Re: [PATCH 2/6] MMU: don't bail on PAT bits in PTE

From: Avi Kivity <avi@redhat.com>
To: Joerg Roedel <joerg.roedel@amd.com>
Cc: Alexander Graf <agraf@suse.de>,
	"Michael S. Tsirkin" <mst@redhat.com>,
	kvm@vger.kernel.org
Subject: Re: [PATCH 2/6] MMU: don't bail on PAT bits in PTE
Date: Sun, 17 May 2009 12:51:40 +0300	[thread overview]
Message-ID: <4A0FDE2C.5020305@redhat.com> (raw)
In-Reply-To: <20090515131943.GT9835@amd.com>

Joerg Roedel wrote:
> Subject: [PATCH] kvm/mmu: fix reserved bit checking on 4kb pte level
>
> The reserved bits checking code looks at bit 7 of the pte to determine
> if it has to use the mask for a large pte or a normal pde. This does not
> work on 4kb pte level because bit 7 is used there for PAT. Account this
> in the checking function.
>
>  
>  static bool is_rsvd_bits_set(struct kvm_vcpu *vcpu, u64 gpte, int level)
>  {
> -	int bit7;
> +	int bit7 = 0;
> +
> +	if (level != PT_PAGE_TABLE_LEVEL)
> +		bit7 = (gpte >> 7) & 1;
>  
> -	bit7 = (gpte >> 7) & 1;
>  	return (gpte & vcpu->arch.mmu.rsvd_bits_mask[bit7][level-1]) != 0;
>  }
>  
>   

If we make rsvd_bits_mask[1][0] == rsvd_bits_mask[0][0], we don't need 
the extra check.  That's why it is named bit7 and not pse (need to make 
sure bit 7 is not reserved in this case).

-- 
error compiling committee.c: too many arguments to function