Re: [Xen-devel] [PATCH 2/2] x86/HVM: re-order operations in hvm_ud_intercept()

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 09.06.16 at 13:34, <andrew.cooper3@xxxxxxxxxx> wrote:
> On 08/06/16 14:43, Jan Beulich wrote:
>> Don't fetch CS explicitly, leverage the fact that hvm_emulate_prepare()
>> already does (and that hvm_virtual_to_linear_addr() doesn't alter it).
>>
>> At once increase the length passed to hvm_virtual_to_linear_addr() by
>> one: There definitely needs to be at least one more opcode byte, and we
>> can avoid missing a wraparound case this way.
>>
>> Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
> 
> I looked into this when you suggested it, but it latches the wrong eip
> in the emulation state, and you will end up re-emulating the ud2a
> instruction, rather than the following instruction.

Where is there any latching of eip? All hvm_emulate_prepare() does
is storing the regs pointer.

Jan


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