linux-kernel - Re: [PATCH 04/12] swiotlb-xen: ensure to issue well-formed XENMEM

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Message-ID: <d868bbcc-e800-ed30-3524-a30a5feb7e5a@suse.com>
Date:   Mon, 13 Sep 2021 09:17:52 +0200
From:   Jan Beulich <jbeulich@...e.com>
To:     Stefano Stabellini <sstabellini@...nel.org>
Cc:     Juergen Gross <jgross@...e.com>,
        Boris Ostrovsky <boris.ostrovsky@...cle.com>,
        lkml <linux-kernel@...r.kernel.org>,
        "xen-devel@...ts.xenproject.org" <xen-devel@...ts.xenproject.org>
Subject: Re: [PATCH 04/12] swiotlb-xen: ensure to issue well-formed
 XENMEM_exchange requests

On 11.09.2021 01:14, Stefano Stabellini wrote:
> On Tue, 7 Sep 2021, Jan Beulich wrote:
>> While the hypervisor hasn't been enforcing this, we would still better
>> avoid issuing requests with GFNs not aligned to the requested order.
>>
>> Signed-off-by: Jan Beulich <jbeulich@...e.com>
>> ---
>> I wonder how useful it is to include the alignment in the panic()
>> message.
> 
> Not very useful given that it is static. I don't mind either way but you
> can go ahead and remove it if you prefer (and it would make the line
> shorter.)
> 
> 
>> I further wonder how useful it is to wrap "bytes" in
>> PAGE_ALIGN(), when it is a multiple of a segment's size anyway (or at
>> least was supposed to be, prior to "swiotlb-xen: maintain slab count
>> properly").
> 
> This one I would keep, to make sure to print out the same amount passed
> to memblock_alloc.

Oh - if I was to drop it from the printk(), I would have been meaning to
also drop it there. If it's useless, then it's useless everywhere.

Jan