From patchwork Mon Nov 6 10:39:52 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: David Woodhouse X-Patchwork-Id: 13446572 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org 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 smtp.lore.kernel.org (Postfix) with ESMTPS id 248EAC4167B for ; Mon, 6 Nov 2023 10:41:46 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1qzx1u-0001UZ-H2; Mon, 06 Nov 2023 05:40:27 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1qzx1k-0001R3-E2; Mon, 06 Nov 2023 05:40:16 -0500 Received: from casper.infradead.org ([2001:8b0:10b:1236::1]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1qzx1e-0007hF-EK; Mon, 06 Nov 2023 05:40:16 -0500 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=Sender:Content-Transfer-Encoding: MIME-Version:References:In-Reply-To:Message-ID:Date:Subject:Cc:To:From: Reply-To:Content-Type:Content-ID:Content-Description; bh=UEnjaXF9IbVpfGR6pVwSlj7B+44LHx3n6ww2MVgkTpA=; b=v9GGJRYSotjmH5aMKb615be3Wh A1SIx3pqMqmeGy+3oNTCGKnqFJdb5KIGg/zpCYxMEK7EBG7CvNqv+7uzJTgzNZhqT0p2zeACSmuQA AE9Kr3tGyv2X7LVTKZOoFBHE46N3ry/HY7XkMw5A+oxo7NStJih00MnU/DfEkCStM2lAuuFIbtAo8 Spa3GytWn1hjEQUXwjU6P8Y23QDIdFc+5uHZFRkSkz0ARD998Lnm06p8S8FoaQUDm1amp/qKAkVpx 9pHknZWs5urn5hg6GhsU81PlAY/6Iu3JLqi8s6vVBCnHktWnbr8Ks22660tRwpyHG5cuC/T6JHDQ5 N2C6zWEA==; Received: from [2001:8b0:10b:1::ebe] (helo=i7.infradead.org) by casper.infradead.org with esmtpsa (Exim 4.94.2 #2 (Red Hat Linux)) id 1qzx1P-005R1h-Og; Mon, 06 Nov 2023 10:39:56 +0000 Received: from dwoodhou by i7.infradead.org with local (Exim 4.96.2 #2 (Red Hat Linux)) id 1qzx1Q-000qG9-09; Mon, 06 Nov 2023 10:39:56 +0000 From: David Woodhouse To: qemu-devel@nongnu.org, qemu-stable@nongnu.org Cc: Stefano Stabellini , Anthony Perard , Paul Durrant , Kevin Wolf , Hanna Reitz , "Michael S. Tsirkin" , Marcel Apfelbaum , Paolo Bonzini , Richard Henderson , Eduardo Habkost , Marcelo Tosatti , xen-devel@lists.xenproject.org, qemu-block@nongnu.org, kvm@vger.kernel.org Subject: [PULL 4/7] hw/xen: don't clear map_track[] in xen_gnttab_reset() Date: Mon, 6 Nov 2023 10:39:52 +0000 Message-ID: <20231106103955.200867-5-dwmw2@infradead.org> X-Mailer: git-send-email 2.41.0 In-Reply-To: <20231106103955.200867-1-dwmw2@infradead.org> References: <20231106103955.200867-1-dwmw2@infradead.org> MIME-Version: 1.0 X-SRS-Rewrite: SMTP reverse-path rewritten from by casper.infradead.org. See http://www.infradead.org/rpr.html Received-SPF: none client-ip=2001:8b0:10b:1236::1; envelope-from=BATV+7ad6dfa9aff48d363c6b+7379+infradead.org+dwmw2@casper.srs.infradead.org; helo=casper.infradead.org X-Spam_score_int: -43 X-Spam_score: -4.4 X-Spam_bar: ---- X-Spam_report: (-4.4 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_MED=-2.3, SPF_HELO_NONE=0.001, SPF_NONE=0.001, T_SCC_BODY_TEXT_LINE=-0.01 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org From: David Woodhouse The refcounts actually correspond to 'active_ref' structures stored in a GHashTable per "user" on the backend side (mostly, per XenDevice). If we zero map_track[] on reset, then when the backend drivers get torn down and release their mapping we hit the assert(s->map_track[ref] != 0) in gnt_unref(). So leave them in place. Each backend driver will disconnect and reconnect as the guest comes back up again and reconnects, and it all works out OK in the end as the old refs get dropped. Cc: qemu-stable@nongnu.org Fixes: de26b2619789 ("hw/xen: Implement soft reset for emulated gnttab") Signed-off-by: David Woodhouse Reviewed-by: Paul Durrant --- hw/i386/kvm/xen_gnttab.c | 2 -- 1 file changed, 2 deletions(-) diff --git a/hw/i386/kvm/xen_gnttab.c b/hw/i386/kvm/xen_gnttab.c index 21c30e3659..839ec920a1 100644 --- a/hw/i386/kvm/xen_gnttab.c +++ b/hw/i386/kvm/xen_gnttab.c @@ -541,7 +541,5 @@ int xen_gnttab_reset(void) s->entries.v1[GNTTAB_RESERVED_XENSTORE].flags = GTF_permit_access; s->entries.v1[GNTTAB_RESERVED_XENSTORE].frame = XEN_SPECIAL_PFN(XENSTORE); - memset(s->map_track, 0, s->max_frames * ENTRIES_PER_FRAME_V1); - return 0; }