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Subject: Re: [PATCH v3 2/5] KVM: MMU: check guest CR3 reserved bits based on
 its physical address width.
To: Yu Zhang <yu.c.zhang@linux.intel.com>, kvm@vger.kernel.org
Cc: linux-kernel@vger.kernel.org, rkrcmar@redhat.com, tglx@linutronix.de,
        mingo@redhat.com, hpa@zytor.com, xiaoguangrong@tencent.com,
        joro@8bytes.org
References: <1503577676-12345-1-git-send-email-yu.c.zhang@linux.intel.com>
 <1503577676-12345-3-git-send-email-yu.c.zhang@linux.intel.com>
From: Paolo Bonzini <pbonzini@redhat.com>
Message-ID: <0bce2df3-79ac-599b-19fa-8ebeaff23623@redhat.com>
Date: Thu, 24 Aug 2017 15:40:04 +0200
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On 24/08/2017 14:27, Yu Zhang wrote:
> diff --git a/arch/x86/kvm/mmu.h b/arch/x86/kvm/mmu.h
> index 3ed6192..67e7ec2 100644
> --- a/arch/x86/kvm/mmu.h
> +++ b/arch/x86/kvm/mmu.h
> @@ -48,6 +48,9 @@
>  
>  static inline u64 rsvd_bits(int s, int e)
>  {
> +	if (e < s)
> +		return 0;
> +
>  	return ((1ULL << (e - s + 1)) - 1) << s;
>  }

e = s - 1 is already supported; why do you need e <= s - 2?

Paolo