Avi Kivity a écrit :
> Aurelien Jarno wrote:
>> The patch below removes the check for c->modrm_reg == 7 to detect the
>> invlpg instruction, as it was the case before before commit
>> aa38840d3d2e0a804e628077df8d8879b496d741. This fixes the boot of FreeBSD
>> on an AMD64 CPU.
>>
>> It also moves the assignation of c->src.bytes after the test as it is
>> not needed for the invlpg instruction.
>>
>> Signed-off-by: Aurelien Jarno <[EMAIL PROTECTED]>
>>
>> diff --git a/drivers/kvm/x86_emulate.c b/drivers/kvm/x86_emulate.c
>> index fa33fcd..01aa952 100644
>> --- a/drivers/kvm/x86_emulate.c
>> +++ b/drivers/kvm/x86_emulate.c
>> @@ -824,12 +824,10 @@ modrm_done:
>> c->src.bytes = 4;
>> goto srcmem_common;
>> case SrcMem:
>> - c->src.bytes = (c->d & ByteOp) ? 1 :
>> - c->op_bytes;
>> /* Don't fetch the address for invlpg: it could be unmapped. */
>> - if (c->twobyte && c->b == 0x01
>> - && c->modrm_reg == 7)
>> + if (c->twobyte && c->b == 0x01)
>> break;
>> + c->src.bytes = (c->d & ByteOp) ? 1 : c->op_bytes;
>>
>>
>
> I don't understand why this helps. All of the other instructions in
> this group either have modrm_mod == 3 or do require evaluation of the
^^^^^^^^^
The test actually concerns modrm_reg and not modrm_mod. Maybe it is wrong?
> source. invlpg is the only one that doesn't.
I have marked the invlpg instruction the same way as it is done in
kvm-37 to know what happens. I get either modrm_reg = 4 or = 6 when the
invlpg instruction is executed, but never = 7.
> It looks like this patch would break lgdt and lidt (which are only
> needed on Intel).
>
I admit I haven't tried on Intel.
--
.''`. Aurelien Jarno | GPG: 1024D/F1BCDB73
: :' : Debian developer | Electrical Engineer
`. `' [EMAIL PROTECTED] | [EMAIL PROTECTED]
`- people.debian.org/~aurel32 | www.aurel32.net
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