Re: [PATCH v2 4/6] KVM: x86: Introduce KVM_GET_SREGS2 / KVM_SET_SREGS2

[Paolo Bonzini]

On 26/04/21 14:56, Maxim Levitsky wrote:
> On Mon, 2021-04-26 at 14:32 +0200, Paolo Bonzini wrote:
> > On 26/04/21 13:13, Maxim Levitsky wrote:
> > > +	if (sregs2->flags & KVM_SREGS2_FLAGS_PDPTRS_VALID) {
> > > +
> > > +		if (!is_pae_paging(vcpu))
> > > +			return -EINVAL;
> > > +
> > > +		for (i = 0 ; i < 4 ; i++)
> > > +			kvm_pdptr_write(vcpu, i, sregs2->pdptrs[i]);
> > > +
> > > +		kvm_register_mark_dirty(vcpu, VCPU_EXREG_PDPTR);
> > > +		mmu_reset_needed = 1;
> > > +	}
> >
> > I think this should also have
> >
> > 	else {
> > 		if (is_pae_paging(vcpu))
> > 			return -EINVAL;
> > 	}
>
>
> What about the case when we migrate from qemu that doesn't use
> this ioctl to qemu that does?

Right, that makes sense but then the "else" branch should do the same as 
KVM_SET_SREGS.  Maybe add a "load_pdptrs" bool to __set_sregs_common?

Paolo