From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-oi0-f72.google.com (mail-oi0-f72.google.com [209.85.218.72]) by kanga.kvack.org (Postfix) with ESMTP id A2D4A6B0314 for ; Mon, 5 Jun 2017 18:37:13 -0400 (EDT) Received: by mail-oi0-f72.google.com with SMTP id r84so73846857oif.0 for ; Mon, 05 Jun 2017 15:37:13 -0700 (PDT) Received: from mail.kernel.org (mail.kernel.org. [198.145.29.99]) by mx.google.com with ESMTPS id e206si2939505oib.0.2017.06.05.15.37.12 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 05 Jun 2017 15:37:12 -0700 (PDT) From: Andy Lutomirski Subject: [RFC 10/11] x86/mm: Enable CR4.PCIDE on supported systems Date: Mon, 5 Jun 2017 15:36:34 -0700 Message-Id: <1de32b6e3ff026886713adab887a9454548d8374.1496701658.git.luto@kernel.org> In-Reply-To: References: In-Reply-To: References: Sender: owner-linux-mm@kvack.org List-ID: To: X86 ML Cc: Borislav Petkov , Linus Torvalds , Andrew Morton , Mel Gorman , "linux-mm@kvack.org" , Nadav Amit , Rik van Riel , Andy Lutomirski , Juergen Gross , Boris Ostrovsky We can use PCID if the CPU has PCID and PGE and we're not on Xen. By itself, this has no effect. The next patch will start using PCID. Cc: Juergen Gross Cc: Boris Ostrovsky Signed-off-by: Andy Lutomirski --- arch/x86/include/asm/tlbflush.h | 8 ++++++++ arch/x86/kernel/cpu/common.c | 15 +++++++++++++++ arch/x86/xen/setup.c | 6 ++++++ 3 files changed, 29 insertions(+) diff --git a/arch/x86/include/asm/tlbflush.h b/arch/x86/include/asm/tlbflush.h index 87b13e51e867..57b305e13c4c 100644 --- a/arch/x86/include/asm/tlbflush.h +++ b/arch/x86/include/asm/tlbflush.h @@ -243,6 +243,14 @@ static inline void __flush_tlb_all(void) __flush_tlb_global(); else __flush_tlb(); + + /* + * Note: if we somehow had PCID but not PGE, then this wouldn't work -- + * we'd end up flushing kernel translations for the current ASID but + * we might fail to flush kernel translations for other cached ASIDs. + * + * To avoid this issue, we force PCID off if PGE is off. + */ } static inline void __flush_tlb_one(unsigned long addr) diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c index 904485e7b230..01caf66b270f 100644 --- a/arch/x86/kernel/cpu/common.c +++ b/arch/x86/kernel/cpu/common.c @@ -1143,6 +1143,21 @@ static void identify_cpu(struct cpuinfo_x86 *c) setup_smep(c); setup_smap(c); + /* Set up PCID */ + if (cpu_has(c, X86_FEATURE_PCID)) { + if (cpu_has(c, X86_FEATURE_PGE)) { + cr4_set_bits(X86_CR4_PCIDE); + } else { + /* + * flush_tlb_all(), as currently implemented, won't + * work if PCID is on but PGE is not. Since that + * combination doesn't exist on real hardware, there's + * no reason to try to fully support it. + */ + clear_cpu_cap(c, X86_FEATURE_PCID); + } + } + /* * The vendor-specific functions might have changed features. * Now we do "generic changes." diff --git a/arch/x86/xen/setup.c b/arch/x86/xen/setup.c index a5bf7c451435..7681202b2857 100644 --- a/arch/x86/xen/setup.c +++ b/arch/x86/xen/setup.c @@ -1037,6 +1037,12 @@ void __init xen_arch_setup(void) } #endif + /* + * Xen would need some work to support PCID: CR3 handling as well + * as xen_flush_tlb_others() would need updating. + */ + setup_clear_cpu_cap(X86_FEATURE_PCID); + memcpy(boot_command_line, xen_start_info->cmd_line, MAX_GUEST_CMDLINE > COMMAND_LINE_SIZE ? COMMAND_LINE_SIZE : MAX_GUEST_CMDLINE); -- 2.9.3 -- 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