Re: [kvm-unit-tests PATCH v2 08/18] lib: arm: Implement flush_tlb_all

[Alexandru Elisei <alexandru.elisei@arm.com>]

Hi Andre,

On 11/28/19 11:24 PM, André Przywara wrote:
> On 28/11/2019 18:04, Alexandru Elisei wrote:
>
> Hi,
>
>> flush_tlb_all performs a TLBIALL, which affects only the executing PE; fix
>> that by executing a TLBIALLIS. Note that virtualization extensions imply
>> the multiprocessing extensions, so we're safe to use that instruction.
>>
>> While we're at it, let's add a comment to flush_dcache_addr stating what
>> instruction is uses (unsurprisingly, it's a dcache clean and invalidate to
>> PoC).
> Good idea, but for people not fluent in ARMish I might be even better to
> actually spell that out there in the comment, also mentioning VA, maybe.
>
> Apart from that this looks good, also checked the encodings.

Sure, I'll explain what the tlb maintenance operation do.

Thanks,
Alex
> Cheers,
> Andre
>
>> Signed-off-by: Alexandru Elisei <alexandru.elisei@arm.com>
>> ---
>>  lib/arm/asm/mmu.h | 7 +++++--
>>  1 file changed, 5 insertions(+), 2 deletions(-)
>>
>> diff --git a/lib/arm/asm/mmu.h b/lib/arm/asm/mmu.h
>> index 361f3cdcc3d5..7c9ee3dbc079 100644
>> --- a/lib/arm/asm/mmu.h
>> +++ b/lib/arm/asm/mmu.h
>> @@ -25,8 +25,10 @@ static inline void local_flush_tlb_all(void)
>>  
>>  static inline void flush_tlb_all(void)
>>  {
>> -	//TODO
>> -	local_flush_tlb_all();
>> +	/* TLBIALLIS */
>> +	asm volatile("mcr p15, 0, %0, c8, c3, 0" :: "r" (0));
>> +	dsb();
>> +	isb();
>>  }
>>  
>>  static inline void flush_tlb_page(unsigned long vaddr)
>> @@ -39,6 +41,7 @@ static inline void flush_tlb_page(unsigned long vaddr)
>>  
>>  static inline void flush_dcache_addr(unsigned long vaddr)
>>  {
>> +	/* DCCIMVAC */
>>  	asm volatile("mcr p15, 0, %0, c7, c14, 1" :: "r" (vaddr));
>>  }
>>  
>>