[xen stable-4.8] x86/emul: Fix backport of "x86/emul: Fix the decoding of segment overrides in 64bit mode"
Author: Andrew Cooper <[hidden email]>
AuthorDate: Mon Apr 9 12:23:48 2018 +0200
Commit: Jan Beulich <[hidden email]>
CommitDate: Mon Apr 9 12:23:48 2018 +0200
x86/emul: Fix backport of "x86/emul: Fix the decoding of segment overrides in 64bit mode"
The logic in c/s b7dce29d is correct for master, but depends on c/s 216c29765
"x86emul: don't assume a memory operand", and in particular changed the type
of override_seg and the constant used to signify "no override".
When backported, the "no override in place" case causes x86_seg_none to be
used in place of x86_seg_ds, which has implications for the correctness of
emulated memory reads and writes.
Problems from this manifest as a reliable failure to boot shadow guests in the
(d3) [15145.989017] Press F12 for boot menu.
(d3) [15146.000273] Boot device: CD-Rom5814MB medium detected
(d3) [15146.013234] - success.
(XEN) [15146.324244] paging.c:694:d0v3 Tried to do a paging op on itself.
(XEN) [15204.719457] sh error: sh_remove_shadows(): can't find all shadows of mfn 112cd54 (shadow_flags=00002000)
(XEN) [15204.719462] domain_crash called from common.c:2884
(XEN) [15204.719466] Domain 3 (vcpu#0) crashed on cpu#31:
Other problems with regular MMIO emulation haven't been observed, but
shouldn't be ruled out.
Signed-off-by: Andrew Cooper <[hidden email]>
Reviewed-by: Jan Beulich <[hidden email]>
xen/arch/x86/x86_emulate/x86_emulate.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)