From: Andrew Cooper <andrew.cooper3@citrix.com>
To: Jan Beulich <JBeulich@suse.com>
Cc: xen-devel <xen-devel@lists.xenproject.org>, Keir Fraser <keir@xen.org>
Subject: Re: [PATCH 2/3] x86emul: check host features alongside guest ones where needed
Date: Mon, 14 Mar 2016 08:52:09 +0000 [thread overview]
Message-ID: <56E67BB9.9020504@citrix.com> (raw)
In-Reply-To: <56E6847802000078000DBEB9@prv-mh.provo.novell.com>
On 14/03/2016 08:29, Jan Beulich wrote:
>>>> On 11.03.16 at 18:41, <andrew.cooper3@citrix.com> wrote:
>> On 11/03/16 17:34, Jan Beulich wrote:
>>> Signed-off-by: Jan Beulich <jbeulich@suse.com>
>>>
>>> --- a/xen/arch/x86/x86_emulate/x86_emulate.c
>>> +++ b/xen/arch/x86/x86_emulate/x86_emulate.c
>>> @@ -1093,6 +1093,22 @@ static bool_t vcpu_has(
>>> #define vcpu_must_have_cx16() vcpu_must_have(0x00000001, ECX, 13)
>>> #define vcpu_must_have_avx() vcpu_must_have(0x00000001, ECX, 28)
>>>
>>> +#ifdef __XEN__
>>> +/*
>>> + * Note the (subtle?) difference between vcpu_must_have_<feature>() and
>>> + * vcpu_must_have(<feature>): The former only checks guest feature flags,
>>> + * while the latter also checks host ones, i.e. is required to be used when
>>> + * emulation code is using the same instruction class for carrying out the
>>> + * actual operation).
>>> + */
>> This comment is now stale.
>>
>> With this dropped, Reviewed-by: Andrew Cooper <andrew.cooper3@citrix.com>
> I suppose you're okay with it being adjusted instead of fully dropped:
>
> /*
> * Note the difference between vcpu_must_have_<feature>() and
> * host_and_vcpu_must_have(<feature>): The latter needs to be used when
> * emulation code is using the same instruction class for carrying out
> * the actual operation.
> */
Yes - that's great.
~Andrew
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next prev parent reply other threads:[~2016-03-14 8:52 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-03-11 17:29 [PATCH 0/3] x86: instruction emulator improvements Jan Beulich
2016-03-11 17:33 ` [PATCH 1/3] x86: rename XMM* features to SSE* Jan Beulich
2016-03-11 17:34 ` [PATCH 2/3] x86emul: check host features alongside guest ones where needed Jan Beulich
2016-03-11 17:41 ` Andrew Cooper
2016-03-14 8:29 ` Jan Beulich
2016-03-14 8:52 ` Andrew Cooper [this message]
2016-03-11 17:35 ` [PATCH 3/3] x86emul: support MOVBE and CRC32 Jan Beulich
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