[PATCH 0/5] iommu/amd: Fix race conditions around increase_address_space()

[PATCH 0/5] iommu/amd: Fix race conditions around increase_address_space()

[Joerg Roedel]

Hi,

Qian reported more race conditions around the dma-mapping
code path in the AMD IOMMU driver. The race condtions are
between increas_address_space() and fetch_pte(), there were
two of them:

	1) the 'pt_root' and 'mode' fields of 'struct
	   protection_domain' relate to each other so that
	   they must be updated together atomically.

	2) The increase_address_space() function publishes
	   the updated page-table before it has been written
	   to the DTE. This might cause PTEs to be mapped
	   and addresses handed to the device which are not
	   yet reachable through the DTE entry, causing IO
	   page-faults.

This patch-set fixes these issues, as tested by Qian Cai.

Thanks a lot again for reporting these issued and testing
the fixes!

Regards,

	Joerg


Joerg Roedel (5):
  iommu/amd: Fix race in increase_address_space()/fetch_pte()
  iommu/amd: Do not loop forever when trying to increase address space
  iommu/amd: Call domain_flush_complete() in update_domain()
  iommu/amd: Update Device Table in increase_address_space()
  iommu/amd: Do not flush Device Table in iommu_map_page()

 drivers/iommu/amd_iommu.c       | 198 +++++++++++++++++++++++++-------
 drivers/iommu/amd_iommu_types.h |   9 +-
 2 files changed, 161 insertions(+), 46 deletions(-)

-- 
2.17.1

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[PATCH 1/5] iommu/amd: Fix race in increase_address_space()/fetch_pte()

[Joerg Roedel]

From: Joerg Roedel <jroedel@suse.de>

The 'pt_root' and 'mode' struct members of 'struct protection_domain'
need to be get/set atomically, otherwise the page-table of the domain
can get corrupted.

Merge the fields into one atomic64_t struct member which can be
get/set atomically.

Fixes: 92d420ec028d ("iommu/amd: Relax locking in dma_ops path")
Reported-by: Qian Cai <cai@lca.pw>
Tested-by: Qian Cai <cai@lca.pw>
Signed-off-by: Joerg Roedel <jroedel@suse.de>
---
 drivers/iommu/amd_iommu.c       | 140 ++++++++++++++++++++++++--------
 drivers/iommu/amd_iommu_types.h |   9 +-
 2 files changed, 112 insertions(+), 37 deletions(-)

diff --git a/drivers/iommu/amd_iommu.c b/drivers/iommu/amd_iommu.c
index 20cce366e951..28229a38af4d 100644
--- a/drivers/iommu/amd_iommu.c
+++ b/drivers/iommu/amd_iommu.c
@@ -151,6 +151,26 @@ static struct protection_domain *to_pdomain(struct iommu_domain *dom)
 	return container_of(dom, struct protection_domain, domain);
 }
 
+static void amd_iommu_domain_get_pgtable(struct protection_domain *domain,
+					 struct domain_pgtable *pgtable)
+{
+	u64 pt_root = atomic64_read(&domain->pt_root);
+
+	pgtable->root = (u64 *)(pt_root & PAGE_MASK);
+	pgtable->mode = pt_root & 7; /* lowest 3 bits encode pgtable mode */
+}
+
+static u64 amd_iommu_domain_encode_pgtable(u64 *root, int mode)
+{
+	u64 pt_root;
+
+	/* lowest 3 bits encode pgtable mode */
+	pt_root = mode & 7;
+	pt_root |= (u64)root;
+
+	return pt_root;
+}
+
 static struct iommu_dev_data *alloc_dev_data(u16 devid)
 {
 	struct iommu_dev_data *dev_data;
@@ -1397,13 +1417,18 @@ static struct page *free_sub_pt(unsigned long root, int mode,
 
 static void free_pagetable(struct protection_domain *domain)
 {
-	unsigned long root = (unsigned long)domain->pt_root;
+	struct domain_pgtable pgtable;
 	struct page *freelist = NULL;
+	unsigned long root;
+
+	amd_iommu_domain_get_pgtable(domain, &pgtable);
+	atomic64_set(&domain->pt_root, 0);
 
-	BUG_ON(domain->mode < PAGE_MODE_NONE ||
-	       domain->mode > PAGE_MODE_6_LEVEL);
+	BUG_ON(pgtable.mode < PAGE_MODE_NONE ||
+	       pgtable.mode > PAGE_MODE_6_LEVEL);
 
-	freelist = free_sub_pt(root, domain->mode, freelist);
+	root = (unsigned long)pgtable.root;
+	freelist = free_sub_pt(root, pgtable.mode, freelist);
 
 	free_page_list(freelist);
 }
@@ -1417,24 +1442,28 @@ static bool increase_address_space(struct protection_domain *domain,
 				   unsigned long address,
 				   gfp_t gfp)
 {
+	struct domain_pgtable pgtable;
 	unsigned long flags;
 	bool ret = false;
-	u64 *pte;
+	u64 *pte, root;
 
 	spin_lock_irqsave(&domain->lock, flags);
 
-	if (address <= PM_LEVEL_SIZE(domain->mode) ||
-	    WARN_ON_ONCE(domain->mode == PAGE_MODE_6_LEVEL))
+	amd_iommu_domain_get_pgtable(domain, &pgtable);
+
+	if (address <= PM_LEVEL_SIZE(pgtable.mode) ||
+	    WARN_ON_ONCE(pgtable.mode == PAGE_MODE_6_LEVEL))
 		goto out;
 
 	pte = (void *)get_zeroed_page(gfp);
 	if (!pte)
 		goto out;
 
-	*pte             = PM_LEVEL_PDE(domain->mode,
-					iommu_virt_to_phys(domain->pt_root));
-	domain->pt_root  = pte;
-	domain->mode    += 1;
+	*pte = PM_LEVEL_PDE(pgtable.mode, iommu_virt_to_phys(pgtable.root));
+
+	root = amd_iommu_domain_encode_pgtable(pte, pgtable.mode + 1);
+
+	atomic64_set(&domain->pt_root, root);
 
 	ret = true;
 
@@ -1451,16 +1480,22 @@ static u64 *alloc_pte(struct protection_domain *domain,
 		      gfp_t gfp,
 		      bool *updated)
 {
+	struct domain_pgtable pgtable;
 	int level, end_lvl;
 	u64 *pte, *page;
 
 	BUG_ON(!is_power_of_2(page_size));
 
-	while (address > PM_LEVEL_SIZE(domain->mode))
+	amd_iommu_domain_get_pgtable(domain, &pgtable);
+
+	while (address > PM_LEVEL_SIZE(pgtable.mode)) {
 		*updated = increase_address_space(domain, address, gfp) || *updated;
+		amd_iommu_domain_get_pgtable(domain, &pgtable);
+	}
+
 
-	level   = domain->mode - 1;
-	pte     = &domain->pt_root[PM_LEVEL_INDEX(level, address)];
+	level   = pgtable.mode - 1;
+	pte     = &pgtable.root[PM_LEVEL_INDEX(level, address)];
 	address = PAGE_SIZE_ALIGN(address, page_size);
 	end_lvl = PAGE_SIZE_LEVEL(page_size);
 
@@ -1536,16 +1571,19 @@ static u64 *fetch_pte(struct protection_domain *domain,
 		      unsigned long address,
 		      unsigned long *page_size)
 {
+	struct domain_pgtable pgtable;
 	int level;
 	u64 *pte;
 
 	*page_size = 0;
 
-	if (address > PM_LEVEL_SIZE(domain->mode))
+	amd_iommu_domain_get_pgtable(domain, &pgtable);
+
+	if (address > PM_LEVEL_SIZE(pgtable.mode))
 		return NULL;
 
-	level	   =  domain->mode - 1;
-	pte	   = &domain->pt_root[PM_LEVEL_INDEX(level, address)];
+	level	   =  pgtable.mode - 1;
+	pte	   = &pgtable.root[PM_LEVEL_INDEX(level, address)];
 	*page_size =  PTE_LEVEL_PAGE_SIZE(level);
 
 	while (level > 0) {
@@ -1806,6 +1844,7 @@ static void dma_ops_domain_free(struct protection_domain *domain)
 static struct protection_domain *dma_ops_domain_alloc(void)
 {
 	struct protection_domain *domain;
+	u64 *pt_root, root;
 
 	domain = kzalloc(sizeof(struct protection_domain), GFP_KERNEL);
 	if (!domain)
@@ -1814,12 +1853,14 @@ static struct protection_domain *dma_ops_domain_alloc(void)
 	if (protection_domain_init(domain))
 		goto free_domain;
 
-	domain->mode = PAGE_MODE_3_LEVEL;
-	domain->pt_root = (void *)get_zeroed_page(GFP_KERNEL);
-	domain->flags = PD_DMA_OPS_MASK;
-	if (!domain->pt_root)
+	pt_root = (void *)get_zeroed_page(GFP_KERNEL);
+	if (!pt_root)
 		goto free_domain;
 
+	root = amd_iommu_domain_encode_pgtable(pt_root, PAGE_MODE_3_LEVEL);
+	atomic64_set(&domain->pt_root, root);
+	domain->flags = PD_DMA_OPS_MASK;
+
 	if (iommu_get_dma_cookie(&domain->domain) == -ENOMEM)
 		goto free_domain;
 
@@ -1843,14 +1884,17 @@ static bool dma_ops_domain(struct protection_domain *domain)
 static void set_dte_entry(u16 devid, struct protection_domain *domain,
 			  bool ats, bool ppr)
 {
+	struct domain_pgtable pgtable;
 	u64 pte_root = 0;
 	u64 flags = 0;
 	u32 old_domid;
 
-	if (domain->mode != PAGE_MODE_NONE)
-		pte_root = iommu_virt_to_phys(domain->pt_root);
+	amd_iommu_domain_get_pgtable(domain, &pgtable);
+
+	if (pgtable.mode != PAGE_MODE_NONE)
+		pte_root = iommu_virt_to_phys(pgtable.root);
 
-	pte_root |= (domain->mode & DEV_ENTRY_MODE_MASK)
+	pte_root |= (pgtable.mode & DEV_ENTRY_MODE_MASK)
 		    << DEV_ENTRY_MODE_SHIFT;
 	pte_root |= DTE_FLAG_IR | DTE_FLAG_IW | DTE_FLAG_V | DTE_FLAG_TV;
 
@@ -2375,6 +2419,7 @@ static struct protection_domain *protection_domain_alloc(void)
 static struct iommu_domain *amd_iommu_domain_alloc(unsigned type)
 {
 	struct protection_domain *pdomain;
+	u64 *pt_root, root;
 
 	switch (type) {
 	case IOMMU_DOMAIN_UNMANAGED:
@@ -2382,13 +2427,15 @@ static struct iommu_domain *amd_iommu_domain_alloc(unsigned type)
 		if (!pdomain)
 			return NULL;
 
-		pdomain->mode    = PAGE_MODE_3_LEVEL;
-		pdomain->pt_root = (void *)get_zeroed_page(GFP_KERNEL);
-		if (!pdomain->pt_root) {
+		pt_root = (void *)get_zeroed_page(GFP_KERNEL);
+		if (!pt_root) {
 			protection_domain_free(pdomain);
 			return NULL;
 		}
 
+		root = amd_iommu_domain_encode_pgtable(pt_root, PAGE_MODE_3_LEVEL);
+		atomic64_set(&pdomain->pt_root, root);
+
 		pdomain->domain.geometry.aperture_start = 0;
 		pdomain->domain.geometry.aperture_end   = ~0ULL;
 		pdomain->domain.geometry.force_aperture = true;
@@ -2406,7 +2453,7 @@ static struct iommu_domain *amd_iommu_domain_alloc(unsigned type)
 		if (!pdomain)
 			return NULL;
 
-		pdomain->mode = PAGE_MODE_NONE;
+		atomic64_set(&pdomain->pt_root, PAGE_MODE_NONE);
 		break;
 	default:
 		return NULL;
@@ -2418,6 +2465,7 @@ static struct iommu_domain *amd_iommu_domain_alloc(unsigned type)
 static void amd_iommu_domain_free(struct iommu_domain *dom)
 {
 	struct protection_domain *domain;
+	struct domain_pgtable pgtable;
 
 	domain = to_pdomain(dom);
 
@@ -2435,7 +2483,9 @@ static void amd_iommu_domain_free(struct iommu_domain *dom)
 		dma_ops_domain_free(domain);
 		break;
 	default:
-		if (domain->mode != PAGE_MODE_NONE)
+		amd_iommu_domain_get_pgtable(domain, &pgtable);
+
+		if (pgtable.mode != PAGE_MODE_NONE)
 			free_pagetable(domain);
 
 		if (domain->flags & PD_IOMMUV2_MASK)
@@ -2518,10 +2568,12 @@ static int amd_iommu_map(struct iommu_domain *dom, unsigned long iova,
 			 gfp_t gfp)
 {
 	struct protection_domain *domain = to_pdomain(dom);
+	struct domain_pgtable pgtable;
 	int prot = 0;
 	int ret;
 
-	if (domain->mode == PAGE_MODE_NONE)
+	amd_iommu_domain_get_pgtable(domain, &pgtable);
+	if (pgtable.mode == PAGE_MODE_NONE)
 		return -EINVAL;
 
 	if (iommu_prot & IOMMU_READ)
@@ -2541,8 +2593,10 @@ static size_t amd_iommu_unmap(struct iommu_domain *dom, unsigned long iova,
 			      struct iommu_iotlb_gather *gather)
 {
 	struct protection_domain *domain = to_pdomain(dom);
+	struct domain_pgtable pgtable;
 
-	if (domain->mode == PAGE_MODE_NONE)
+	amd_iommu_domain_get_pgtable(domain, &pgtable);
+	if (pgtable.mode == PAGE_MODE_NONE)
 		return 0;
 
 	return iommu_unmap_page(domain, iova, page_size);
@@ -2553,9 +2607,11 @@ static phys_addr_t amd_iommu_iova_to_phys(struct iommu_domain *dom,
 {
 	struct protection_domain *domain = to_pdomain(dom);
 	unsigned long offset_mask, pte_pgsize;
+	struct domain_pgtable pgtable;
 	u64 *pte, __pte;
 
-	if (domain->mode == PAGE_MODE_NONE)
+	amd_iommu_domain_get_pgtable(domain, &pgtable);
+	if (pgtable.mode == PAGE_MODE_NONE)
 		return iova;
 
 	pte = fetch_pte(domain, iova, &pte_pgsize);
@@ -2708,16 +2764,26 @@ EXPORT_SYMBOL(amd_iommu_unregister_ppr_notifier);
 void amd_iommu_domain_direct_map(struct iommu_domain *dom)
 {
 	struct protection_domain *domain = to_pdomain(dom);
+	struct domain_pgtable pgtable;
 	unsigned long flags;
+	u64 pt_root;
 
 	spin_lock_irqsave(&domain->lock, flags);
 
+	/* First save pgtable configuration*/
+	amd_iommu_domain_get_pgtable(domain, &pgtable);
+
 	/* Update data structure */
-	domain->mode    = PAGE_MODE_NONE;
+	pt_root = amd_iommu_domain_encode_pgtable(NULL, PAGE_MODE_NONE);
+	atomic64_set(&domain->pt_root, pt_root);
 
 	/* Make changes visible to IOMMUs */
 	update_domain(domain);
 
+	/* Restore old pgtable in domain->ptroot to free page-table */
+	pt_root = amd_iommu_domain_encode_pgtable(pgtable.root, pgtable.mode);
+	atomic64_set(&domain->pt_root, pt_root);
+
 	/* Page-table is not visible to IOMMU anymore, so free it */
 	free_pagetable(domain);
 
@@ -2908,9 +2974,11 @@ static u64 *__get_gcr3_pte(u64 *root, int level, int pasid, bool alloc)
 static int __set_gcr3(struct protection_domain *domain, int pasid,
 		      unsigned long cr3)
 {
+	struct domain_pgtable pgtable;
 	u64 *pte;
 
-	if (domain->mode != PAGE_MODE_NONE)
+	amd_iommu_domain_get_pgtable(domain, &pgtable);
+	if (pgtable.mode != PAGE_MODE_NONE)
 		return -EINVAL;
 
 	pte = __get_gcr3_pte(domain->gcr3_tbl, domain->glx, pasid, true);
@@ -2924,9 +2992,11 @@ static int __set_gcr3(struct protection_domain *domain, int pasid,
 
 static int __clear_gcr3(struct protection_domain *domain, int pasid)
 {
+	struct domain_pgtable pgtable;
 	u64 *pte;
 
-	if (domain->mode != PAGE_MODE_NONE)
+	amd_iommu_domain_get_pgtable(domain, &pgtable);
+	if (pgtable.mode != PAGE_MODE_NONE)
 		return -EINVAL;
 
 	pte = __get_gcr3_pte(domain->gcr3_tbl, domain->glx, pasid, false);
diff --git a/drivers/iommu/amd_iommu_types.h b/drivers/iommu/amd_iommu_types.h
index ca8c4522045b..7a8fdec138bd 100644
--- a/drivers/iommu/amd_iommu_types.h
+++ b/drivers/iommu/amd_iommu_types.h
@@ -468,8 +468,7 @@ struct protection_domain {
 				       iommu core code */
 	spinlock_t lock;	/* mostly used to lock the page table*/
 	u16 id;			/* the domain id written to the device table */
-	int mode;		/* paging mode (0-6 levels) */
-	u64 *pt_root;		/* page table root pointer */
+	atomic64_t pt_root;	/* pgtable root and pgtable mode */
 	int glx;		/* Number of levels for GCR3 table */
 	u64 *gcr3_tbl;		/* Guest CR3 table */
 	unsigned long flags;	/* flags to find out type of domain */
@@ -477,6 +476,12 @@ struct protection_domain {
 	unsigned dev_iommu[MAX_IOMMUS]; /* per-IOMMU reference count */
 };
 
+/* For decocded pt_root */
+struct domain_pgtable {
+	int mode;
+	u64 *root;
+};
+
 /*
  * Structure where we save information about one hardware AMD IOMMU in the
  * system.
-- 
2.17.1

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[PATCH 2/5] iommu/amd: Do not loop forever when trying to increase address space

[Joerg Roedel]

From: Joerg Roedel <jroedel@suse.de>

When increase_address_space() fails to allocate memory, alloc_pte()
will call it again until it succeeds. Do not loop forever while trying
to increase the address space and just return an error instead.

Tested-by: Qian Cai <cai@lca.pw>
Signed-off-by: Joerg Roedel <jroedel@suse.de>
---
 drivers/iommu/amd_iommu.c | 13 ++++++++++++-
 1 file changed, 12 insertions(+), 1 deletion(-)

diff --git a/drivers/iommu/amd_iommu.c b/drivers/iommu/amd_iommu.c
index 28229a38af4d..68da484a69dd 100644
--- a/drivers/iommu/amd_iommu.c
+++ b/drivers/iommu/amd_iommu.c
@@ -1489,8 +1489,19 @@ static u64 *alloc_pte(struct protection_domain *domain,
 	amd_iommu_domain_get_pgtable(domain, &pgtable);
 
 	while (address > PM_LEVEL_SIZE(pgtable.mode)) {
-		*updated = increase_address_space(domain, address, gfp) || *updated;
+		bool upd = increase_address_space(domain, address, gfp);
+
+		/* Read new values to check if update was successful */
 		amd_iommu_domain_get_pgtable(domain, &pgtable);
+
+		/*
+		 * Return an error if there is no memory to update the
+		 * page-table.
+		 */
+		if (!upd && (address > PM_LEVEL_SIZE(pgtable.mode)))
+			return NULL;
+
+		*updated = *updated || upd;
 	}
 
 
-- 
2.17.1

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[PATCH 3/5] iommu/amd: Call domain_flush_complete() in update_domain()

[Joerg Roedel]

From: Joerg Roedel <jroedel@suse.de>

The update_domain() function is expected to also inform the hardware
about domain changes. This needs a COMPLETION_WAIT command to be sent
to all IOMMUs which use the domain.

Tested-by: Qian Cai <cai@lca.pw>
Signed-off-by: Joerg Roedel <jroedel@suse.de>
---
 drivers/iommu/amd_iommu.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/iommu/amd_iommu.c b/drivers/iommu/amd_iommu.c
index 68da484a69dd..d2499c86d395 100644
--- a/drivers/iommu/amd_iommu.c
+++ b/drivers/iommu/amd_iommu.c
@@ -2321,6 +2321,7 @@ static void update_domain(struct protection_domain *domain)
 
 	domain_flush_devices(domain);
 	domain_flush_tlb_pde(domain);
+	domain_flush_complete(domain);
 }
 
 int __init amd_iommu_init_api(void)
-- 
2.17.1

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[PATCH 4/5] iommu/amd: Update Device Table in increase_address_space()

[Joerg Roedel]

From: Joerg Roedel <jroedel@suse.de>

The Device Table needs to be updated before the new page-table root
can be published in domain->pt_root. Otherwise a concurrent call to
fetch_pte might fetch a PTE which is not reachable through the Device
Table Entry.

Fixes: 92d420ec028d ("iommu/amd: Relax locking in dma_ops path")
Reported-by: Qian Cai <cai@lca.pw>
Tested-by: Qian Cai <cai@lca.pw>
Signed-off-by: Joerg Roedel <jroedel@suse.de>
---
 drivers/iommu/amd_iommu.c | 49 ++++++++++++++++++++++++++++-----------
 1 file changed, 36 insertions(+), 13 deletions(-)

diff --git a/drivers/iommu/amd_iommu.c b/drivers/iommu/amd_iommu.c
index d2499c86d395..2ae1daac888a 100644
--- a/drivers/iommu/amd_iommu.c
+++ b/drivers/iommu/amd_iommu.c
@@ -101,6 +101,8 @@ struct kmem_cache *amd_iommu_irq_cache;
 static void update_domain(struct protection_domain *domain);
 static int protection_domain_init(struct protection_domain *domain);
 static void detach_device(struct device *dev);
+static void update_and_flush_device_table(struct protection_domain *domain,
+					  struct domain_pgtable *pgtable);
 
 /****************************************************************************
  *
@@ -1461,8 +1463,16 @@ static bool increase_address_space(struct protection_domain *domain,
 
 	*pte = PM_LEVEL_PDE(pgtable.mode, iommu_virt_to_phys(pgtable.root));
 
-	root = amd_iommu_domain_encode_pgtable(pte, pgtable.mode + 1);
+	pgtable.root  = pte;
+	pgtable.mode += 1;
+	update_and_flush_device_table(domain, &pgtable);
+	domain_flush_complete(domain);
 
+	/*
+	 * Device Table needs to be updated and flushed before the new root can
+	 * be published.
+	 */
+	root = amd_iommu_domain_encode_pgtable(pte, pgtable.mode);
 	atomic64_set(&domain->pt_root, root);
 
 	ret = true;
@@ -1893,19 +1903,17 @@ static bool dma_ops_domain(struct protection_domain *domain)
 }
 
 static void set_dte_entry(u16 devid, struct protection_domain *domain,
+			  struct domain_pgtable *pgtable,
 			  bool ats, bool ppr)
 {
-	struct domain_pgtable pgtable;
 	u64 pte_root = 0;
 	u64 flags = 0;
 	u32 old_domid;
 
-	amd_iommu_domain_get_pgtable(domain, &pgtable);
+	if (pgtable->mode != PAGE_MODE_NONE)
+		pte_root = iommu_virt_to_phys(pgtable->root);
 
-	if (pgtable.mode != PAGE_MODE_NONE)
-		pte_root = iommu_virt_to_phys(pgtable.root);
-
-	pte_root |= (pgtable.mode & DEV_ENTRY_MODE_MASK)
+	pte_root |= (pgtable->mode & DEV_ENTRY_MODE_MASK)
 		    << DEV_ENTRY_MODE_SHIFT;
 	pte_root |= DTE_FLAG_IR | DTE_FLAG_IW | DTE_FLAG_V | DTE_FLAG_TV;
 
@@ -1978,6 +1986,7 @@ static void clear_dte_entry(u16 devid)
 static void do_attach(struct iommu_dev_data *dev_data,
 		      struct protection_domain *domain)
 {
+	struct domain_pgtable pgtable;
 	struct amd_iommu *iommu;
 	bool ats;
 
@@ -1993,7 +2002,9 @@ static void do_attach(struct iommu_dev_data *dev_data,
 	domain->dev_cnt                 += 1;
 
 	/* Update device table */
-	set_dte_entry(dev_data->devid, domain, ats, dev_data->iommu_v2);
+	amd_iommu_domain_get_pgtable(domain, &pgtable);
+	set_dte_entry(dev_data->devid, domain, &pgtable,
+		      ats, dev_data->iommu_v2);
 	clone_aliases(dev_data->pdev);
 
 	device_flush_dte(dev_data);
@@ -2304,22 +2315,34 @@ static int amd_iommu_domain_get_attr(struct iommu_domain *domain,
  *
  *****************************************************************************/
 
-static void update_device_table(struct protection_domain *domain)
+static void update_device_table(struct protection_domain *domain,
+				struct domain_pgtable *pgtable)
 {
 	struct iommu_dev_data *dev_data;
 
 	list_for_each_entry(dev_data, &domain->dev_list, list) {
-		set_dte_entry(dev_data->devid, domain, dev_data->ats.enabled,
-			      dev_data->iommu_v2);
+		set_dte_entry(dev_data->devid, domain, pgtable,
+			      dev_data->ats.enabled, dev_data->iommu_v2);
 		clone_aliases(dev_data->pdev);
 	}
 }
 
+static void update_and_flush_device_table(struct protection_domain *domain,
+					  struct domain_pgtable *pgtable)
+{
+	update_device_table(domain, pgtable);
+	domain_flush_devices(domain);
+}
+
 static void update_domain(struct protection_domain *domain)
 {
-	update_device_table(domain);
+	struct domain_pgtable pgtable;
 
-	domain_flush_devices(domain);
+	/* Update device table */
+	amd_iommu_domain_get_pgtable(domain, &pgtable);
+	update_and_flush_device_table(domain, &pgtable);
+
+	/* Flush domain TLB(s) and wait for completion */
 	domain_flush_tlb_pde(domain);
 	domain_flush_complete(domain);
 }
-- 
2.17.1

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[PATCH 5/5] iommu/amd: Do not flush Device Table in iommu_map_page()

[Joerg Roedel]

From: Joerg Roedel <jroedel@suse.de>

The flush of the Device Table Entries for the domain has already
happened in increase_address_space(), if necessary. Do no flush them
again in iommu_map_page().

Tested-by: Qian Cai <cai@lca.pw>
Signed-off-by: Joerg Roedel <jroedel@suse.de>
---
 drivers/iommu/amd_iommu.c | 27 ++++++++++++++++-----------
 1 file changed, 16 insertions(+), 11 deletions(-)

diff --git a/drivers/iommu/amd_iommu.c b/drivers/iommu/amd_iommu.c
index 2ae1daac888a..1dc3718560d0 100644
--- a/drivers/iommu/amd_iommu.c
+++ b/drivers/iommu/amd_iommu.c
@@ -1446,15 +1446,18 @@ static bool increase_address_space(struct protection_domain *domain,
 {
 	struct domain_pgtable pgtable;
 	unsigned long flags;
-	bool ret = false;
+	bool ret = true;
 	u64 *pte, root;
 
 	spin_lock_irqsave(&domain->lock, flags);
 
 	amd_iommu_domain_get_pgtable(domain, &pgtable);
 
-	if (address <= PM_LEVEL_SIZE(pgtable.mode) ||
-	    WARN_ON_ONCE(pgtable.mode == PAGE_MODE_6_LEVEL))
+	if (address <= PM_LEVEL_SIZE(pgtable.mode))
+		goto out;
+
+	ret = false;
+	if (WARN_ON_ONCE(pgtable.mode == PAGE_MODE_6_LEVEL))
 		goto out;
 
 	pte = (void *)get_zeroed_page(gfp);
@@ -1499,19 +1502,15 @@ static u64 *alloc_pte(struct protection_domain *domain,
 	amd_iommu_domain_get_pgtable(domain, &pgtable);
 
 	while (address > PM_LEVEL_SIZE(pgtable.mode)) {
-		bool upd = increase_address_space(domain, address, gfp);
-
-		/* Read new values to check if update was successful */
-		amd_iommu_domain_get_pgtable(domain, &pgtable);
-
 		/*
 		 * Return an error if there is no memory to update the
 		 * page-table.
 		 */
-		if (!upd && (address > PM_LEVEL_SIZE(pgtable.mode)))
+		if (!increase_address_space(domain, address, gfp))
 			return NULL;
 
-		*updated = *updated || upd;
+		/* Read new values to check if update was successful */
+		amd_iommu_domain_get_pgtable(domain, &pgtable);
 	}
 
 
@@ -1719,7 +1718,13 @@ static int iommu_map_page(struct protection_domain *dom,
 		unsigned long flags;
 
 		spin_lock_irqsave(&dom->lock, flags);
-		update_domain(dom);
+		/*
+		 * Flush domain TLB(s) and wait for completion. Any Device-Table
+		 * Updates and flushing already happened in
+		 * increase_address_space().
+		 */
+		domain_flush_tlb_pde(dom);
+		domain_flush_complete(dom);
 		spin_unlock_irqrestore(&dom->lock, flags);
 	}
 
-- 
2.17.1

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Re: [PATCH 0/5] iommu/amd: Fix race conditions around increase_address_space()

[Joerg Roedel]

On Mon, May 04, 2020 at 02:54:08PM +0200, Joerg Roedel wrote:
> Joerg Roedel (5):
>   iommu/amd: Fix race in increase_address_space()/fetch_pte()
>   iommu/amd: Do not loop forever when trying to increase address space
>   iommu/amd: Call domain_flush_complete() in update_domain()
>   iommu/amd: Update Device Table in increase_address_space()
>   iommu/amd: Do not flush Device Table in iommu_map_page()
> 
>  drivers/iommu/amd_iommu.c       | 198 +++++++++++++++++++++++++-------
>  drivers/iommu/amd_iommu_types.h |   9 +-
>  2 files changed, 161 insertions(+), 46 deletions(-)

Applied for v5.7.
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