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

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Message-ID: <20171101165426.1388.24866.stgit@tlendack-t1.amdoffice.net>
Date:   Wed, 01 Nov 2017 11:54:26 -0500
From:   Tom Lendacky <thomas.lendacky@....com>
To:     x86@...nel.org
Cc:     Peter Zijlstra <peterz@...radead.org>,
        linux-kernel@...r.kernel.org, Dave Hansen <dave.hansen@...el.com>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        "H. Peter Anvin" <hpa@...or.com>,
        Thomas Gleixner <tglx@...utronix.de>
Subject: [PATCH] x86/mm: Remove unneeded TLB flush for in-place encryption

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@...el.com>
Signed-off-by: Tom Lendacky <thomas.lendacky@....com>
---
 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();
 
 	/*