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From: "Roger Pau Monné" <roger.pau@citrix.com>
To: Andrew Cooper <andrew.cooper3@citrix.com>
Cc: <xen-devel@lists.xenproject.org>,
	Ian Jackson <iwj@xenproject.org>, Wei Liu <wl@xen.org>,
	Anthony PERARD <anthony.perard@citrix.com>
Subject: Re: [PATCH 15/21] libs/guest: obtain a compatible cpu policy from two input ones
Date: Fri, 9 Apr 2021 12:56:21 +0200	[thread overview]
Message-ID: <YHAy1e7a4aEAKTYc@Air-de-Roger> (raw)
In-Reply-To: <d24e9172-3939-44c3-e5f8-08b76ab23c17@citrix.com>

On Thu, Apr 01, 2021 at 05:26:03PM +0100, Andrew Cooper wrote:
> On 23/03/2021 09:58, Roger Pau Monne wrote:
> > Introduce a helper to obtain a compatible cpu policy based on two
> > input cpu policies. Currently this is done by and'ing all CPUID leaves
> > and MSR entries, except for MSR_ARCH_CAPABILITIES which has the RSBA
> > bit or'ed.
> >
> > The _AC macro is pulled from libxl_internal.h into xen-tools/libs.h
> > since it's required in order to use the msr-index.h header.
> >
> > Note there's no need to place this helper in libx86, since the
> > calculation of a compatible policy shouldn't be done from the
> > hypervisor.
> >
> > No callers of the interface introduced.
> >
> > Signed-off-by: Roger Pau Monné <roger.pau@citrix.com>
> 
> I think this wants to be in libx86, because we'll want it to replace the
> opencoded derivation logic in init_cpuid()

I think you mean init_domain_cpuid_policy or recalculate_cpuid_policy?
I cannot find any init_cpuid.

I'm not convinced we need this in libx86 for the hypervisor, as I
don't know exactly how we would use it there. I expect the hypervisor
to validate policies provided by the toolstack, but not for it to
create such policies unless for very specific domains (ie: dom0 or
similar) which shouldn't require any leveling.

I'm happy to place it libx86, but I think I need to understand better
why it needs to be there.

> Also, we absolutely want to unit test it.  (I could have sworn I already
> started some work there - maybe its hidden in one of my WIP branches).

I don't think we have unit tests for the xenguest library?

Thanks, Roger.


  reply	other threads:[~2021-04-09 10:57 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
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 [this message]
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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