Re: [Xen-devel] [PATCH v3 8/9] viridian: add implementation of synthetic timers

[Wei Liu <wei.liu2@xxxxxxxxxx>]

On Thu, Jan 31, 2019 at 10:47:29AM +0000, Paul Durrant wrote:
> This patch introduces an implementation of the STIMER0-15_CONFIG/COUNT MSRs
> and hence a the first SynIC message source.
> 
> The new (and documented) 'stimer' viridian enlightenment group may be
> specified to enable this feature.
> 
> NOTE: It is necessary for correct operation that timer expiration and
>       message delivery time-stamping use the same time source as the guest.
>       The specification is ambiguous but testing with a Windows 10 1803
>       guest has shown that using the partition reference counter as a
>       source whilst the guest is using RDTSC and the reference tsc page
>       does not work correctly. Therefore the time_now() function is used.
>       This implements the algorithm for acquiring partition reference time
>       that is documented in the specifiction. This requires use of 128-bit
>       arithmetic and hence __int128_t values are used in the calculation,
>       although the result is a signed 64-bit value.
> 
> Signed-off-by: Paul Durrant <paul.durrant@xxxxxxxxxx>
> ---
> Cc: Ian Jackson <ian.jackson@xxxxxxxxxxxxx>
> Cc: Wei Liu <wei.liu2@xxxxxxxxxx>
> Cc: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
> Cc: George Dunlap <George.Dunlap@xxxxxxxxxxxxx>
> Cc: Jan Beulich <jbeulich@xxxxxxxx>
> Cc: Julien Grall <julien.grall@xxxxxxx>
> Cc: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
> Cc: Stefano Stabellini <sstabellini@xxxxxxxxxx>
> Cc: Tim Deegan <tim@xxxxxxx>
> Cc: "Roger Pau Monné" <roger.pau@xxxxxxxxxx>
> 
> v3:
>  - Re-worked missed ticks calculation
> ---
>  docs/man/xl.cfg.5.pod.in               |  12 +-
>  tools/libxl/libxl.h                    |   6 +
>  tools/libxl/libxl_dom.c                |   4 +
>  tools/libxl/libxl_types.idl            |   1 +

Acked-by: Wei Liu <wei.liu2@xxxxxxxxxx>

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