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Date: Mon, 15 Sep 2008 12:48:43 -0300
From: Eduardo Habkost <ehabkost@redhat.com>
Subject: Re: [Qemu-devel] Re: [PATCH] Make page_find() return 0 for
	too-large addresses
Message-ID: <20080915154843.GC12539@blackpad>
References: <20080912185856.GM3982@blackpad> <48CAC809.5000901@codemonkey.ws>
	<20080912201406.GA10147@blackpad> <20080912204404.GB10147@blackpad>
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To: Anthony Liguori <anthony@codemonkey.ws>
Cc: qemu-devel@nongnu.org, kvm@vger.kernel.org, gcosta@redhat.com

On Mon, Sep 15, 2008 at 10:29:14AM -0500, Anthony Liguori wrote:
> Eduardo Habkost wrote:
<snip>
>>
>> New patch, reusing the range check from page_find_alloc() on
>> page_find(). Untested.
>>  =20
>
> Have you tested this patch yet?  I like to avoid being the first one to=
 =20
> test something when it's not my code :-)

I've tested it now, both with KVM enabled and with KVM disabled. My
machine didn't explode yet, so it seems to be fine.  :)

>
> Regards,
>
> Anthony Liguori
>
>> Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
>> ---
>> Index: qemu/exec.c
>> =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
>> --- qemu/exec.c	(revis=E3o 5200)
>> +++ qemu/exec.c	(c=F3pia de trabalho)
>> @@ -279,17 +279,24 @@ static void page_init(void)
>>  #endif
>>  }
>>  -static inline PageDesc *page_find_alloc(target_ulong index)
>> +static inline PageDesc **page_l1_map(target_ulong index)
>>  {
>> -    PageDesc **lp, *p;
>> -
>>  #if TARGET_LONG_BITS > 32
>>      /* Host memory outside guest VM.  For 32-bit targets we have alre=
ady
>>         excluded high addresses.  */
>>      if (index > ((target_ulong)L2_SIZE * L1_SIZE))
>>          return NULL;
>>  #endif
>> -    lp =3D &l1_map[index >> L2_BITS];
>> +    return &l1_map[index >> L2_BITS];
>> +}
>> +
>> +static inline PageDesc *page_find_alloc(target_ulong index)
>> +{
>> +    PageDesc **lp, *p;
>> +    lp =3D page_l1_map(index);
>> +    if (!lp)
>> +        return NULL;
>> +
>>      p =3D *lp;
>>      if (!p) {
>>          /* allocate if not found */
>> @@ -316,9 +323,12 @@ static inline PageDesc *page_find_alloc(
>>   static inline PageDesc *page_find(target_ulong index)
>>  {
>> -    PageDesc *p;
>> +    PageDesc **lp, *p;
>> +    lp =3D page_l1_map(index);
>> +    if (!lp)
>> +        return NULL;
>>  -    p =3D l1_map[index >> L2_BITS];
>> +    p =3D *lp;
>>      if (!p)
>>          return 0;
>>      return p + (index & (L2_SIZE - 1));
>>
>>
>>  =20
>
>

--=20
Eduardo