From owner-svn-src-head@freebsd.org Mon Nov 11 21:59:21 2019 Return-Path: Delivered-To: svn-src-head@mailman.nyi.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mailman.nyi.freebsd.org (Postfix) with ESMTP id 6FEC61BF791; Mon, 11 Nov 2019 21:59:21 +0000 (UTC) (envelope-from kib@FreeBSD.org) Received: from mxrelay.nyi.freebsd.org (mxrelay.nyi.freebsd.org [IPv6:2610:1c1:1:606c::19:3]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) server-signature RSA-PSS (4096 bits) client-signature RSA-PSS (4096 bits) client-digest SHA256) (Client CN "mxrelay.nyi.freebsd.org", Issuer "Let's Encrypt Authority X3" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id 47BlCF281wz3Drf; Mon, 11 Nov 2019 21:59:21 +0000 (UTC) (envelope-from kib@FreeBSD.org) Received: from repo.freebsd.org (repo.freebsd.org [IPv6:2610:1c1:1:6068::e6a:0]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) by mxrelay.nyi.freebsd.org (Postfix) with ESMTPS id 2CFE11DCB7; Mon, 11 Nov 2019 21:59:21 +0000 (UTC) (envelope-from kib@FreeBSD.org) Received: from repo.freebsd.org ([127.0.1.37]) by repo.freebsd.org (8.15.2/8.15.2) with ESMTP id xABLxLSA054438; Mon, 11 Nov 2019 21:59:21 GMT (envelope-from kib@FreeBSD.org) Received: (from kib@localhost) by repo.freebsd.org (8.15.2/8.15.2/Submit) id xABLxLOS054437; Mon, 11 Nov 2019 21:59:21 GMT (envelope-from kib@FreeBSD.org) Message-Id: <201911112159.xABLxLOS054437@repo.freebsd.org> X-Authentication-Warning: repo.freebsd.org: kib set sender to kib@FreeBSD.org using -f From: Konstantin Belousov Date: Mon, 11 Nov 2019 21:59:21 +0000 (UTC) To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r354630 - head/sys/amd64/amd64 X-SVN-Group: head X-SVN-Commit-Author: kib X-SVN-Commit-Paths: head/sys/amd64/amd64 X-SVN-Commit-Revision: 354630 X-SVN-Commit-Repository: base MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-BeenThere: svn-src-head@freebsd.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: SVN commit messages for the src tree for head/-current List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 11 Nov 2019 21:59:21 -0000 Author: kib Date: Mon Nov 11 21:59:20 2019 New Revision: 354630 URL: https://svnweb.freebsd.org/changeset/base/354630 Log: amd64: Issue MFENCE on context switch on AMD CPUs when reusing address space. On some AMD CPUs, in particular, machines that do not implement CLFLUSHOPT but do provide CLFLUSH, the CLFLUSH instruction is only synchronized with MFENCE. Code using CLFLUSH typicall needs to brace it with MFENCE both before and after flush, see for instance pmap_invalidate_cache_range(). If context switch occurs while inside the protected region, we need to ensure visibility of flushes done on the old CPU, to new CPU. For all other machines, locked operation done to lock switched thread, should be enough. For case of different address spaces, reload of %cr3 is serializing. Reviewed by: cem, jhb, scottph Sponsored by: The FreeBSD Foundation MFC after: 1 week Differential revision: https://reviews.freebsd.org/D22007 Modified: head/sys/amd64/amd64/pmap.c Modified: head/sys/amd64/amd64/pmap.c ============================================================================== --- head/sys/amd64/amd64/pmap.c Mon Nov 11 20:44:30 2019 (r354629) +++ head/sys/amd64/amd64/pmap.c Mon Nov 11 21:59:20 2019 (r354630) @@ -8810,8 +8810,11 @@ pmap_activate_sw(struct thread *td) oldpmap = PCPU_GET(curpmap); pmap = vmspace_pmap(td->td_proc->p_vmspace); - if (oldpmap == pmap) + if (oldpmap == pmap) { + if (cpu_vendor_id != CPU_VENDOR_INTEL) + mfence(); return; + } cpuid = PCPU_GET(cpuid); #ifdef SMP CPU_SET_ATOMIC(cpuid, &pmap->pm_active);