linux-kernel - Re: [PATCH v2 9/9] KVM: vmx: vmx instructions handling does not consider cs.l

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Message-Id: <E364EC9D-EC0D-43BC-B946-473CBFCAFAC1@gmail.com>
Date:	Wed, 18 Jun 2014 20:51:06 +0300
From:	Nadav Amit <nadav.amit@...il.com>
To:	Paolo Bonzini <pbonzini@...hat.com>
Cc:	Nadav Amit <namit@...technion.ac.il>, gleb@...nel.org,
	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>,
	"H. Peter Anvin" <hpa@...or.com>, x86@...nel.org,
	linux-kernel@...r.kernel.org, kvm@...r.kernel.org
Subject: Re: [PATCH v2 9/9] KVM: vmx: vmx instructions handling does not consider cs.l


On Jun 18, 2014, at 7:06 PM, Paolo Bonzini <pbonzini@...hat.com> wrote:

> Il 18/06/2014 18:01, Nadav Amit ha scritto:
>>> 
>> 
>> Perhaps I am missing something, but I don't see where my mistake is.
>> The VMREAD source operand is always read as 64-bits and I made no
>> changes there. Therefore, if bits 63:32 are not zero, the instruction
>> should fail when attempting to access the field.
> 
> In 32-bit mode, it should be read as 32 bits: "Outside IA-32e mode, the source operand has 32 bits, regardless of the value of CS.D" (so it's never 16 bits, but it's also never 64 bits).

Oh. I now get it. I misunderstood what the SDM said, as I was thinking that 62:32 will lead to failure also on 32-bit mode.
If you fix it, please fix both VMREAD and VMWRITE. If not, I would resubmit.

Thanks,
Nadav--
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