Re: [Xen-devel] [For Xen-4.10 Resend PATCH 3/3] Avoid excess icache flushes in populate_physmap() before domain has been created

[Punit Agrawal <punit.agrawal@xxxxxxx>]

Jan Beulich <JBeulich@xxxxxxxx> writes:

>>>> On 15.05.17 at 16:10, <punit.agrawal@xxxxxxx> wrote:
>> --- a/xen/include/asm-x86/page.h
>> +++ b/xen/include/asm-x86/page.h
>> @@ -375,6 +375,10 @@ perms_strictly_increased(uint32_t old_flags, uint32_t 
>> new_flags)
>>  
>>  #define PAGE_ALIGN(x) (((x) + PAGE_SIZE - 1) & PAGE_MASK)
>>  
>> +static inline void invalidate_icache(void)
>> +{
>> +}
>
> This function clearly does not what its name says, so there should
> be a brief comment saying why.

Ack. I've added the following comment block above the function
definition.

/*
 * While allocating memory for a domain, invalidate_icache() is called
 * to ensure that guest vcpu does not execute any stale instructions
 * from the recently allocated memory. There is nothing to be done
 * here as icaches are coherent on x86.
 */

My x86 foo is weak and I'd appreciate if somebody familiar with x86
could give this a once over.

>
> Everything else looks reasonable.

Thanks, Jan. I'll post a new version once the ARM maintainers have had a
chance to comment.

>
> Jan

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