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From: Avi Kivity <avi@redhat.com>
To: "Roedel, Joerg" <Joerg.Roedel@amd.com>
Cc: Marcelo Tosatti <mtosatti@redhat.com>,
	"kvm@vger.kernel.org" <kvm@vger.kernel.org>
Subject: Re: [PATCH 3/4] test: Add mode-switch test for nested svm
Date: Mon, 02 Aug 2010 17:24:43 +0300	[thread overview]
Message-ID: <4C56D52B.2050804@redhat.com> (raw)
In-Reply-To: <20100802141146.GB25471@amd.com>

  On 08/02/2010 05:11 PM, Roedel, Joerg wrote:
>
>> What is this testing exactly?  There is no svm function directly
>> associated with mode switch.  In fact, most L1s will intercept cr and
>> efer access and emulate the mode switch, rather than letting L2 perform
>> the mode switch directly.
> This is testing the failure case without the nested-svm efer patch I
> submitted last week. The sequence above (which switches from long mode
> to real mode and back to long mode) fails without this patch.

A direct test would be to

   mov $MSR_EFER, %ecx
   rdmsr
   xor $EFER_NX, %eax
   wrmsr

and see that L1 EFER was updated.

I don't object to the more complicated test, but in general prefer 
simpler, direct tests so that when they fail we know exactly why.

-- 
error compiling committee.c: too many arguments to function


  reply	other threads:[~2010-08-02 14:24 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2010-08-02 13:33 [PATCH 0/4] qemu-kvm: Add some nested svm tests Joerg Roedel
2010-08-02 13:33 ` [PATCH 1/4] test: Run tests with asid 1 Joerg Roedel
2010-08-02 13:33 ` [PATCH 2/4] test: Add nested svm next_rip test Joerg Roedel
2010-08-02 13:33 ` [PATCH 3/4] test: Add mode-switch test for nested svm Joerg Roedel
2010-08-02 13:55   ` Avi Kivity
2010-08-02 14:11     ` Roedel, Joerg
2010-08-02 14:24       ` Avi Kivity [this message]
2010-08-02 14:56         ` Roedel, Joerg
2010-08-02 13:33 ` [PATCH 4/4] test: Add test to check if asid 0 is allowed Joerg Roedel
2010-08-02 14:44 ` [PATCH 0/4] qemu-kvm: Add some nested svm tests Avi Kivity

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