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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 0D265C433EF for ; Thu, 28 Apr 2022 08:28:19 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1344357AbiD1Ib2 (ORCPT ); Thu, 28 Apr 2022 04:31:28 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:48170 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1344174AbiD1IbH (ORCPT ); Thu, 28 Apr 2022 04:31:07 -0400 Received: from smtp-out1.suse.de (smtp-out1.suse.de [195.135.220.28]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id CF461A0BE7 for ; Thu, 28 Apr 2022 01:27:51 -0700 (PDT) Received: from imap2.suse-dmz.suse.de (imap2.suse-dmz.suse.de [192.168.254.74]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-521) server-digest SHA512) (No client certificate requested) by smtp-out1.suse.de (Postfix) with ESMTPS id 7D74021876; Thu, 28 Apr 2022 08:27:50 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1651134470; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=YDGIDWKPRWQB7unVe+D0Q46rvuLr6BdasgzAbPg2LQ4=; b=T5xs3W2ptqXsPfAvqIrcBVCVmeIIst8eIXsa6BQstyNsdU/WQh1htmsRml82tfTV2fGZ3M 7cGIdDix3zSa2IetRSiHt7IZIEFkNcvniiOV1J8BaTLWaoZ1RioIq/s150J0i7xKAcImqK uRJEG3SHaqX4FP/qg/DOiCvut/Qn7YI= Received: from imap2.suse-dmz.suse.de (imap2.suse-dmz.suse.de [192.168.254.74]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-521) server-digest SHA512) (No client certificate requested) by imap2.suse-dmz.suse.de (Postfix) with ESMTPS id 5049213491; Thu, 28 Apr 2022 08:27:50 +0000 (UTC) Received: from dovecot-director2.suse.de ([192.168.254.65]) by imap2.suse-dmz.suse.de with ESMTPSA id CKAEEgZQamIBLgAAMHmgww (envelope-from ); Thu, 28 Apr 2022 08:27:50 +0000 From: Juergen Gross To: xen-devel@lists.xenproject.org, linux-kernel@vger.kernel.org Cc: Juergen Gross , Boris Ostrovsky , Stefano Stabellini Subject: [PATCH v2 10/19] xen/xenbus: add xenbus_setup_ring() service function Date: Thu, 28 Apr 2022 10:27:34 +0200 Message-Id: <20220428082743.16593-11-jgross@suse.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20220428082743.16593-1-jgross@suse.com> References: <20220428082743.16593-1-jgross@suse.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Most PV device frontends share very similar code for setting up shared ring buffers: - allocate page(s) - init the ring admin data - give the backend access to the ring via grants Tearing down the ring requires similar actions in all frontends again: - remove grants - free the page(s) Provide service functions xenbus_setup_ring() and xenbus_teardown_ring() for that purpose. Signed-off-by: Juergen Gross --- drivers/xen/xenbus/xenbus_client.c | 69 ++++++++++++++++++++++++++++++ include/xen/xenbus.h | 4 ++ 2 files changed, 73 insertions(+) diff --git a/drivers/xen/xenbus/xenbus_client.c b/drivers/xen/xenbus/xenbus_client.c index df6890681231..1a2e0d94ccd1 100644 --- a/drivers/xen/xenbus/xenbus_client.c +++ b/drivers/xen/xenbus/xenbus_client.c @@ -407,6 +407,75 @@ int xenbus_grant_ring(struct xenbus_device *dev, void *vaddr, } EXPORT_SYMBOL_GPL(xenbus_grant_ring); +/* + * xenbus_setup_ring + * @dev: xenbus device + * @vaddr: pointer to starting virtual address of the ring + * @nr_pages: number of pages to be granted + * @grefs: grant reference array to be filled in + * + * Allocate physically contiguous pages for a shared ring buffer and grant it + * to the peer of the given device. The ring buffer is initially filled with + * zeroes. The virtual address of the ring is stored at @vaddr and the + * grant references are stored in the @grefs array. In case of error @vaddr + * will be set to NULL and @grefs will be filled with INVALID_GRANT_REF. + */ +int xenbus_setup_ring(struct xenbus_device *dev, gfp_t gfp, void **vaddr, + unsigned int nr_pages, grant_ref_t *grefs) +{ + unsigned long ring_size = nr_pages * XEN_PAGE_SIZE; + unsigned int i; + int ret; + + *vaddr = alloc_pages_exact(ring_size, gfp | __GFP_ZERO); + if (!*vaddr) { + ret = -ENOMEM; + goto err; + } + + ret = xenbus_grant_ring(dev, *vaddr, nr_pages, grefs); + if (ret) + goto err; + + return 0; + + err: + if (*vaddr) + free_pages_exact(*vaddr, ring_size); + for (i = 0; i < nr_pages; i++) + grefs[i] = INVALID_GRANT_REF; + *vaddr = NULL; + + return ret; +} +EXPORT_SYMBOL_GPL(xenbus_setup_ring); + +/* + * xenbus_teardown_ring + * @vaddr: starting virtual address of the ring + * @nr_pages: number of pages + * @grefs: grant reference array + * + * Remove grants for the shared ring buffer and free the associated memory. + * On return the grant reference array is filled with INVALID_GRANT_REF. + */ +void xenbus_teardown_ring(void **vaddr, unsigned int nr_pages, + grant_ref_t *grefs) +{ + unsigned int i; + + for (i = 0; i < nr_pages; i++) { + if (grefs[i] != INVALID_GRANT_REF) { + gnttab_end_foreign_access(grefs[i], 0); + grefs[i] = INVALID_GRANT_REF; + } + } + + if (*vaddr) + free_pages_exact(*vaddr, nr_pages * XEN_PAGE_SIZE); + *vaddr = NULL; +} +EXPORT_SYMBOL_GPL(xenbus_teardown_ring); /** * Allocate an event channel for the given xenbus_device, assigning the newly diff --git a/include/xen/xenbus.h b/include/xen/xenbus.h index b13eb86395e0..b533b4adc835 100644 --- a/include/xen/xenbus.h +++ b/include/xen/xenbus.h @@ -226,6 +226,10 @@ int xenbus_watch_pathfmt(struct xenbus_device *dev, struct xenbus_watch *watch, int xenbus_switch_state(struct xenbus_device *dev, enum xenbus_state new_state); int xenbus_grant_ring(struct xenbus_device *dev, void *vaddr, unsigned int nr_pages, grant_ref_t *grefs); +int xenbus_setup_ring(struct xenbus_device *dev, gfp_t gfp, void **vaddr, + unsigned int nr_pages, grant_ref_t *grefs); +void xenbus_teardown_ring(void **vaddr, unsigned int nr_pages, + grant_ref_t *grefs); int xenbus_map_ring_valloc(struct xenbus_device *dev, grant_ref_t *gnt_refs, unsigned int nr_grefs, void **vaddr); -- 2.34.1