From: Fenghua Yu <fenghua.yu@intel.com>
To: Dave Hansen <dave.hansen@intel.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, H Peter Anvin <hpa@zytor.com>,
Ashok Raj <ashok.raj@intel.com>, Alan Cox <alan@linux.intel.com>,
Peter Zijlstra <peterz@infradead.org>,
Rafael Wysocki <rafael.j.wysocki@intel.com>,
Tony Luck <tony.luck@intel.com>,
Ravi V Shankar <ravi.v.shankar@intel.com>,
linux-kernel <linux-kernel@vger.kernel.org>, x86 <x86@kernel.org>
Subject: Re: [PATCH v2 2/4] x86/split_lock: Align x86_capability to unsigned long to avoid split locked access
Date: Fri, 29 Jun 2018 14:10:30 -0700 [thread overview]
Message-ID: <20180629211030.GB68178@romley-ivt3.sc.intel.com> (raw)
In-Reply-To: <8fdfb671-f223-163b-12cd-3c97d94f91b4@intel.com>
On Fri, Jun 29, 2018 at 01:48:45PM -0700, Dave Hansen wrote:
> On 06/29/2018 01:38 PM, Fenghua Yu wrote:
> > How to handle data that is used in generic code which can be used on
> > non-Intel platform? For exmple, if I do this change for struct efi in
> > include/linux/efi.h because set_bit() sets bits in efi.flags:
> > - unsigned long flags;
> > + unsigned long flags __aligned(unsigned long);
> > } efi;
> >
> > People may argue that the alignment unnecessarily increases size of 'efi'
> > on non-Intel platform which doesn't have split lock issue. Do we care this
> > argument?
>
> Unaligned memory accesses are bad, pretty much universally. This is a
> general good practice that we should have been doing anyway. Let folks
> complain. Don't let it stop you.
>
> Also, look at the size of that structure. Look at how many pointers it
> has. Do you think *anyone* is going to complain about an extra 4 bytes
> in a 400-byte structure?
>
> > Another question, there will be a bunch of one-line changes for
> > the alignment (i.e. adding __aligned(unsigned long)) in various files.
> > Will the changes be put in one big patch or in separate one-liner patches?
>
> Just group them logically.
Sure.
Thanks.
-Fenghua
next prev parent reply other threads:[~2018-06-29 21:11 UTC|newest]
Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-06-29 14:33 [PATCH v2 0/4] x86/split_lock: Enable #AC exception for split locked accesses Fenghua Yu
2018-06-29 14:33 ` [PATCH v2 1/4] x86/split_lock: Enumerate #AC exception for split locked access feature Fenghua Yu
2018-06-29 14:56 ` Dave Hansen
2018-06-29 16:23 ` Thomas Gleixner
2018-06-29 16:32 ` Dave Hansen
2018-07-04 20:07 ` Eduardo Habkost
2018-07-10 18:45 ` Fenghua Yu
2018-07-10 18:54 ` Dave Hansen
2018-07-10 19:47 ` Thomas Gleixner
2018-07-11 19:59 ` Dave Hansen
2018-07-12 20:00 ` Thomas Gleixner
2018-06-29 14:33 ` [PATCH v2 2/4] x86/split_lock: Align x86_capability to unsigned long to avoid split locked access Fenghua Yu
2018-06-29 16:04 ` Dave Hansen
2018-06-29 16:35 ` Thomas Gleixner
2018-06-29 19:03 ` Fenghua Yu
2018-06-29 20:08 ` Thomas Gleixner
2018-06-29 20:38 ` Fenghua Yu
2018-06-29 20:48 ` Dave Hansen
2018-06-29 21:10 ` Fenghua Yu [this message]
2018-06-29 21:44 ` Thomas Gleixner
2018-06-30 0:00 ` Fenghua Yu
2018-06-30 0:14 ` Fenghua Yu
2018-06-30 6:23 ` Thomas Gleixner
2018-07-02 12:18 ` Peter Zijlstra
2018-07-02 14:11 ` Fenghua Yu
2018-06-29 14:33 ` [PATCH v2 3/4] x86/split_lock: Handle #AC exception for split lock Fenghua Yu
2018-06-29 16:29 ` Dave Hansen
2018-06-29 16:33 ` Luck, Tony
2018-06-29 17:16 ` Fenghua Yu
2018-06-29 17:29 ` Dave Hansen
2018-06-29 17:39 ` Fenghua Yu
2018-06-29 17:47 ` Dave Hansen
2018-06-29 14:33 ` [PATCH v2 4/4] x86/split_lock: Disable #AC for split locked accesses Fenghua Yu
2018-06-29 16:31 ` Dave Hansen
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