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Jan Beulich
81d3a0b26c
All branches need to #GP when their target violates the segment limit (in 16- and 32-bit modes) or is non-canonical (in 64-bit mode). For near branches facilitate this via a zero-byte instruction fetch from the target address (resulting in address translation and validation without an actual read from memory), while far branches get dealt with by breaking up the segment register loading into a read-and-validate part and a write one. The latter at once allows correcting some ordering issues in how the individual emulation steps get carried out: Before updating machine state, all exceptions unrelated to that state updating should have got raised (i.e. the only ones possibly resulting in partly updated state are faulting memory writes [pushes]). Note that while not immediately needed here, write and distinct read emulation routines get updated to deal with zero byte accesses too, for overall consistency. Reported-by: 刘令 <liuling-it@360.cn> Signed-off-by: Jan Beulich <jbeulich@suse.com> Reviewed-by: Andrew Cooper <andrew.cooper3@citrix.com> Acked-by: Tim Deegan <tim@xen.org>