linux-kernel - [PATCH 1/3] iommu/vt-d: skip RMRR entries that fail the sanity check

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Message-Id: <20191211194606.87940-2-brho@google.com>
Date:   Wed, 11 Dec 2019 14:46:04 -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 1/3] iommu/vt-d: skip RMRR entries that fail the sanity check

RMRR entries describe memory regions that are DMA targets for devices
outside the kernel's control.

RMRR entries that fail the sanity check are pointing to regions of
memory that the firmware did not tell the kernel are reserved or
otherwise should not be used.

Instead of aborting DMAR processing, this commit skips these RMRR
entries.  They will not be mapped into the IOMMU, but the IOMMU can
still be utilized.  If anything, when the IOMMU is on, those devices
will not be able to clobber RAM that the kernel has allocated from those
regions.

Signed-off-by: Barret Rhoden <brho@...gle.com>
---
 drivers/iommu/intel-iommu.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c
index f168cd8ee570..f7e09244c9e4 100644
--- a/drivers/iommu/intel-iommu.c
+++ b/drivers/iommu/intel-iommu.c
@@ -4316,7 +4316,7 @@ int __init dmar_parse_one_rmrr(struct acpi_dmar_header *header, void *arg)
 	rmrr = (struct acpi_dmar_reserved_memory *)header;
 	ret = arch_rmrr_sanity_check(rmrr);
 	if (ret)
-		return ret;
+		return 0;
 
 	rmrru = kzalloc(sizeof(*rmrru), GFP_KERNEL);
 	if (!rmrru)
-- 
2.24.0.525.g8f36a354ae-goog