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Date:   Thu, 30 Jun 2022 10:58:50 +0100
From:   Jean-Philippe Brucker <jean-philippe@linaro.org>
To:     Eric Auger <eric.auger@redhat.com>
Cc:     eric.auger.pro@gmail.com, jroedel@suse.de,
        linux-acpi@vger.kernel.org, iommu@lists.linux-foundation.org,
        rafael@kernel.org, lenb@kernel.org, linux-kernel@vger.kernel.org,
        iommu@lists.linux.dev, jinl@redhat.com
Subject: Re: [PATCH v2] ACPI: VIOT: Fix ACS setup
Message-ID: <Yr1z2gC0+8zbzpFf@myrica>
References: <20220630094059.1204283-1-eric.auger@redhat.com>
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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>