From: Paolo Bonzini <pbonzini@redhat.com>
To: Xiao Guangrong <guangrong.xiao@linux.intel.com>
Cc: gleb@kernel.org, mtosatti@redhat.com, kvm@vger.kernel.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH 07/15] KVM: MTRR: improve kvm_mtrr_get_guest_memory_type
Date: Wed, 03 Jun 2015 09:57:16 +0200 [thread overview]
Message-ID: <556EB35C.6040601@redhat.com> (raw)
In-Reply-To: <556E6270.2060701@linux.intel.com>
On 03/06/2015 04:12, Xiao Guangrong wrote:
>>
>> Perhaps just use type = MIN(type, curr_type), which also happens to get
>> WT vs. WB right? You can also add a
>>
>> BUILD_BUG_ON(MTRR_TYPE_WRTHROUGH > MTRR_TYPE_WRBACK);
>>
>> to ensure that the WT vs. WB precedence is correct.
>
> Only WT and WB are allowed to be overlapped here otherwise is
> "undefined behavior". For example if the types are MTRR_TYPE_WRPROT
> and MTRR_TYPE_WRTHROUGH, min() will get MTRR_TYPE_WRTHROUGH rather than
> "undefined behavior".
Choosing MTRR_TYPE_WRTHROUGH is one example of achieve undefined
behavior. Picking one type arbitrarily is just a different kind of
undefined behavior.
Paolo
next prev parent reply other threads:[~2015-06-03 7:57 UTC|newest]
Thread overview: 44+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-05-30 10:59 [PATCH 00/15] KVM: x86: fully implement vMTRR Xiao Guangrong
2015-05-30 10:58 ` Xiao Guangrong
2015-05-30 10:59 ` [PATCH 01/15] KVM: x86: move MTRR related code to a separate file Xiao Guangrong
2015-05-30 10:59 ` [PATCH 02/15] KVM: MTRR: handle MSR_MTRRcap in kvm_mtrr_get_msr Xiao Guangrong
2015-05-30 10:59 ` [PATCH 03/15] KVM: MTRR: remove mtrr_state.have_fixed Xiao Guangrong
2015-05-30 10:59 ` [PATCH 04/15] KVM: MTRR: exactly define the size of variable MTRRs Xiao Guangrong
2015-05-30 10:59 ` [PATCH 05/15] KVM: MTRR: clean up mtrr default type Xiao Guangrong
2015-06-01 9:11 ` Paolo Bonzini
2015-06-03 1:55 ` Xiao Guangrong
2015-06-09 0:35 ` David Matlack
2015-05-30 10:59 ` [PATCH 06/15] KVM: MTRR: do not split 64 bits MSR content Xiao Guangrong
2015-05-30 10:59 ` [PATCH 07/15] KVM: MTRR: improve kvm_mtrr_get_guest_memory_type Xiao Guangrong
2015-06-01 9:16 ` Paolo Bonzini
2015-06-03 2:12 ` Xiao Guangrong
2015-06-03 7:57 ` Paolo Bonzini [this message]
2015-05-30 10:59 ` [PATCH 08/15] KVM: MTRR: introduce fixed_mtrr_segment table Xiao Guangrong
2015-06-01 9:25 ` Paolo Bonzini
2015-06-03 2:29 ` Xiao Guangrong
2015-05-30 10:59 ` [PATCH 09/15] KVM: MTRR: introduce var_mtrr_range Xiao Guangrong
2015-06-09 0:36 ` David Matlack
2015-06-09 2:38 ` Xiao Guangrong
2015-05-30 10:59 ` [PATCH 10/15] KVM: MTRR: sort variable MTRRs Xiao Guangrong
2015-06-01 9:27 ` Paolo Bonzini
2015-06-03 2:31 ` Xiao Guangrong
2015-05-30 10:59 ` [PATCH 11/15] KVM: MTRR: introduce fixed_mtrr_addr_* functions Xiao Guangrong
2015-05-30 10:59 ` [PATCH 12/15] KVM: MTRR: introduce mtrr_for_each_mem_type Xiao Guangrong
2015-06-01 9:33 ` Paolo Bonzini
2015-06-01 14:26 ` Paolo Bonzini
2015-06-03 2:57 ` Xiao Guangrong
2015-06-03 2:40 ` Xiao Guangrong
2015-06-09 0:36 ` David Matlack
2015-06-09 2:45 ` Xiao Guangrong
2015-05-30 10:59 ` [PATCH 13/15] KVM: MTRR: simplify kvm_mtrr_get_guest_memory_type Xiao Guangrong
2015-05-30 10:59 ` [PATCH 14/15] KVM: MTRR: do not map huage page for non-consistent range Xiao Guangrong
2015-06-01 9:36 ` Paolo Bonzini
2015-06-01 9:38 ` Paolo Bonzini
2015-06-03 2:56 ` Xiao Guangrong
2015-06-03 7:55 ` Paolo Bonzini
2015-06-04 8:23 ` Xiao Guangrong
2015-06-04 8:26 ` Xiao Guangrong
2015-06-04 8:34 ` Paolo Bonzini
2015-06-04 8:36 ` Paolo Bonzini
2015-06-05 6:33 ` Xiao Guangrong
2015-05-30 10:59 ` [PATCH 15/15] KVM: VMX: fully implement guest MTRR virtualization Xiao Guangrong
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