From owner-svn-src-head@freebsd.org Wed Aug 26 02:04:05 2020 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 0C9603C51C5; Wed, 26 Aug 2020 02:04:05 +0000 (UTC) (envelope-from scottph@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) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256 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 4Bbq0h6X4Hz4VLX; Wed, 26 Aug 2020 02:04:04 +0000 (UTC) (envelope-from scottph@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 C3440BB25; Wed, 26 Aug 2020 02:04:04 +0000 (UTC) (envelope-from scottph@FreeBSD.org) Received: from repo.freebsd.org ([127.0.1.37]) by repo.freebsd.org (8.15.2/8.15.2) with ESMTP id 07Q24460027526; Wed, 26 Aug 2020 02:04:04 GMT (envelope-from scottph@FreeBSD.org) Received: (from scottph@localhost) by repo.freebsd.org (8.15.2/8.15.2/Submit) id 07Q244dt027525; Wed, 26 Aug 2020 02:04:04 GMT (envelope-from scottph@FreeBSD.org) Message-Id: <202008260204.07Q244dt027525@repo.freebsd.org> X-Authentication-Warning: repo.freebsd.org: scottph set sender to scottph@FreeBSD.org using -f From: D Scott Phillips Date: Wed, 26 Aug 2020 02:04:04 +0000 (UTC) To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r364794 - head/sys/arm64/arm64 X-SVN-Group: head X-SVN-Commit-Author: scottph X-SVN-Commit-Paths: head/sys/arm64/arm64 X-SVN-Commit-Revision: 364794 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: 2.1.33 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: Wed, 26 Aug 2020 02:04:05 -0000 Author: scottph Date: Wed Aug 26 02:04:04 2020 New Revision: 364794 URL: https://svnweb.freebsd.org/changeset/base/364794 Log: arm64: Make local stores observable before sending IPIs Add a synchronizing instruction to flush and wait until the local CPU's writes are observable to other CPUs before sending IPIs. This fixes an issue where recipient CPUs doing a rendezvous could enter the rendezvous handling code before the initiator's writes to the smp_rv_* variables were visible. This manifested as a system hang, where a single CPU's increment of smp_rv_waiters[0] actually happened "before" the initiator's zeroing of that field, so all CPUs were stuck with the field appearing to be at ncpus - 1. Reviewed by: andrew, markj Approved by: scottl (implicit) MFC after: 1 week Sponsored by: Ampere Computing, Inc. Differential Revision: https://reviews.freebsd.org/D25798 Modified: head/sys/arm64/arm64/mp_machdep.c Modified: head/sys/arm64/arm64/mp_machdep.c ============================================================================== --- head/sys/arm64/arm64/mp_machdep.c Wed Aug 26 01:55:37 2020 (r364793) +++ head/sys/arm64/arm64/mp_machdep.c Wed Aug 26 02:04:04 2020 (r364794) @@ -304,6 +304,13 @@ pic_ipi_send(void *arg, cpuset_t cpus, u_int ipi) { KASSERT(intr_irq_root_dev != NULL, ("%s: no root attached", __func__)); + + /* + * Ensure that this CPU's stores will be visible to IPI + * recipients before starting to send the interrupts. + */ + dsb(ishst); + PIC_IPI_SEND(intr_irq_root_dev, arg, cpus, ipi); }