From patchwork Thu Jun 24 17:17:57 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Doug Anderson X-Patchwork-Id: 12342679 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=-19.1 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, 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_GIT autolearn=unavailable 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 8FFA3C49EA7 for ; Thu, 24 Jun 2021 17:18:37 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 7D399613EE for ; Thu, 24 Jun 2021 17:18:37 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232178AbhFXRUv (ORCPT ); Thu, 24 Jun 2021 13:20:51 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:54802 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232051AbhFXRUr (ORCPT ); Thu, 24 Jun 2021 13:20:47 -0400 Received: from mail-pf1-x42e.google.com (mail-pf1-x42e.google.com [IPv6:2607:f8b0:4864:20::42e]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 60682C061574 for ; Thu, 24 Jun 2021 10:18:27 -0700 (PDT) Received: by mail-pf1-x42e.google.com with SMTP id k6so5726635pfk.12 for ; Thu, 24 Jun 2021 10:18:27 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=chromium.org; s=google; h=from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=IsTJoDNngEMlkAn/n6JPF2A0qmwgdP70DkZ0WXOjNOY=; b=YxZMzszw+nsXLPhGNhV2myye4gK/wRHBlmjreXJlWAVzJm0ZFytYlX9Rhu7tXDdANy XP1z9XjdXqim9N+/fnHAr0XwqqNu+9bp2809pZLHqN7ql8Lr5NEoIcZuY3dcG8iAoXf+ A/rp72coTwhCjbCFAAXwSsCuz5cEkE50kotnQ= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=IsTJoDNngEMlkAn/n6JPF2A0qmwgdP70DkZ0WXOjNOY=; b=hIokvPFupZWsFP5mBt9unpn4vnelfJE8h8aiKxVfdD03aeBQxsN7n6XObUxTuGGjqy C13dqJ9EPG+nkISjDfd2Beq0cSHP6GIsnVNYYVOiuRk1poOQyv90JcdSP5jXq3NsH0P1 2a9imIZPVknpN1MWVsW9efIT32LfCCDqOLEndOdaOC0cmKxpiLLZu1Y48V0/huHS6euP wf4fWiAGpNQw1v+CHe5wCFxCsiGcLsF8wo/hWfxlt85uD5OVJAiuOLPIUHSHtw7Y4VSp 2KK2ntBXWLifYyMIxuyK4IBTpKPY5VBtOKMbnPSqdBauxH9LD2Z0HH2bfNNHn3Utj0lU ZXKA== X-Gm-Message-State: AOAM533ovOBrFc9UHXprmpHnNN34yoW7WnzpbdVKcKCXFbYWumTifgBW NC+9dpEN2he4ePhKO5jdpgy6LA== X-Google-Smtp-Source: ABdhPJwajpWmjQoylie1eDc67SDX5JHn0tkLIkBmw0/8N+zayKuUy7HrB9/qTrgy2P3lRFk7RypkmA== X-Received: by 2002:a63:ee11:: with SMTP id e17mr5579673pgi.323.1624555106903; Thu, 24 Jun 2021 10:18:26 -0700 (PDT) Received: from tictac2.mtv.corp.google.com ([2620:15c:202:201:fd74:62bc:19e3:a43b]) by smtp.gmail.com with ESMTPSA id z9sm3365960pfa.2.2021.06.24.10.18.24 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 24 Jun 2021 10:18:26 -0700 (PDT) From: Douglas Anderson To: will@kernel.org, robin.murphy@arm.com, joro@8bytes.org, bjorn.andersson@linaro.org, ulf.hansson@linaro.org, adrian.hunter@intel.com, bhelgaas@google.com Cc: john.garry@huawei.com, robdclark@chromium.org, quic_c_gdjako@quicinc.com, saravanak@google.com, rajatja@google.com, saiprakash.ranjan@codeaurora.org, vbadigan@codeaurora.org, linux-mmc@vger.kernel.org, linux-arm-msm@vger.kernel.org, linux-pci@vger.kernel.org, iommu@lists.linux-foundation.org, sonnyrao@chromium.org, joel@joelfernandes.org, Douglas Anderson , Andrew Morton , Jonathan Corbet , "Maciej W. Rozycki" , "Paul E. McKenney" , Peter Zijlstra , Randy Dunlap , Viresh Kumar , Vlastimil Babka , linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH v2 1/3] iommu: Add per-domain strictness and combine with the global default Date: Thu, 24 Jun 2021 10:17:57 -0700 Message-Id: <20210624101557.v2.1.Id84a954e705fcad3fdb35beb2bc372e4bf2108c7@changeid> X-Mailer: git-send-email 2.32.0.93.g670b81a890-goog In-Reply-To: <20210624171759.4125094-1-dianders@chromium.org> References: <20210624171759.4125094-1-dianders@chromium.org> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-mmc@vger.kernel.org Strictness has the semantic of being a per-domain property. This is why iommu_get_dma_strict() takes a "struct iommu_domain" as a parameter. Let's add knowledge to the "struct iommu_domain" so we can know whether we'd like each domain to be strict. In this patch nothing sets the per-domain strictness, it just paves the way for future patches to do so. Prior to this patch we could only affect strictness at a global level. We'll still honor the global strictness level if it has been explicitly set and it's stricter than the one requested per-domain. NOTE: it's even more obvious that iommu_set_dma_strict() and iommu_get_dma_strict() are non-symmetric after this change. However, they have always been asymmetric by design [0]. The function iommu_get_dma_strict() should now make it super obvious where strictness comes from and who overides who. Though the function changed a bunch to make the logic clearer, the only two new rules should be: * Devices can force strictness for themselves, overriding the cmdline "iommu.strict=0" or a call to iommu_set_dma_strict(false)). * Devices can request non-strictness for themselves, assuming there was no cmdline "iommu.strict=1" or a call to iommu_set_dma_strict(true). [0] https://lore.kernel.org/r/a023af85-5060-0a3c-4648-b00f8b8c0430@arm.com/ Signed-off-by: Douglas Anderson --- This patch clearly will cause conflicts if John Garry's patches [1] land before it. It shouldn't be too hard to rebase, though. Essentially with John's patches it'll be impossible for what's called `cmdline_dma_strict` in my patch to be "default". It'll probably make sense to rearrange the logic/names a bit though just to make things clearer. [1] https://lore.kernel.org/r/1624016058-189713-1-git-send-email-john.garry@huawei.com/ Changes in v2: - No longer based on changes adding strictness to "struct device" - Updated kernel-parameters docs. .../admin-guide/kernel-parameters.txt | 5 ++- drivers/iommu/iommu.c | 43 +++++++++++++++---- include/linux/iommu.h | 7 +++ 3 files changed, 45 insertions(+), 10 deletions(-) diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt index cb89dbdedc46..7675fd79f9a9 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -1995,9 +1995,12 @@ throughput at the cost of reduced device isolation. Will fall back to strict mode if not supported by the relevant IOMMU driver. - 1 - Strict mode (default). + 1 - Strict mode. DMA unmap operations invalidate IOMMU hardware TLBs synchronously. + NOTE: if "iommu.strict" is not specified in the command + line then it's up to the system to try to determine the + proper strictness. iommu.passthrough= [ARM64, X86] Configure DMA to bypass the IOMMU by default. diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c index 808ab70d5df5..7943d2105b2f 100644 --- a/drivers/iommu/iommu.c +++ b/drivers/iommu/iommu.c @@ -29,7 +29,8 @@ static struct kset *iommu_group_kset; static DEFINE_IDA(iommu_group_ida); static unsigned int iommu_def_domain_type __read_mostly; -static bool iommu_dma_strict __read_mostly = true; +static enum iommu_strictness cmdline_dma_strict __read_mostly; +static enum iommu_strictness driver_dma_strict __read_mostly; static u32 iommu_cmd_line __read_mostly; struct iommu_group { @@ -69,7 +70,6 @@ static const char * const iommu_group_resv_type_string[] = { }; #define IOMMU_CMD_LINE_DMA_API BIT(0) -#define IOMMU_CMD_LINE_STRICT BIT(1) static int iommu_alloc_default_domain(struct iommu_group *group, struct device *dev); @@ -334,27 +334,52 @@ static int __init iommu_set_def_domain_type(char *str) } early_param("iommu.passthrough", iommu_set_def_domain_type); +static inline enum iommu_strictness bool_to_strictness(bool strict) +{ + return strict ? IOMMU_STRICT : IOMMU_NOT_STRICT; +} + static int __init iommu_dma_setup(char *str) { - int ret = kstrtobool(str, &iommu_dma_strict); + bool strict; + int ret = kstrtobool(str, &strict); if (!ret) - iommu_cmd_line |= IOMMU_CMD_LINE_STRICT; + cmdline_dma_strict = bool_to_strictness(strict); return ret; } early_param("iommu.strict", iommu_dma_setup); void iommu_set_dma_strict(bool strict) { - if (strict || !(iommu_cmd_line & IOMMU_CMD_LINE_STRICT)) - iommu_dma_strict = strict; + /* + * Valid transitions: + * - DEFAULT -> NON_STRICT + * - DEFAULT -> STRICT + * - NON_STRICT -> STRICT + * + * Everything else is ignored. + */ + if (driver_dma_strict != IOMMU_STRICT) + driver_dma_strict = bool_to_strictness(strict); } bool iommu_get_dma_strict(struct iommu_domain *domain) { - /* only allow lazy flushing for DMA domains */ - if (domain->type == IOMMU_DOMAIN_DMA) - return iommu_dma_strict; + /* Non-DMA domains or anyone forcing it to strict makes it strict */ + if (domain->type != IOMMU_DOMAIN_DMA || + cmdline_dma_strict == IOMMU_STRICT || + driver_dma_strict == IOMMU_STRICT || + domain->strictness == IOMMU_STRICT) + return true; + + /* Anyone requesting non-strict (if no forces) makes it non-strict */ + if (cmdline_dma_strict == IOMMU_NOT_STRICT || + driver_dma_strict == IOMMU_NOT_STRICT || + domain->strictness == IOMMU_NOT_STRICT) + return false; + + /* Nobody said anything, so it's strict by default */ return true; } EXPORT_SYMBOL_GPL(iommu_get_dma_strict); diff --git a/include/linux/iommu.h b/include/linux/iommu.h index 32d448050bf7..2e172059c931 100644 --- a/include/linux/iommu.h +++ b/include/linux/iommu.h @@ -79,8 +79,15 @@ struct iommu_domain_geometry { #define IOMMU_DOMAIN_DMA (__IOMMU_DOMAIN_PAGING | \ __IOMMU_DOMAIN_DMA_API) +enum iommu_strictness { + IOMMU_DEFAULT_STRICTNESS = 0, /* zero-init ends up at default */ + IOMMU_NOT_STRICT, + IOMMU_STRICT, +}; + struct iommu_domain { unsigned type; + enum iommu_strictness strictness; const struct iommu_ops *ops; unsigned long pgsize_bitmap; /* Bitmap of page sizes in use */ iommu_fault_handler_t handler;