From: Andrew Cooper <andrew.cooper3@citrix.com>
To: Jan Beulich <JBeulich@suse.com>
Cc: xen-devel <xen-devel@lists.xenproject.org>,
Wei Liu <wei.liu2@citrix.com>,
Roger Pau Monne <roger.pau@citrix.com>
Subject: Re: [Xen-devel] [PATCH] libx86: Elide more empty CPUID leaves when serialising a policy
Date: Thu, 23 May 2019 11:38:27 +0100 [thread overview]
Message-ID: <1292e300-400d-5612-76aa-8139c1e0c7fa@citrix.com> (raw)
Message-ID: <20190523103827.Ue8BslnSZFqyJuWtV4PoSyk6yOkVKfQZQIu538xjg4k@z> (raw)
In-Reply-To: <5CE65AF002000078002319A7@prv1-mh.provo.novell.com>
On 23/05/2019 09:33, Jan Beulich wrote:
>>>> On 22.05.19 at 17:50, <andrew.cooper3@citrix.com> wrote:
>> x86_cpuid_copy_to_buffer() currently serialises the full content of the
>> various subleaf unions. While leaves 4, 0xb and 0xd don't have a concrete
>> max_subleaf field, they do have well defined upper bounds.
>>
>> Diffing the results of `xen-cpuid -p` shows the resutling saving:
>>
>> @@ -1,5 +1,5 @@
>> Xen reports there are maximum 114 leaves and 1 MSRs
>> -Raw policy: 93 leaves, 1 MSRs
>> +Raw policy: 38 leaves, 1 MSRs
>> CPUID:
>> leaf subleaf -> eax ebx ecx edx
>> 00000000:ffffffff -> 00000016:756e6547:6c65746e:49656e69
>> @@ -32,7 +32,7 @@ Raw policy: 93 leaves, 1 MSRs
>> MSRs:
>> index -> value
>> 000000ce -> 0000000080000000
>> -Host policy: 93 leaves, 1 MSRs
>> +Host policy: 33 leaves, 1 MSRs
>> CPUID:
>> leaf subleaf -> eax ebx ecx edx
>> 00000000:ffffffff -> 0000000d:756e6547:6c65746e:49656e69
>>
>> which is mostly due to no longer writing out 64 leaves for xstate when (on
>> this CoffeeLake system) 8 will do.
>>
>> Extend the unit tests to cover empty and partially filled subleaf unions.
>>
>> Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
> For the lib/x86/ part
> Reviewed-by: Jan Beulich <jbeulich@suse.com>
Thanks.
> For the test harness part
> Acked-by: Jan Beulich <jbeulich@suse.com>
> No idea how else I should represent that I didn't look overly closely
> at the harness additions.
Well - I can state that the additions to the test harness did find bugs.
Overall, I think the content of tools/tests/ is of relatively little
importance in the grand scheme of things. I certainly don't spend as
much time reviewing the test_x86_emulator changes as the changes to
x86_emulate() itself.
~Andrew
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next prev parent reply other threads:[~2019-05-23 10:38 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-05-22 15:50 [PATCH] libx86: Elide more empty CPUID leaves when serialising a policy Andrew Cooper
2019-05-22 15:50 ` [Xen-devel] " Andrew Cooper
2019-05-23 8:33 ` Jan Beulich
2019-05-23 8:33 ` [Xen-devel] " Jan Beulich
2019-05-23 10:38 ` Andrew Cooper [this message]
2019-05-23 10:38 ` Andrew Cooper
2019-05-23 10:27 ` [PATCH] libx86: Introduce wrappers for extracting XCR0/XSS from a cpuid policy Andrew Cooper
2019-05-23 10:27 ` [Xen-devel] " Andrew Cooper
2019-05-23 11:52 ` Jan Beulich
2019-05-23 11:52 ` [Xen-devel] " Jan Beulich
2019-05-23 11:59 ` Andrew Cooper
2019-05-23 11:59 ` [Xen-devel] " Andrew Cooper
2019-05-23 12:08 ` Jan Beulich
2019-05-23 12:08 ` [Xen-devel] " Jan Beulich
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