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 bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (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 333EDCCA462 for ; Thu, 15 Oct 2026 14:27:39 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:Content-Transfer-Encoding: MIME-Version:References:In-Reply-To:Message-ID:Date:Subject:Cc:To:From: Reply-To:Content-Type:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=THdXiYAEn5Oz4oBQv+RuuXZHfCgfy9dp1ghQ5rbYac0=; b=ij/nWJD9L1dyQgla4Vinov7UVo /6xAT5CuVCqkM1TOcak3RxJ4TEzsQRmYUIPEO+9OBH5N9nwU52SxkRZXj55iUebftX6O1+u3h3Dwl 3OV00gyr8h69BR6BvCYlvYOAMYXBLijKLrOKmoscmwKX/QVkhq80RRQtMKKmqF5n35vwK2Yu+YHRc gfjl/BacOM37NJ68MaK8TEVjFwGQt62KO7QTa8dgh2Vi9kyNwKddkz3yaF59Sohaio1Uvh27XHNjr +rPY3pscSJpGlO9bbeu80qBJip+KWMG9YUqZ2sVQyEGyZzAkd9epvy6JXDDa+ZxWuFqXXk69MQuFY KXJQOHjg==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.99.1 #2 (Red Hat Linux)) id 1xHMQW-00000000NAn-075y; Thu, 15 Oct 2026 14:27:24 +0000 Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.99.1 #2 (Red Hat Linux)) id 1xHMQ0-00000000Mbc-3EEc for linux-arm-kernel@lists.infradead.org; Thu, 15 Oct 2026 14:26:57 +0000 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id E2CC11516; Thu, 15 Oct 2026 07:26:48 -0700 (PDT) Received: from e125769.cambridge.arm.com (e125769.cambridge.arm.com [10.2.198.107]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 5CE483F871; Thu, 15 Oct 2026 07:26:49 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=arm.com; s=foss; t=1792074412; bh=DNQETDEyak8naSY4EIpo/+mHp8XBiRhp+IR8g1J6GgY=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=WSqW9q7XxyuwSmz+6ydn2qmvCylqqdgvQfEHsW3ZI+CVk3toxpkOv3457nY01jAmL oWUcu0zVjHtRyNGSfcRP8POyzvzunYIOcPRzXWxewluJvrIlTeKE6qgG26Zlih/5MS N5PAD9oOQ+iEmQkBbG+Lt+WGtdQFCc3+qpopbsKY= From: Ryan Roberts To: Greg Kroah-Hartman , Arnd Bergmann , Catalin Marinas , Will Deacon , Mark Rutland , Marc Zyngier , Oliver Upton , Alex Williamson , Jason Gunthorpe , Rob Herring , Krzysztof Kozlowski , Conor Dooley , Jean-Philippe Brucker , Oded Gabbay , Jonathan Corbet Cc: Ryan Roberts , linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, kvmarm@lists.linux.dev, kvm@vger.kernel.org, devicetree@vger.kernel.org, dri-devel@lists.freedesktop.org, linux-doc@vger.kernel.org Subject: [RFC PATCH v2 14/15] misc/arm-cla: Support exclusive context assignment Date: Thu, 15 Oct 2026 15:25:48 +0100 Message-ID: <20261015142552.4128028-15-ryan.roberts@arm.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20261015142552.4128028-1-ryan.roberts@arm.com> References: <20261015142552.4128028-1-ryan.roberts@arm.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.9.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20261015_072653_848377_1CAB9B6F X-CRM114-Status: GOOD ( 19.43 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org From: Jean-Philippe Brucker Introduce a nr_contexts members to cla_domain to count the mapped contexts. At the moment PL0 contexts share the domain, while PL1 contexts require exclusive assignment, since there is no context save/restore. A negative count indicates the domain is exclusive. Signed-off-by: Jean-Philippe Brucker --- drivers/misc/arm-cla/arm-cla.h | 2 ++ drivers/misc/arm-cla/cla-ctx.c | 44 ++++++++++++++++++++++++++++++++-- 2 files changed, 44 insertions(+), 2 deletions(-) diff --git a/drivers/misc/arm-cla/arm-cla.h b/drivers/misc/arm-cla/arm-cla.h index c9ecab5ab6bf..43a58a329525 100644 --- a/drivers/misc/arm-cla/arm-cla.h +++ b/drivers/misc/arm-cla/arm-cla.h @@ -105,6 +105,7 @@ struct cla_dev { * @lock: Protects the following members. * @ctxs: All live contexts, keyed on cla_ctx_key. * @queued_ctxs: Queue of contexts waiting for assignment. + * @nr_ctxs: Context count. Negative value for exclusive assignment. * @worker: Kthread worker to coordinate reassignment. * @reassign: Delayed work that switches contexts with time slicing. * @@ -120,6 +121,7 @@ struct cla_domain { struct mutex lock; bool broken; + long nr_ctxs; struct rhashtable ctxs; struct list_head queued_ctxs; struct cla_ctx *assigned_ctx; diff --git a/drivers/misc/arm-cla/cla-ctx.c b/drivers/misc/arm-cla/cla-ctx.c index 0489bf7a103f..f956cc88909f 100644 --- a/drivers/misc/arm-cla/cla-ctx.c +++ b/drivers/misc/arm-cla/cla-ctx.c @@ -39,6 +39,38 @@ static inline void cla_ctx_put_pl1(struct cla_ctx *ctx) } #endif +static int cla_domain_get(struct cla_domain *domain, bool share) +{ + lockdep_assert_held(&domain->lock); + + if (share) { + /* Time share the domain with other contexts. */ + if (domain->nr_ctxs < 0) + return -EBUSY; + domain->nr_ctxs++; + WARN_ON(domain->nr_ctxs < 0); /* LONG_MAX contexts?! */ + } else { + /* Reserve the domain for exclusive assignment. */ + if (domain->nr_ctxs != 0) + return -EBUSY; + domain->nr_ctxs--; + } + return 0; +} + +/* Undo cla_domain_get() */ +static void cla_domain_put(struct cla_domain *domain) +{ + lockdep_assert_held(&domain->lock); + + if (domain->nr_ctxs == -1) + domain->nr_ctxs = 0; + else if (domain->nr_ctxs > 0) + domain->nr_ctxs--; + else + WARN(1, "invalid domain refcount %ld\n", domain->nr_ctxs); +} + /** * cla_ctx_create - Create a context or increase its user count * @domain: CLA domain @@ -53,7 +85,7 @@ struct cla_ctx *cla_ctx_create(struct cla_domain *domain, struct cla_ctx_key *key) { struct cla_ctx *ctx; - int ret = -ENOMEM; + int ret; mutex_lock(&domain->lock); ctx = cla_domain_lookup_ctx(domain, key); @@ -68,9 +100,14 @@ struct cla_ctx *cla_ctx_create(struct cla_domain *domain, goto err_unlock; } + ret = cla_domain_get(domain, key->type == CLA_CTX_PL0); + if (ret) + goto err_unlock; + + ret = -ENOMEM; ctx = kzalloc_obj(*ctx, GFP_KERNEL_ACCOUNT); if (!ctx) - goto err_unlock; + goto err_put_domain; kref_init(&ctx->refcnt); refcount_set(&ctx->users, 1); @@ -116,6 +153,8 @@ struct cla_ctx *cla_ctx_create(struct cla_domain *domain, cla_ctx_put_pl1(ctx); } kfree(ctx); +err_put_domain: + cla_domain_put(domain); err_unlock: mutex_unlock(&domain->lock); return ERR_PTR(ret); @@ -161,6 +200,7 @@ void cla_ctx_destroy(struct cla_domain *domain, struct cla_ctx_key *key) */ if (domain->assigned_ctx == ctx) cla_domain_schedule_reassignment(domain); + cla_domain_put(domain); mutex_unlock(&domain->lock); /* Release initial reference from cla_ctx_create(). */ -- 2.43.0