From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-yw1-f202.google.com (mail-yw1-f202.google.com [209.85.128.202]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 5E4EA4D110 for ; Wed, 21 Feb 2024 11:35:52 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.128.202 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1708515353; cv=none; b=Az/liQA81qq9x7mR1QX8JvNOMsMNgt/530febYZvLpy5GwXJZ/JZLPGmOWm5xGbSNouTkJxjpYWQc9HFjxCYq/clEHICMqqaOBNpnh56fYhld2ANYaNzkhYIsMcQtHsxLpkiUPsc2NNKWyaTe7M9+oGnZIfOJSrLXX+mo5UZtmM= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1708515353; c=relaxed/simple; bh=+vNI1MmLFGS1GivHerZyjgoY4sNAT6wDfnGDYRsl6Po=; h=Date:In-Reply-To:Mime-Version:References:Message-ID:Subject:From: To:Cc:Content-Type; b=t+241yYx6Fj+/6oce7AX697G9pNKblPVAzOECxn9xX2nfm9ynnVI37Wcr/LS7eJDpupCQzVGdt71G/XpUE+IKFcGU4rx/cLqV9wrubYbIIkUb7QbNETIEK7iJYMzvBsBEvkQ6E7R/UjZ6YQB+XBmeF0i+pg9kbuqFRKqoF1l23o= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com; spf=pass smtp.mailfrom=flex--ardb.bounces.google.com; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b=HUdSHzvF; arc=none smtp.client-ip=209.85.128.202 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=flex--ardb.bounces.google.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="HUdSHzvF" Received: by mail-yw1-f202.google.com with SMTP id 00721157ae682-607e8e8c2f1so106138077b3.3 for ; Wed, 21 Feb 2024 03:35:52 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1708515351; x=1709120151; darn=vger.kernel.org; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:from:to:cc:subject:date:message-id:reply-to; bh=EkxcLENiSlDOPoQNco4VFPfOwd/QcirP1cMQb5AjsLI=; b=HUdSHzvFKPPDstZtNL3AuROXQglCVOQW91cKv2q4pk+2jsrpvNUxc6qdc4t1/mPRX5 AlB+Cr5BCSgREX05P0N5nOYVKEFQm8RfZXG1ya6ffkcRoNiOXpTJTrNQClXDp6lI7D2D k8KDOgLGC6L3M4pZgtaEpkKet2jWRduZXsl/Ybzf0ggM4OGkJdQ4ghu+idGoug8xLJsu KEbCSokgZjWd5j4CJEctAhPwwHBPsn6R+/0hew/rxEPd425BhMyKaBe6gsK0sqyx1gZG 0bz3mrfsKf/x3lT/Z/+3nBIePxWybSuo+78weNarM2CHbv6sLEIbpzTXW2VbJ4s0q8AY Q7wQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1708515351; x=1709120151; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=EkxcLENiSlDOPoQNco4VFPfOwd/QcirP1cMQb5AjsLI=; b=mbxZ9pAYDVgsqB6yPCOnOTTgkLj/dK0YMAUee9r/ppIT6vwWepdxKn0hiDB5QbeBKj 3PgJBeQgMB0ldzM4GsEhN9uLpySdjFDH0mSTcMDsKXmtJHR6Ee/tXOdUKaQf8mxXoQ4S +ba8bREqpuMvYhSRWGREeM5myZ676rI6PKh6q9JpB4CTcrY3Vb3xVVWPRW1wWVmk9sLx B58utURHvEqzGXhxXzFAk3dYGZP2rrF2in/ehKUAqCHPqWx/qi8/gkZ+1+7APrcZ/ZhC 3C8bH03WJ8mB4c3Rj+/UySPsYQSuovq6ddz5f3hmPwkcnEY9FwQyNnM+D+gnZFkMRGDn h/TQ== X-Forwarded-Encrypted: i=1; AJvYcCXVHCA/D2v+6an3kpcHizXWL69nsP0fgE5U4SZKwkvxicggiYmB4hyR0PGpePYxiWX1M9p9Cgn8dawMDL7c6P+NnD6oDjTuD5b46g== X-Gm-Message-State: AOJu0Yw3F/iE0KOWAIMfUYspIw8lhZ4LvJeOVEHvGp2U8JjLkqUWv3UF EpEy7yl6BhADTLpnna26okBPCnvZZiCSvpjQES9IDXPzCq05u7f3uBB30A8xWDk9wLut3w== X-Google-Smtp-Source: AGHT+IFTRE+rjlo0n123vKQQ/YSTuUniFgCWLLvxLk3zUHW0XkwfLMGbBSM3H4ZXpfRdO6tGiZoXr62j X-Received: from palermo.c.googlers.com ([fda3:e722:ac3:cc00:28:9cb1:c0a8:118a]) (user=ardb job=sendgmr) by 2002:a0d:d790:0:b0:608:1fec:1dd8 with SMTP id z138-20020a0dd790000000b006081fec1dd8mr1741929ywd.6.1708515351508; Wed, 21 Feb 2024 03:35:51 -0800 (PST) Date: Wed, 21 Feb 2024 12:35:14 +0100 In-Reply-To: <20240221113506.2565718-18-ardb+git@google.com> Precedence: bulk X-Mailing-List: linux-arch@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20240221113506.2565718-18-ardb+git@google.com> X-Developer-Key: i=ardb@kernel.org; a=openpgp; fpr=F43D03328115A198C90016883D200E9CA6329909 X-Developer-Signature: v=1; a=openpgp-sha256; l=2455; i=ardb@kernel.org; h=from:subject; bh=yaS/9ovMSw8F0QV6XZaoG3EypsAj0QA2cGCCi/EyQdM=; b=owGbwMvMwCFmkMcZplerG8N4Wi2JIfXq/Q+6elITfjUkXFxSXNX0UuVCU/Pf1rdHz2ydK3dXK 7z/yoWTHaUsDGIcDLJiiiwCs/++23l6olSt8yxZmDmsTCBDGLg4BWAij18wMvQIb7OtV6/2qrBx Cv98yNPx7toM9qoPhkYHVx1mi2xTXs7I8NctSEVKctq3g9P4dr+z/LD31RzWlr/pAolrNTynt09 3ZgAA X-Mailer: git-send-email 2.44.0.rc0.258.g7320e95886-goog Message-ID: <20240221113506.2565718-25-ardb+git@google.com> Subject: [PATCH v5 07/16] x86/startup_64: Simplify CR4 handling in startup code From: Ard Biesheuvel To: linux-kernel@vger.kernel.org Cc: Ard Biesheuvel , Kevin Loughlin , Tom Lendacky , Dionna Glaze , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , Andy Lutomirski , Arnd Bergmann , Nathan Chancellor , Nick Desaulniers , Justin Stitt , Kees Cook , Brian Gerst , linux-arch@vger.kernel.org, llvm@lists.linux.dev Content-Type: text/plain; charset="UTF-8" From: Ard Biesheuvel When paging is enabled, the CR4.PAE and CR4.LA57 control bits cannot be changed, and so they can simply be preserved rather than reason about whether or not they need to be set. CR4.MCE should be preserved unless the kernel was built without CONFIG_X86_MCE, in which case it must be cleared. CR4.PSE should be set explicitly, regardless of whether or not it was set before. CR4.PGE is set explicitly, and then cleared and set again after programming CR3 in order to flush TLB entries based on global translations. This makes the first assignment redundant, and can therefore be omitted. Signed-off-by: Ard Biesheuvel --- arch/x86/kernel/head_64.S | 24 +++++++------------- 1 file changed, 8 insertions(+), 16 deletions(-) diff --git a/arch/x86/kernel/head_64.S b/arch/x86/kernel/head_64.S index fb2a98c29094..426f6fdc0075 100644 --- a/arch/x86/kernel/head_64.S +++ b/arch/x86/kernel/head_64.S @@ -185,6 +185,8 @@ SYM_INNER_LABEL(secondary_startup_64_no_verify, SYM_L_GLOBAL) addq $(init_top_pgt - __START_KERNEL_map), %rax 1: + /* Create a mask of CR4 bits to preserve */ + movl $(X86_CR4_PAE | X86_CR4_LA57), %edx #ifdef CONFIG_X86_MCE /* * Preserve CR4.MCE if the kernel will enable #MC support. @@ -193,20 +195,13 @@ SYM_INNER_LABEL(secondary_startup_64_no_verify, SYM_L_GLOBAL) * configured will crash the system regardless of the CR4.MCE value set * here. */ - movq %cr4, %rcx - andl $X86_CR4_MCE, %ecx -#else - movl $0, %ecx + orl $X86_CR4_MCE, %edx #endif + movq %cr4, %rcx + andl %edx, %ecx - /* Enable PAE mode, PSE, PGE and LA57 */ - orl $(X86_CR4_PAE | X86_CR4_PSE | X86_CR4_PGE), %ecx -#ifdef CONFIG_X86_5LEVEL - testb $1, __pgtable_l5_enabled(%rip) - jz 1f - orl $X86_CR4_LA57, %ecx -1: -#endif + /* Even if ignored in long mode, set PSE uniformly on all logical CPUs. */ + btsl $X86_CR4_PSE_BIT, %ecx movq %rcx, %cr4 /* Setup early boot stage 4-/5-level pagetables. */ @@ -226,11 +221,8 @@ SYM_INNER_LABEL(secondary_startup_64_no_verify, SYM_L_GLOBAL) * Do a global TLB flush after the CR3 switch to make sure the TLB * entries from the identity mapping are flushed. */ - movq %cr4, %rcx - movq %rcx, %rax - xorq $X86_CR4_PGE, %rcx + btsl $X86_CR4_PGE_BIT, %ecx movq %rcx, %cr4 - movq %rax, %cr4 /* Ensure I am executing from virtual addresses */ movq $1f, %rax -- 2.44.0.rc0.258.g7320e95886-goog