From: Jan Beulich <jbeulich@suse.com>
To: "Boris Ostrovsky" <boris.ostrovsky@oracle.com>,
"Roger Pau Monné" <roger.pau@citrix.com>
Cc: xen-devel@lists.xenproject.org, iwj@xenproject.org, wl@xen.org,
anthony.perard@citrix.com, andrew.cooper3@citrix.com,
jun.nakajima@intel.com, kevin.tian@intel.com
Subject: Re: [PATCH v2 2/4] x86: Introduce MSR_UNHANDLED
Date: Tue, 23 Feb 2021 08:57:00 +0100 [thread overview]
Message-ID: <307a4765-1c54-63fd-b3fb-ecb47ba3dbca@suse.com> (raw)
In-Reply-To: <ce2ef7a3-0583-ffff-182a-0ab078f45b82@oracle.com>
On 22.02.2021 22:19, Boris Ostrovsky wrote:
>
> On 2/22/21 6:08 AM, Roger Pau Monné wrote:
>> On Fri, Feb 19, 2021 at 09:56:32AM -0500, Boris Ostrovsky wrote:
>>> On 2/18/21 5:51 AM, Roger Pau Monné wrote:
>>>> On Wed, Jan 20, 2021 at 05:49:10PM -0500, Boris Ostrovsky wrote:
>>>>> When toolstack updates MSR policy, this MSR offset (which is the last
>>>>> index in the hypervisor MSR range) is used to indicate hypervisor
>>>>> behavior when guest accesses an MSR which is not explicitly emulated.
>>>> It's kind of weird to use an MSR to store this. I assume this is done
>>>> for migration reasons?
>>>
>>> Not really. It just seemed to me that MSR policy is the logical place to do that. Because it *is* a policy of how to deal with such accesses, isn't it?
>> I agree that using the msr_policy seems like the most suitable place
>> to convey this information between the toolstack and Xen. I wonder if
>> it would be fine to have fields in msr_policy that don't directly
>> translate into an MSR value?
>
>
> We have xen_msr_entry_t.flags that we can use when passing policy array back and forth. Then we can ignore xen_msr_entry_t.idx for that entry (although in earlier version of this series Jan preferred to use idx and leave flags alone).
Which, just to clarify, was not the least because of the flags
field being per-entry, i.e. per MSR, while here we want a global
indicator.
Jan
next prev parent reply other threads:[~2021-02-23 7:57 UTC|newest]
Thread overview: 53+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-01-20 22:49 [PATCH v2 0/4] Permit fault-less access to non-emulated MSRs Boris Ostrovsky
2021-01-20 22:49 ` [PATCH v2 1/4] xl: Add support for ignore_msrs option Boris Ostrovsky
2021-01-21 14:56 ` Wei Liu
2021-01-21 22:43 ` Boris Ostrovsky
2021-01-22 9:52 ` Julien Grall
2021-01-22 18:28 ` Boris Ostrovsky
2021-01-22 18:33 ` Julien Grall
2021-01-22 18:39 ` Boris Ostrovsky
2021-01-22 20:42 ` Julien Grall
2021-02-18 10:42 ` Roger Pau Monné
2021-02-18 11:54 ` Jan Beulich
2021-02-18 15:52 ` Roger Pau Monné
2021-02-18 15:57 ` Jan Beulich
2021-02-19 14:50 ` Boris Ostrovsky
2021-02-22 10:24 ` Roger Pau Monné
2021-02-22 10:33 ` Jan Beulich
2021-01-20 22:49 ` [PATCH v2 2/4] x86: Introduce MSR_UNHANDLED Boris Ostrovsky
2021-01-22 11:51 ` Jan Beulich
2021-01-22 18:56 ` Boris Ostrovsky
2021-02-02 17:01 ` Boris Ostrovsky
2021-02-18 10:51 ` Roger Pau Monné
2021-02-19 14:56 ` Boris Ostrovsky
2021-02-22 11:08 ` Roger Pau Monné
2021-02-22 21:19 ` Boris Ostrovsky
2021-02-23 7:57 ` Jan Beulich [this message]
2021-02-23 9:34 ` Roger Pau Monné
2021-02-23 10:15 ` Jan Beulich
2021-02-23 12:17 ` Roger Pau Monné
2021-02-23 13:23 ` Jan Beulich
2021-02-23 15:39 ` Boris Ostrovsky
2021-02-23 16:10 ` Jan Beulich
2021-02-23 18:00 ` Roger Pau Monné
2021-02-23 16:11 ` Roger Pau Monné
2021-02-23 16:40 ` Boris Ostrovsky
2021-02-23 18:02 ` Roger Pau Monné
2021-02-23 18:45 ` Boris Ostrovsky
2021-01-20 22:49 ` [PATCH v2 3/4] x86: Allow non-faulting accesses to non-emulated MSRs if policy permits this Boris Ostrovsky
2021-01-22 12:51 ` Jan Beulich
2021-01-22 19:52 ` Boris Ostrovsky
2021-01-25 10:22 ` Jan Beulich
2021-01-25 18:42 ` Boris Ostrovsky
2021-01-26 9:05 ` Jan Beulich
2021-01-26 16:02 ` Boris Ostrovsky
2021-01-26 16:35 ` Jan Beulich
2021-02-18 11:24 ` Roger Pau Monné
2021-02-18 11:57 ` Jan Beulich
2021-02-18 15:53 ` Roger Pau Monné
2021-01-20 22:49 ` [PATCH v2 4/4] tools/libs: Apply MSR policy to a guest Boris Ostrovsky
2021-01-21 14:58 ` Wei Liu
2021-01-22 9:56 ` Julien Grall
2021-01-22 18:35 ` Boris Ostrovsky
2021-02-18 11:48 ` Roger Pau Monné
2021-02-19 14:57 ` Boris Ostrovsky
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