From: Julien Grall <julien.grall@linaro.org>
To: Andrii Tseglytskyi <andrii.tseglytskyi@globallogic.com>,
Ian Campbell <ian.campbell@citrix.com>,
Stefano Stabellini <stefano.stabellini@citrix.com>,
xen-devel@lists.xen.org
Subject: Re: [PATCH v03 01/10] xen: implement guest_physmap_pin_range
Date: Wed, 10 Sep 2014 18:12:46 -0700 [thread overview]
Message-ID: <5410F70E.9040806@linaro.org> (raw)
In-Reply-To: <1409672770-23164-2-git-send-email-andrii.tseglytskyi@globallogic.com>
Hi Andrii,
On 02/09/14 08:46, Andrii Tseglytskyi wrote:
> int guest_physmap_mark_populate_on_demand(struct domain *d,
> unsigned long gfn,
> unsigned int order)
> @@ -478,10 +551,18 @@ static int apply_one_level(struct domain *d,
> struct p2m_domain *p2m = &d->arch.p2m;
> lpae_t pte;
> const lpae_t orig_pte = *entry;
> + struct page_info *page = NULL;
> int rc;
>
> BUG_ON(level > 3);
>
> + if ( guest_physmap_pinned_range(d, orig_pte.p2m.base, 0) )
This change is wrong, orig_pte.p2m.base may not be valid. I think you
have to do this check only on REMOVE and INSERT op.
Also few general questions about this patch:
- What about the destruction of the domain? Shouldn't you remove the
flag?
- In case of REMOVE, if the page is pinned, the error value will be
ignored (this is because guest_physmap_remove_page is returning void).
So the upper code (see guest_remove_page in common/memory.c) will think
the mapping has effectively been removed and will put back the page to
the memory allocator... This is because we don't take a reference when
is mapped.
Overall, AFIU your usage in this patch, I don't think we care if the
guest decides to remove the page from the P2M. The most important things
is to avoid Xen using the page for another guest. I suspect this could
be done by taking a reference on the page.
Regards,
--
Julien Grall
next prev parent reply other threads:[~2014-09-11 1:12 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-09-02 15:46 [PATCH v03 00/10] arm: introduce remoteprocessor iommu module Andrii Tseglytskyi
2014-09-02 15:46 ` [PATCH v03 01/10] xen: implement guest_physmap_pin_range Andrii Tseglytskyi
2014-09-03 9:43 ` Jan Beulich
2014-09-11 1:12 ` Julien Grall [this message]
2014-09-02 15:46 ` [PATCH v03 02/10] domctl: introduce access_remote_pagetable call Andrii Tseglytskyi
2014-09-03 9:46 ` Jan Beulich
2014-09-02 15:46 ` [PATCH v03 03/10] xsm: arm: create domU_rpc_t security label Andrii Tseglytskyi
2014-09-02 15:46 ` [PATCH v03 04/10] arm: introduce remoteprocessor iommu module Andrii Tseglytskyi
2014-09-11 0:41 ` Julien Grall
2014-09-02 15:46 ` [PATCH v03 05/10] arm: omap: introduce iommu translation for IPU remoteproc Andrii Tseglytskyi
2014-09-02 15:46 ` [PATCH v03 06/10] arm: omap: introduce iommu translation for GPU remoteproc Andrii Tseglytskyi
2014-09-02 15:46 ` [PATCH v03 07/10] arm: introduce remoteproc_mmu_translate_pagetable mem subops call Andrii Tseglytskyi
2014-09-03 9:48 ` Jan Beulich
2014-09-13 0:04 ` Stefano Stabellini
2014-09-02 15:46 ` [PATCH v03 08/10] arm: add trap for remoteproc mmio accesses Andrii Tseglytskyi
2014-09-03 9:52 ` Jan Beulich
2014-09-02 15:46 ` [PATCH v03 09/10] arm: omap: introduce print pagetable function for IPU remoteproc Andrii Tseglytskyi
2014-09-02 15:46 ` [PATCH v03 10/10] arm: omap: introduce print pagetable function for GPU remoteproc Andrii Tseglytskyi
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