From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-17.2 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id E82D6C433ED for ; Thu, 15 Apr 2021 09:41:44 +0000 (UTC) Received: from lists.xenproject.org (lists.xenproject.org [192.237.175.120]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 97E6760FD8 for ; Thu, 15 Apr 2021 09:41:44 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 97E6760FD8 Authentication-Results: mail.kernel.org; dmarc=fail (p=quarantine dis=none) header.from=suse.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=xen-devel-bounces@lists.xenproject.org Received: from list by lists.xenproject.org with outflank-mailman.110976.212070 (Exim 4.92) (envelope-from ) id 1lWyV9-0001Wq-UG; Thu, 15 Apr 2021 09:41:31 +0000 X-Outflank-Mailman: Message body and most headers restored to incoming version Received: by outflank-mailman (output) from mailman id 110976.212070; Thu, 15 Apr 2021 09:41:31 +0000 Received: from localhost ([127.0.0.1] helo=lists.xenproject.org) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1lWyV9-0001Wj-RS; Thu, 15 Apr 2021 09:41:31 +0000 Received: by outflank-mailman (input) for mailman id 110976; Thu, 15 Apr 2021 09:41:31 +0000 Received: from us1-rack-iad1.inumbo.com ([172.99.69.81]) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1lWyV9-0001We-6G for xen-devel@lists.xenproject.org; Thu, 15 Apr 2021 09:41:31 +0000 Received: from mx2.suse.de (unknown [195.135.220.15]) by us1-rack-iad1.inumbo.com (Halon) with ESMTPS id 87f9c48e-6b83-45f4-b161-bd061daff44d; Thu, 15 Apr 2021 09:41:30 +0000 (UTC) Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id 38852AC87; Thu, 15 Apr 2021 09:41:29 +0000 (UTC) X-BeenThere: xen-devel@lists.xenproject.org List-Id: Xen developer discussion List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Errors-To: xen-devel-bounces@lists.xenproject.org Precedence: list Sender: "Xen-devel" X-Inumbo-ID: 87f9c48e-6b83-45f4-b161-bd061daff44d X-Virus-Scanned: by amavisd-new at test-mx.suse.de DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1618479689; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding; bh=DJ55pGTV1Ycmrz3jU7NCoDWaPsEth8XN2XbbDgtsXps=; b=VMdxY6pVbLmlOd8UNH5jMmtZrZlbg6cpeJARtuShvfJ64cctg7gEptccF9PlI13E7QaDjo jBTocpRsma0J43aTzw7uptnEY0wqlfflfaqy1YX2XQIwfnrc9hMCjen4r4ieeNbzs6+KDZ MQl7WfFmVT2ovdTRtRoeKxqZPc8X+Ho= From: Jan Beulich Subject: [PATCH v3] gnttab: defer allocation of status frame tracking array To: "xen-devel@lists.xenproject.org" Cc: Andrew Cooper , George Dunlap , Ian Jackson , Julien Grall , Stefano Stabellini , Wei Liu Message-ID: Date: Thu, 15 Apr 2021 11:41:29 +0200 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101 Thunderbird/78.9.1 MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit This array can be large when many grant frames are permitted; avoid allocating it when it's not going to be used anyway, by doing this only in gnttab_populate_status_frames(). Signed-off-by: Jan Beulich --- v3: Drop smp_wmb(). Re-base. v2: Defer allocation to when a domain actually switches to the v2 grant API. --- a/xen/common/grant_table.c +++ b/xen/common/grant_table.c @@ -1747,6 +1747,17 @@ gnttab_populate_status_frames(struct dom /* Make sure, prior version checks are architectural visible */ block_speculation(); + if ( gt->status == ZERO_BLOCK_PTR ) + { + gt->status = xzalloc_array(grant_status_t *, + grant_to_status_frames(gt->max_grant_frames)); + if ( !gt->status ) + { + gt->status = ZERO_BLOCK_PTR; + return -ENOMEM; + } + } + for ( i = nr_status_frames(gt); i < req_status_frames; i++ ) { if ( (gt->status[i] = alloc_xenheap_page()) == NULL ) @@ -1767,18 +1778,23 @@ status_alloc_failed: free_xenheap_page(gt->status[i]); gt->status[i] = NULL; } + if ( !nr_status_frames(gt) ) + { + xfree(gt->status); + gt->status = ZERO_BLOCK_PTR; + } return -ENOMEM; } static int gnttab_unpopulate_status_frames(struct domain *d, struct grant_table *gt) { - unsigned int i; + unsigned int i, n = nr_status_frames(gt); /* Make sure, prior version checks are architectural visible */ block_speculation(); - for ( i = 0; i < nr_status_frames(gt); i++ ) + for ( i = 0; i < n; i++ ) { struct page_info *pg = virt_to_page(gt->status[i]); gfn_t gfn = gnttab_get_frame_gfn(gt, true, i); @@ -1833,12 +1849,11 @@ gnttab_unpopulate_status_frames(struct d page_set_owner(pg, NULL); } - for ( i = 0; i < nr_status_frames(gt); i++ ) - { - free_xenheap_page(gt->status[i]); - gt->status[i] = NULL; - } gt->nr_status_frames = 0; + for ( i = 0; i < n; i++ ) + free_xenheap_page(gt->status[i]); + xfree(gt->status); + gt->status = ZERO_BLOCK_PTR; return 0; } @@ -1969,11 +1984,11 @@ int grant_table_init(struct domain *d, i if ( gt->shared_raw == NULL ) goto out; - /* Status pages for grant table - for version 2 */ - gt->status = xzalloc_array(grant_status_t *, - grant_to_status_frames(gt->max_grant_frames)); - if ( gt->status == NULL ) - goto out; + /* + * Status page tracking array for v2 gets allocated on demand. But don't + * leave a NULL pointer there. + */ + gt->status = ZERO_BLOCK_PTR; grant_write_lock(gt); @@ -4047,11 +4062,12 @@ int gnttab_acquire_resource( if ( gt->gt_version != 2 ) break; + rc = gnttab_get_status_frame_mfn(d, final_frame, &tmp); + /* Check that void ** is a suitable representation for gt->status. */ BUILD_BUG_ON(!__builtin_types_compatible_p( typeof(gt->status), grant_status_t **)); vaddrs = (void **)gt->status; - rc = gnttab_get_status_frame_mfn(d, final_frame, &tmp); break; }