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>,
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 4/6] xentrace: ARM platform DOMID_XEN mapping support
Date: Thu, 17 Mar 2016 15:53:45 +0000 [thread overview]
Message-ID: <56EAD309.6010807@arm.com> (raw)
In-Reply-To: <1458161499-15313-5-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 xenmem_add_to_physmap_one() to provide support for xentrace on the ARM platform. Checks for DOMID_XEN added via new function, get_pg_owner, ported from x86 code base. This provides correct calls to rcu_lock_domain() when DOMID_XEN is requested. DOMID_XEN checks also adde to skip page to MFN translation (xentrace sends a MFN dirrectly and so does not need to be translated).
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/mm.c | 56 +++++++++++++++++++++++++++++++++++++++++++++++++++++--
> 1 file changed, 54 insertions(+), 2 deletions(-)
>
> diff --git a/xen/arch/arm/mm.c b/xen/arch/arm/mm.c
> index 81f9e2e..b1d834f 100644
> --- a/xen/arch/arm/mm.c
> +++ b/xen/arch/arm/mm.c
> @@ -41,6 +41,7 @@
> #include <xen/pfn.h>
>
> struct domain *dom_xen, *dom_io, *dom_cow;
> +static struct domain *get_pg_owner(domid_t domid);
I would rather avoid to forward declare a function if there is no strict
dependency on other functions. Instead, I would add the function before
the caller.
>
> /* Static start-of-day pagetables that we use before the allocators
> * are up. These are used by all CPUs during bringup before switching
> @@ -1099,7 +1100,8 @@ int xenmem_add_to_physmap_one(
> {
> struct domain *od;
> p2m_type_t p2mt;
> - od = rcu_lock_domain_by_any_id(foreign_domid);
> + od = get_pg_owner(foreign_domid);
> +
> if ( od == NULL )
> return -ESRCH;
>
> @@ -1132,7 +1134,17 @@ int xenmem_add_to_physmap_one(
> return -EINVAL;
> }
>
> - mfn = page_to_mfn(page);
> + /* If DOMID_XEN then no page to MFN translation is
> + needed as we already have the MFN directly */
> + if(DOMID_XEN !=od->domain_id)
> + {
> + mfn = page_to_mfn(page);
> + }
> + else
> + {
> + mfn = idx;
> + }
> +
Please avoid to spread the DOMID_ID specific case everywhere. The cost
to calculate the MFN of a page is very limited.
> t = p2m_map_foreign;
>
> rcu_unlock_domain(od);
> @@ -1312,6 +1324,46 @@ void clear_and_clean_page(struct page_info *page)
> unmap_domain_page(p);
> }
>
> +/* Ported from x86 architecture: checks for special domain requests for
> +DOMID_XEN or DOMID_IO which must be handled differently then guest domain
> +requests */
> +static struct domain *get_pg_owner(domid_t domid)
This function is very similar to the x86 one. I think it would benefit
to implement get_pg_owner in the common code and add arch specific
helper when it's necessary.
Also, please introduce the helper put_pg_owner to stay consistent.
> +{
> + struct domain *pg_owner = NULL, *curr = current->domain;
> +
> + if ( likely(domid == DOMID_SELF) )
> + {
> + pg_owner = rcu_lock_current_domain();
> + goto out;
> + }
> +
> + if ( unlikely(domid == curr->domain_id) )
> + {
> + goto out;
> + }
> +
> + /* check for special domain cases of DOMID_IO or DOMID_XEN which
> + must use rcu_lock_domain() and dom_xen/dom_io as the domid_t */
> + switch ( domid )
> + {
> + case DOMID_IO:
> + pg_owner = rcu_lock_domain(dom_io);
> + break;
> + case DOMID_XEN:
> + pg_owner = rcu_lock_domain(dom_xen);
> + break;
> + default:
> + if ( (pg_owner = rcu_lock_domain_by_id(domid)) == NULL )
> + {
> + break;
> + }
> + break;
> + }
> +
> + out:
> + return pg_owner;
> +}
> +
> /*
> * Local variables:
> * mode: C
>
Regards,
--
Julien Grall
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next prev parent reply other threads:[~2016-03-17 15:53 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
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 [this message]
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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