iommu/amd: Remove domain->updated

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>

diff --git a/drivers/iommu/amd_iommu.c b/drivers/iommu/amd_iommu.c
index 7bdce3b..042854b 100644 (file)
--- a/drivers/iommu/amd_iommu.c
+++ b/drivers/iommu/amd_iommu.c
@@ -1458,10 +1458,11 @@ static void free_pagetable(struct protection_domain *domain)
  * 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);
@@ -1478,19 +1479,21 @@ static void increase_address_space(struct protection_domain *domain,
                                        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;
@@ -1498,7 +1501,7 @@ static u64 *alloc_pte(struct protection_domain *domain,
        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)];
@@ -1530,7 +1533,7 @@ static u64 *alloc_pte(struct protection_domain *domain,
                        for (i = 0; i < count; ++i)
                                cmpxchg64(&lpte[i], __pte, 0ULL);
 
-                       domain->updated = true;
+                       *updated = true;
                        continue;
                }
 
@@ -1547,7 +1550,7 @@ static u64 *alloc_pte(struct protection_domain *domain,
                        if (cmpxchg64(pte, __pte, __npte) != __pte)
                                free_page((unsigned long)page);
                        else if (IOMMU_PTE_PRESENT(__pte))
-                               domain->updated = true;
+                               *updated = true;
 
                        continue;
                }
@@ -1656,28 +1659,29 @@ static int iommu_map_page(struct protection_domain *dom,
                          gfp_t gfp)
 {
        struct page *freelist = NULL;
+       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));
 
+       ret = -EINVAL;
        if (!(prot & IOMMU_PROT_MASK))
-               return -EINVAL;
+               goto out;
 
        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);
 
-       if (!pte) {
-               update_domain(dom);
-               return -ENOMEM;
-       }
+       ret = -ENOMEM;
+       if (!pte)
+               goto out;
 
        for (i = 0; i < count; ++i)
                freelist = free_clear_pte(&pte[i], pte[i], freelist);
 
        if (freelist != NULL)
-               dom->updated = true;
+               updated = true;
 
        if (count > 1) {
                __pte = PAGE_SIZE_PTE(__sme_set(phys_addr), page_size);
@@ -1693,12 +1697,16 @@ static int iommu_map_page(struct protection_domain *dom,
        for (i = 0; i < count; ++i)
                pte[i] = __pte;
 
-       update_domain(dom);
+       ret = 0;
+
+out:
+       if (updated)
+               update_domain(dom);
 
        /* Everything flushed out, free pages now */
        free_page_list(freelist);
 
-       return 0;
+       return ret;
 }
 
 static unsigned long iommu_unmap_page(struct protection_domain *dom,
@@ -2399,15 +2407,10 @@ static void update_device_table(struct protection_domain *domain)
 
 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)
@@ -3333,7 +3336,6 @@ void amd_iommu_domain_direct_map(struct iommu_domain *dom)
 
        /* Update data structure */
        domain->mode    = PAGE_MODE_NONE;
-       domain->updated = true;
 
        /* Make changes visible to IOMMUs */
        update_domain(domain);
@@ -3379,7 +3381,6 @@ int amd_iommu_domain_enable_v2(struct iommu_domain *dom, int pasids)
 
        domain->glx      = levels;
        domain->flags   |= PD_IOMMUV2_MASK;
-       domain->updated  = true;
 
        update_domain(domain);
 

diff --git a/drivers/iommu/amd_iommu_types.h b/drivers/iommu/amd_iommu_types.h
index 9ac229e..0186501 100644 (file)
--- a/drivers/iommu/amd_iommu_types.h
+++ b/drivers/iommu/amd_iommu_types.h
@@ -475,7 +475,6 @@ 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 */
 };