if ( op_bytes == 4 )
                 regs->eax = 0;
             else
-                regs->eax &= ~((1u << (op_bytes * 8)) - 1);
+                regs->eax &= ~((1 << (op_bytes * 8)) - 1);
             regs->eax |= guest_io_read(port, op_bytes, v, regs);
         }
         bpmatch = check_guest_io_breakpoint(v, port, op_bytes);
--
generated by git-patchbot for /home/xen/git/xen.git#stable-4.5

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