From: Stefano Stabellini <sstabellini@kernel.org>
To: Julien Grall <julien.grall@arm.com>
Cc: "xen-devel@lists.xenproject.org" <xen-devel@lists.xenproject.org>,
Stefano Stabellini <sstabellini@kernel.org>,
Volodymyr Babchuk <Volodymyr_Babchuk@epam.com>
Subject: Re: [Xen-devel] [PATCH v4 6/7] xen/arm: don't iomem_permit_access for reserved-memory regions
Date: Mon, 12 Aug 2019 10:45:40 -0700 (PDT) [thread overview]
Message-ID: <alpine.DEB.2.21.1908121036040.7788@sstabellini-ThinkPad-T480s> (raw)
In-Reply-To: <32e83068-b4ed-0226-5629-d2cab2311873@arm.com>
On Mon, 12 Aug 2019, Julien Grall wrote:
> On 09/08/2019 23:56, Stefano Stabellini wrote:
> > On Thu, 8 Aug 2019, Volodymyr Babchuk wrote:
> > > Hi Stefano,
> > >
> > > Stefano Stabellini writes:
> > >
> > > > Don't allow reserved-memory regions to be remapped into any guests,
> > > > until reserved-memory regions are properly supported in Xen. For now,
> > > > do not call iomem_permit_access for them.
> > > >
> > > > Signed-off-by: Stefano Stabellini <stefanos@xilinx.com>
> > > > ---
> > > >
> > > > Changes in v4:
> > > > - compare the parent name with reserved-memory
> > > > - use dt_node_cmp
> > > >
> > > > Changes in v3:
> > > > - new patch
> > > > ---
> > > > xen/arch/arm/domain_build.c | 24 ++++++++++++++++--------
> > > > 1 file changed, 16 insertions(+), 8 deletions(-)
> > > >
> > > > diff --git a/xen/arch/arm/domain_build.c b/xen/arch/arm/domain_build.c
> > > > index 4c8404155a..267e0549e2 100644
> > > > --- a/xen/arch/arm/domain_build.c
> > > > +++ b/xen/arch/arm/domain_build.c
> > > > @@ -1153,17 +1153,25 @@ static int __init map_range_to_domain(const
> > > > struct dt_device_node *dev,
> > > > struct map_range_data *mr_data = data;
> > > > struct domain *d = mr_data->d;
> > > > bool need_mapping = !dt_device_for_passthrough(dev);
> > > > + const struct dt_device_node *parent = dt_get_parent(dev);
> > > > int res;
> > > >
> > > > - res = iomem_permit_access(d, paddr_to_pfn(addr),
> > > > - paddr_to_pfn(PAGE_ALIGN(addr + len -
> > > > 1)));
> > > > - if ( res )
> > > > + /*
> > > > + * Don't give iomem permissions for reserved-memory ranges until
> > > > + * reserved-memory support is complete.
> > > > + */
> > > > + if ( dt_node_cmp(dt_node_name(parent), "reserved-memory") == 0 )
> > > Am I missing something, or you are permitting access only if it from a
> > > "reserved-memory" node? This contradicts with patch description.
> >
> > Well spotted! I inverted the condition by mistake.
> >
> >
> > > > {
> > > > - printk(XENLOG_ERR "Unable to permit to dom%d access to"
> > > > - " 0x%"PRIx64" - 0x%"PRIx64"\n",
> > > > - d->domain_id,
> > > > - addr & PAGE_MASK, PAGE_ALIGN(addr + len) - 1);
> > > > - return res;
> > > > + res = iomem_permit_access(d, paddr_to_pfn(addr),
> > > > + paddr_to_pfn(PAGE_ALIGN(addr + len -
> > > > 1)));
> > > > + if ( res )
> > > > + {
> > > > + printk(XENLOG_ERR "Unable to permit to dom%d access to"
> > > > + " 0x%"PRIx64" - 0x%"PRIx64"\n",
> > > > + d->domain_id,
> > > > + addr & PAGE_MASK, PAGE_ALIGN(addr + len) - 1);
> > > > + return res;
> > > > + }
> > > > }
> > > >
> > > > if ( need_mapping )
> > > So, this region cold be mapped, but without the access?
>
> IOMEM access and mapping are two different things. The former gives a domain
> control over managing the region (i.e mapping, unmapping, giving access to
> another domain). The latter will map the region in the P2M so the domain can
> read/write into it.
>
> >
> > I'll change it to return early from the function for reserved-memory
> > regions.
>
> I am not sure to understand you suggestion here... You still need to have
> reserved-regions mapped into the hardware domain. The only thing we want to
> prevent is the domain to manage the region.
I forgot that giving iomem permission to dom0 automatically means that
the toolstack can give iomem permission to a domU for the same region.
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next prev parent reply other threads:[~2019-08-13 6:54 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-08-06 21:49 [Xen-devel] [PATCH v4 0/7] reserved-memory in dom0 Stefano Stabellini
2019-08-06 21:49 ` [Xen-devel] [PATCH v4 1/7] xen/arm: extend device_tree_for_each_node Stefano Stabellini
2019-08-07 16:08 ` Julien Grall
2019-08-07 16:16 ` Julien Grall
2019-08-09 22:01 ` Stefano Stabellini
2019-08-06 21:49 ` [Xen-devel] [PATCH v4 2/7] xen/arm: make process_memory_node a device_tree_node_func Stefano Stabellini
2019-08-07 16:19 ` Julien Grall
2019-08-09 21:08 ` Stefano Stabellini
2019-08-06 21:49 ` [Xen-devel] [PATCH v4 3/7] xen/arm: keep track of reserved-memory regions Stefano Stabellini
2019-08-07 16:33 ` Julien Grall
2019-08-09 22:19 ` Stefano Stabellini
2019-08-09 23:57 ` Julien Grall
2019-08-12 18:10 ` Stefano Stabellini
2019-08-07 16:46 ` Julien Grall
2019-08-09 20:37 ` Stefano Stabellini
2019-08-06 21:49 ` [Xen-devel] [PATCH v4 4/7] xen/arm: early_print_info print reserved_mem Stefano Stabellini
2019-08-07 16:36 ` Julien Grall
2019-08-09 20:29 ` Stefano Stabellini
2019-08-06 21:49 ` [Xen-devel] [PATCH v4 5/7] xen/arm: handle reserved-memory in consider_modules and dt_unreserved_regions Stefano Stabellini
2019-08-06 21:49 ` [Xen-devel] [PATCH v4 6/7] xen/arm: don't iomem_permit_access for reserved-memory regions Stefano Stabellini
2019-08-08 19:19 ` Volodymyr Babchuk
2019-08-09 22:56 ` Stefano Stabellini
2019-08-12 10:43 ` Julien Grall
2019-08-12 17:45 ` Stefano Stabellini [this message]
2019-08-06 21:49 ` [Xen-devel] [PATCH v4 7/7] xen/arm: add reserved-memory regions to the dom0 memory node Stefano Stabellini
2019-08-07 18:29 ` Julien Grall
2019-08-08 19:11 ` [Xen-devel] [PATCH v4 0/7] reserved-memory in dom0 Volodymyr Babchuk
2019-08-08 19:16 ` Stefano Stabellini
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