x86/amd-iommu: Protect IOMMU-API map/unmap path

This patch introduces a mutex to lock page table updates in
the IOMMU-API path. We can't use the spin_lock here because
this patch might sleep.

Signed-off-by: Joerg Roedel <joerg.roedel@amd.com>

2 files changed, 11 insertions, 0 deletions

diff --git a/arch/x86/include/asm/amd_iommu_types.h b/arch/x86/include/asm/amd_iommu_types.h
index ba19ad4c47d0..5e46e78f3b1b 100644
--- a/arch/x86/include/asm/amd_iommu_types.h
+++ b/arch/x86/include/asm/amd_iommu_types.h
@@ -21,6 +21,7 @@
 #define _ASM_X86_AMD_IOMMU_TYPES_H
 
 #include <linux/types.h>
+#include <linux/mutex.h>
 #include <linux/list.h>
 #include <linux/spinlock.h>
 
@@ -237,6 +238,7 @@ struct protection_domain {
         struct list_head list;  /* for list of all protection domains */
         struct list_head dev_list; /* List of all devices in this domain */
         spinlock_t lock;        /* mostly used to lock the page table*/
+        struct mutex api_lock;  /* protect page tables in the iommu-api path */
         u16 id;                 /* the domain id written to the device table */
         int mode;               /* paging mode (0-6 levels) */
         u64 *pt_root;           /* page table root pointer */
diff --git a/arch/x86/kernel/amd_iommu.c b/arch/x86/kernel/amd_iommu.c
index 2c4a5012038e..b97f2f1c449a 100644
--- a/arch/x86/kernel/amd_iommu.c
+++ b/arch/x86/kernel/amd_iommu.c
@@ -2327,6 +2327,7 @@ static struct protection_domain *protection_domain_alloc(void)
                 return NULL;
 
         spin_lock_init(&domain->lock);
+        mutex_init(&domain->api_lock);
         domain->id = domain_id_alloc();
         if (!domain->id)
                 goto out_err;
@@ -2456,6 +2457,8 @@ static int amd_iommu_map_range(struct iommu_domain *dom,
         iova  &= PAGE_MASK;
         paddr &= PAGE_MASK;
 
+        mutex_lock(&domain->api_lock);
+
         for (i = 0; i < npages; ++i) {
                 ret = iommu_map_page(domain, iova, paddr, prot, PM_MAP_4k);
                 if (ret)
@@ -2465,6 +2468,8 @@ static int amd_iommu_map_range(struct iommu_domain *dom,
                 paddr += PAGE_SIZE;
         }
 
+        mutex_unlock(&domain->api_lock);
+
         return 0;
 }
 
@@ -2477,12 +2482,16 @@ static void amd_iommu_unmap_range(struct iommu_domain *dom,
 
         iova  &= PAGE_MASK;
 
+        mutex_lock(&domain->api_lock);
+
         for (i = 0; i < npages; ++i) {
                 iommu_unmap_page(domain, iova, PM_MAP_4k);
                 iova  += PAGE_SIZE;
         }
 
         iommu_flush_tlb_pde(domain);
+
+        mutex_unlock(&domain->api_lock);
 }
 
 static phys_addr_t amd_iommu_iova_to_phys(struct iommu_domain *dom,