NAK: [PATCH 2/2 V3] KVM: x86: Emulator should set DR6 upon GD like real CPU

[Stefan Bader]

On 14.02.2017 14:50, Tim Gardner wrote:
> From: Nadav Amit <namit at cs.technion.ac.il>
> 
> BugLink: http://bugs.launchpad.net/bugs/1660519
> 
> It should clear B0-B3 and set BD.
> 
> Signed-off-by: Nadav Amit <namit at cs.technion.ac.il>
> Signed-off-by: Paolo Bonzini <pbonzini at redhat.com>
> (back ported from commit 6d2a0526b09e551d0f395cfb63e7cb965db825af)
> Signed-off-by: Tim Gardner <tim.gardner at canonical.com>
> ---
> 
> v2 - fixed commit log to indicate clean cherry-pick
> v3 - dropped the use of DR6_RTM which had only one
> use and no definition.
> 
>  arch/x86/kvm/emulate.c | 9 ++++++++-
>  1 file changed, 8 insertions(+), 1 deletion(-)
> 
> diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c
> index f8eea19..23717df 100644
> --- a/arch/x86/kvm/emulate.c
> +++ b/arch/x86/kvm/emulate.c
> @@ -3533,8 +3533,15 @@ static int check_dr_read(struct x86_emulate_ctxt *ctxt)
>  	if ((cr4 & X86_CR4_DE) && (dr == 4 || dr == 5))
>  		return emulate_ud(ctxt);
>  
> -	if (check_dr7_gd(ctxt))
> +	if (check_dr7_gd(ctxt)) {
> +		ulong dr6;
> +
> +		ctxt->ops->get_dr(ctxt, 6, &dr6);
> +		dr6 &= ~15;
> +		dr6 |= DR6_BD;

This now sets only bit 13 and not bit 16 ... (it was defined in the original
patch by picking the definition from another patch).


> +		ctxt->ops->set_dr(ctxt, 6, dr6);
>  		return emulate_db(ctxt);
> +	}
>  
>  	return X86EMUL_CONTINUE;
>  }
> 


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