Re: [PATCH v3 10/11] x86/vpt: remove vPT timers per-vCPU lists

[Jan Beulich <jbeulich@suse.com>]

On 31.03.2021 12:33, Roger Pau Monne wrote:
> No longer add vPT timers to lists on specific vCPUs, since there's no
> need anymore to check if timer interrupts have been injected on return
> to HVM guest.
> 
> Such change allows to get rid of virtual timers vCPU migration, and
> also cleanup some of the virtual timers fields that are no longer
> required.
> 
> The model is also slightly different now in that timers are not
> stopped when a vCPU is de-scheduled. Such timers will continue
> running, and when triggered the function will try to inject the
> corresponding interrupt to the guest (which might be different than
> the currently running one). Note that the timer triggering when the
> guest is no longer running can only happen once, as the timer callback
> will not reset the interrupt to fire again. Such resetting if required
> will be done by the EOI callback.
> 
> Since virtual timers are no longer added to per-VCPU lists when active
> a new 'masked' field is added to the structure, to signal whether a
> timer has it's interrupt source currently masked.

I guess this paragraph has become stale with ...

> Signed-off-by: Roger Pau Monné <roger.pau@citrix.com>
> ---
> Changes since v2:
>  - Remove pt_{save/restore}_timer and instead use
>    pt_{freeze/thaw}_time.
>  - Remove the introduction of the 'masked' field, it's not needed.

... this change?

Other than this
Reviewed-by: Jan Beulich <jbeulich@suse.com>

>  - Rework pt_active to use timer_is_active.
> 
> Changes since v1:
>  - New in this version.
> ---
>  xen/arch/x86/domain.c          |   4 +-
>  xen/arch/x86/hvm/hvm.c         |   4 +-
>  xen/arch/x86/hvm/vlapic.c      |   1 -
>  xen/arch/x86/hvm/vpt.c         | 174 ++++-----------------------------
>  xen/include/asm-x86/hvm/vcpu.h |   3 +-
>  xen/include/asm-x86/hvm/vpt.h  |  12 +--
>  6 files changed, 27 insertions(+), 171 deletions(-)

Yet nicer than the previous one!

Jan