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[23.128.96.18]) by mx.google.com with ESMTP id w12si294798edf.351.2020.10.23.04.43.21; Fri, 23 Oct 2020 04:43:43 -0700 (PDT) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18; Authentication-Results: mx.google.com; dkim=pass header.i=@linaro.org header.s=google header.b=Ij8dIfvA; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=linaro.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S463112AbgJWLmP (ORCPT + 99 others); Fri, 23 Oct 2020 07:42:15 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:59888 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S463083AbgJWLmO (ORCPT ); Fri, 23 Oct 2020 07:42:14 -0400 Received: from mail-ej1-x644.google.com (mail-ej1-x644.google.com [IPv6:2a00:1450:4864:20::644]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 15D31C0613CE for ; Fri, 23 Oct 2020 04:42:13 -0700 (PDT) Received: by mail-ej1-x644.google.com with SMTP id gs25so1962544ejb.1 for ; Fri, 23 Oct 2020 04:42:13 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linaro.org; s=google; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=gA8+CjJlncVTA5tTIhpR8Iykc8SEIsErIVYnGmyFNI4=; b=Ij8dIfvAABQKPbABPuO1LdAyvmXuRZmmDFS7rJgeDo/U7pvB+1+1OBXm9gLYS3cWRd bSrP8L13OaKlLIU6MIZ/n0EKgMJENrlo8E+4/T2RBgZ08thhhvQc7p5aljKUjKq9+0oi njwdZEStttOw0Ucn2VlKYzSk2oxIIv2Q3rOL0W0h5yl5XaukoT2HZBWKGeEpK79WEe1i tjnHYDwyHjmxcy7JWSUBDKSaLFlWTB7GZJ43Bfxcb2xHBqzkhY2Kmf1j04gIZEER8wjN K4EGc2mnA2ZaUPxVURu5qdxJx9QfJTH6gIt2OGMGYi+5Q5sQNxIcPZ3TsYszCx+m/rpi BnJg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=gA8+CjJlncVTA5tTIhpR8Iykc8SEIsErIVYnGmyFNI4=; b=fEXuv9jWAM7EdJRKWMbXiNb8MwYmymJlikss3RQDAx8fhF7eEUlSuE4KLILOEyu8ja 3slCCzDQRZlfODkfDsbJEfYjVVMbPRbx4wcHxxQVjF0D7SA8DxU4XsHujsfE+Q9CvO63 5yTxNhaI9B5t38JsYes/8vH8Kfv1pVPdzpyyOc4Rw7V7yADLXv+leyu1jHv6F32Mj6tL leU9PPtOkbgh9vFXBWD5IkUKJfCjl2iP1lNVxAKj0VQ0l9HIEeAJ3foGInoetNXVzjmw l7zSc6GUzndhOnb3+4IJUot8tpDhWFEyrWbXksGezyClbAWF02co0OXY11VcRFAwIp49 ep+g== X-Gm-Message-State: AOAM532a49qKjXwDEOGslCjpllPrNQ7vDxDXcgoaUI/8XJ8/gHLxbkS8 O9YrSGPNJCmiVc+FSNTro6SoNw== X-Received: by 2002:a17:906:354c:: with SMTP id s12mr1556614eja.263.1603453331577; Fri, 23 Oct 2020 04:42:11 -0700 (PDT) Received: from myrica ([2001:1715:4e26:a7e0:116c:c27a:3e7f:5eaf]) by smtp.gmail.com with ESMTPSA id d24sm636604edq.34.2020.10.23.04.42.10 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 23 Oct 2020 04:42:10 -0700 (PDT) Date: Fri, 23 Oct 2020 13:41:51 +0200 From: Jean-Philippe Brucker To: Jacob Pan Cc: iommu@lists.linux-foundation.org, LKML , Joerg Roedel , Alex Williamson , Lu Baolu , David Woodhouse , Jonathan Corbet , linux-api@vger.kernel.org, Jean-Philippe Brucker , Eric Auger , Jacob Pan , Yi Liu , "Tian, Kevin" , Raj Ashok , Wu Hao , Yi Sun , Dave Jiang , Randy Dunlap Subject: Re: [PATCH v3 10/14] iommu/ioasid: Introduce notification APIs Message-ID: <20201023114151.GC2265982@myrica> References: <1601329121-36979-1-git-send-email-jacob.jun.pan@linux.intel.com> <1601329121-36979-11-git-send-email-jacob.jun.pan@linux.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1601329121-36979-11-git-send-email-jacob.jun.pan@linux.intel.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Sep 28, 2020 at 02:38:37PM -0700, Jacob Pan wrote: > Relations among IOASID users largely follow a publisher-subscriber > pattern. E.g. to support guest SVA on Intel Scalable I/O Virtualization > (SIOV) enabled platforms, VFIO, IOMMU, device drivers, KVM are all users > of IOASIDs. When a state change occurs, VFIO publishes the change event > that needs to be processed by other users/subscribers. > > This patch introduced two types of notifications: global and per > ioasid_set. The latter is intended for users who only needs to handle > events related to the IOASID of a given set. > For more information, refer to the kernel documentation at > Documentation/ioasid.rst. > > Signed-off-by: Liu Yi L > Signed-off-by: Wu Hao > Signed-off-by: Jacob Pan > --- > drivers/iommu/ioasid.c | 141 +++++++++++++++++++++++++++++++++++++++++++++++++ > include/linux/ioasid.h | 57 +++++++++++++++++++- > 2 files changed, 197 insertions(+), 1 deletion(-) > > diff --git a/drivers/iommu/ioasid.c b/drivers/iommu/ioasid.c > index 378fef8f23d9..894b17c06ead 100644 > --- a/drivers/iommu/ioasid.c > +++ b/drivers/iommu/ioasid.c > @@ -10,12 +10,35 @@ > #include > #include > > +/* > + * An IOASID can have multiple consumers where each consumer may have > + * hardware contexts associated with the IOASID. > + * When a status change occurs, like on IOASID deallocation, notifier chains > + * are used to keep the consumers in sync. > + * This is a publisher-subscriber pattern where publisher can change the > + * state of each IOASID, e.g. alloc/free, bind IOASID to a device and mm. > + * On the other hand, subscribers get notified for the state change and > + * keep local states in sync. > + */ > +static ATOMIC_NOTIFIER_HEAD(ioasid_notifier); > +/* List to hold pending notification block registrations */ > +static LIST_HEAD(ioasid_nb_pending_list); nit: it might be tidier to deal with the pending list in the next patch, since it's only relevant for mm set notifier > +static DEFINE_SPINLOCK(ioasid_nb_lock); > + > /* Default to PCIe standard 20 bit PASID */ > #define PCI_PASID_MAX 0x100000 > static ioasid_t ioasid_capacity = PCI_PASID_MAX; > static ioasid_t ioasid_capacity_avail = PCI_PASID_MAX; > static DEFINE_XARRAY_ALLOC(ioasid_sets); > > +struct ioasid_set_nb { > + struct list_head list; > + struct notifier_block *nb; > + void *token; > + struct ioasid_set *set; > + bool active; > +}; > + > enum ioasid_state { > IOASID_STATE_INACTIVE, > IOASID_STATE_ACTIVE, > @@ -365,6 +388,42 @@ void ioasid_detach_data(ioasid_t ioasid) > } > EXPORT_SYMBOL_GPL(ioasid_detach_data); > > +/** > + * ioasid_notify - Send notification on a given IOASID for status change. > + * > + * @data: The IOASID data to which the notification will send > + * @cmd: Notification event sent by IOASID external users, can be > + * IOASID_BIND or IOASID_UNBIND. > + * > + * @flags: Special instructions, e.g. notify within a set or global by > + * IOASID_NOTIFY_FLAG_SET or IOASID_NOTIFY_FLAG_ALL flags > + * Caller must hold ioasid_allocator_lock and reference to the IOASID > + */ > +static int ioasid_notify(struct ioasid_data *data, > + enum ioasid_notify_val cmd, unsigned int flags) > +{ > + struct ioasid_nb_args args = { 0 }; > + int ret = 0; > + > + /* IOASID_FREE/ALLOC are internal events emitted by IOASID core only */ > + if (cmd <= IOASID_NOTIFY_FREE) > + return -EINVAL; This function is now called with ALLOC and FREE > + > + if (flags & ~(IOASID_NOTIFY_FLAG_ALL | IOASID_NOTIFY_FLAG_SET)) > + return -EINVAL; > + > + args.id = data->id; > + args.set = data->set; > + args.pdata = data->private; > + args.spid = data->spid; > + if (flags & IOASID_NOTIFY_FLAG_ALL) > + ret = atomic_notifier_call_chain(&ioasid_notifier, cmd, &args); > + if (flags & IOASID_NOTIFY_FLAG_SET) > + ret = atomic_notifier_call_chain(&data->set->nh, cmd, &args); If both flags are set, we'll miss errors within the global notification. Is that a problem? > + > + return ret; > +} > + > static ioasid_t ioasid_find_by_spid_locked(struct ioasid_set *set, ioasid_t spid) > { > ioasid_t ioasid = INVALID_IOASID; > @@ -417,6 +476,7 @@ int ioasid_attach_spid(ioasid_t ioasid, ioasid_t spid) > goto done_unlock; > } > data->spid = spid; > + ioasid_notify(data, IOASID_NOTIFY_BIND, IOASID_NOTIFY_FLAG_SET); > > done_unlock: > spin_unlock(&ioasid_allocator_lock); > @@ -436,6 +496,7 @@ void ioasid_detach_spid(ioasid_t ioasid) > goto done_unlock; > } > data->spid = INVALID_IOASID; > + ioasid_notify(data, IOASID_NOTIFY_UNBIND, IOASID_NOTIFY_FLAG_SET); > > done_unlock: > spin_unlock(&ioasid_allocator_lock); > @@ -469,6 +530,28 @@ static inline bool ioasid_set_is_valid(struct ioasid_set *set) > return xa_load(&ioasid_sets, set->id) == set; > } > > +static void ioasid_add_pending_nb(struct ioasid_set *set) > +{ > + struct ioasid_set_nb *curr; > + > + if (set->type != IOASID_SET_TYPE_MM) > + return; > + > + /* > + * Check if there are any pending nb requests for the given token, if so > + * add them to the notifier chain. > + */ > + spin_lock(&ioasid_nb_lock); > + list_for_each_entry(curr, &ioasid_nb_pending_list, list) { > + if (curr->token == set->token && !curr->active) { > + atomic_notifier_chain_register(&set->nh, curr->nb); > + curr->set = set; > + curr->active = true; > + } > + } > + spin_unlock(&ioasid_nb_lock); > +} > + > /** > * ioasid_set_alloc - Allocate a new IOASID set for a given token > * > @@ -556,6 +639,13 @@ struct ioasid_set *ioasid_set_alloc(void *token, ioasid_t quota, int type) > set->quota = quota; > set->id = id; > refcount_set(&set->ref, 1); > + ATOMIC_INIT_NOTIFIER_HEAD(&set->nh); > + > + /* > + * Check if there are any pending nb requests for the given token, if so > + * add them to the notifier chain. > + */ > + ioasid_add_pending_nb(set); > > /* > * Per set XA is used to store private IDs within the set, get ready > @@ -641,6 +731,7 @@ ioasid_t ioasid_alloc(struct ioasid_set *set, ioasid_t min, ioasid_t max, > goto exit_free; > } > set->nr_ioasids++; > + ioasid_notify(data, IOASID_NOTIFY_ALLOC, IOASID_NOTIFY_FLAG_SET); > goto done_unlock; > exit_free: > kfree(data); > @@ -687,6 +778,8 @@ static void ioasid_free_locked(struct ioasid_set *set, ioasid_t ioasid) > return; > > data->state = IOASID_STATE_FREE_PENDING; > + ioasid_notify(data, IOASID_NOTIFY_FREE, > + IOASID_NOTIFY_FLAG_ALL | IOASID_NOTIFY_FLAG_ALL); > if (!refcount_dec_and_test(&data->users)) > return; > > @@ -726,6 +819,7 @@ EXPORT_SYMBOL_GPL(ioasid_set_get); > > static void ioasid_set_put_locked(struct ioasid_set *set) > { > + struct ioasid_set_nb *curr; > struct ioasid_data *entry; > unsigned long index; > > @@ -757,6 +851,16 @@ static void ioasid_set_put_locked(struct ioasid_set *set) > /* Return the quota back to system pool */ > ioasid_capacity_avail += set->quota; > > + /* Restore pending status of the set NBs */ > + list_for_each_entry(curr, &ioasid_nb_pending_list, list) { > + if (curr->token == set->token) { > + if (curr->active) > + curr->active = false; > + else > + pr_warn("Set token exists but not active!\n"); > + } > + } > + > /* > * Token got released right away after the ioasid_set is freed. > * If a new set is created immediately with the newly released token, > @@ -778,7 +882,9 @@ static void ioasid_set_put_locked(struct ioasid_set *set) > void ioasid_set_put(struct ioasid_set *set) > { > spin_lock(&ioasid_allocator_lock); > + spin_lock(&ioasid_nb_lock); > ioasid_set_put_locked(set); > + spin_unlock(&ioasid_nb_lock); > spin_unlock(&ioasid_allocator_lock); > } > EXPORT_SYMBOL_GPL(ioasid_set_put); > @@ -980,6 +1086,41 @@ void *ioasid_find(struct ioasid_set *set, ioasid_t ioasid, > } > EXPORT_SYMBOL_GPL(ioasid_find); > > +int ioasid_register_notifier(struct ioasid_set *set, struct notifier_block *nb) A comment might be useful, explaining that @set is optional and that the caller should set a priority within ioasid_notifier_prios in @nb. > +{ > + if (set) > + return atomic_notifier_chain_register(&set->nh, nb); > + else > + return atomic_notifier_chain_register(&ioasid_notifier, nb); > +} > +EXPORT_SYMBOL_GPL(ioasid_register_notifier); > + Here as well, a comment saying that a reference to the set must be held, though maybe that's obvious. Thanks, Jean > +void ioasid_unregister_notifier(struct ioasid_set *set, > + struct notifier_block *nb) > +{ > + struct ioasid_set_nb *curr; > + > + spin_lock(&ioasid_nb_lock); > + /* > + * Pending list is registered with a token without an ioasid_set, > + * therefore should not be unregistered directly. > + */ > + list_for_each_entry(curr, &ioasid_nb_pending_list, list) { > + if (curr->nb == nb) { > + pr_warn("Cannot unregister NB from pending list\n"); > + spin_unlock(&ioasid_nb_lock); > + return; > + } > + } > + spin_unlock(&ioasid_nb_lock); > + > + if (set) > + atomic_notifier_chain_unregister(&set->nh, nb); > + else > + atomic_notifier_chain_unregister(&ioasid_notifier, nb); > +} > +EXPORT_SYMBOL_GPL(ioasid_unregister_notifier); > + > MODULE_AUTHOR("Jean-Philippe Brucker "); > MODULE_AUTHOR("Jacob Pan "); > MODULE_DESCRIPTION("IO Address Space ID (IOASID) allocator"); > diff --git a/include/linux/ioasid.h b/include/linux/ioasid.h > index 2dfe85e6cb7e..1b551c99d568 100644 > --- a/include/linux/ioasid.h > +++ b/include/linux/ioasid.h > @@ -23,6 +23,7 @@ enum ioasid_set_type { > > /** > * struct ioasid_set - Meta data about ioasid_set > + * @nh: List of notifiers private to that set > * @xa: XArray to store ioasid_set private IDs, can be used for > * guest-host IOASID mapping, or just a private IOASID namespace. > * @token: Unique to identify an IOASID set > @@ -33,6 +34,7 @@ enum ioasid_set_type { > * @ref: Reference count of the users > */ > struct ioasid_set { > + struct atomic_notifier_head nh; > struct xarray xa; > void *token; > int type; > @@ -58,6 +60,47 @@ struct ioasid_allocator_ops { > void *pdata; > }; > > +/* Notification data when IOASID status changed */ > +enum ioasid_notify_val { > + IOASID_NOTIFY_ALLOC = 1, > + IOASID_NOTIFY_FREE, > + IOASID_NOTIFY_BIND, > + IOASID_NOTIFY_UNBIND, > +}; > + > +#define IOASID_NOTIFY_FLAG_ALL BIT(0) > +#define IOASID_NOTIFY_FLAG_SET BIT(1) > +/** > + * enum ioasid_notifier_prios - IOASID event notification order > + * > + * When status of an IOASID changes, users might need to take actions to > + * reflect the new state. For example, when an IOASID is freed due to > + * exception, the hardware context in virtual CPU, DMA device, and IOMMU > + * shall be cleared and drained. Order is required to prevent life cycle > + * problems. > + */ > +enum ioasid_notifier_prios { > + IOASID_PRIO_LAST, > + IOASID_PRIO_DEVICE, > + IOASID_PRIO_IOMMU, > + IOASID_PRIO_CPU, > +}; > + > +/** > + * struct ioasid_nb_args - Argument provided by IOASID core when notifier > + * is called. > + * @id: The IOASID being notified > + * @spid: The set private ID associated with the IOASID > + * @set: The IOASID set of @id > + * @pdata: The private data attached to the IOASID > + */ > +struct ioasid_nb_args { > + ioasid_t id; > + ioasid_t spid; > + struct ioasid_set *set; > + void *pdata; > +}; > + > #if IS_ENABLED(CONFIG_IOASID) > void ioasid_install_capacity(ioasid_t total); > ioasid_t ioasid_get_capacity(void); > @@ -82,7 +125,10 @@ void ioasid_detach_data(ioasid_t ioasid); > int ioasid_attach_spid(ioasid_t ioasid, ioasid_t spid); > void ioasid_detach_spid(ioasid_t ioasid); > ioasid_t ioasid_find_by_spid(struct ioasid_set *set, ioasid_t spid); > - > +int ioasid_register_notifier(struct ioasid_set *set, > + struct notifier_block *nb); > +void ioasid_unregister_notifier(struct ioasid_set *set, > + struct notifier_block *nb); > void ioasid_set_for_each_ioasid(struct ioasid_set *sdata, > void (*fn)(ioasid_t id, void *data), > void *data); > @@ -145,6 +191,15 @@ static inline void *ioasid_find(struct ioasid_set *set, ioasid_t ioasid, bool (* > return NULL; > } > > +static inline int ioasid_register_notifier(struct notifier_block *nb) > +{ > + return -ENOTSUPP; > +} > + > +static inline void ioasid_unregister_notifier(struct notifier_block *nb) > +{ > +} > + > static inline int ioasid_register_allocator(struct ioasid_allocator_ops *allocator) > { > return -ENOTSUPP; > -- > 2.7.4 >