linux-kernel - Re: [Xen-devel] [PATCH V2 3/7]: PVH: mmu related changes.

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Message-ID: <1350032276.14806.53.camel@zakaz.uk.xensource.com>
Date:	Fri, 12 Oct 2012 09:57:56 +0100
From:	Ian Campbell <Ian.Campbell@...rix.com>
To:	Mukesh Rathor <mukesh.rathor@...cle.com>
CC:	Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>,
	"Xen-devel@...ts.xensource.com" <Xen-devel@...ts.xensource.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [Xen-devel] [PATCH V2 3/7]: PVH:  mmu related changes.

On Thu, 2012-10-11 at 22:58 +0100, Mukesh Rathor wrote:
> @@ -2177,8 +2210,19 @@ static const struct pv_mmu_ops xen_mmu_ops __initconst = {
> 
>  void __init xen_init_mmu_ops(void)
>  {
> -       x86_init.mapping.pagetable_reserve = xen_mapping_pagetable_reserve;
>         x86_init.paging.pagetable_init = xen_pagetable_init;
> +
> +       if (xen_feature(XENFEAT_auto_translated_physmap)) {
> +               pv_mmu_ops.flush_tlb_others = xen_flush_tlb_others;
> +
> +               /* For PCI devices to map iomem. */
> +               if (xen_initial_domain()) {
> +                       pv_mmu_ops.set_pte = native_set_pte;
> +                       pv_mmu_ops.set_pte_at = native_set_pte_at;

What do these end up being for the !xen_initial_domain case? I'd have
expected native_FOO.

> +int xen_unmap_domain_mfn_range(struct vm_area_struct *vma)
> +{
> +       int numpgs = (vma->vm_end - vma->vm_start) >> PAGE_SHIFT;
> +       struct page **pages = vma ? vma->vm_private_data : NULL;

I thought we agreed to keep uses of vm_private_data in the privcmd
driver?

I think you should just add pages and nr as direct parameters to this
function, which is symmetric with the map call.

> +
> +       if (!pages || !xen_feature(XENFEAT_auto_translated_physmap))
> +               return 0;
> +
> +       while (numpgs--) {
> +
> +               /* the mmu has already cleaned up the process mmu resources at
> +                * this point (lookup_address will return NULL). */
> +               unsigned long pfn = page_to_pfn(pages[numpgs]);
> +
> +               pvh_rem_xen_p2m(pfn, 1);
> +       }
> +       /* We don't need to flush tlbs because as part of pvh_rem_xen_p2m(),
> +        * the hypervisor will do tlb flushes after removing the p2m entries
> +        * from the EPT/NPT */
> +       return 0;
> +}
> +EXPORT_SYMBOL_GPL(xen_unmap_domain_mfn_range);
[...]
> diff --git a/drivers/xen/privcmd.c b/drivers/xen/privcmd.c
> index ef63895..63d9ee8 100644
> --- a/drivers/xen/privcmd.c
> +++ b/drivers/xen/privcmd.c
> @@ -178,7 +178,7 @@ static int mmap_mfn_range(void *data, void *state)
>                                         msg->va & PAGE_MASK,
>                                         msg->mfn, msg->npages,
>                                         vma->vm_page_prot,
> -                                       st->domain);
> +                                       st->domain, NULL);

Might it be useful to BUG_ON(!pages) in pvh_remap_gmfn_range?

Ian.

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