From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pf0-f198.google.com (mail-pf0-f198.google.com [209.85.192.198]) by kanga.kvack.org (Postfix) with ESMTP id B6516680CE3 for ; Tue, 31 Oct 2017 18:32:24 -0400 (EDT) Received: by mail-pf0-f198.google.com with SMTP id h28so378275pfh.16 for ; Tue, 31 Oct 2017 15:32:24 -0700 (PDT) Received: from mga04.intel.com (mga04.intel.com. [192.55.52.120]) by mx.google.com with ESMTPS id m29si2762927pfk.373.2017.10.31.15.32.23 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 31 Oct 2017 15:32:23 -0700 (PDT) Subject: [PATCH 20/23] x86, mm: put mmu-to-h/w ASID translation in one place From: Dave Hansen Date: Tue, 31 Oct 2017 15:32:22 -0700 References: <20171031223146.6B47C861@viggo.jf.intel.com> In-Reply-To: <20171031223146.6B47C861@viggo.jf.intel.com> Message-Id: <20171031223222.E3E7D650@viggo.jf.intel.com> Sender: owner-linux-mm@kvack.org List-ID: To: linux-kernel@vger.kernel.org Cc: linux-mm@kvack.org, dave.hansen@linux.intel.com, moritz.lipp@iaik.tugraz.at, daniel.gruss@iaik.tugraz.at, michael.schwarz@iaik.tugraz.at, luto@kernel.org, torvalds@linux-foundation.org, keescook@google.com, hughd@google.com, x86@kernel.org We effectively have two ASID types: 1. The one stored in the mmu_context that goes from 0->5 2. The one we program into the hardware that goes from 1->6 Let's just put the +1 in a single place which gives us a nice place to comment. KAISER will also need to, given an ASID, know which hardware ASID to flush for the userspace mapping. Signed-off-by: Dave Hansen Cc: Moritz Lipp Cc: Daniel Gruss Cc: Michael Schwarz Cc: Andy Lutomirski Cc: Linus Torvalds Cc: Kees Cook Cc: Hugh Dickins Cc: x86@kernel.org --- b/arch/x86/include/asm/tlbflush.h | 30 ++++++++++++++++++------------ 1 file changed, 18 insertions(+), 12 deletions(-) diff -puN arch/x86/include/asm/tlbflush.h~kaiser-pcid-pre-build-kern arch/x86/include/asm/tlbflush.h --- a/arch/x86/include/asm/tlbflush.h~kaiser-pcid-pre-build-kern 2017-10-31 15:03:59.699555275 -0700 +++ b/arch/x86/include/asm/tlbflush.h 2017-10-31 15:03:59.703555465 -0700 @@ -86,21 +86,26 @@ static inline u64 inc_mm_tlb_gen(struct */ #define NR_AVAIL_ASIDS ((1<= NR_AVAIL_ASIDS); + /* + * If PCID is on, ASID-aware code paths put the ASID+1 into the PCID + * bits. This serves two purposes. It prevents a nasty situation in + * which PCID-unaware code saves CR3, loads some other value (with PCID + * == 0), and then restores CR3, thus corrupting the TLB for ASID 0 if + * the saved ASID was nonzero. It also means that any bugs involving + * loading a PCID-enabled CR3 with CR4.PCIDE off will trigger + * deterministically. + */ + return asid + 1; +} + struct pgd_t; static inline unsigned long build_cr3(pgd_t *pgd, u16 asid) { if (static_cpu_has(X86_FEATURE_PCID)) { - VM_WARN_ON_ONCE(asid > NR_AVAIL_ASIDS); - return __sme_pa(pgd) | (asid + 1); + return __sme_pa(pgd) | kern_asid(asid); } else { VM_WARN_ON_ONCE(asid != 0); return __sme_pa(pgd); @@ -110,7 +115,8 @@ static inline unsigned long build_cr3(pg static inline unsigned long build_cr3_noflush(pgd_t *pgd, u16 asid) { VM_WARN_ON_ONCE(asid > NR_AVAIL_ASIDS); - return __sme_pa(pgd) | (asid + 1) | CR3_NOFLUSH; + VM_WARN_ON_ONCE(!this_cpu_has(X86_FEATURE_PCID)); + return __sme_pa(pgd) | kern_asid(asid) | CR3_NOFLUSH; } #ifdef CONFIG_PARAVIRT _ -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org