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From: "Jan Beulich" <JBeulich@suse.com>
To: Andrew Cooper <andrew.cooper3@citrix.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 02:29:28 -0600	[thread overview]
Message-ID: <56E6847802000078000DBEB9@prv-mh.provo.novell.com> (raw)
In-Reply-To: <56E3034A.9000004@citrix.com>

>>> 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.
 */

Jan


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  reply	other threads:[~2016-03-14  8:29 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 [this message]
2016-03-14  8:52       ` Andrew Cooper
2016-03-11 17:35 ` [PATCH 3/3] x86emul: support MOVBE and CRC32 Jan Beulich

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