Re: [PATCH] x86/vtsc: update vcpu_time after hvm_set_guest_time

[George Dunlap <george.dunlap@eu.citrix.com>]

On 06/04/2013 11:24 AM, Alex Bligh wrote:
> Roger,
>
> --On 4 June 2013 11:10:50 +0200 Roger Pau Monne <roger.pau@citrix.com>
> wrote:
>
>> When using a vtsc, hvm_set_guest_time changes hvm_vcpu.stime_offset,
>> which is used in the vcpu time structure to calculate the
>> tsc_timestamp, so after updating stime_offset we need to propagate the
>> change to vcpu_time in order for the guest to get the right time if
>> using the PV clock.
>>
>> This was not done correctly, since in context_switch
>> update_vcpu_system_time was called before vmx_do_resume, which caused
>> the vcpu_info time structure to be updated with the wrong values. This
>> patch fixes this by calling update_vcpu_system_time after the call to
>> hvm_set_guest_time has happened.
>
> I think this is the 'proper' fix to the bug Diana reported about
> stuck clock - can you confirm? If so, we're happy to test this on
> 4.3 and/or do try our hand at a backport to 4.2.

Yes, and I was going to reply cc'ing you and Diana, but we're still 
having a technical discussion about where the best place is to put the 
fix.  You may wish to wait until we have that resolved before testing 
the patch.

  -George