AMD IOMMU: don't assign preallocated protection domains to devices
In isolation mode the protection domains for the devices are
preallocated and preassigned. This is bad if a device should be passed
to a virtualization guest because the IOMMU code does not know if it is
in use by a driver. This patch changes the code to assign the device to
the preallocated domain only if there are dma mapping requests for it.
Signed-off-by: Joerg Roedel <joerg.roedel@amd.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
diff --git a/arch/x86/kernel/amd_iommu.c b/arch/x86/kernel/amd_iommu.c
index a6a6f8e..7c17914 100644
--- a/arch/x86/kernel/amd_iommu.c
+++ b/arch/x86/kernel/amd_iommu.c
@@ -33,6 +33,10 @@
static DEFINE_RWLOCK(amd_iommu_devtable_lock);
+/* A list of preallocated protection domains */
+static LIST_HEAD(iommu_pd_list);
+static DEFINE_SPINLOCK(iommu_pd_list_lock);
+
/*
* general struct to manage commands send to an IOMMU
*/
@@ -663,6 +667,7 @@
dma_dom->next_bit = 0;
dma_dom->need_flush = false;
+ dma_dom->target_dev = 0xffff;
/* Intialize the exclusion range if necessary */
if (iommu->exclusion_start &&
@@ -769,6 +774,33 @@
}
/*
+ * In this function the list of preallocated protection domains is traversed to
+ * find the domain for a specific device
+ */
+static struct dma_ops_domain *find_protection_domain(u16 devid)
+{
+ struct dma_ops_domain *entry, *ret = NULL;
+ unsigned long flags;
+
+ if (list_empty(&iommu_pd_list))
+ return NULL;
+
+ spin_lock_irqsave(&iommu_pd_list_lock, flags);
+
+ list_for_each_entry(entry, &iommu_pd_list, list) {
+ if (entry->target_dev == devid) {
+ ret = entry;
+ list_del(&ret->list);
+ break;
+ }
+ }
+
+ spin_unlock_irqrestore(&iommu_pd_list_lock, flags);
+
+ return ret;
+}
+
+/*
* In the dma_ops path we only have the struct device. This function
* finds the corresponding IOMMU, the protection domain and the
* requestor id for a given device.
@@ -803,9 +835,11 @@
*iommu = amd_iommu_rlookup_table[*bdf];
if (*iommu == NULL)
return 0;
- dma_dom = (*iommu)->default_dom;
*domain = domain_for_device(*bdf);
if (*domain == NULL) {
+ dma_dom = find_protection_domain(*bdf);
+ if (!dma_dom)
+ dma_dom = (*iommu)->default_dom;
*domain = &dma_dom->domain;
set_device_domain(*iommu, *domain, *bdf);
printk(KERN_INFO "AMD IOMMU: Using protection domain %d for "
@@ -1257,10 +1291,9 @@
if (!dma_dom)
continue;
init_unity_mappings_for_device(dma_dom, devid);
- set_device_domain(iommu, &dma_dom->domain, devid);
- printk(KERN_INFO "AMD IOMMU: Allocated domain %d for device ",
- dma_dom->domain.id);
- print_devid(devid, 1);
+ dma_dom->target_dev = devid;
+
+ list_add_tail(&dma_dom->list, &iommu_pd_list);
}
}