From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Google-Smtp-Source: AG47ELsVYkWAXWaA92VjwCBSiF7p+9FRO3jF08weAgWRKLx/n8qg1V4J80SDGcgwcMRBls3ddsLm ARC-Seal: i=1; a=rsa-sha256; t=1520296001; cv=none; d=google.com; s=arc-20160816; b=fbW+h3/nXAalbQ9LCWFU9+hdEKxFv2hPVikzQAnxWVZdRBJagrCnmkTCRyt6nXkR6E 0BQ3ArOKhLlCe6aQMtbLQD0c3a5zm7/L3oHmE7TIGWhnhwuI39Cs2o9pO8HmRsoZAN1R jRwOyJA0nQIcbYEj0paFjsWYJ0kCjmohF/izlOWfYeq5F6h+89g5jsEHiYi66YjH2xhd IW/9cXvPDIj/f0vkuT3c10/oiHIptqQVl5DAtCct+Pb9cBgk+M3PhTjnGa5pDt2+6kpN QO2QGU+RglIhPqbGpKl3w2HZAqCF8y5dYVxUWDsSqMgPe7n9lVr3QW40R3pgUE0BLuGS V81A== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=references:in-reply-to:message-id:date:subject:to:from :dkim-signature:arc-authentication-results; bh=wXLTMKWi8TLRfsX0c0LMB93k8rT9pEe7faOUktaxoBk=; b=uGz3zKg+H2h6Vc44Xf+elORa1tpMhIzRFJ9kYIlwS2PvhNyJX28HZK913vjOj8yAhD 3EFCecCoa13sDekaIagetBy4e5h7PGZ3MTr2R9yB3VvjK9wlF1Y9YQcQyBRYogfmYaBo +BNQSAL0baXgk+dRQ7+8LGF+W4y1BDmpgx+gGkVpprntyS2jkjaRzc7E5DzcEd0jmsbO IVo1lftuOP1QNlYCYzROgdutg7MaWom12yv7i/DmPr3Tcz6OsDEcrqQaLonia1YMmWx2 H+fBv4rbk2loTem+DjAgefG0KwFMjn97qLoqP+cWdp++Ww6s7FekAhLwqKy+ueqo6So1 6/zg== ARC-Authentication-Results: i=1; mx.google.com; dkim=pass header.i=@oracle.com header.s=corp-2017-10-26 header.b=JgvwmDWJ; spf=pass (google.com: domain of pasha.tatashin@oracle.com designates 156.151.31.85 as permitted sender) smtp.mailfrom=pasha.tatashin@oracle.com; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=oracle.com Authentication-Results: mx.google.com; dkim=pass header.i=@oracle.com header.s=corp-2017-10-26 header.b=JgvwmDWJ; spf=pass (google.com: domain of pasha.tatashin@oracle.com designates 156.151.31.85 as permitted sender) smtp.mailfrom=pasha.tatashin@oracle.com; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=oracle.com From: Pavel Tatashin To: steven.sistare@oracle.com, daniel.m.jordan@oracle.com, linux-kernel@vger.kernel.org, Alexander.Levin@microsoft.com, dan.j.williams@intel.com, sathyanarayanan.kuppuswamy@intel.com, pankaj.laxminarayan.bharadiya@intel.com, akuster@mvista.com, cminyard@mvista.com, pasha.tatashin@oracle.com, gregkh@linuxfoundation.org, stable@vger.kernel.org Subject: [PATCH 4.1 44/65] kaiser: PCID 0 for kernel and 128 for user Date: Mon, 5 Mar 2018 19:25:17 -0500 Message-Id: <20180306002538.1761-45-pasha.tatashin@oracle.com> X-Mailer: git-send-email 2.16.2 In-Reply-To: <20180306002538.1761-1-pasha.tatashin@oracle.com> References: <20180306002538.1761-1-pasha.tatashin@oracle.com> X-Proofpoint-Virus-Version: vendor=nai engine=5900 definitions=8823 signatures=668683 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 suspectscore=0 malwarescore=0 phishscore=0 bulkscore=0 spamscore=0 mlxscore=0 mlxlogscore=953 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1711220000 definitions=main-1803060003 X-getmail-retrieved-from-mailbox: INBOX X-GMAIL-THRID: =?utf-8?q?1594145900041900563?= X-GMAIL-MSGID: =?utf-8?q?1594145900041900563?= X-Mailing-List: linux-kernel@vger.kernel.org List-ID: From: Hugh Dickins Why was 4 chosen for kernel PCID and 6 for user PCID? No good reason in a backport where PCIDs are only used for Kaiser. If we continue with those, then we shall need to add Andy Lutomirski's 4.13 commit 6c690ee1039b ("x86/mm: Split read_cr3() into read_cr3_pa() and __read_cr3()"), which deals with the problem of read_cr3() callers finding stray bits in the cr3 that they expected to be page-aligned; and for hibernation, his 4.14 commit f34902c5c6c0 ("x86/hibernate/64: Mask off CR3's PCID bits in the saved CR3"). But if 0 is used for kernel PCID, then there's no need to add in those commits - whenever the kernel looks, it sees 0 in the lower bits; and 0 for kernel seems an obvious choice. And I naughtily propose 128 for user PCID. Because there's a place in _SWITCH_TO_USER_CR3 where it takes note of the need for TLB FLUSH, but needs to reset that to NOFLUSH for the next occasion. Currently it does so with a "movb $(0x80)" into the high byte of the per-cpu quadword, but that will cause a machine without PCID support to crash. Now, if %al just happened to have 0x80 in it at that point, on a machine with PCID support, but 0 on a machine without PCID support... (That will go badly wrong once the pgd can be at a physical address above 2^56, but even with 5-level paging, physical goes up to 2^52.) Signed-off-by: Hugh Dickins Acked-by: Jiri Kosina Signed-off-by: Greg Kroah-Hartman (cherry picked from commit 3b4ce0e1a17228eec71815d7997e49e403ebf2a7) Signed-off-by: Pavel Tatashin --- arch/x86/include/asm/kaiser.h | 19 ++++++++++++------- arch/x86/include/asm/pgtable_types.h | 7 ++++--- arch/x86/mm/tlb.c | 3 +++ 3 files changed, 19 insertions(+), 10 deletions(-) diff --git a/arch/x86/include/asm/kaiser.h b/arch/x86/include/asm/kaiser.h index 009bca514c20..110a73e0572d 100644 --- a/arch/x86/include/asm/kaiser.h +++ b/arch/x86/include/asm/kaiser.h @@ -29,14 +29,19 @@ orq X86_CR3_PCID_KERN_VAR, \reg movq \reg, %cr3 .endm -.macro _SWITCH_TO_USER_CR3 reg +.macro _SWITCH_TO_USER_CR3 reg regb +/* + * regb must be the low byte portion of reg: because we have arranged + * for the low byte of the user PCID to serve as the high byte of NOFLUSH + * (0x80 for each when PCID is enabled, or 0x00 when PCID and NOFLUSH are + * not enabled): so that the one register can update both memory and cr3. + */ movq %cr3, \reg andq $(~(X86_CR3_PCID_ASID_MASK | KAISER_SHADOW_PGD_OFFSET)), \reg orq PER_CPU_VAR(X86_CR3_PCID_USER_VAR), \reg js 9f -// FLUSH this time, reset to NOFLUSH for next time -// But if nopcid? Consider using 0x80 for user pcid? -movb $(0x80), PER_CPU_VAR(X86_CR3_PCID_USER_VAR+7) +/* FLUSH this time, reset to NOFLUSH for next time (if PCID enabled) */ +movb \regb, PER_CPU_VAR(X86_CR3_PCID_USER_VAR+7) 9: movq \reg, %cr3 .endm @@ -49,7 +54,7 @@ popq %rax .macro SWITCH_USER_CR3 pushq %rax -_SWITCH_TO_USER_CR3 %rax +_SWITCH_TO_USER_CR3 %rax %al popq %rax .endm @@ -61,7 +66,7 @@ movq PER_CPU_VAR(unsafe_stack_register_backup), %rax .macro SWITCH_USER_CR3_NO_STACK movq %rax, PER_CPU_VAR(unsafe_stack_register_backup) -_SWITCH_TO_USER_CR3 %rax +_SWITCH_TO_USER_CR3 %rax %al movq PER_CPU_VAR(unsafe_stack_register_backup), %rax .endm @@ -69,7 +74,7 @@ movq PER_CPU_VAR(unsafe_stack_register_backup), %rax .macro SWITCH_KERNEL_CR3 reg .endm -.macro SWITCH_USER_CR3 reg +.macro SWITCH_USER_CR3 reg regb .endm .macro SWITCH_USER_CR3_NO_STACK .endm diff --git a/arch/x86/include/asm/pgtable_types.h b/arch/x86/include/asm/pgtable_types.h index b3c77e6529c2..93554f37df99 100644 --- a/arch/x86/include/asm/pgtable_types.h +++ b/arch/x86/include/asm/pgtable_types.h @@ -111,16 +111,17 @@ /* Mask for all the PCID-related bits in CR3: */ #define X86_CR3_PCID_MASK (X86_CR3_PCID_NOFLUSH | X86_CR3_PCID_ASID_MASK) +#define X86_CR3_PCID_ASID_KERN (_AC(0x0,UL)) + #if defined(CONFIG_KAISER) && defined(CONFIG_X86_64) -#define X86_CR3_PCID_ASID_KERN (_AC(0x4,UL)) -#define X86_CR3_PCID_ASID_USER (_AC(0x6,UL)) +/* Let X86_CR3_PCID_ASID_USER be usable for the X86_CR3_PCID_NOFLUSH bit */ +#define X86_CR3_PCID_ASID_USER (_AC(0x80,UL)) #define X86_CR3_PCID_KERN_FLUSH (X86_CR3_PCID_ASID_KERN) #define X86_CR3_PCID_USER_FLUSH (X86_CR3_PCID_ASID_USER) #define X86_CR3_PCID_KERN_NOFLUSH (X86_CR3_PCID_NOFLUSH | X86_CR3_PCID_ASID_KERN) #define X86_CR3_PCID_USER_NOFLUSH (X86_CR3_PCID_NOFLUSH | X86_CR3_PCID_ASID_USER) #else -#define X86_CR3_PCID_ASID_KERN (_AC(0x0,UL)) #define X86_CR3_PCID_ASID_USER (_AC(0x0,UL)) /* * PCIDs are unsupported on 32-bit and none of these bits can be diff --git a/arch/x86/mm/tlb.c b/arch/x86/mm/tlb.c index 9c9657f139cd..749e2134bd7a 100644 --- a/arch/x86/mm/tlb.c +++ b/arch/x86/mm/tlb.c @@ -50,6 +50,9 @@ static void load_new_mm_cr3(pgd_t *pgdir) * invpcid_flush_single_context(X86_CR3_PCID_ASID_USER) could * do it here, but can only be used if X86_FEATURE_INVPCID is * available - and many machines support pcid without invpcid. + * + * The line below is a no-op: X86_CR3_PCID_KERN_FLUSH is now 0; + * but keep that line in there in case something changes. */ new_mm_cr3 |= X86_CR3_PCID_KERN_FLUSH; kaiser_flush_tlb_on_return_to_user(); -- 2.16.2