From: Andrew Cooper <andrew.cooper3@citrix.com>
To: Jan Beulich <JBeulich@suse.com>
Cc: xen-devel <xen-devel@lists.xenproject.org>
Subject: Re: [PATCH 3/8] x86emul: support BMI1 insns
Date: Mon, 16 Jan 2017 14:17:10 +0000 [thread overview]
Message-ID: <c318a231-42d2-cb54-a36f-c7fbeab05c9a@citrix.com> (raw)
In-Reply-To: <587CDFAC020000780013080D@prv-mh.provo.novell.com>
On 16/01/17 13:58, Jan Beulich wrote:
>>>> On 16.01.17 at 14:51, <andrew.cooper3@citrix.com> wrote:
>> Right. What happens in reality is this:
>>
>> --- Xen Test Framework ---
>> Environment: HVM 32bit (No paging)
>> Test VEX.W matching mode:
>> andn cccca5a5, ff00ff00 = 00cc00a5
>> Test VEX.W opposite to mode:
>> andn cccca5a5, ff00ff00 = 00cc00a5
>> Test result: SUCCESS
>>
>> --- Xen Test Framework ---
>> Environment: HVM 64bit (Long mode 4 levels)
>> Test VEX.W matching mode:
>> andn cccca5a5cccca5a5, ff00ff00ff00ff00 = 00cc00a500cc00a5
>> Test VEX.W opposite to mode:
>> andn cccca5a5cccca5a5, ff00ff00ff00ff00 = 0000000000cc00a5
>> Test result: SUCCESS
>>
>> So VEX.W is ignored in 32bit (i.e. doesn't raise #UD), and *does* cause
>> 64bit mode to operate on 32bit operands, contrary to the manual.
> Doesn't look so to me: The first result is a 64-bit one, and I'd expect
> VEX.W=1 to be "matching mode".
"matching mode" means "what the assembler generated when using the
mnemonic". I didn't try hand-coding andn it to start with.
Here it is spelt out more clearly.
--- Xen Test Framework ---
Environment: HVM 32bit (No paging)
Test andn
Test VEX.W=0:
andn cccca5a5, ff00ff00 = 00cc00a5
Test VEX.W=1:
andn cccca5a5, ff00ff00 = 00cc00a5
Test result: SUCCESS
--- Xen Test Framework ---
Environment: HVM 64bit (Long mode 4 levels)
Test andn
Test VEX.W=1:
andn cccca5a5cccca5a5, ff00ff00ff00ff00 = 00cc00a500cc00a5
Test VEX.W=0:
andn cccca5a5cccca5a5, ff00ff00ff00ff00 = 0000000000cc00a5
Test result: SUCCESS
My conclusions still stand.
~Andrew
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next prev parent reply other threads:[~2017-01-16 14:17 UTC|newest]
Thread overview: 29+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-01-13 15:11 [PATCH 0/8] x86emul: support various ISA extensions Jan Beulich
2017-01-13 15:30 ` [PATCH 1/8] x86emul: support POPCNT Jan Beulich
2017-01-13 16:31 ` Andrew Cooper
2017-01-13 15:31 ` [PATCH 2/8] x86emul: support ADCX/ADOX Jan Beulich
2017-01-13 16:34 ` Andrew Cooper
2017-01-13 15:31 ` [PATCH 3/8] x86emul: support BMI1 insns Jan Beulich
2017-01-13 17:40 ` Andrew Cooper
2017-01-16 11:19 ` Jan Beulich
2017-01-16 11:59 ` Andrew Cooper
2017-01-16 12:43 ` Jan Beulich
2017-01-16 12:57 ` Jan Beulich
2017-01-16 13:51 ` Andrew Cooper
2017-01-16 13:58 ` Jan Beulich
2017-01-16 14:17 ` Andrew Cooper [this message]
2017-01-16 15:43 ` Jan Beulich
2017-01-13 15:32 ` [PATCH 4/8] x86emul: support BMI2 insns Jan Beulich
2017-01-13 18:20 ` Andrew Cooper
2017-01-16 11:32 ` Jan Beulich
2017-01-13 15:32 ` [PATCH 5/8] x86emul: support TBM insns Jan Beulich
2017-01-13 18:48 ` Andrew Cooper
2017-01-16 11:36 ` Jan Beulich
2017-01-16 14:52 ` Andrew Cooper
2017-01-16 15:45 ` Jan Beulich
2017-01-13 15:34 ` [PATCH 6/8] x86emul: support RDRAND/RDSEED Jan Beulich
2017-01-13 18:55 ` Andrew Cooper
2017-01-13 15:34 ` [PATCH 7/8] x86emul: support RDPID Jan Beulich
2017-01-13 19:00 ` Andrew Cooper
2017-01-13 15:35 ` [PATCH 8/8] x86emul: rename the no_writeback label Jan Beulich
2017-01-13 19:01 ` Andrew Cooper
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