linux-kernel - [PATCH] iommu/amd: Set iommu->int_enabled consistently when interrupts are set up

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Date:   Tue, 05 Jan 2021 01:32:51 +0000
From:   David Woodhouse <dwmw2@...radead.org>
To:     Borislav Petkov <bp@...en8.de>, iommu@...ts.linux-foundation.org
Cc:     Joerg Roedel <joro@...tes.org>, Will Deacon <will@...nel.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        "Rafael J. Wysocki" <rafael@...nel.org>,
        lkml <linux-kernel@...r.kernel.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Suravee Suthikulpanit <suravee.suthikulpanit@....com>
Subject: [PATCH] iommu/amd: Set iommu->int_enabled consistently when
 interrupts are set up

From: David Woodhouse <dwmw@...zon.co.uk>

When I made the INTCAPXT support stop gratuitously pretending to be MSI,
I missed the fact that iommu_setup_msi() also sets the ->int_enabled
flag. I missed this in the iommu_setup_intcapxt() code path, which means
that a resume from suspend will try to allocate the IRQ domains again,
accidentally re-enabling interrupts as it does, resulting in much sadness.

Lift out the bit which sets iommu->int_enabled into the iommu_init_irq()
function which is also where it gets checked.

Link: https://lore.kernel.org/r/20210104132250.GE32151@zn.tnic/
Fixes: d1adcfbb520c ("iommu/amd: Fix IOMMU interrupt generation in X2APIC mode")
Reported-by: Borislav Petkov <bp@...en8.de>
Signed-off-by: David Woodhouse <dwmw@...zon.co.uk>
---
There's a possibility we also need to ensure that the actual
MMIO_INTCAPXT_xxx_OFFSET registers are restored too. Unless you
actually trigger something to generate faults, you'll never know.
I don't see offhand how that was working in the pretend-to-be-MSI case
either.

 drivers/iommu/amd/init.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/drivers/iommu/amd/init.c b/drivers/iommu/amd/init.c
index f54cd79b43e4..6a1f7048dacc 100644
--- a/drivers/iommu/amd/init.c
+++ b/drivers/iommu/amd/init.c
@@ -1973,8 +1973,6 @@ static int iommu_setup_msi(struct amd_iommu *iommu)
 		return r;
 	}
 
-	iommu->int_enabled = true;
-
 	return 0;
 }
 
@@ -2169,6 +2167,7 @@ static int iommu_init_irq(struct amd_iommu *iommu)
 	if (ret)
 		return ret;
 
+	iommu->int_enabled = true;
 enable_faults:
 	iommu_feature_enable(iommu, CONTROL_EVT_INT_EN);
 
-- 
2.29.2


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