[PATCH 2/2] iommu/vt-d: Make sure RMRRs are mapped before domain goes public

From: Joerg Roede
Date: Mon Sep 05 2016 - 07:03:51 EST


From: Joerg Roedel <jroedel@xxxxxxx>

When a domain is allocated through the get_valid_domain_for_dev
path, it will be context-mapped before the RMRR regions are
mapped in the page-table. This opens a short time window
where device-accesses to these regions fail and causing DMAR
faults.

Fix this by mapping the RMRR regions before the domain is
context-mapped.

Signed-off-by: Joerg Roedel <jroedel@xxxxxxx>
---
drivers/iommu/intel-iommu.c | 27 ++++++++++++++++++++-------
1 file changed, 20 insertions(+), 7 deletions(-)

diff --git a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c
index bcdbe9d..a4407ea 100644
--- a/drivers/iommu/intel-iommu.c
+++ b/drivers/iommu/intel-iommu.c
@@ -3428,17 +3428,18 @@ static unsigned long intel_alloc_iova(struct device *dev,

static struct dmar_domain *__get_valid_domain_for_dev(struct device *dev)
{
+ struct dmar_domain *domain, *tmp;
struct dmar_rmrr_unit *rmrr;
- struct dmar_domain *domain;
struct device *i_dev;
int i, ret;

- domain = get_domain_for_dev(dev, DEFAULT_DOMAIN_ADDRESS_WIDTH);
- if (!domain) {
- pr_err("Allocating domain for %s failed\n",
- dev_name(dev));
- return NULL;
- }
+ domain = find_domain(dev);
+ if (domain)
+ goto out;
+
+ domain = find_or_alloc_domain(dev, DEFAULT_DOMAIN_ADDRESS_WIDTH);
+ if (!domain)
+ goto out;

/* We have a new domain - setup possible RMRRs for the device */
rcu_read_lock();
@@ -3457,6 +3458,18 @@ static struct dmar_domain *__get_valid_domain_for_dev(struct device *dev)
}
rcu_read_unlock();

+ tmp = set_domain_for_dev(dev, domain);
+ if (!tmp || domain != tmp) {
+ domain_exit(domain);
+ domain = tmp;
+ }
+
+out:
+
+ if (!domain)
+ pr_err("Allocating domain for %s failed\n", dev_name(dev));
+
+
return domain;
}

--
2.6.6