> -----Original Message-----
> From: Wood Scott-B07421
> Sent: Saturday, August 10, 2013 6:35 AM
> To: Bhushan Bharat-R65777
> Cc: benh@xxxxxxxxxxxxxxxxxxx; agraf@xxxxxxx; paulus@xxxxxxxxx;
> kvm@xxxxxxxxxxxxxxx; kvm-ppc@xxxxxxxxxxxxxxx; linuxppc-dev@xxxxxxxxxxxxxxxx;
> Bhushan Bharat-R65777
> Subject: Re: [PATCH 6/6 v3] kvm: powerpc: use caching attributes as per linux
> pte
>
> On Tue, 2013-08-06 at 17:01 +0530, Bharat Bhushan wrote:
> > @@ -449,7 +446,16 @@ static inline int kvmppc_e500_shadow_map(struct
> kvmppc_vcpu_e500 *vcpu_e500,
> > gvaddr &= ~((tsize_pages << PAGE_SHIFT) - 1);
> > }
> >
> > - kvmppc_e500_ref_setup(ref, gtlbe, pfn);
> > + pgdir = vcpu_e500->vcpu.arch.pgdir;
> > + ptep = lookup_linux_pte(pgdir, hva, &tsize_pages);
> > + if (pte_present(*ptep)) {
> > + wimg = (pte_val(*ptep) >> PTE_WIMGE_SHIFT) & MAS2_WIMGE_MASK;
> > + } else {
> > + printk(KERN_ERR "pte not present: gfn %lx, pfn %lx\n",
> > + (long)gfn, pfn);
> > + return -EINVAL;
>
> Don't let the guest spam the host kernel console by repeatedly accessing bad
> mappings (even if it requires host userspace to assist by pointing a memslot at
> a bad hva). This should at most be printk_ratelimited(), and probably just
> pr_debug(). It should also have __func__ context.
Very good point, I will make this printk_ratelimited() in this patch. And convert this and other error prints to pr_debug() when we will send machine check on error in this flow.
>
> Also, I don't see the return value getting checked (the immediate callers check
> it and propogate the error, but kvmppc_mmu_map() doesn't).
> We want to send a machine check to the guest if this happens (or possibly exit
> to userspace since it indicates a bad memslot, not just a guest bug). We don't
> want to just silently retry over and over.
I completely agree with you, but this was something already missing (error return by this function is nothing new added in this patch), So I would like to take that separately.
>
> Otherwise, this series looks good to me.
Thank you. :)
-Bharat
>
> -Scott
>
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