Re: [PATCH] x86/mm: Remove unneeded TLB flush for in-place encryption

From: Borislav Petkov
Date: Thu Nov 02 2017 - 07:53:36 EST


On Wed, Nov 01, 2017 at 11:54:26AM -0500, Tom Lendacky wrote:
> A TLB flush is not required when doing in-place encryption or decryption
> since the area's pagetable attributes are not being altered. To avoid
> confusion between what the routine is doing and what is documented in
> the AMD APM, delete the local_flush_tlb() call.
>
> Suggested-by: Dave Hansen <dave.hansen@xxxxxxxxx>
> Signed-off-by: Tom Lendacky <thomas.lendacky@xxxxxxx>
> ---
> arch/x86/mm/mem_encrypt.c | 1 -
> 1 file changed, 1 deletion(-)
>
> diff --git a/arch/x86/mm/mem_encrypt.c b/arch/x86/mm/mem_encrypt.c
> index 16c5f37..53680a9 100644
> --- a/arch/x86/mm/mem_encrypt.c
> +++ b/arch/x86/mm/mem_encrypt.c
> @@ -63,7 +63,6 @@ static void __init __sme_early_enc_dec(resource_size_t paddr,
> if (!sme_me_mask)
> return;
>
> - local_flush_tlb();
> wbinvd();
>
> /*

Reviewed-by: Borislav Petkov <bp@xxxxxxx>

--
Regards/Gruss,
Boris.

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