Re: [PATCH] KVM: x86 emulator: switch 'pop reg' instruction to emulate_pop()

Re: [PATCH] KVM: x86 emulator: switch 'pop reg' instruction to emulate_pop()

[Guillaume Thouvenin]

On Thu, 27 Nov 2008 19:43:53 -0000
Avi Kivity <avi@redhat.com> wrote:

> From: Avi Kivity <avi@redhat.com>
> 
> Signed-off-by: Avi Kivity <avi@qumranet.com>
> 
> diff --git a/arch/x86/kvm/x86_emulate.c b/arch/x86/kvm/x86_emulate.c
> index 70242f5..702de98 100644
> --- a/arch/x86/kvm/x86_emulate.c
> +++ b/arch/x86/kvm/x86_emulate.c
> @@ -1389,14 +1389,11 @@ special_insn:
>  		break;
>  	case 0x58 ... 0x5f: /* pop reg */
>  	pop_instruction:
> -		if ((rc = ops->read_std(register_address(c, ss_base(ctxt),
> -			c->regs[VCPU_REGS_RSP]), c->dst.ptr,
> -			c->op_bytes, ctxt->vcpu)) != 0)
> +		c->src.bytes = c->op_bytes;
> +		rc = emulate_pop(ctxt, ops);
> +		if (rc != 0)
>  			goto done;
> -
> -		register_address_increment(c, &c->regs[VCPU_REGS_RSP],
> -					   c->op_bytes);
> -		c->dst.type = OP_NONE;	/* Disable writeback. */
> +		c->dst.val = c->src.val;
>  		break;
>  	case 0x63:		/* movsxd */
>  		if (ctxt->mode != X86EMUL_MODE_PROT64)

With this patch kvmctl ./user/test/x86/realmode.flat failed if
emulate_invalid_guest_state is enabled. The error is:

emulation failed (emulation failure) rip 99 66 2d 9a 01

It seems that instruction pointer is wrong.

Regards,
Guillaume

Re: [PATCH] KVM: x86 emulator: switch 'pop reg' instruction to emulate_pop()

[Avi Kivity]

Guillaume Thouvenin wrote:
> With this patch kvmctl ./user/test/x86/realmode.flat failed if
> emulate_invalid_guest_state is enabled. The error is:
>
> emulation failed (emulation failure) rip 99 66 2d 9a 01
>
> It seems that instruction pointer is wrong.
>
>   

Yes, 'call' was using the pop_instruction path.  I fixed it up.

-- 
I have a truly marvellous patch that fixes the bug which this
signature is too narrow to contain.