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From: "Roger Pau Monné" <roger.pau@citrix.com>
To: Jan Beulich <jbeulich@suse.com>
Cc: Andrew Cooper <andrew.cooper3@citrix.com>,
	Ian Jackson <iwj@xenproject.org>, Wei Liu <wl@xen.org>,
	<xen-devel@lists.xenproject.org>
Subject: Re: [PATCH 14/21] libs/guest: introduce helper to check cpu policy compatibility
Date: Wed, 31 Mar 2021 14:40:46 +0200	[thread overview]
Message-ID: <YGRtzlUmuRjKh6er@Air-de-Roger> (raw)
In-Reply-To: <8f7a2f44-c006-0f94-8f44-b6b3ee3e9d1f@suse.com>

On Tue, Mar 30, 2021 at 06:02:45PM +0200, Jan Beulich wrote:
> On 23.03.2021 10:58, Roger Pau Monne wrote:
> > --- a/tools/libs/guest/xg_cpuid_x86.c
> > +++ b/tools/libs/guest/xg_cpuid_x86.c
> > @@ -1098,3 +1098,20 @@ int xc_cpu_policy_update_msrs(xc_interface *xch, xc_cpu_policy_t policy,
> >      return rc;
> >  
> >  }
> > +
> > +bool xc_cpu_policy_is_compatible(xc_interface *xch, const xc_cpu_policy_t p1,
> > +                                 const xc_cpu_policy_t p2)
> > +{
> > +    struct cpu_policy_errors err;
> 
> Don't you need an initializer here for ...
> 
> > +    int rc = x86_cpu_policies_are_compatible(p1, p2, &err);
> > +
> > +    if ( !rc )
> > +        return true;
> > +
> > +    if ( err.leaf != -1 )
> > +        ERROR("Leaf %#x subleaf %#x is not compatible", err.leaf, err.subleaf);
> > +    if ( err.msr != -1 )
> > +        ERROR("MSR index %#x is not compatible", err.msr);
> 
> ... these checks to have a chance of actually triggering? (I'm also
> not certain -1 is a good indicator, but I guess we have been using it
> elsewhere as well.)

Well, this is strictly the error path, at which point I would expect
err to be properly set by x86_cpu_policies_are_compatible. I can
however initialize err for safety here.

Thanks, Roger.


  reply	other threads:[~2021-03-31 12:41 UTC|newest]

Thread overview: 52+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-03-23  9:58 [PATCH 00/21] libs/guest: new CPUID/MSR interface Roger Pau Monne
2021-03-23  9:58 ` [PATCH 01/21] libxl: don't ignore the return value from xc_cpuid_apply_policy Roger Pau Monne
2021-03-30 15:21   ` Jan Beulich
2021-03-30 15:38   ` Andrew Cooper
2021-03-31 18:12   ` Andrew Cooper
2021-03-23  9:58 ` [PATCH 02/21] libs/guest: rename xc_get_cpu_policy_size to xc_cpu_policy_get_size Roger Pau Monne
2021-03-31 19:03   ` Andrew Cooper
2021-03-23  9:58 ` [PATCH 03/21] libs/guest: introduce xc_cpu_policy_t Roger Pau Monne
2021-03-31 20:10   ` Andrew Cooper
2021-04-01  8:48     ` Roger Pau Monné
2021-03-23  9:58 ` [PATCH 04/21] libs/guest: introduce helper to fetch a system cpu policy Roger Pau Monne
2021-03-30 15:35   ` Jan Beulich
2021-04-01 13:56   ` Andrew Cooper
2021-03-23  9:58 ` [PATCH 05/21] libs/guest: introduce helper to fetch a domain " Roger Pau Monne
2021-03-30 15:37   ` Jan Beulich
2021-03-31 11:06     ` Roger Pau Monné
2021-04-01 13:32       ` Andrew Cooper
2021-03-23  9:58 ` [PATCH 06/21] libs/guest: introduce helper to serialize a " Roger Pau Monne
2021-03-23  9:58 ` [PATCH 07/21] tools: switch existing users of xc_get_{system,domain}_cpu_policy Roger Pau Monne
2021-03-23  9:58 ` [PATCH 08/21] libs/guest: introduce a helper to apply a cpu policy to a domain Roger Pau Monne
2021-03-23  9:58 ` [PATCH 09/21] libs/guest: allow fetching a specific CPUID leaf from a cpu policy Roger Pau Monne
2021-04-01 14:47   ` Andrew Cooper
2021-04-08 15:53     ` Roger Pau Monné
2021-03-23  9:58 ` [PATCH 10/21] libs/guest: allow fetching a specific MSR entry " Roger Pau Monne
2021-03-23  9:58 ` [PATCH 11/21] libs/guest: allow updating a cpu policy CPUID data Roger Pau Monne
2021-03-30 15:56   ` Jan Beulich
2021-03-31 12:47     ` Roger Pau Monné
2021-04-01 14:55   ` Andrew Cooper
2021-03-23  9:58 ` [PATCH 12/21] libs/guest: allow updating a cpu policy MSR data Roger Pau Monne
2021-03-23  9:58 ` [PATCH 13/21] libs/guest: switch users of xc_set_domain_cpu_policy Roger Pau Monne
2021-04-01 15:04   ` Andrew Cooper
2021-03-23  9:58 ` [PATCH 14/21] libs/guest: introduce helper to check cpu policy compatibility Roger Pau Monne
2021-03-30 16:02   ` Jan Beulich
2021-03-31 12:40     ` Roger Pau Monné [this message]
2021-03-31 14:57       ` Jan Beulich
2021-04-01 16:14   ` Andrew Cooper
2021-03-23  9:58 ` [PATCH 15/21] libs/guest: obtain a compatible cpu policy from two input ones Roger Pau Monne
2021-03-31 15:24   ` Jan Beulich
2021-04-01 16:26   ` Andrew Cooper
2021-04-09 10:56     ` Roger Pau Monné
2021-03-23  9:58 ` [PATCH 16/21] libs/guest: make a cpu policy compatible with older Xen versions Roger Pau Monne
2021-03-31 15:29   ` Jan Beulich
2021-04-01 16:31   ` Andrew Cooper
2021-03-23  9:58 ` [PATCH 17/21] libs/guest: introduce helper set cpu topology in cpu policy Roger Pau Monne
2021-04-01 17:22   ` Andrew Cooper
2021-03-23  9:58 ` [PATCH 18/21] libs/guest: rework xc_cpuid_xend_policy Roger Pau Monne
2021-03-23  9:58 ` [PATCH 19/21] libs/guest: apply a featureset into a cpu policy Roger Pau Monne
2021-03-23  9:58 ` [PATCH 20/21] libs/{light,guest}: implement xc_cpuid_apply_policy in libxl Roger Pau Monne
2021-04-01 17:44   ` Andrew Cooper
2021-04-09 14:57     ` Roger Pau Monné
2021-03-23  9:58 ` [PATCH 21/21] libs/guest: (re)move xc_cpu_policy_apply_cpuid Roger Pau Monne
2021-04-01 17:53   ` Andrew Cooper

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