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Re: [Patch v1] Bug fix - Integer overflow when cpu frequency > u32 max value.


  • To: Andrew Cooper <Andrew.Cooper3@xxxxxxxxxx>, Neowutran <xen@xxxxxxxxxxxxx>
  • From: Jan Beulich <jbeulich@xxxxxxxx>
  • Date: Mon, 19 Dec 2022 08:46:52 +0100
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  • Cc: Roger Pau Monne <roger.pau@xxxxxxxxxx>, Wei Liu <wl@xxxxxxx>, "xen-devel@xxxxxxxxxxxxxxxxxxxx" <xen-devel@xxxxxxxxxxxxxxxxxxxx>
  • Delivery-date: Mon, 19 Dec 2022 07:47:09 +0000
  • List-id: Xen developer discussion <xen-devel.lists.xenproject.org>

On 18.12.2022 01:18, Andrew Cooper wrote:
> On 17/12/2022 5:42 pm, Neowutran wrote:
>> diff --git a/xen/arch/x86/time.c b/xen/arch/x86/time.c
>> index b01acd390d..7c77ec8902 100644
>> --- a/xen/arch/x86/time.c
>> +++ b/xen/arch/x86/time.c
>> @@ -2585,7 +2585,7 @@ int tsc_set_info(struct domain *d,
>>      case TSC_MODE_ALWAYS_EMULATE:
>>          d->arch.vtsc_offset = get_s_time() - elapsed_nsec;
>>          d->arch.tsc_khz = gtsc_khz ?: cpu_khz;
>> -        set_time_scale(&d->arch.vtsc_to_ns, d->arch.tsc_khz * 1000);
>> +        set_time_scale(&d->arch.vtsc_to_ns, (u64)d->arch.tsc_khz * 1000);
> 
> Ah - I see you tracked down your bug in the end.  One minor thing, we
> prefer to use (uint64_t) rather than (u64).

And yet better we like cast-less code, e.g. in this case by simply using
1000UL.

Jan



 


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