linux-kernel - [PATCH v2 0/2] iommu/vt-d bad RMRR workarounds

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Message-Id: <20200107191610.178185-1-brho@google.com>
Date:   Tue,  7 Jan 2020 14:16:08 -0500
From:   Barret Rhoden <brho@...gle.com>
To:     Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        "H. Peter Anvin" <hpa@...or.com>,
        David Woodhouse <dwmw2@...radead.org>,
        Joerg Roedel <joro@...tes.org>,
        Yian Chen <yian.chen@...el.com>,
        Sohil Mehta <sohil.mehta@...el.com>
Cc:     linux-kernel@...r.kernel.org, iommu@...ts.linux-foundation.org,
        x86@...nel.org
Subject: [PATCH v2 0/2] iommu/vt-d bad RMRR workarounds

Commit f036c7fa0ab6 ("iommu/vt-d: Check VT-d RMRR region in BIOS is
reported as reserved") caused a machine to fail to boot for me, but only
after a kexec.

Buggy firmware provided an RMRR entry with base and end both == 0.  That
is an invalid RMRR format, and only happens to pass the RMRR sanity
check.  After a kexec, that entry fails the RMRR sanity check, due to a
slight change in the first e820 mapping.  See the v1 link for details.

v1->v2:
v1: https://lore.kernel.org/lkml/20191211194606.87940-1-brho@google.com/
- Added the TAINT_FIRMWARE_WORKAROUND
- Dropped the commit that treated missing e820 regions as "RMRR OK"


Barret Rhoden (2):
  iommu/vt-d: skip RMRR entries that fail the sanity check
  iommu/vt-d: skip invalid RMRR entries

 drivers/iommu/intel-iommu.c | 26 ++++++++++++++++++++++----
 1 file changed, 22 insertions(+), 4 deletions(-)

-- 
2.24.1.735.g03f4e72817-goog