linux-kernel - [PATCH v3 0/7] iommu/amd: Enforce IOMMU restrictions for SNP-enabled system

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Message-ID: <20220622171131.11870-1-suravee.suthikulpanit@amd.com>
Date:   Wed, 22 Jun 2022 12:11:24 -0500
From:   Suravee Suthikulpanit <suravee.suthikulpanit@....com>
To:     <linux-kernel@...r.kernel.org>, <iommu@...ts.linux-foundation.org>
CC:     <joro@...tes.org>, <robin.murphy@....com>, <ashish.kalra@....com>,
        <vasant.hegde@....com>, <thomas.lendacky@....com>,
        Suravee Suthikulpanit <suravee.suthikulpanit@....com>
Subject: [PATCH v3 0/7] iommu/amd: Enforce IOMMU restrictions for SNP-enabled system

SNP-enabled system requires IOMMU v1 page table to be configured with
non-zero DTE[Mode] for DMA-capable devices. This effects a number of
usecases such as IOMMU pass-through mode and AMD IOMMUv2 APIs for
binding/unbinding pasid.

The series introduce a global variable to check SNP-enabled state
during driver initialization, and use it to enforce the SNP restrictions
during runtime.

Also, for non-DMA-capable devices such as IOAPIC, the recommendation
is to set DTE[TV] and DTE[Mode] to zero on SNP-enabled system.
Therefore, additinal checks is added before setting DTE[TV].

Testing:
  - Tested booting and verify dmesg.
  - Tested booting with iommu=pt
  - Tested loading amd_iommu_v2 driver
  - Tested changing the iommu domain at runtime
  - Tested booting SEV/SNP-enabled guest
  - Tested when CONFIG_AMD_MEM_ENCRYPT is not set

Pre-requisite:
  - [PATCH v3 00/35] iommu/amd: Add multiple PCI segments support
    https://lore.kernel.org/linux-iommu/20220511072141.15485-29-vasant.hegde@amd.com/T/

Chanages from V2:
(https://lists.linuxfoundation.org/pipermail/iommu/2022-June/066392.html)
  - Patch 4:
     * Update pr_err message to report SNP not supported.
     * Remove export GPL.
     * Remove function stub when CONFIG_AMD_MEM_ENCRYPT is not set.
  - Patch 6: Change to WARN_ONCE.

Best Regards,
Suravee

Brijesh Singh (1):
  iommu/amd: Introduce function to check and enable SNP

Suravee Suthikulpanit (6):
  iommu/amd: Warn when found inconsistency EFR mask
  iommu/amd: Process all IVHDs before enabling IOMMU features
  iommu/amd: Introduce an iommu variable for tracking SNP support status
  iommu/amd: Set translation valid bit only when IO page tables are in
    use
  iommu/amd: Do not support IOMMU_DOMAIN_IDENTITY after SNP is enabled
  iommu/amd: Do not support IOMMUv2 APIs when SNP is enabled

 drivers/iommu/amd/amd_iommu_types.h |   5 ++
 drivers/iommu/amd/init.c            | 109 +++++++++++++++++++++++-----
 drivers/iommu/amd/iommu.c           |  27 ++++++-
 include/linux/amd-iommu.h           |   4 +
 4 files changed, 123 insertions(+), 22 deletions(-)

-- 
2.32.0