From: Tamas K Lengyel <tamas.lengyel@zentific.com>
To: Jan Beulich <JBeulich@suse.com>
Cc: Ian Campbell <ian.campbell@citrix.com>, Tim Deegan <tim@xen.org>,
Julien Grall <julien.grall@linaro.org>,
Ian Jackson <ian.jackson@eu.citrix.com>,
"xen-devel@lists.xen.org" <xen-devel@lists.xen.org>,
Stefano Stabellini <stefano.stabellini@citrix.com>,
Andres Lagar-Cavilla <andres@lagarcavilla.org>,
Daniel De Graaf <dgdegra@tycho.nsa.gov>,
Tamas K Lengyel <tklengyel@sec.in.tum.de>
Subject: Re: [PATCH for-4.5 v7 05/21] xen: Relocate p2m_access_t into common and swap the order
Date: Thu, 18 Sep 2014 12:52:31 +0200 [thread overview]
Message-ID: <CAErYnshHWoEj2R7kaLbSYkZDOut_Rc_fPti-NdFzNuEeFr8wew@mail.gmail.com> (raw)
In-Reply-To: <541AC0620200007800036152@mail.emea.novell.com>
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On Thu, Sep 18, 2014 at 11:22 AM, Jan Beulich <JBeulich@suse.com> wrote:
> >>> On 17.09.14 at 22:51, <tklengyel@sec.in.tum.de> wrote:
> > We swap the order of the enum of types n ... rwx, as to have rwx at 0.
> This
> > allows
> > us to memset the permission store to 0, without having to specify rwx as
> the
> > default
> > permission when memaccess is not in use. This also has performance
> benefits
> > for
> > non-memaccess paths, as now comparison is to 0 when checking if
> memaccess is
> > in use,
> > which is usually faster.
>
> I'd say often instead of usually here.
>
Ack.
>
> And then the description leaves open whether any dependency on
> rwx now being first is getting introduced (no memset() is being added
> here, yet wherever an explicit one would get added a respective
> BUILD_BUG_ON() should be put along with it).
>
> Jan
>
I guess the commit message is a bit ambiguous, the paths I see all set
mem_access explicitly afterwards to default_access, so there is no reliance
on pure memset initializing it right now. This patch really just opens the
door to have such an approach in the future (if needed).
Tamas
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next prev parent reply other threads:[~2014-09-18 10:52 UTC|newest]
Thread overview: 46+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-09-17 20:51 [PATCH for-4.5 v7 00/21] Mem_event and mem_access for ARM Tamas K Lengyel
2014-09-17 20:51 ` [PATCH for-4.5 v7 01/21] xen: Relocate mem_access and mem_event into common Tamas K Lengyel
2014-09-17 20:51 ` [PATCH for-4.5 v7 02/21] xen: Relocate struct npfec definition " Tamas K Lengyel
2014-09-17 20:51 ` [PATCH for-4.5 v7 03/21] xen: Relocate mem_event_op domctl and access_op memop " Tamas K Lengyel
2014-09-17 20:51 ` [PATCH for-4.5 v7 04/21] xen: Relocate set_access_required domctl " Tamas K Lengyel
2014-09-18 9:18 ` Jan Beulich
2014-09-18 10:36 ` Tamas K Lengyel
2014-09-18 10:37 ` Tamas K Lengyel
2014-09-18 11:17 ` Tim Deegan
2014-09-18 11:21 ` Tamas K Lengyel
2014-09-18 12:34 ` Jan Beulich
2014-09-18 13:02 ` Tamas K Lengyel
2014-09-17 20:51 ` [PATCH for-4.5 v7 05/21] xen: Relocate p2m_access_t into common and swap the order Tamas K Lengyel
2014-09-18 9:22 ` Jan Beulich
2014-09-18 10:52 ` Tamas K Lengyel [this message]
2014-09-17 20:51 ` [PATCH for-4.5 v7 06/21] xen: Relocate p2m_mem_access_resume to mem_access common Tamas K Lengyel
2014-09-17 20:51 ` [PATCH for-4.5 v7 07/21] xen: Relocate p2m_mem_access_check into common and refactor it Tamas K Lengyel
2014-09-18 9:28 ` Jan Beulich
2014-09-18 10:39 ` Tim Deegan
2014-09-18 10:47 ` Tamas K Lengyel
2014-09-18 11:13 ` Tim Deegan
2014-09-22 12:08 ` Ian Campbell
2014-09-17 20:51 ` [PATCH for-4.5 v7 08/21] x86/p2m: Typo fix for spelling ambiguous Tamas K Lengyel
2014-09-17 20:51 ` [PATCH for-4.5 v7 09/21] x86/p2m: Fix conversion macro of p2m_access to XENMEM_access Tamas K Lengyel
2014-09-18 9:35 ` Jan Beulich
2014-09-18 9:41 ` Tamas K Lengyel
2014-09-17 20:51 ` [PATCH for-4.5 v7 10/21] xen/mem_event: Clean out superfluous white-spaces Tamas K Lengyel
2014-09-17 20:51 ` [PATCH for-4.5 v7 11/21] xen/mem_event: Relax error condition on debug builds Tamas K Lengyel
2014-09-17 20:51 ` [PATCH for-4.5 v7 12/21] xen/mem_event: Abstract architecture specific sanity checks Tamas K Lengyel
2014-09-17 20:51 ` [PATCH for-4.5 v7 13/21] xen/mem_access: Abstract architecture specific sanity check Tamas K Lengyel
2014-09-17 20:51 ` [PATCH for-4.5 v7 14/21] xen/arm: p2m changes for mem_access support Tamas K Lengyel
2014-09-22 12:20 ` Ian Campbell
2014-09-22 17:16 ` Tamas K Lengyel
2014-09-17 20:51 ` [PATCH for-4.5 v7 15/21] xen/arm: Implement domain_get_maximum_gpfn Tamas K Lengyel
2014-09-17 20:51 ` [PATCH for-4.5 v7 16/21] xen/arm: Add p2m_set_permission and p2m_shatter_page helpers Tamas K Lengyel
2014-09-22 12:24 ` Ian Campbell
2014-09-22 18:24 ` Tamas K Lengyel
2014-09-17 20:51 ` [PATCH for-4.5 v7 17/21] xen/arm: Data abort exception (R/W) mem_events Tamas K Lengyel
2014-09-17 20:51 ` [PATCH for-4.5 v7 18/21] xen/arm: Instruction prefetch abort (X) mem_event handling Tamas K Lengyel
2014-09-17 20:51 ` [PATCH for-4.5 v7 19/21] xen/arm: Enable the compilation of mem_access and mem_event on ARM Tamas K Lengyel
2014-09-17 20:51 ` [PATCH for-4.5 v7 20/21] tools/libxc: Allocate magic page for mem access " Tamas K Lengyel
2014-09-17 20:51 ` [PATCH for-4.5 v7 21/21] tools/tests: Enable xen-access " Tamas K Lengyel
2014-09-22 12:29 ` Ian Campbell
2014-09-22 17:11 ` Tamas K Lengyel
2014-09-23 8:37 ` Ian Campbell
2014-09-18 9:21 ` [PATCH for-4.5 v7 00/21] Mem_event and mem_access for ARM Tim Deegan
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