From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.linuxfoundation.org ([140.211.169.12]:51554 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2387804AbeHNUNQ (ORCPT ); Tue, 14 Aug 2018 16:13:16 -0400 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Vlastimil Babka , Thomas Gleixner Subject: [PATCH 4.18 28/79] x86/speculation/l1tf: Extend 64bit swap file size limit Date: Tue, 14 Aug 2018 19:16:47 +0200 Message-Id: <20180814171337.873950726@linuxfoundation.org> In-Reply-To: <20180814171336.799314117@linuxfoundation.org> References: <20180814171336.799314117@linuxfoundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: stable-owner@vger.kernel.org List-ID: 4.18-stable review patch. If anyone has any objections, please let me know. ------------------ From: Vlastimil Babka The previous patch has limited swap file size so that large offsets cannot clear bits above MAX_PA/2 in the pte and interfere with L1TF mitigation. It assumed that offsets are encoded starting with bit 12, same as pfn. But on x86_64, offsets are encoded starting with bit 9. Thus the limit can be raised by 3 bits. That means 16TB with 42bit MAX_PA and 256TB with 46bit MAX_PA. Fixes: 377eeaa8e11f ("x86/speculation/l1tf: Limit swap file size to MAX_PA/2") Signed-off-by: Vlastimil Babka Signed-off-by: Thomas Gleixner Signed-off-by: Greg Kroah-Hartman --- arch/x86/mm/init.c | 10 +++++++++- 1 file changed, 9 insertions(+), 1 deletion(-) --- a/arch/x86/mm/init.c +++ b/arch/x86/mm/init.c @@ -891,7 +891,15 @@ unsigned long max_swapfile_size(void) if (boot_cpu_has_bug(X86_BUG_L1TF)) { /* Limit the swap file size to MAX_PA/2 for L1TF workaround */ - pages = min_t(unsigned long, l1tf_pfn_limit() + 1, pages); + unsigned long l1tf_limit = l1tf_pfn_limit() + 1; + /* + * We encode swap offsets also with 3 bits below those for pfn + * which makes the usable limit higher. + */ +#ifdef CONFIG_X86_64 + l1tf_limit <<= PAGE_SHIFT - SWP_OFFSET_FIRST_BIT; +#endif + pages = min_t(unsigned long, l1tf_limit, pages); } return pages; }