From: Yury Norov <yury.norov@gmail.com>
To: David Hildenbrand <david@redhat.com>
Cc: linux-kernel@vger.kernel.org,
Alexander Gordeev <agordeev@linux.ibm.com>,
Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
Christian Borntraeger <borntraeger@linux.ibm.com>,
Claudio Imbrenda <imbrenda@linux.ibm.com>,
Heiko Carstens <hca@linux.ibm.com>,
Janosch Frank <frankja@linux.ibm.com>,
Rasmus Villemoes <linux@rasmusvillemoes.dk>,
Sven Schnelle <svens@linux.ibm.com>,
Vasily Gorbik <gor@linux.ibm.com>,
linux-s390@vger.kernel.org, kvm@vger.kernel.org
Subject: Re: [PATCH 3/4] KVM: s390: replace bitmap_copy with bitmap_{from,to}_arr64 where appropriate
Date: Thu, 21 Apr 2022 06:01:23 -0700 [thread overview]
Message-ID: <YmFVo8gR8UQ9uu2e@yury-laptop> (raw)
In-Reply-To: <f2edeb89-54be-6100-9464-c99fdc4bd439@redhat.com>
On Thu, Apr 21, 2022 at 09:24:20AM +0200, David Hildenbrand wrote:
> On 21.04.22 00:25, Yury Norov wrote:
> > Copying bitmaps from/to 64-bit arrays with bitmap_copy is not safe
> > in general case. Use designated functions instead.
> >
>
> Just so I understand correctly: there is no BUG, it's just cleaner to do
> it that way, correct?
Yes. there's no bug, but the pattern is considered bad.
https://lore.kernel.org/all/YiCWNdWd+AsLbDkp@smile.fi.intel.com/T/#m9080cbb8a8235d7d4b7e38292cee8e4903f9afe4q
> IIUC, bitmap_to_arr64() translates to bitmap_copy_clear_tail() on s390x.
Yes.
> As the passed length is always 1024 (KVM_S390_VM_CPU_FEAT_NR_BITS), we
> essentially end up with bitmap_copy() again.
>
>
> Looks cleaner to me
Thanks.
> Reviewed-by: David Hildenbrand <david@redhat.com>
>
>
> --
> Thanks,
>
> David / dhildenb
next prev parent reply other threads:[~2022-04-21 13:01 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-04-20 22:25 [PATCH 0/4] bitmap: fix conversion from/to fix-sized arrays Yury Norov
2022-04-20 22:25 ` [PATCH 1/4] lib/bitmap: extend comment for bitmap_(from,to)_arr32() Yury Norov
2022-04-20 22:25 ` [PATCH 2/4] lib: add bitmap_{from,to}_arr64 Yury Norov
2022-04-21 7:40 ` David Laight
2022-04-21 16:31 ` Yury Norov
2022-04-20 22:25 ` [PATCH 3/4] KVM: s390: replace bitmap_copy with bitmap_{from,to}_arr64 where appropriate Yury Norov
2022-04-21 7:24 ` David Hildenbrand
2022-04-21 13:01 ` Yury Norov [this message]
2022-04-20 22:41 ` [PATCH 4/4] drm/amd/pm: use bitmap_{from,to}_arr32 " Yury Norov
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