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Re: [PATCH v2] Bug fix - Integer overflow when cpu frequency > u32 max value.


  • To: Neowutran <xen@xxxxxxxxxxxxx>
  • From: Jan Beulich <jbeulich@xxxxxxxx>
  • Date: Mon, 19 Dec 2022 09:00:17 +0100
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  • Cc: xen-devel@xxxxxxxxxxxxxxxxxxxx, Andrew Cooper <andrew.cooper3@xxxxxxxxxx>, Roger Pau Monné <roger.pau@xxxxxxxxxx>, Wei Liu <wl@xxxxxxx>, Elliott Mitchell <ehem+xen@xxxxxxx>
  • Delivery-date: Mon, 19 Dec 2022 08:00:27 +0000
  • List-id: Xen developer discussion <xen-devel.lists.xenproject.org>

On 18.12.2022 22:47, Elliott Mitchell wrote:
> On Sun, Dec 18, 2022 at 01:14:07PM +0100, Neowutran wrote:
>> xen/x86: prevent overflow with high frequency TSCs
>>
>> Promote tsc_khz to a 64-bit type before multiplying by 1000 to avoid a
>> 'overflow before widen' bug.
>> Otherwise just above 4.294GHz the value will overflow.
>> Processors with clocks this high are now in production and require this to 
>> work
>> correctly.
>>
>> Signed-off-by: Neowutran <xen@xxxxxxxxxxxxx>
> 
> Needing a bit of word-wrapping, but that can be adjusted during commit to
> the Xen tree.

Right - also the first line of the body really wants to be the title.
I'd be happy to make edits while committing, but as said in reply to
v1 I also would prefer to suffix the literal "1000" instead of adding
a cast. I'd also be happy to make that adjustment (including to the
description), but I'd prefer to do so with your agreement.

Jan



 


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