Re: [PATCH RFC 5/6] KVM: mark requests that do not need a wakeup

[Marc Zyngier]

On 06/04/17 21:20, Radim KrÄmÃÅ wrote:
> Some operations must ensure that the guest is not running with stale
> data, but if the guest is halted, then the update can wait until another
> event happens.  kvm_make_all_requests() currently doesn't wake up, so we
> can mark all requests used with it.
> 
> First 8 bits were arbitrarily reserved for request numbers.
> 
> Most uses of requests have the request type as a constant, so a compiler
> will optimize the '&'.
> 
> An alternative would be to have an inline function that would return
> whether the request needs a wake-up or not, but I like this one better
> even though it might produce worse assembly.
> 
> Suggested-by: Christoffer Dall <cdall@xxxxxxxxxx>
> Signed-off-by: Radim KrÄmÃÅ <rkrcmar@xxxxxxxxxx>
> ---
>   Btw. do you recall which macro allowed to define bitmasks?  (It has
>   two arguments, FROM and TO.)

GENMASK (and its _ULL variant), defined in include/linux/bitops.h.

Thanks,

	M.
-- 
Jazz is not dead. It just smells funny...