linux-kernel - Re: [PATCH 3/4] KVM: s390: replace bitmap_copy with bitmap_{from,to}

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Message-ID: <f2edeb89-54be-6100-9464-c99fdc4bd439@redhat.com>
Date:   Thu, 21 Apr 2022 09:24:20 +0200
From:   David Hildenbrand <david@...hat.com>
To:     Yury Norov <yury.norov@...il.com>, linux-kernel@...r.kernel.org,
        Alexander Gordeev <agordeev@...ux.ibm.com>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        Christian Borntraeger <borntraeger@...ux.ibm.com>,
        Claudio Imbrenda <imbrenda@...ux.ibm.com>,
        Heiko Carstens <hca@...ux.ibm.com>,
        Janosch Frank <frankja@...ux.ibm.com>,
        Rasmus Villemoes <linux@...musvillemoes.dk>,
        Sven Schnelle <svens@...ux.ibm.com>,
        Vasily Gorbik <gor@...ux.ibm.com>, linux-s390@...r.kernel.org,
        kvm@...r.kernel.org
Subject: Re: [PATCH 3/4] KVM: s390: replace bitmap_copy with
 bitmap_{from,to}_arr64 where appropriate

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?

IIUC, bitmap_to_arr64() translates to bitmap_copy_clear_tail() on s390x.

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

Reviewed-by: David Hildenbrand <david@...hat.com>


-- 
Thanks,

David / dhildenb