Re: [PATCH] KVM: svm: remove KVM_QUIRK_CD_NW_CLEARED quirk

From: Joerg Roedel
Date: Fri Jul 10 2015 - 11:16:17 EST


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@xxxxxxxxxx>
> ---
> arch/x86/kvm/svm.c | 14 +++++++-------
> 1 file changed, 7 insertions(+), 7 deletions(-)

Looks good to me.

Reviewed-by: Joerg Roedel <jroedel@xxxxxxx>

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