Re: [PATCH v4 4/6] x86/PV: allow PV guests to have an emulated PIT

From: "Jan Beulich" <JBeulich@suse.com>
To: Roger Pau Monne <roger.pau@citrix.com>
Cc: Andrew Cooper <andrew.cooper3@citrix.com>,
	xen-devel@lists.xenproject.org
Subject: Re: [PATCH v4 4/6] x86/PV: allow PV guests to have an emulated PIT
Date: Fri, 22 Jan 2016 03:48:44 -0700	[thread overview]
Message-ID: <56A2171C02000078000C9FAB@prv-mh.provo.novell.com> (raw)
In-Reply-To: <1453395092-88090-5-git-send-email-roger.pau@citrix.com>

>>> On 21.01.16 at 17:51, <roger.pau@citrix.com> wrote:
> This fixes the fallout from the HVMlite series, that removed the emulated
> PIT from PV(H) guests. Also, this patch forces the hardware domain to
> always have an emulated PIT, regardless of whether the toolstack specified
> one or not.
> 
> Signed-off-by: Roger Pau Monné <roger.pau@citrix.com>

Reviewed-by: Jan Beulich <jbeulich@suse.com>
albeit ...

> --- a/xen/arch/x86/domain.c
> +++ b/xen/arch/x86/domain.c
> @@ -542,8 +542,11 @@ int arch_domain_create(struct domain *d, unsigned int 
> domcr_flags,
>                     d->domain_id, config->emulation_flags);
>              return -EINVAL;
>          }
> +        if ( is_hardware_domain(d) )
> +            config->emulation_flags |= XEN_X86_EMU_PIT;
>          if ( config->emulation_flags != 0 &&
> -             (!is_hvm_domain(d) || config->emulation_flags != XEN_X86_EMU_ALL) )
> +             (is_hvm_domain(d) ? (config->emulation_flags != XEN_X86_EMU_ALL) :
> +                                 (config->emulation_flags != XEN_X86_EMU_PIT)) )
>          {

... you having chosen the != route instead of the suggested &
one, I guess I'll take the liberty to further simplify this while
committing (as the ?: is now only needed on the right side of the
!= and I'm generally of the opinion that redundancy like this is
hampering readability).

Jan

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