From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id BB9C4C433F5 for ; Thu, 14 Oct 2021 03:42:47 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id A03566101E for ; Thu, 14 Oct 2021 03:42:47 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230054AbhJNDot (ORCPT ); Wed, 13 Oct 2021 23:44:49 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:33594 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229997AbhJNDnz (ORCPT ); Wed, 13 Oct 2021 23:43:55 -0400 Received: from mail-pf1-x433.google.com (mail-pf1-x433.google.com [IPv6:2607:f8b0:4864:20::433]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 37A3DC061570 for ; Wed, 13 Oct 2021 20:41:23 -0700 (PDT) Received: by mail-pf1-x433.google.com with SMTP id x130so4287305pfd.6 for ; Wed, 13 Oct 2021 20:41:23 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=5BlKZBSYzGKeJ7dR8x6r3jtlj/6PUsFcD4Ka+y7mVPo=; b=LSqXcfpd3k5YJwKc/d8KBoRPBKYU/uZRGnUN9s+iWgSKYxOdCrjzGVbh6zt/F9qZIF xw1HrPSf8fGKx342vjVoo/wuUsBxm3THaF/7zA5iscPjVKgF8lEOyh4Hdq5N+lE8c5+o yvfDlaMUEcuB88oInxOlsBdbdQ0/bmGecxE/9Xo5E7N4DJnsjVSQkMcMtPq15TYF/BdE jWZ4bahKUPEDc5x5TdQM5HpeSUawBVFstc+/XQy8nyf8LULHHFHqZk9MVfeCLdbnuEFU js96IN9wsjSAdMxde7wRzw+HZgQjg5Iu8AeZOuQJi8ma11ZdfkB9BAPgR/4oUY+iWJ5t LJSw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=5BlKZBSYzGKeJ7dR8x6r3jtlj/6PUsFcD4Ka+y7mVPo=; b=aoD17IA5OC3DE2sll7VmLg3YK92XX+VRy4CL9+qNLUSX+86/mdM6FNSciddNy9ePBp 7L1H4+A6toV41edFme7q+K4X5lfw+N8xnUBDJshA/xa//vQx85TW+6OOgWqw2xF3sI4V SVSMi15l9UC1v4Dg5iF19GZf1xK96kSjhtmFgAsF5O2iiMbj50US6hjC9N3KFZphmGdV 0Fx9ZqlO4H9mBMWytBY7fcKUIwLmr4DX3gFhqdgBJuXsOyD6xthlKgwil8kq9VOosmii iyy54ioyQZRbDBhWwv6BzzaVIN6IRQqtgXyPfhT4vwMn+KfbIcKcZzbbDcek1Ma2X9gR DwlQ== X-Gm-Message-State: AOAM533b0uL6DLkysRYKjvUhG+WbFp2l328XwznIOyU/EeDAhO46Vliu twEre352acTHiRh98jsmRofdXPtPVaE= X-Google-Smtp-Source: ABdhPJwbSrFgmoB3vpmcFuYz+uK3Jyu3tkboCW3G7kjJPu545Ue0fYwgrqY5ES+nc26ubFCjNuzI0Q== X-Received: by 2002:a63:1444:: with SMTP id 4mr2401946pgu.251.1634182882565; Wed, 13 Oct 2021 20:41:22 -0700 (PDT) Received: from localhost ([198.11.178.15]) by smtp.gmail.com with ESMTPSA id u9sm844799pfk.82.2021.10.13.20.41.21 (version=TLS1_2 cipher=ECDHE-ECDSA-AES128-GCM-SHA256 bits=128/128); Wed, 13 Oct 2021 20:41:22 -0700 (PDT) From: Lai Jiangshan To: linux-kernel@vger.kernel.org Cc: x86@kernel.org, Lai Jiangshan , Andy Lutomirski , Thomas Gleixner , Ingo Molnar , Borislav Petkov , "H. Peter Anvin" Subject: [PATCH V3 32/49] x86/entry: Add the C version ist_restore_cr3() Date: Thu, 14 Oct 2021 11:41:04 +0800 Message-Id: <20211014034121.17025-1-jiangshanlai@gmail.com> X-Mailer: git-send-email 2.19.1.6.gb485710b In-Reply-To: <20211014031413.14471-1-jiangshanlai@gmail.com> References: <20211014031413.14471-1-jiangshanlai@gmail.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Lai Jiangshan It implements the C version of RESTORE_CR3(). Not functional difference intended except the ASM code uses bit test and clear operations while the C version uses mask check and 'AND' operations. The resulted asm code of both versions are very similar. Signed-off-by: Lai Jiangshan --- arch/x86/entry/entry64.c | 46 ++++++++++++++++++++++++++++++++++++++++ 1 file changed, 46 insertions(+) diff --git a/arch/x86/entry/entry64.c b/arch/x86/entry/entry64.c index 7e6c1b8a93d1..5edbb4bb4786 100644 --- a/arch/x86/entry/entry64.c +++ b/arch/x86/entry/entry64.c @@ -11,6 +11,7 @@ * environments that the GS base is user controlled value, or the CR3 * is PTI user CR3 or both. */ +#include #include extern unsigned char asm_load_gs_index_gs_change[]; @@ -30,6 +31,26 @@ static __always_inline void pti_switch_to_kernel_cr3(unsigned long user_cr3) native_write_cr3(cr3); } +static __always_inline void pti_switch_to_user_cr3(unsigned long user_cr3) +{ +#define KERN_PCID_MASK (CR3_PCID_MASK & ~PTI_USER_PCID_MASK) + + if (static_cpu_has(X86_FEATURE_PCID)) { + int pcid = user_cr3 & KERN_PCID_MASK; + unsigned short pcid_mask = 1ull << pcid; + + /* + * Check if there's a pending flush for the user ASID we're + * about to set. + */ + if (!(this_cpu_read(cpu_tlbstate.user_pcid_flush_mask) & pcid_mask)) + user_cr3 |= X86_CR3_PCID_NOFLUSH; + else + this_cpu_and(cpu_tlbstate.user_pcid_flush_mask, ~pcid_mask); + } + native_write_cr3(user_cr3); +} + static __always_inline void switch_to_kernel_cr3(void) { if (static_cpu_has(X86_FEATURE_PTI)) @@ -49,9 +70,34 @@ static __always_inline unsigned long ist_switch_to_kernel_cr3(void) return cr3; } + +static __always_inline void ist_restore_cr3(unsigned long cr3) +{ + if (!static_cpu_has(X86_FEATURE_PTI)) + return; + + if (unlikely(cr3 & PTI_USER_PGTABLE_MASK)) { + pti_switch_to_user_cr3(cr3); + return; + } + + /* + * KERNEL pages can always resume with NOFLUSH as we do + * explicit flushes. + */ + if (static_cpu_has(X86_FEATURE_PCID)) + cr3 |= X86_CR3_PCID_NOFLUSH; + + /* + * The CR3 write could be avoided when not changing its value, + * but would require a CR3 read. + */ + native_write_cr3(cr3); +} #else static __always_inline void switch_to_kernel_cr3(void) {} static __always_inline unsigned long ist_switch_to_kernel_cr3(void) { return 0; } +static __always_inline void ist_restore_cr3(unsigned long cr3) {} #endif /* -- 2.19.1.6.gb485710b