Re: [Xen-devel] [PATCH for-4.9] Restore HVM_OP hypercall continuation

[George Dunlap <george.dunlap@xxxxxxxxxx>]

On Mon, Jun 5, 2017 at 12:20 PM, George Dunlap <george.dunlap@xxxxxxxxxx> wrote:
> On 05/06/17 12:18, George Dunlap wrote:
>> Commit ae20ccf removed the hypercall continuation logic from the end
>> of do_hvm_op(), claiming:
>>
>> "This patch removes the need for handling HVMOP restarts, so that
>> infrastructure is removed."
>>
>> That turns out to be only half true.  The removal of
>> HVMOP_set_mem_type removed the need to store a start iteration value
>> in the hypercall continuation, but a grep through hvm.c for ERESTART
>> turns up at least two places where do_hvm_op() may still need a
>> hypercall continuation:
>>
>>  * HVMOP_set_hvm_param can return -ERESTART when setting
>> HVM_PARAM_IDENT_PT in the event that it fails to acquire the domctl
>> lock
>>
>>  * HVMOP_flush_tlbs can return -ERESTART if several vcpus call it at
>>    the same time
>>
>> In both cases, a simple restart (with no stored iteration information)
>> is necessary.
>>
>> Add a check for -ERESTART again, along with a comment at the top of
>> the function regarding the lack of decoding any information from the
>> op value.
>>
>> Remove a stray blank line at the end of the file while we're here.
>>
>> Reported-by: Xudong Hao <xudong.hao@xxxxxxxxx>
>> Signed-off-by: George Dunlap <george.dunlap@xxxxxxxxxx>
>
> Oh, actually Andy and Julien both already acked this.  I'll check it in
> on staging and cherry-pick it to staging-4.9 unless I hear otherwise soon.

Either that, or I'll discover that it's already been checked in and I
didn't notice because I failed to merge origin/staging into staging.

Sorry for the noise everyone.

 -George

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