From: Joerg Roedel <jroedel@suse.de>
To: Paolo Bonzini <pbonzini@redhat.com>
Cc: linux-kernel@vger.kernel.org, kvm@vger.kernel.org,
guangrong.xiao@linux.intel.com, joerg.roedel@suse.de
Subject: Re: [PATCH] KVM: svm: remove KVM_QUIRK_CD_NW_CLEARED quirk
Date: Fri, 10 Jul 2015 17:16:03 +0200 [thread overview]
Message-ID: <20150710151603.GI2566@suse.de> (raw)
In-Reply-To: <1436529693-9743-1-git-send-email-pbonzini@redhat.com>
On Fri, Jul 10, 2015 at 02:01:33PM +0200, 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.
>
> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
> ---
> arch/x86/kvm/svm.c | 14 +++++++-------
> 1 file changed, 7 insertions(+), 7 deletions(-)
Looks good to me.
Reviewed-by: Joerg Roedel <jroedel@suse.de>
next prev parent reply other threads:[~2015-07-10 15:16 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-07-10 12:01 [PATCH] KVM: svm: remove KVM_QUIRK_CD_NW_CLEARED quirk Paolo Bonzini
2015-07-10 15:16 ` Joerg Roedel [this message]
2015-07-10 16:04 ` Xiao Guangrong
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