Guillaume Thouvenin wrote:
> On Fri, 18 Apr 2008 08:23:07 -0500
> Anthony Liguori <[EMAIL PROTECTED]> wrote:
>
>
>
>> This doesn't seem right. You should have been able to break out of the
>> emulator long before encountering an out instruction. The next
>> instruction you encounter should be a mov instruction. Are you sure
>> you're updating eip correctly?
>>
>
> I think that eip is updated correctly but you're right, I think that
> the condition to stop emulation is not well implemented. I emulate a
> lot of mov instructions and I remain blocked in the emulation loop
> until I reach the "out" instruction. The loop is the following:
>
> [...]
> cs_rpl = vmcs_read16(GUEST_CS_SELECTOR) & SELECTOR_RPL_MASK;
> ss_rpl = vmcs_read16(GUEST_SS_SELECTOR) & SELECTOR_RPL_MASK;
>
> while (cs_rpl != ss_rpl) {
> if (emulate_instruction(vcpu, NULL, 0,0, 0) == EMULATE_FAIL) {
> printk(KERN_INFO "%s: emulation of 0x%x failed\n",
> __FUNCTION__,
> vcpu->arch.emulate_ctxt.decode.b);
> return -1;
> }
> cs_rpl = vmcs_read16(GUEST_CS_SELECTOR) & SELECTOR_RPL_MASK;
> ss_rpl = vmcs_read16(GUEST_SS_SELECTOR) & SELECTOR_RPL_MASK;
> }
> printk(KERN_INFO "%s: VMX friendly state recovered\n", __FUNCTION__);
> // I never reach this point
>
> Maybe CS and SS selector are not well updated. I will add trace to see
> their values before and after the emulation.
>
I'd prefer you not do an emulate_instruction loop at all. Just emulate
one instruction on vmentry failure and let VT tell you what instructions
you need to emulate.
It's only four instructions so I don't think the performance is going to
matter. Take a look at the patch I posted previously.
Regards,
Anthony Liguori
> Regards,
> Guillaume
>
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