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From: Andrew Cooper <andrew.cooper3@citrix.com>
To: Euan Harris <euan.harris@citrix.com>, Jan Beulich <JBeulich@suse.com>
Cc: xen-devel@lists.xenproject.org, kevin.tian@intel.com,
	jun.nakajima@intel.com
Subject: Re: [PATCH] nested vmx: Intercept guest rdmsr for MSR_IA32_VMX_VMFUNC
Date: Tue, 7 Jun 2016 12:39:20 +0100	[thread overview]
Message-ID: <5756B268.6090303@citrix.com> (raw)
In-Reply-To: <20160607105344.GA21058@citrix.com>

On 07/06/16 11:53, Euan Harris wrote:
> On Tue, Jun 07, 2016 at 04:35:28AM -0600, Jan Beulich wrote:
>>> @@ -2624,7 +2624,7 @@ static int vmx_msr_read_intercept(unsigned int msr, uint64_t *msr_content)
>>>          __vmread(GUEST_IA32_DEBUGCTL, msr_content);
>>>          break;
>>>      case IA32_FEATURE_CONTROL_MSR:
>>> -    case MSR_IA32_VMX_BASIC...MSR_IA32_VMX_TRUE_ENTRY_CTLS:
>>> +    case MSR_IA32_VMX_BASIC...MSR_IA32_VMX_VMFUNC:
>>>          if ( !nvmx_msr_read_intercept(msr, msr_content) )
>>>              goto gp_fault;
>>>          break;
>> ... retaining this code structure makes it likely that some future
>> addition will lead to the same problem again.
> The safest solution would be to whitelist the MSRs which Xen handles and
> which the guest should be allowed to see, rather than blacklisting which
> is essentially what is happening now.   That would involve a substantial
> change in the code, but aside from that is there any fundamental reason
> why it would be a bad idea?

I do have plans which will eventually turn all cpuid information and
msrs visible to guests into a whitelist rather than a blacklist, but
there is indeed a lot of infrastructure work required to make this happen.

It is certainly the longterm plan.

~Andrew

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  reply	other threads:[~2016-06-07 11:39 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-06-07 10:18 Euan Harris
2016-06-07 10:35 ` Jan Beulich
2016-06-07 10:53   ` Euan Harris
2016-06-07 11:39     ` Andrew Cooper [this message]
2016-06-08  6:09 ` Tian, Kevin
2016-06-08 11:54 ` Wei Liu

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