From: Julien Grall <julien.grall@arm.com>
To: Benjamin Sanda <ben.sanda@dornerworks.com>,
xen-devel@lists.xenproject.org
Cc: Keir Fraser <keir@xen.org>,
Stefano Stabellini <stefano.stabellini@eu.citrix.com>,
Ian Jackson <ian.jackson@eu.citrix.com>,
Dario Faggioli <dario.faggioli@citrix.com>,
Tim Deegan <tim@xen.org>,
George Dunlap <george.dunlap@citrix.com>,
Jan Beulich <jbeulich@suse.com>,
Andrew Cooper <andrew.cooper3@citrix.com>,
Paul Sujkov <psujkov@gmail.com>
Subject: Re: [PATCH 3/6] xentrace: P2M lookup suport for ARM platform
Date: Thu, 17 Mar 2016 16:21:27 +0000 [thread overview]
Message-ID: <56EAD987.6080204@arm.com> (raw)
In-Reply-To: <1458161499-15313-4-git-send-email-ben.sanda@dornerworks.com>
Hello Benjamin,
Thank you for the patch.
On 16/03/16 20:51, Benjamin Sanda wrote:
> From: bensanda <ben.sanda@dornerworks.com>
>
> Modified p2m_lookup() to provide support for xentrace on the ARM platform. Added check for DOMID_XEN which skips PFN to MFN translation. xentrace sends a MFN dirrectly when requesting DOMID_XEN, so no translation is needed. Also sets page memory type, p2m_type_t, to p2m_ram_rw to provide correct access.
A line in the commit message should not be longer than 72 characters.
>
> Signed-off-by: Benjamin Sanda <ben.sanda@dornerworks.com>
> ---
> xen/arch/arm/p2m.c | 19 +++++++++++++++----
> 1 file changed, 15 insertions(+), 4 deletions(-)
>
> diff --git a/xen/arch/arm/p2m.c b/xen/arch/arm/p2m.c
> index a2a9c4b..2e7da43 100644
> --- a/xen/arch/arm/p2m.c
> +++ b/xen/arch/arm/p2m.c
> @@ -228,10 +228,21 @@ paddr_t p2m_lookup(struct domain *d, paddr_t paddr, p2m_type_t *t)
> paddr_t ret;
> struct p2m_domain *p2m = &d->arch.p2m;
>
> - spin_lock(&p2m->lock);
> - ret = __p2m_lookup(d, paddr, t);
> - spin_unlock(&p2m->lock);
> -
> + /* Check for DOMID_XEN: If we are called with DOMID_XEN (from xentrace)
Multi-lines comment in Xen should be:
/*
* Foo
* Bar
*/
You can find the coding style in CODING_STYLE.
> + then paddr is already a MFN and no translation is needed. We only set the
> + page type as p2m_raw_rw and return the MFN directly */
DOMID_XEN is not specific to xentrace. It's a mechanism to share xenheap
page to any guest.
xentrace is using directly an MFN because DOMID_XEN is considered as a
PV guest on x86 (i.e MFN == GFN). And we don't have a such concept on ARM.
> + if(DOMID_XEN != d->domain_id)
if ( d->domain_id != DOMID_XEN )
> + {
> + spin_lock(&p2m->lock);
> + ret = __p2m_lookup(d, paddr, t);
> + spin_unlock(&p2m->lock);
> + }
> + else
> + {
> + *t = p2m_ram_rw;
A DOMID_XEN page could be read only too. For instance, the meta-data of
the trace buffer is read-only (see t_info), we don't want a domain to be
able to overwrite them.
However, all the foreign page are mapped read-write. You will need to
rework the code to map a foreign domain (see XENMAPSPACE_gmfn_foreign)
to allow read-only foreign page (maybe by adding a new p2m_type_t?).
> + ret = paddr;
> + }
> +
> return ret;
> }
>
>
Regards,
--
Julien Grall
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next prev parent reply other threads:[~2016-03-17 16:21 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-03-16 20:51 [PATCH 0/6] xentrace/xenalyze support on ARM Benjamin Sanda
2016-03-16 20:51 ` [PATCH 1/6] Flask: Support for ARM xentrace Benjamin Sanda
2016-03-17 14:56 ` Julien Grall
2016-03-17 15:03 ` Julien Grall
2016-03-25 19:27 ` Konrad Rzeszutek Wilk
2016-03-28 15:52 ` Ben Sanda
2016-03-16 20:51 ` [PATCH 2/6] xenalyze: Support for ARM platform Benjamin Sanda
2016-03-16 20:59 ` Andrew Cooper
2016-03-17 10:39 ` George Dunlap
2016-03-16 20:51 ` [PATCH 3/6] xentrace: P2M lookup suport " Benjamin Sanda
2016-03-17 16:21 ` Julien Grall [this message]
2016-03-28 18:55 ` Ben Sanda
2016-03-30 18:38 ` Julien Grall
2016-03-16 20:51 ` [PATCH 4/6] xentrace: ARM platform DOMID_XEN mapping support Benjamin Sanda
2016-03-17 15:53 ` Julien Grall
2016-03-16 20:51 ` [PATCH 5/6] xentrace: Trace buffer support for ARM platform Benjamin Sanda
2016-03-16 20:51 ` [PATCH 6/6] xentrace: ARM platform timestamp support Benjamin Sanda
2016-03-25 19:31 ` Konrad Rzeszutek Wilk
2016-03-31 16:38 ` Stefano Stabellini
2016-03-31 16:44 ` Ben Sanda
2016-04-01 13:05 ` Stefano Stabellini
2016-03-17 15:00 ` [PATCH 0/6] xentrace/xenalyze support on ARM Julien Grall
2016-03-17 16:50 ` Ben Sanda
2016-03-17 17:01 ` Julien Grall
2016-03-17 17:04 ` Ben Sanda
2016-03-18 17:12 ` Wei Liu
2016-03-17 17:23 ` George Dunlap
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