[PATCH 5.6 026/194] iommu/amd: Update Device Table in increase_address_space()

Greg Kroah-Hartman
2020-05-18T18:00:50Z

From: Joerg Roedel <jroedel@suse.de>

[ Upstream commit 19c6978fba68a2cdedee7d55fb8c3063d47982d9 ]

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>
Signed-off-by: Joerg Roedel <jroedel@suse.de>
Tested-by: Qian Cai <cai@lca.pw>
Link: https://lore.kernel.org/r/20200504125413.16798-5-joro@8bytes.org
Signed-off-by: Joerg Roedel <jroedel@suse.de>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
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 28229a38af4d2..500d0a8c966fc 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;
@@ -1882,19 +1892,17 @@ 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;

@@ -1967,6 +1975,7 @@ 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;

@@ -1982,7 +1991,9 @@ 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);
@@ -2293,22 +2304,34 @@ 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);
}

--
2.20.1