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 ABFFFC982D0 for ; Thu, 17 Sep 2026 19:47:13 +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:In-Reply-To:Content-Type: MIME-Version:Message-ID:Subject:Cc:To:From:Date:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:References: List-Owner; bh=FIVFF1Gz0qTcL6D0qsjU7Wz5A7oH5Uxjc4mt3x0Rb8M=; b=c6Jf+CLcX2qEcy hOrnpP+3lUcjOtL1z3pTM2wSxN1cngHAieTVe36G7Tqu1fxXH/FrYALJkD3xmOSaSri/sTNI1MzG0 2MvmI3KRB2huA0KhcJFLAMCPmWfkD40AK8sfimf0S6DUJLpTiFW2b6NSKpGlPlgRiqQccqFmbSZoq bkt2pQLQv6SQJQnsGt8ZJH6fk8t58y0HnnzS/cftSZidk9m+FA7hLLu8Pv32wuAnFNSoXE7y5eWXy EeiTU+colakvyKGqzhk1PnOH8Z8KjEb+feR+kOeWtH9evimmCVKHyBpaZ9IMyeXPvNIhiWwNMByCE yMdVfXvRbu/PuXvmEUqg==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.99.1 #2 (Red Hat Linux)) id 1x7I4d-0000000CMev-2dOr; Thu, 17 Sep 2026 19:47:11 +0000 Received: from tor.source.kernel.org ([172.105.4.254]) by bombadil.infradead.org with esmtps (Exim 4.99.1 #2 (Red Hat Linux)) id 1x7I4b-0000000CMei-436v for kexec@lists.infradead.org; Thu, 17 Sep 2026 19:47:10 +0000 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) by tor.source.kernel.org (Postfix) with ESMTP id 695B9601EF; Thu, 17 Sep 2026 19:47:09 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id E96EC1F000FF; Thu, 17 Sep 2026 19:47:08 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1789674429; bh=FIVFF1Gz0qTcL6D0qsjU7Wz5A7oH5Uxjc4mt3x0Rb8M=; h=Date:From:To:Cc:Subject:In-Reply-To; b=ITACFmTuRMNQBN70r1LnmUlyRzCHXOzNKwQta9Q3q8IXvtIZGGZC0HnDjiuVGz78R EI93ZUJBBCPLeovbDy0Ya2s+Jizc+FiJeJ9wBZfFKMjqoaH52DlK4Xoo4X2+aED1PO 11Tu3BmmyNrTrknb2wJyGvUs8xJD893qs2vSLN/6pGC4pfbcMZAsUQQ6hTvbLLsDxB A1Un69fr/uNRVwYmEKSRf/2s2tCjcBCliZfkAx5MkL96mrCZXc6aA42BYjNJjlyYri wmyHxC0nRKKJiVpWROfJSOnMgC3KzaifYv19mCGGyI3yp1TqpS9tRfTJ6cXz8tNlc5 QykvFjSC7e2Uw== Date: Thu, 17 Sep 2026 14:47:07 -0500 From: Bjorn Helgaas To: David Matlack Cc: kexec@lists.infradead.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-pci@vger.kernel.org, Adithya Jayachandran , Alexander Graf , Alex Williamson , Bjorn Helgaas , Chris Li , David Rientjes , Jacob Pan , Jason Gunthorpe , Jonathan Corbet , Josh Hilke , Leon Romanovsky , Lukas Wunner , Mike Rapoport , Parav Pandit , Pasha Tatashin , Pranjal Shrivastava , Pratyush Yadav , Saeed Mahameed , Samiullah Khawaja , Shuah Khan , Vipin Sharma , William Tu , Yi Liu Subject: Re: [PATCH v8 09/12] PCI: liveupdate: Adopt ARI Forwarding Enable on preserved bridges Message-ID: <20260917194707.GA1047156@bhelgaas> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260728221007.2098560-10-dmatlack@google.com> X-BeenThere: kexec@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "kexec" Errors-To: kexec-bounces+kexec=archiver.kernel.org@lists.infradead.org On Tue, Jul 28, 2026 at 10:10:03PM +0000, David Matlack wrote: > Adopt the ARI Forwarding Enable bit on preserved bridges and update > pci_dev->ari_enabled accordingly during a Live Update. This ensures that > the preserved devices on the bridge's secondary bus can be identified > with the same expanded 8-bit function number after a Live Update. > > Signed-off-by: David Matlack Reviewed-by: Bjorn Helgaas > --- > drivers/pci/liveupdate.c | 30 ++++++++++++++++++++++++++++++ > drivers/pci/liveupdate.h | 6 ++++++ > drivers/pci/pci.c | 8 +++++++- > 3 files changed, 43 insertions(+), 1 deletion(-) > > diff --git a/drivers/pci/liveupdate.c b/drivers/pci/liveupdate.c > index fb602dd3933e..744513ee11ed 100644 > --- a/drivers/pci/liveupdate.c > +++ b/drivers/pci/liveupdate.c > @@ -128,6 +128,10 @@ > * way after Live Update and ensures that IOMMU groups do not change. Note > * that a device will use its adopted ACS controls for the lifetime of its > * struct pci_dev (i.e. even after pci_liveupdate_finish()). > + * > + * * The PCI core adopts ARI Forwarding Enable on all bridges with downstream > + * preserved devices to ensure that all preserved devices on the bridge's > + * secondary bus are addressable after the Live Update. > */ > > #define pr_fmt(fmt) "PCI: liveupdate: " fmt > @@ -833,6 +837,32 @@ int pci_liveupdate_enable_adopted_acs_controls(struct pci_dev *dev) > return 0; > } > > +/** > + * pci_liveupdate_adopt_ari() - Adopt ARI configuration > + * @dev: The PCI device to adopt ARI configuration for > + * > + * For devices preserved across a Live Update, read the ARI state from > + * hardware and adopt it. This ensures the device continues to use the ARI > + * configuration established by the previous kernel. > + * > + * Return: 0 on success, or -EINVAL if the device was not preserved. > + */ > +int pci_liveupdate_adopt_ari(struct pci_dev *dev) > +{ > + u16 val; > + > + guard(rwsem_read)(&pci_liveupdate.rwsem); > + > + if (!dev->liveupdate.incoming) > + return -EINVAL; > + > + pcie_capability_read_word(dev, PCI_EXP_DEVCTL2, &val); > + > + /* Safe to modify dev->ari_enabled bitfield during enumeration. */ > + dev->ari_enabled = !!(val & PCI_EXP_DEVCTL2_ARI); > + return 0; > +} > + > /** > * pci_liveupdate_is_incoming() - Check if a device is incoming-preserved > * @dev: The PCI device to check > diff --git a/drivers/pci/liveupdate.h b/drivers/pci/liveupdate.h > index ac5b8bf2edf5..ccc23031e99d 100644 > --- a/drivers/pci/liveupdate.h > +++ b/drivers/pci/liveupdate.h > @@ -18,6 +18,7 @@ bool pci_liveupdate_preserve_bus_numbers(struct pci_bus *bus, > void pci_liveupdate_scan_bridge_end(struct pci_dev *dev); > void pci_liveupdate_cache_adopted_acs_controls(struct pci_dev *dev); > int pci_liveupdate_enable_adopted_acs_controls(struct pci_dev *dev); > +int pci_liveupdate_adopt_ari(struct pci_dev *dev); > #else > static inline void pci_liveupdate_setup_device(struct pci_dev *dev) > { > @@ -45,6 +46,11 @@ static inline int pci_liveupdate_enable_adopted_acs_controls(struct pci_dev *dev > { > return -EINVAL; > } > + > +static inline int pci_liveupdate_adopt_ari(struct pci_dev *dev) > +{ > + return -EINVAL; > +} > #endif > > #endif /* DRIVERS_PCI_LIVEUPDATE_H */ > diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c > index 22001bdf4c97..6922f361a89e 100644 > --- a/drivers/pci/pci.c > +++ b/drivers/pci/pci.c > @@ -3528,7 +3528,7 @@ void pci_configure_ari(struct pci_dev *dev) > u32 cap; > struct pci_dev *bridge; > > - if (pcie_ari_disabled || !pci_is_pcie(dev) || dev->devfn) > + if (!pci_is_pcie(dev) || dev->devfn) > return; > > bridge = dev->bus->self; > @@ -3539,6 +3539,12 @@ void pci_configure_ari(struct pci_dev *dev) > if (!(cap & PCI_EXP_DEVCAP2_ARI)) > return; > > + if (!pci_liveupdate_adopt_ari(bridge)) > + return; > + > + if (pcie_ari_disabled) > + return; > + > if (pci_find_ext_capability(dev, PCI_EXT_CAP_ID_ARI)) { > pcie_capability_set_word(bridge, PCI_EXP_DEVCTL2, > PCI_EXP_DEVCTL2_ARI); > -- > 2.55.0.487.gaf234c4eb3-goog >