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References: <20220630094059.1204283-1-eric.auger@redhat.com> <Yr1z2gC0+8zbzpFf@myrica>
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From:   "Rafael J. Wysocki" <rafael@kernel.org>
Date:   Tue, 5 Jul 2022 20:27:19 +0200
Message-ID: <CAJZ5v0hqcUUTVzkHxGr9pB5G-T5ye5g_=DQVO6L347DpXipwOg@mail.gmail.com>
Subject: Re: [PATCH v2] ACPI: VIOT: Fix ACS setup
To:     Jean-Philippe Brucker <jean-philippe@linaro.org>,
        Eric Auger <eric.auger@redhat.com>
Cc:     eric.auger.pro@gmail.com, Joerg Roedel <jroedel@suse.de>,
        ACPI Devel Maling List <linux-acpi@vger.kernel.org>,
        "open list:AMD IOMMU (AMD-VI)" <iommu@lists.linux-foundation.org>,
        "Rafael J. Wysocki" <rafael@kernel.org>,
        Len Brown <lenb@kernel.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        iommu@lists.linux.dev, jinl@redhat.com
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On Thu, Jun 30, 2022 at 11:59 AM Jean-Philippe Brucker
<jean-philippe@linaro.org> wrote:
>
> On Thu, Jun 30, 2022 at 11:40:59AM +0200, Eric Auger wrote:
> > Currently acpi_viot_init() gets called after the pci
> > device has been scanned and pci_enable_acs() has been called.
> > So pci_request_acs() fails to be taken into account leading
> > to wrong single iommu group topologies when dealing with
> > multi-function root ports for instance.
> >
> > We cannot simply move the acpi_viot_init() earlier, similarly
> > as the IORT init because the VIOT parsing relies on the pci
> > scan. However we can detect VIOT is present earlier and in
> > such a case, request ACS. Introduce a new acpi_viot_early_init()
> > routine that allows to call pci_request_acs() before the scan.
> >
> > While at it, guard the call to pci_request_acs() with #ifdef
> > CONFIG_PCI.
> >
> > Fixes: 3cf485540e7b ("ACPI: Add driver for the VIOT table")
> > Signed-off-by: Eric Auger <eric.auger@redhat.com>
> > Reported-by: Jin Liu <jinl@redhat.com>
>
> Reviewed-by: Jean-Philippe Brucker <jean-philippe@linaro.org>
> Tested-by: Jean-Philippe Brucker <jean-philippe@linaro.org>

Applied as 5.20 material, thanks!