From patchwork Fri Apr 21 09:16:27 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Gerd Hoffmann X-Patchwork-Id: 753226 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Received: from lists.gnu.org (lists.gnu.org [IPv6:2001:4830:134:3::11]) (using TLSv1 with cipher AES256-SHA (256/256 bits)) (No client certificate requested) by ozlabs.org (Postfix) with ESMTPS id 3w8VYv3Ph3z9ryv for ; Fri, 21 Apr 2017 19:19:47 +1000 (AEST) Received: from localhost ([::1]:58104 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1d1Uj9-0003gW-O6 for incoming@patchwork.ozlabs.org; Fri, 21 Apr 2017 05:19:43 -0400 Received: from eggs.gnu.org ([2001:4830:134:3::10]:37100) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1d1UgF-0001wf-RI for qemu-devel@nongnu.org; Fri, 21 Apr 2017 05:16:45 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1d1UgC-0001Eg-Jc for qemu-devel@nongnu.org; Fri, 21 Apr 2017 05:16:43 -0400 Received: from mx1.redhat.com ([209.132.183.28]:41634) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1d1UgC-0001EG-AL for qemu-devel@nongnu.org; Fri, 21 Apr 2017 05:16:40 -0400 Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.phx2.redhat.com [10.5.11.12]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id E1D66335EAF for ; Fri, 21 Apr 2017 09:16:38 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mx1.redhat.com E1D66335EAF Authentication-Results: ext-mx05.extmail.prod.ext.phx2.redhat.com; dmarc=none (p=none dis=none) header.from=redhat.com Authentication-Results: ext-mx05.extmail.prod.ext.phx2.redhat.com; spf=pass smtp.mailfrom=kraxel@redhat.com DKIM-Filter: OpenDKIM Filter v2.11.0 mx1.redhat.com E1D66335EAF Received: from nilsson.home.kraxel.org (ovpn-116-18.ams2.redhat.com [10.36.116.18]) by smtp.corp.redhat.com (Postfix) with ESMTP id 470A660F8B; Fri, 21 Apr 2017 09:16:36 +0000 (UTC) Received: by nilsson.home.kraxel.org (Postfix, from userid 500) id 3C989814C5; Fri, 21 Apr 2017 11:16:34 +0200 (CEST) From: Gerd Hoffmann To: qemu-devel@nongnu.org Date: Fri, 21 Apr 2017 11:16:27 +0200 Message-Id: <20170421091632.30900-5-kraxel@redhat.com> In-Reply-To: <20170421091632.30900-1-kraxel@redhat.com> References: <20170421091632.30900-1-kraxel@redhat.com> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.12 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.29]); Fri, 21 Apr 2017 09:16:39 +0000 (UTC) X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] [fuzzy] X-Received-From: 209.132.183.28 Subject: [Qemu-devel] [PATCH 4/9] vga: make display updates thread safe. X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Gerd Hoffmann Errors-To: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org Sender: "Qemu-devel" The vga code clears the dirty bits *after* reading the framebuffer memory. So if the guest framebuffer updates hits the race window between vga reading the framebuffer and vga clearing the dirty bits vga will miss that update Fix it by using the new memory_region_copy_and_clear_dirty() memory_region_copy_get_dirty() functions. That way we clear the dirty bitmap before reading the framebuffer. Any guest display updates happening in parallel will be properly tracked in the dirty bitmap then and the next display refresh will pick them up. Problem triggers with mttcg only. Before mttcg was merged tcg never ran in parallel to vga emulation. Using kvm will hide the problem too, due to qemu operating on a userspace copy of the kernel's dirty bitmap. Signed-off-by: Gerd Hoffmann --- hw/display/vga.c | 36 +++++++++++++++++------------------- 1 file changed, 17 insertions(+), 19 deletions(-) diff --git a/hw/display/vga.c b/hw/display/vga.c index 3991b88aac..b2516c8d21 100644 --- a/hw/display/vga.c +++ b/hw/display/vga.c @@ -1465,7 +1465,8 @@ static void vga_draw_graphic(VGACommonState *s, int full_update) DisplaySurface *surface = qemu_console_surface(s->con); int y1, y, update, linesize, y_start, double_scan, mask, depth; int width, height, shift_control, line_offset, bwidth, bits; - ram_addr_t page0, page1, page_min, page_max; + ram_addr_t page0, page1; + DirtyBitmapSnapshot *snap = NULL; int disp_width, multi_scan, multi_run; uint8_t *d; uint32_t v, addr1, addr; @@ -1480,9 +1481,6 @@ static void vga_draw_graphic(VGACommonState *s, int full_update) full_update |= update_basic_params(s); - if (!full_update) - vga_sync_dirty_bitmap(s); - s->get_resolution(s, &width, &height); disp_width = width; @@ -1625,11 +1623,17 @@ static void vga_draw_graphic(VGACommonState *s, int full_update) addr1 = (s->start_addr * 4); bwidth = (width * bits + 7) / 8; y_start = -1; - page_min = -1; - page_max = 0; d = surface_data(surface); linesize = surface_stride(surface); y1 = 0; + + if (!full_update) { + vga_sync_dirty_bitmap(s); + snap = memory_region_snapshot_and_clear_dirty(&s->vram, addr1, + bwidth * height, + DIRTY_MEMORY_VGA); + } + for(y = 0; y < height; y++) { addr = addr1; if (!(s->cr[VGA_CRTC_MODE] & 1)) { @@ -1644,17 +1648,17 @@ static void vga_draw_graphic(VGACommonState *s, int full_update) update = full_update; page0 = addr; page1 = addr + bwidth - 1; - update |= memory_region_get_dirty(&s->vram, page0, page1 - page0, - DIRTY_MEMORY_VGA); + if (full_update) { + update = 1; + } else { + update = memory_region_snapshot_get_dirty(&s->vram, snap, + page0, page1 - page0); + } /* explicit invalidation for the hardware cursor (cirrus only) */ update |= vga_scanline_invalidated(s, y); if (update) { if (y_start < 0) y_start = y; - if (page0 < page_min) - page_min = page0; - if (page1 > page_max) - page_max = page1; if (!(is_buffer_shared(surface))) { vga_draw_line(s, d, s->vram_ptr + addr, width); if (s->cursor_draw_line) @@ -1687,13 +1691,7 @@ static void vga_draw_graphic(VGACommonState *s, int full_update) dpy_gfx_update(s->con, 0, y_start, disp_width, y - y_start); } - /* reset modified pages */ - if (page_max >= page_min) { - memory_region_reset_dirty(&s->vram, - page_min, - page_max - page_min, - DIRTY_MEMORY_VGA); - } + g_free(snap); memset(s->invalidated_y_table, 0, sizeof(s->invalidated_y_table)); }