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SubjectRe: [PATCH 1/4] KVM: SVM: nested: Don't allocate VMCB structures on stack
Hi Sean,

thanks for your review!

On Wed, Jul 29, 2020 at 08:14:55AM -0700, Sean Christopherson wrote:
> On Wed, Jul 29, 2020 at 03:22:31PM +0200, Joerg Roedel wrote:
> Speaking of too large, would it be overly paranoid to add:
>
> BUILD_BUG_ON(sizeof(struct vmcb_control_area) + sizeof(struct vmcb_save_area) <
> KVM_STATE_NESTED_SVM_VMCB_SIZE)
>
> More so for documentation than for any real concern that the SVM architecture
> will do something silly, e.g. to make it obvious that patch 2 in this series
> won't break backwards compatibility.

The check should actually be '>', but then it makes sense. The control-
and save-area together are still way smaller than 4k. I will add the
check for '>' to this patch.

> > + ret = -EFAULT;
> > + if (copy_from_user(ctl, &user_vmcb->control, sizeof(ctl)))
>
> The sizeof() calc is wrong, this is now calculating the size of the pointer,
> not the size of the struct. It'd need to be sizeof(*ctl).
>
> > + goto out_free;
> > + if (copy_from_user(save, &user_vmcb->save, sizeof(save)))
>
> Same bug here.

Thanks, fixed that.

Regards,

Joerg

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