On 02/11/18 13:45, Jan Beulich wrote:
>>>> On 02.11.18 at 14:08, <[email protected]> wrote:
>> On Mon, Oct 29, 2018 at 09:03:18AM -0600, Jan Beulich wrote:
>>>>>> On 19.10.18 at 16:28, <[email protected]> wrote:
>>>> @@ -548,10 +550,14 @@ ENTRY(ret_from_intr)
>>>>          GET_CURRENT(bx)
>>>>          testb $3, UREGS_cs(%rsp)
>>>>          jz    restore_all_xen
>>>> +#ifdef CONFIG_PV
>>>>          movq  VCPU_domain(%rbx), %rax
>>>>          cmpb  $0, DOMAIN_is_32bit_pv(%rax)
>>>>          je    test_all_events
>>>>          jmp   compat_test_all_events
>>>> +#else
>>>> +        BUG
>>>> +#endif
>>> Hmm, not sure here (and elsewhere): Another option is to
>>> streamline execution by replacing the conditional branch with an
>>> unconditional one in the !PV case. Andrew, do you have any
>>> thoughts either way?
>> My original thought was to catch potential issues in Xen code which
>> messes up with the permission level.  Using unconditional jump is fine
>> by me, too. But in that case I will seek to at least add an assertion
>> for debug build.
> Assertion additions are definitely fine with me.

Yeah - I'd also err on the side of an assertion and an unconditional jump.

~Andrew

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