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Thu, 10 Sep 2020 21:32:30 +0000 (UTC) Received: from localhost (localhost [127.0.0.1]) by silver.osuosl.org (Postfix) with ESMTP id 63B9D20426 for ; Thu, 10 Sep 2020 21:32:30 +0000 (UTC) X-Virus-Scanned: amavisd-new at osuosl.org Received: from silver.osuosl.org ([127.0.0.1]) by localhost (.osuosl.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id atrQZqF-eJcD for ; Thu, 10 Sep 2020 21:32:28 +0000 (UTC) X-Greylist: domain auto-whitelisted by SQLgrey-1.7.6 Received: from mail-lj1-f196.google.com (mail-lj1-f196.google.com [209.85.208.196]) by silver.osuosl.org (Postfix) with ESMTPS id 3751C1FE32 for ; Thu, 10 Sep 2020 21:32:28 +0000 (UTC) Received: by mail-lj1-f196.google.com with SMTP id c2so10064417ljj.12 for ; Thu, 10 Sep 2020 14:32:28 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=PT5RewSLErP4ScRi2owXD3TsugrP80kcF1hvqbJMudU=; b=Kx64mjnIaD20tcXvEM0BQWjIQfETdv9/KX7GdJ3ELP3iJDm15pe1jeA5eGgZ9Sb7C1 txt4kXnEUJQJ8KBHbuJwPFGoHJ7xGGyBR/BqPa8BYDUHMeYnxoF6NNJ35WK1bH2GWHT/ OLahqkAc2+JziRsf5CyIuFp0xUUN1U767NCZpa94bcFLsOAix1e9gFIyoJxog1alewph OOeynGTzZZ+TaLZ32IoKsWhG76dz03af8zeNoMrNjTC/7i4blbbrxok14hBWBxJlhvx/ VZNH+EYtd/EC6tWFnFtpVo8MJKN8rFYPL3U7Cc/u3a58WvtbPdXfisyFhAn4LONwDb20 UgVg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=PT5RewSLErP4ScRi2owXD3TsugrP80kcF1hvqbJMudU=; b=tWssT5CL3LZaYFaje3xXNnSa0CvuP6EDTaWkZkUKBgi5UEszFqWxec6GHNczxWF4iO 7qcgWRVm2uNRDoF1chG2qYaVIU/17+pbcMc6v4KlP3LH3Z7BMLbQeav45n2l8zT7Y+Vl M+caOUCpviizMfet/kBLdLk7aBtDjVpxAmTJ8hug+FC9IUftYlMvvu7SgNo6UKrL2Ykd f7AtTYuA6yg8C3gAwd1m9YbIqvadxcngbmhKeef3UnNSyxMMBCAfUAp24DIlnRHcEKPe tp64UXJXD/20cPbNDk5DbXwSXfFzTtuEo9/fGMDBpDlJBWRy32IVgxRqyU6RO1bWgyLy ViOA== X-Gm-Message-State: AOAM532zDyJmzfFlHW0pBZczta1LpMk2dBG+bRcpW4du+Dp+kYqd2UBm IP+bs2/v44rzIROUnpQYsTHz6Cka4OpP98YL7BqZaA== X-Google-Smtp-Source: ABdhPJxKOrQhe9I0H+n3lmdZVu32MqhEB6ra+xjy+Mu67YGel8du2z2t9yktrh5y45ZORSGg8lgEyqEZMK0A5DWMDF0= X-Received: by 2002:a2e:98d1:: with SMTP id s17mr5317839ljj.188.1599773545804; Thu, 10 Sep 2020 14:32:25 -0700 (PDT) MIME-Version: 1.0 References: <20200714201540.3139140-1-rajatja@google.com> In-Reply-To: Date: Thu, 10 Sep 2020 14:31:49 -0700 Message-ID: Subject: Re: [PATCH v5] PCI/ACS: Enable PCI_ACS_TB and disable only when needed for ATS To: Rajat Jain Cc: Todd Broch , linux-pci , "Krishnakumar, Lalithambika" , Heikki Krogerus , Diego Rivas , Jean-Philippe Brucker , Furquan Shaikh , Raj Ashok , Saravana Kannan , ACPI Devel Maling List , Christian Kellner , Mattias Nissler , Jesse Barnes , Len Brown , Prashant Malani , Suzuki K Poulose , Aaron Durbin , Alex Williamson , Bjorn Helgaas , Mika Westerberg , Bernie Keany , Duncan Laurie , Greg Kroah-Hartman , "Rafael J. Wysocki" , Linux Kernel Mailing List , "open list:AMD IOMMU \(AMD-VI\)" , Arnd Bergmann , Oliver O'Halloran , Benson Leung , David Woodhouse , Alex Levin X-BeenThere: iommu@lists.linux-foundation.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: Development issues for Linux IOMMU support List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , From: Rajat Jain via iommu Reply-To: Rajat Jain Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: iommu-bounces@lists.linux-foundation.org Sender: "iommu" Hello Bjorn, On Mon, Aug 17, 2020 at 3:50 PM Rajat Jain wrote: > > Hello Bjorn, > > > On Sat, Aug 1, 2020 at 5:30 PM Rajat Jain wrote: > > > > Hi Bjorn, > > > > > > On Tue, Jul 14, 2020 at 1:24 PM Rajat Jain wrote: > > > > > > On Tue, Jul 14, 2020 at 1:15 PM Rajat Jain wrote: > > > > > > > > The ACS "Translation Blocking" bit blocks the translated addresses from > > > > the devices. We don't expect such traffic from devices unless ATS is > > > > enabled on them. A device sending such traffic without ATS enabled, > > > > indicates malicious intent, and thus should be blocked. > > > > > > > > Enable PCI_ACS_TB by default for all devices, and it stays enabled until > > > > atleast one of the devices downstream wants to enable ATS. It gets > > > > disabled to enable ATS on a device downstream it, and then gets enabled > > > > back on once all the downstream devices don't need ATS. > > > > > > > > Signed-off-by: Rajat Jain > > > > Just checking to see if you got a chance to look at this V5 patch. > > Any feedback on this patch? Gentle reminder? Thanks & Best Regards, Rajat > > Thanks & Best Regards, > > Rajat > > > > > Thanks & Best Regards, > > > > Rajat > > > > > > --- > > > > Note that I'm ignoring the devices that require quirks to enable or > > > > disable ACS, instead of using the standard way for ACS configuration. > > > > The reason is that it would require adding yet another quirk table or > > > > quirk function pointer, that I don't know how to implement for those > > > > devices, and will neither have the devices to test that code. > > > > > > > > v5: Enable TB and disable ATS for all devices on boot. Disable TB later > > > > only if needed to enable ATS on downstream devices. > > > > v4: Add braces to avoid warning from kernel robot > > > > print warning for only external-facing devices. > > > > v3: print warning if ACS_TB not supported on external-facing/untrusted ports. > > > > Minor code comments fixes. > > > > v2: Commit log change > > > > > > > > drivers/pci/ats.c | 5 ++++ > > > > drivers/pci/pci.c | 57 +++++++++++++++++++++++++++++++++++++++++++++ > > > > drivers/pci/pci.h | 2 ++ > > > > drivers/pci/probe.c | 2 +- > > > > include/linux/pci.h | 2 ++ > > > > 5 files changed, 67 insertions(+), 1 deletion(-) > > > > > > > > diff --git a/drivers/pci/ats.c b/drivers/pci/ats.c > > > > index b761c1f72f67..e2ea9083f30f 100644 > > > > --- a/drivers/pci/ats.c > > > > +++ b/drivers/pci/ats.c > > > > @@ -28,6 +28,9 @@ void pci_ats_init(struct pci_dev *dev) > > > > return; > > > > > > > > dev->ats_cap = pos; > > > > + > > > > + dev->ats_enabled = 1; /* To avoid WARN_ON from pci_disable_ats() */ > > > > + pci_disable_ats(dev); > > > > } > > > > > > > > /** > > > > @@ -82,6 +85,7 @@ int pci_enable_ats(struct pci_dev *dev, int ps) > > > > } > > > > pci_write_config_word(dev, dev->ats_cap + PCI_ATS_CTRL, ctrl); > > > > > > > > + pci_disable_acs_trans_blocking(dev); > > > > dev->ats_enabled = 1; > > > > return 0; > > > > } > > > > @@ -102,6 +106,7 @@ void pci_disable_ats(struct pci_dev *dev) > > > > ctrl &= ~PCI_ATS_CTRL_ENABLE; > > > > pci_write_config_word(dev, dev->ats_cap + PCI_ATS_CTRL, ctrl); > > > > > > > > + pci_enable_acs_trans_blocking(dev); > > > > dev->ats_enabled = 0; > > > > } > > > > EXPORT_SYMBOL_GPL(pci_disable_ats); > > > > diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c > > > > index 73a862782214..614e3c1e8c56 100644 > > > > --- a/drivers/pci/pci.c > > > > +++ b/drivers/pci/pci.c > > > > @@ -876,6 +876,9 @@ static void pci_std_enable_acs(struct pci_dev *dev) > > > > /* Upstream Forwarding */ > > > > ctrl |= (cap & PCI_ACS_UF); > > > > > > > > + /* Translation Blocking */ > > > > + ctrl |= (cap & PCI_ACS_TB); > > > > + > > > > pci_write_config_word(dev, pos + PCI_ACS_CTRL, ctrl); > > > > } > > > > > > > > @@ -904,6 +907,60 @@ static void pci_enable_acs(struct pci_dev *dev) > > > > pci_disable_acs_redir(dev); > > > > } > > > > > > > > +void pci_disable_acs_trans_blocking(struct pci_dev *pdev) > > > > +{ > > > > + u16 cap, ctrl, pos; > > > > + struct pci_dev *dev; > > > > + > > > > + if (!pci_acs_enable) > > > > + return; > > > > + > > > > + for (dev = pdev; dev; dev = pci_upstream_bridge(pdev)) { > > > > + > > > > + pos = dev->acs_cap; > > > > + if (!pos) > > > > + continue; > > > > + > > > > + /* > > > > + * Disable translation blocking when first downstream > > > > + * device that needs it (for ATS) wants to enable ATS > > > > + */ > > > > + if (++dev->ats_dependencies == 1) { > > > > > > I am a little worried about a potential race condition here. I know > > > that 2 PCI devices cannot be enumerating at the same time. Do we know > > > if multiple pci_enable_ats() and pci_disable_ats() function calls can > > > be simultaneously executing (even for different devices)? If so, we > > > may need an atomic_t variable for ats_dependencies. > > > > > > Thanks, > > > > > > Rajat > > > > > > > > > > + pci_read_config_word(dev, pos + PCI_ACS_CAP, &cap); > > > > + pci_read_config_word(dev, pos + PCI_ACS_CTRL, &ctrl); > > > > + ctrl &= ~(cap & PCI_ACS_TB); > > > > + pci_write_config_word(dev, pos + PCI_ACS_CTRL, ctrl); > > > > + } > > > > + } > > > > +} > > > > + > > > > +void pci_enable_acs_trans_blocking(struct pci_dev *pdev) > > > > +{ > > > > + u16 cap, ctrl, pos; > > > > + struct pci_dev *dev; > > > > + > > > > + if (!pci_acs_enable) > > > > + return; > > > > + > > > > + for (dev = pdev; dev; dev = pci_upstream_bridge(pdev)) { > > > > + > > > > + pos = dev->acs_cap; > > > > + if (!pos) > > > > + continue; > > > > + > > > > + /* > > > > + * Enable translation blocking when last downstream device > > > > + * that depends on it (for ATS), doesn't need ATS anymore > > > > + */ > > > > + if (--dev->ats_dependencies == 0) { > > > > + pci_read_config_word(dev, pos + PCI_ACS_CAP, &cap); > > > > + pci_read_config_word(dev, pos + PCI_ACS_CTRL, &ctrl); > > > > + ctrl |= (cap & PCI_ACS_TB); > > > > + pci_write_config_word(dev, pos + PCI_ACS_CTRL, ctrl); > > > > + } > > > > + } > > > > +} > > > > + > > > > /** > > > > * pci_restore_bars - restore a device's BAR values (e.g. after wake-up) > > > > * @dev: PCI device to have its BARs restored > > > > diff --git a/drivers/pci/pci.h b/drivers/pci/pci.h > > > > index 12fb79fbe29d..f5d8ecb6ba96 100644 > > > > --- a/drivers/pci/pci.h > > > > +++ b/drivers/pci/pci.h > > > > @@ -552,6 +552,8 @@ static inline int pci_dev_specific_disable_acs_redir(struct pci_dev *dev) > > > > return -ENOTTY; > > > > } > > > > #endif > > > > +void pci_disable_acs_trans_blocking(struct pci_dev *dev); > > > > +void pci_enable_acs_trans_blocking(struct pci_dev *dev); > > > > > > > > /* PCI error reporting and recovery */ > > > > pci_ers_result_t pcie_do_recovery(struct pci_dev *dev, > > > > diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c > > > > index 8c40c00413e7..e2ff3a94e621 100644 > > > > --- a/drivers/pci/probe.c > > > > +++ b/drivers/pci/probe.c > > > > @@ -2387,10 +2387,10 @@ static void pci_init_capabilities(struct pci_dev *dev) > > > > pci_vpd_init(dev); /* Vital Product Data */ > > > > pci_configure_ari(dev); /* Alternative Routing-ID Forwarding */ > > > > pci_iov_init(dev); /* Single Root I/O Virtualization */ > > > > + pci_acs_init(dev); /* Access Control Services */ > > > > pci_ats_init(dev); /* Address Translation Services */ > > > > pci_pri_init(dev); /* Page Request Interface */ > > > > pci_pasid_init(dev); /* Process Address Space ID */ > > > > - pci_acs_init(dev); /* Access Control Services */ > > > > pci_ptm_init(dev); /* Precision Time Measurement */ > > > > pci_aer_init(dev); /* Advanced Error Reporting */ > > > > pci_dpc_init(dev); /* Downstream Port Containment */ > > > > diff --git a/include/linux/pci.h b/include/linux/pci.h > > > > index 7a40cd5caed0..31da4355f0fd 100644 > > > > --- a/include/linux/pci.h > > > > +++ b/include/linux/pci.h > > > > @@ -480,6 +480,8 @@ struct pci_dev { > > > > u16 ats_cap; /* ATS Capability offset */ > > > > u8 ats_stu; /* ATS Smallest Translation Unit */ > > > > #endif > > > > + /* Total number of downstream devices below a bridge that need ATS */ > > > > + u8 ats_dependencies; > > > > #ifdef CONFIG_PCI_PRI > > > > u16 pri_cap; /* PRI Capability offset */ > > > > u32 pri_reqs_alloc; /* Number of PRI requests allocated */ > > > > -- > > > > 2.27.0.389.gc38d7665816-goog > > > > _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu