linux-kernel - [PATCH 0/2] iommu/vt-d: Select PCI_PRI for INTEL_IOMMU

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Message-Id: <20191009224551.179497-1-helgaas@kernel.org>
Date:   Wed,  9 Oct 2019 17:45:49 -0500
From:   Bjorn Helgaas <helgaas@...nel.org>
To:     Kuppuswamy Sathyanarayanan 
        <sathyanarayanan.kuppuswamy@...ux.intel.com>,
        David Woodhouse <dwmw2@...radead.org>,
        Joerg Roedel <joro@...tes.org>
Cc:     Ashok Raj <ashok.raj@...el.com>,
        Keith Busch <keith.busch@...el.com>, linux-pci@...r.kernel.org,
        linux-kernel@...r.kernel.org, iommu@...ts.linux-foundation.org,
        Bjorn Helgaas <bhelgaas@...gle.com>
Subject: [PATCH 0/2] iommu/vt-d: Select PCI_PRI for INTEL_IOMMU_SVM

From: Bjorn Helgaas <bhelgaas@...gle.com>

I think intel-iommu.c depends on CONFIG_AMD_IOMMU in an undesirable way:

When CONFIG_INTEL_IOMMU_SVM=y, iommu_enable_dev_iotlb() calls PRI
interfaces (pci_reset_pri() and pci_enable_pri()), but those are only
implemented when CONFIG_PCI_PRI is enabled.  If CONFIG_PCI_PRI is not
enabled, there are stubs that just return failure.

The INTEL_IOMMU_SVM Kconfig does nothing with PCI_PRI, but AMD_IOMMU
selects PCI_PRI.  So if AMD_IOMMU is enabled, intel-iommu.c gets the full
PRI interfaces.  If AMD_IOMMU is not enabled, it gets the PRI stubs.

This seems wrong.  The first patch here makes INTEL_IOMMU_SVM select
PCI_PRI so intel-iommu.c always gets the full PRI interfaces.

The second patch moves pci_prg_resp_pasid_required(), which simply returns
a bit from the PCI capability, from #ifdef CONFIG_PCI_PASID to #ifdef
CONFIG_PCI_PRI.  This is related because INTEL_IOMMU_SVM already *does*
select PCI_PASID, so it previously always got pci_prg_resp_pasid_required()
even though it got stubs for other PRI things.

Since these are related and I have several follow-on ATS-related patches in
the queue, I'd like to take these both via the PCI tree.

Bjorn Helgaas (2):
  iommu/vt-d: Select PCI_PRI for INTEL_IOMMU_SVM
  PCI/ATS: Move pci_prg_resp_pasid_required() to CONFIG_PCI_PRI

 drivers/iommu/Kconfig   |  1 +
 drivers/pci/ats.c       | 55 +++++++++++++++++++----------------------
 include/linux/pci-ats.h | 11 ++++-----
 3 files changed, 31 insertions(+), 36 deletions(-)

-- 
2.23.0.581.g78d2f28ef7-goog