From: Joerg Roedel <jroedel@suse.de>
Date: Wed, 25 Sep 2019 15:22:55 +0200
Subject: iommu/amd: Remove domain->updated
Git-commit: f15d9a992f901d4f22db868adf800844d1cac9f2
Patch-mainline: v5.4-rc1
References: bsc#1154610

This struct member was used to track whether a domain
change requires updates to the device-table and IOMMU cache
flushes. The problem is, that access to this field is racy
since locking in the common mapping code-paths has been
eliminated.

Move the updated field to the stack to get rid of all
potential races and remove the field from the struct.

Fixes: 92d420ec028d ("iommu/amd: Relax locking in dma_ops path")
Reviewed-by: Filippo Sironi <sironi@amazon.de>
Reviewed-by: Jerry Snitselaar <jsnitsel@redhat.com>
Signed-off-by: Joerg Roedel <jroedel@suse.de>
---
 drivers/iommu/amd_iommu.c       | 49 +++++++++++++++++++++--------------------
 drivers/iommu/amd_iommu_types.h |  1 -
 2 files changed, 25 insertions(+), 25 deletions(-)

--- a/drivers/iommu/amd_iommu.c
+++ b/drivers/iommu/amd_iommu.c
@@ -1382,10 +1382,11 @@ static void domain_flush_devices(struct
  * another level increases the size of the address space by 9 bits to a size up
  * to 64 bits.
  */
-static void increase_address_space(struct protection_domain *domain,
+static bool increase_address_space(struct protection_domain *domain,
 				   gfp_t gfp)
 {
 	unsigned long flags;
+	bool ret = false;
 	u64 *pte;
 
 	spin_lock_irqsave(&domain->lock, flags);
@@ -1402,19 +1403,21 @@ static void increase_address_space(struc
 					iommu_virt_to_phys(domain->pt_root));
 	domain->pt_root  = pte;
 	domain->mode    += 1;
-	domain->updated  = true;
+
+	ret = true;
 
 out:
 	spin_unlock_irqrestore(&domain->lock, flags);
 
-	return;
+	return ret;
 }
 
 static u64 *alloc_pte(struct protection_domain *domain,
 		      unsigned long address,
 		      unsigned long page_size,
 		      u64 **pte_page,
-		      gfp_t gfp)
+		      gfp_t gfp,
+		      bool *updated)
 {
 	int level, end_lvl;
 	u64 *pte, *page;
@@ -1422,7 +1425,7 @@ static u64 *alloc_pte(struct protection_
 	BUG_ON(!is_power_of_2(page_size));
 
 	while (address > PM_LEVEL_SIZE(domain->mode))
-		increase_address_space(domain, gfp);
+		*updated = increase_address_space(domain, gfp) || *updated;
 
 	level   = domain->mode - 1;
 	pte     = &domain->pt_root[PM_LEVEL_INDEX(level, address)];
@@ -1535,8 +1538,9 @@ static int iommu_map_page(struct protect
 			  int prot,
 			  gfp_t gfp)
 {
+	bool updated = false;
 	u64 __pte, *pte;
-	int i, count;
+	int ret, i, count;
 
 	BUG_ON(!IS_ALIGNED(bus_addr, page_size));
 	BUG_ON(!IS_ALIGNED(phys_addr, page_size));
@@ -1545,14 +1549,16 @@ static int iommu_map_page(struct protect
 		return -EINVAL;
 
 	count = PAGE_SIZE_PTE_COUNT(page_size);
-	pte   = alloc_pte(dom, bus_addr, page_size, NULL, gfp);
+	pte   = alloc_pte(dom, bus_addr, page_size, NULL, gfp, &updated);
 
+	ret = -ENOMEM;
 	if (!pte)
-		return -ENOMEM;
+		goto out;
 
+	ret = -EBUSY;
 	for (i = 0; i < count; ++i)
 		if (IOMMU_PTE_PRESENT(pte[i]))
-			return -EBUSY;
+			goto out;
 
 	if (count > 1) {
 		__pte = PAGE_SIZE_PTE(__sme_set(phys_addr), page_size);
@@ -1568,9 +1574,13 @@ static int iommu_map_page(struct protect
 	for (i = 0; i < count; ++i)
 		pte[i] = __pte;
 
-	update_domain(dom);
+	ret = 0;
+
+out:
+	if (updated)
+		update_domain(dom);
 
-	return 0;
+	return ret;
 }
 
 static unsigned long iommu_unmap_page(struct protection_domain *dom,
@@ -2556,15 +2566,10 @@ static void update_device_table(struct p
 
 static void update_domain(struct protection_domain *domain)
 {
-	if (!domain->updated)
-		return;
-
 	update_device_table(domain);
 
 	domain_flush_devices(domain);
 	domain_flush_tlb_pde(domain);
-
-	domain->updated = false;
 }
 
 static int dir2prot(enum dma_data_direction direction)
@@ -3486,7 +3491,6 @@ void amd_iommu_domain_direct_map(struct
 
 	/* Update data structure */
 	domain->mode    = PAGE_MODE_NONE;
-	domain->updated = true;
 
 	/* Make changes visible to IOMMUs */
 	update_domain(domain);
@@ -3532,7 +3536,6 @@ int amd_iommu_domain_enable_v2(struct io
 
 	domain->glx      = levels;
 	domain->flags   |= PD_IOMMUV2_MASK;
-	domain->updated  = true;
 
 	update_domain(domain);
 
--- a/drivers/iommu/amd_iommu_types.h
+++ b/drivers/iommu/amd_iommu_types.h
@@ -483,7 +483,6 @@ struct protection_domain {
 	int glx;		/* Number of levels for GCR3 table */
 	u64 *gcr3_tbl;		/* Guest CR3 table */
 	unsigned long flags;	/* flags to find out type of domain */
-	bool updated;		/* complete domain flush required */
 	unsigned dev_cnt;	/* devices assigned to this domain */
 	unsigned dev_iommu[MAX_IOMMUS]; /* per-IOMMU reference count */
 };