From: Paolo Bonzini <pbonzini@redhat.com>
To: Andy Lutomirski <luto@kernel.org>,
linux-kernel@vger.kernel.org, kvm@vger.kernel.org
Cc: guangrong.xiao@linux.intel.com, jroedel@suse.de,
alex.williamson@redhat.com, ogerlitz@mellanox.com,
amirv@mellanox.com
Subject: Re: [PATCH 2/4] KVM: SVM: use NPT page attributes
Date: Fri, 17 Jul 2015 04:31:14 +0200 [thread overview]
Message-ID: <55A868F2.4040304@redhat.com> (raw)
In-Reply-To: <55A84DD0.9040008@kernel.org>
On 17/07/2015 02:35, Andy Lutomirski wrote:
>
>> Right now, NPT page attributes are not used, and the final page
>> attribute depends solely on gPAT (which however is not synced
>> correctly), the guest MTRRs and the guest page attributes.
>>
>> However, we can do better by mimicking what is done for VMX.
>> In the absence of PCI passthrough, the guest PAT can be ignored
>> and the page attributes can be just WB. If passthrough is being
>> used, instead, keep respecting the guest PAT, and emulate the guest
>> MTRRs through the PAT field of the nested page tables.
>>
>> The only snag is that WP memory cannot be emulated correctly,
>> because Linux's default PAT setting only includes the other types.
>>
>
> As of quite recently, Linux understands that the PAT has eight slots,
> and we can probably give you WP. Do you want it?
It doesn't really matter, it's mostly used in the firmware.
Paolo
next prev parent reply other threads:[~2015-07-17 2:31 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-07-07 13:45 [RFC/RFT PATCH v2 0/4] KVM: x86: full virtualization of guest MTRR Paolo Bonzini
2015-07-07 13:45 ` [PATCH 1/4] KVM: count number of assigned devices Paolo Bonzini
2015-07-07 15:22 ` Alex Williamson
2015-07-07 15:36 ` Paolo Bonzini
2015-07-07 13:45 ` [PATCH 2/4] KVM: SVM: use NPT page attributes Paolo Bonzini
2015-07-08 5:59 ` Xiao Guangrong
2015-07-08 11:19 ` Paolo Bonzini
2015-07-09 2:30 ` Xiao Guangrong
2015-07-09 15:18 ` Paolo Bonzini
2015-07-10 1:19 ` Xiao Guangrong
2015-07-10 10:47 ` Paolo Bonzini
2015-07-10 16:02 ` Xiao Guangrong
2015-07-17 0:35 ` Andy Lutomirski
2015-07-17 2:31 ` Paolo Bonzini [this message]
2015-07-07 13:45 ` [PATCH 3/4] KVM: SVM: Sync g_pat with guest-written PAT value Paolo Bonzini
2015-07-07 13:45 ` [PATCH 4/4] KVM: x86: apply guest MTRR virtualization on host reserved pages Paolo Bonzini
2015-07-07 14:06 ` [RFC/RFT PATCH v2 0/4] KVM: x86: full virtualization of guest MTRR Joerg Roedel
2015-07-07 14:09 ` Paolo Bonzini
2015-07-07 14:14 ` Joerg Roedel
-- strict thread matches above, loose matches on Subject: below --
2015-07-08 15:18 [RFC/RFT PATCH v3 " Paolo Bonzini
2015-07-08 15:18 ` [PATCH 2/4] KVM: SVM: use NPT page attributes Paolo Bonzini
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