Message-ID: <559FECF8.5090205@linux.intel.com>
Date: Sat, 11 Jul 2015 00:04:08 +0800
From: Xiao Guangrong <guangrong.xiao@linux.intel.com>
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To: Paolo Bonzini <pbonzini@redhat.com>, linux-kernel@vger.kernel.org,
        kvm@vger.kernel.org
CC: joerg.roedel@suse.de
Subject: Re: [PATCH] KVM: svm: remove KVM_QUIRK_CD_NW_CLEARED quirk
References: <1436529693-9743-1-git-send-email-pbonzini@redhat.com>
In-Reply-To: <1436529693-9743-1-git-send-email-pbonzini@redhat.com>
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On 07/10/2015 08:01 PM, Paolo Bonzini wrote:
> We can disable CD unconditionally when there is no assigned device.
> KVM now forces guest PAT to all-writeback in that case, so it makes
> sense to also force CR0.CD=0.
>
> When there are assigned devices, emulate cache-disabled operation
> through the page tables.  This behavior is consistent with VMX,
> where CD/NW are not touched by vmentry/vmexit.
>
> Note that buggy firmware that does not clear CD/NW is _seriously_
> old: SeaBIOS for example has been doing it since October 2008.

Reviewed-by: Xiao Guangrong <guangrong.xiao@linux.intel.com>
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