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From: Boris Ostrovsky <boris.ostrovsky@oracle.com>
To: Andrew Cooper <andrew.cooper3@citrix.com>,
	xen-devel <xen-devel@lists.xen.org>
Subject: Re: MSR_SPEC_CTRL intercept
Date: Wed, 23 May 2018 17:59:54 -0400	[thread overview]
Message-ID: <8a74c779-8f9b-eec7-8d3b-2f2baaa3dcfd@oracle.com> (raw)
In-Reply-To: <e2c1e06d-239d-1ba8-1180-34c47caa1065@citrix.com>

On 05/23/2018 05:49 PM, Andrew Cooper wrote:
> On 23/05/2018 22:40, Boris Ostrovsky wrote:
>> Looking at vmx_cpuid_policy_changed():
>>
>>
>>    if ( cp->feat.ibrsb )
>>         vmx_clear_msr_intercept(v, MSR_SPEC_CTRL, VMX_MSR_RW);
>>     else
>>         vmx_set_msr_intercept(v, MSR_SPEC_CTRL, VMX_MSR_RW);
>>
>>
>> Is there a reason why we are not checking cp->feat.ssbd as well?
> Yes.  Read the final hunk of
> http://xenbits.xen.org/gitweb/?p=xen.git;a=commitdiff;h=9df52a25e0e95a0b9971aa2fc26c5c6a5cbdf4ef

SSBD implies IBRS --- yes, that's true. But not the other way around, no?

-boris

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  reply	other threads:[~2018-05-23 21:59 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-05-23 21:40 MSR_SPEC_CTRL intercept Boris Ostrovsky
2018-05-23 21:49 ` Andrew Cooper
2018-05-23 21:59   ` Boris Ostrovsky [this message]
2018-05-23 22:09     ` Andrew Cooper
2018-05-23 22:27       ` Boris Ostrovsky
2018-05-23 22:34         ` Andrew Cooper
2018-05-23 22:53           ` Boris Ostrovsky
2018-05-23 22:56             ` Andrew Cooper
2018-05-24  8:13       ` Jan Beulich
2018-05-24 10:13         ` Andrew Cooper
2018-05-24 10:23           ` Jan Beulich
2018-05-25 15:25             ` Andrew Cooper
2018-05-25 15:42               ` Jan Beulich

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