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From:   Sasha Levin <Alexander.Levin@microsoft.com>
To:     "stable@vger.kernel.org" <stable@vger.kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
CC:     Geert Uytterhoeven <geert+renesas@glider.be>,
        Joerg Roedel <jroedel@suse.de>,
        Sasha Levin <Alexander.Levin@microsoft.com>
Subject: [PATCH AUTOSEL 4.18 110/131] iommu/ipmmu-vmsa: Fix allocation in
 atomic context
Thread-Topic: [PATCH AUTOSEL 4.18 110/131] iommu/ipmmu-vmsa: Fix allocation in
 atomic context
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Date:   Sun, 2 Sep 2018 13:05:21 +0000
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From: Geert Uytterhoeven <geert+renesas@glider.be>

[ Upstream commit 46583e8c48c5a094ba28060615b3a7c8c576690f ]

When attaching a device to an IOMMU group with
CONFIG_DEBUG_ATOMIC_SLEEP=3Dy:

    BUG: sleeping function called from invalid context at mm/slab.h:421
    in_atomic(): 1, irqs_disabled(): 128, pid: 61, name: kworker/1:1
    ...
    Call trace:
     ...
     arm_lpae_alloc_pgtable+0x114/0x184
     arm_64_lpae_alloc_pgtable_s1+0x2c/0x128
     arm_32_lpae_alloc_pgtable_s1+0x40/0x6c
     alloc_io_pgtable_ops+0x60/0x88
     ipmmu_attach_device+0x140/0x334

ipmmu_attach_device() takes a spinlock, while arm_lpae_alloc_pgtable()
allocates memory using GFP_KERNEL.  Originally, the ipmmu-vmsa driver
had its own custom page table allocation implementation using
GFP_ATOMIC, hence the spinlock was fine.

Fix this by replacing the spinlock by a mutex, like the arm-smmu driver
does.

Fixes: f20ed39f53145e45 ("iommu/ipmmu-vmsa: Use the ARM LPAE page table all=
ocator")
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Joerg Roedel <jroedel@suse.de>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
---
 drivers/iommu/ipmmu-vmsa.c | 9 ++++-----
 1 file changed, 4 insertions(+), 5 deletions(-)

diff --git a/drivers/iommu/ipmmu-vmsa.c b/drivers/iommu/ipmmu-vmsa.c
index 40ae6e87cb88..ef566b4989d6 100644
--- a/drivers/iommu/ipmmu-vmsa.c
+++ b/drivers/iommu/ipmmu-vmsa.c
@@ -73,7 +73,7 @@ struct ipmmu_vmsa_domain {
 	struct io_pgtable_ops *iop;
=20
 	unsigned int context_id;
-	spinlock_t lock;			/* Protects mappings */
+	struct mutex mutex;			/* Protects mappings */
 };
=20
 static struct ipmmu_vmsa_domain *to_vmsa_domain(struct iommu_domain *dom)
@@ -595,7 +595,7 @@ static struct iommu_domain *__ipmmu_domain_alloc(unsign=
ed type)
 	if (!domain)
 		return NULL;
=20
-	spin_lock_init(&domain->lock);
+	mutex_init(&domain->mutex);
=20
 	return &domain->io_domain;
 }
@@ -641,7 +641,6 @@ static int ipmmu_attach_device(struct iommu_domain *io_=
domain,
 	struct iommu_fwspec *fwspec =3D dev->iommu_fwspec;
 	struct ipmmu_vmsa_device *mmu =3D to_ipmmu(dev);
 	struct ipmmu_vmsa_domain *domain =3D to_vmsa_domain(io_domain);
-	unsigned long flags;
 	unsigned int i;
 	int ret =3D 0;
=20
@@ -650,7 +649,7 @@ static int ipmmu_attach_device(struct iommu_domain *io_=
domain,
 		return -ENXIO;
 	}
=20
-	spin_lock_irqsave(&domain->lock, flags);
+	mutex_lock(&domain->mutex);
=20
 	if (!domain->mmu) {
 		/* The domain hasn't been used yet, initialize it. */
@@ -674,7 +673,7 @@ static int ipmmu_attach_device(struct iommu_domain *io_=
domain,
 	} else
 		dev_info(dev, "Reusing IPMMU context %u\n", domain->context_id);
=20
-	spin_unlock_irqrestore(&domain->lock, flags);
+	mutex_unlock(&domain->mutex);
=20
 	if (ret < 0)
 		return ret;
--=20
2.17.1