From patchwork Tue Jun 18 11:23:41 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Anthony PERARD X-Patchwork-Id: 1117806 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Authentication-Results: ozlabs.org; spf=pass (mailfrom) smtp.mailfrom=nongnu.org (client-ip=209.51.188.17; helo=lists.gnu.org; envelope-from=qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org; receiver=) Authentication-Results: ozlabs.org; dmarc=none (p=none dis=none) header.from=citrix.com Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ozlabs.org (Postfix) with ESMTPS id 45Sm3f21CHz9s3C for ; Tue, 18 Jun 2019 21:25:45 +1000 (AEST) Received: from localhost ([::1]:55682 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.86_2) (envelope-from ) id 1hdCFB-0001nM-DI for incoming@patchwork.ozlabs.org; Tue, 18 Jun 2019 07:25:41 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:44020) by lists.gnu.org with esmtp (Exim 4.86_2) (envelope-from ) id 1hdCDN-0001ld-UJ for qemu-devel@nongnu.org; Tue, 18 Jun 2019 07:23:51 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1hdCDM-00070t-BA for qemu-devel@nongnu.org; Tue, 18 Jun 2019 07:23:49 -0400 Received: from esa4.hc3370-68.iphmx.com ([216.71.155.144]:60646) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1hdCDM-0006zD-2N for qemu-devel@nongnu.org; Tue, 18 Jun 2019 07:23:48 -0400 Authentication-Results: esa4.hc3370-68.iphmx.com; dkim=none (message not signed) header.i=none; spf=None smtp.pra=anthony.perard@citrix.com; spf=Pass smtp.mailfrom=anthony.perard@citrix.com; spf=None smtp.helo=postmaster@mail.citrix.com Received-SPF: None (esa4.hc3370-68.iphmx.com: no sender authenticity information available from domain of anthony.perard@citrix.com) identity=pra; client-ip=162.221.158.21; receiver=esa4.hc3370-68.iphmx.com; envelope-from="anthony.perard@citrix.com"; x-sender="anthony.perard@citrix.com"; x-conformance=sidf_compatible Received-SPF: Pass (esa4.hc3370-68.iphmx.com: domain of anthony.perard@citrix.com designates 162.221.158.21 as permitted sender) identity=mailfrom; client-ip=162.221.158.21; receiver=esa4.hc3370-68.iphmx.com; envelope-from="anthony.perard@citrix.com"; x-sender="anthony.perard@citrix.com"; x-conformance=sidf_compatible; x-record-type="v=spf1"; x-record-text="v=spf1 ip4:209.167.231.154 ip4:178.63.86.133 ip4:195.66.111.40/30 ip4:85.115.9.32/28 ip4:199.102.83.4 ip4:192.28.146.160 ip4:192.28.146.107 ip4:216.52.6.88 ip4:216.52.6.188 ip4:162.221.158.21 ip4:162.221.156.83 ~all" Received-SPF: None (esa4.hc3370-68.iphmx.com: no sender authenticity information available from domain of postmaster@mail.citrix.com) identity=helo; client-ip=162.221.158.21; receiver=esa4.hc3370-68.iphmx.com; envelope-from="anthony.perard@citrix.com"; x-sender="postmaster@mail.citrix.com"; x-conformance=sidf_compatible IronPort-SDR: 0YgI770VsdhoIsphZWcQsKcBuzjS8UWsFf1zYfmmFTerRJBZpdH3Nf+9s4UWKHZShSF14ImmcB /ywwj7hsJ6tXiTtcUPx0/rK19zftTQnCI4eWjBFGTn3jyI0Q6XAPgBo6BfWETnS8xXlz6GqSfQ q/lh0RoR6DAoNC1jhXHn9BCAD3JL24Yo0Rq4euZ+H7gweGm4dctu76L4ECTuURCOp0eTNUed+6 79K0L+sOuXsp6q04UVCEcdOLd0SC9+llZydC1lxgM3wHNtgX7B22OEh3dKtXCDytK0bdEsEyib h9Y= X-SBRS: 2.7 X-MesageID: 1889399 X-Ironport-Server: esa4.hc3370-68.iphmx.com X-Remote-IP: 162.221.158.21 X-Policy: $RELAYED X-IronPort-AV: E=Sophos;i="5.63,389,1557201600"; d="scan'208";a="1889399" From: Anthony PERARD To: Date: Tue, 18 Jun 2019 12:23:41 +0100 Message-ID: <20190618112341.513-5-anthony.perard@citrix.com> X-Mailer: git-send-email 2.22.0 In-Reply-To: <20190618112341.513-1-anthony.perard@citrix.com> References: <20190618112341.513-1-anthony.perard@citrix.com> MIME-Version: 1.0 X-detected-operating-system: by eggs.gnu.org: FreeBSD 9.x X-Received-From: 216.71.155.144 Subject: [Qemu-devel] [PATCH v2 4/4] xen: Avoid VLA X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Anthony PERARD , xen-devel@lists.xenproject.org, Paul Durrant , Stefano Stabellini Errors-To: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org Sender: "Qemu-devel" Avoid using a variable length array. We allocate the `dirty_bitmap' buffer only once when we start tracking for dirty bits. Signed-off-by: Anthony PERARD Reviewed-by: Philippe Mathieu-Daudé Reviewed-by: Paul Durrant --- Notes: v2: - Allocate the bitmap buffer only once when we start tracking dirty bits. (instead of at every function call) Was suggested by Peter here: "should we try to stop using variable length arrays?" hw/i386/xen/xen-hvm.c | 15 +++++++++++---- 1 file changed, 11 insertions(+), 4 deletions(-) diff --git a/hw/i386/xen/xen-hvm.c b/hw/i386/xen/xen-hvm.c index ae3deb4ef3..469f1260a4 100644 --- a/hw/i386/xen/xen-hvm.c +++ b/hw/i386/xen/xen-hvm.c @@ -119,6 +119,8 @@ typedef struct XenIOState { DeviceListener device_listener; hwaddr free_phys_offset; const XenPhysmap *log_for_dirtybit; + /* Buffer used by xen_sync_dirty_bitmap */ + unsigned long *dirty_bitmap; Notifier exit; Notifier suspend; @@ -464,6 +466,8 @@ static int xen_remove_from_physmap(XenIOState *state, QLIST_REMOVE(physmap, list); if (state->log_for_dirtybit == physmap) { state->log_for_dirtybit = NULL; + g_free(state->dirty_bitmap); + state->dirty_bitmap = NULL; } g_free(physmap); @@ -614,7 +618,7 @@ static void xen_sync_dirty_bitmap(XenIOState *state, { hwaddr npages = size >> TARGET_PAGE_BITS; const int width = sizeof(unsigned long) * 8; - unsigned long bitmap[DIV_ROUND_UP(npages, width)]; + size_t bitmap_size = DIV_ROUND_UP(npages, width); int rc, i, j; const XenPhysmap *physmap = NULL; @@ -626,13 +630,14 @@ static void xen_sync_dirty_bitmap(XenIOState *state, if (state->log_for_dirtybit == NULL) { state->log_for_dirtybit = physmap; + state->dirty_bitmap = g_new(unsigned long, bitmap_size); } else if (state->log_for_dirtybit != physmap) { /* Only one range for dirty bitmap can be tracked. */ return; } rc = xen_track_dirty_vram(xen_domid, start_addr >> TARGET_PAGE_BITS, - npages, bitmap); + npages, state->dirty_bitmap); if (rc < 0) { #ifndef ENODATA #define ENODATA ENOENT @@ -646,8 +651,8 @@ static void xen_sync_dirty_bitmap(XenIOState *state, return; } - for (i = 0; i < ARRAY_SIZE(bitmap); i++) { - unsigned long map = bitmap[i]; + for (i = 0; i < bitmap_size; i++) { + unsigned long map = state->dirty_bitmap[i]; while (map != 0) { j = ctzl(map); map &= ~(1ul << j); @@ -677,6 +682,8 @@ static void xen_log_stop(MemoryListener *listener, MemoryRegionSection *section, if (old & ~new & (1 << DIRTY_MEMORY_VGA)) { state->log_for_dirtybit = NULL; + g_free(state->dirty_bitmap); + state->dirty_bitmap = NULL; /* Disable dirty bit tracking */ xen_track_dirty_vram(xen_domid, 0, 0, NULL); }