[PATCH v8 0/6] iommu/dma: s390 DMA API conversion and optimized IOTLB flushing

[PATCH v8 0/6] iommu/dma: s390 DMA API conversion and optimized IOTLB flushing

[Niklas Schnelle]

Hi All,

This patch series converts s390's PCI support from its platform specific DMA
API implementation in arch/s390/pci/pci_dma.c to the common DMA IOMMU layer.
The conversion itself is done in patches 3-4 with patch 2 providing the final
necessary IOMMU driver improvement to handle s390's special IOTLB flush
out-of-resource indication in virtualized environments. Patches 1-2 may be
applied independently. The conversion itself only touches the s390 IOMMU driver
and s390 arch code moving over remaining functions from the s390 DMA API
implementation. No changes to common code are necessary.

After patch 4 the basic conversion is done and on our partitioning machine
hypervisor LPAR performance matches or exceeds the existing code. When running
under z/VM or KVM however, performance plummets to about half of the existing
code due to a much higher rate of IOTLB flushes for unmapped pages. Due to the
hypervisors use of IOTLB flushes to synchronize their shadow tables these are
very expensive and minimizing them is key for regaining the performance loss.

To this end patches 5-6 propose a new, single queue, IOTLB flushing scheme as
an alternative to the existing per-CPU flush queues. Introducing an alternative
scheme was also suggested by Robin Murphy[1]. In the previous RFC of this
conversion Robin suggested reusing more of the existing queuing logic which
I incorporated since v2. The single queue mode is introduced in patch
5 together with a new dma_iommu_options struct and tune_dma_iommu callback in
IOMMU ops which allows IOMMU drivers to switch to a single flush queue.

Then patch 6 enables variable queue sizes using power of 2 queue sizes and
shift/mask to keep performance as close to the existing code as possible. The
variable queue size and a variable timeout are added to the dma_iommu_options
struct and utilized by s390 in the z/VM and KVM guest cases. As it is
implemented in common code the single queue IOTLB flushing scheme can of course
be used by other platforms with expensive IOTLB flushes. Particularly
virtio-iommu may be a candidate.

In a previous version I verified that the new scheme does work on my x86_64
Ryzen workstation by locally modifying iommu_subsys_init() to default to the
single queue mode and verifying its use via "/sys/.../iommu_group/type". I did
not find problems with an AMD GPU, Intel NIC (with SR-IOV and KVM
pass-through), NVMes or any on board peripherals.

For this version I switched to b4 prep/b4 send so this is now available
with b4 generated tags in the b4/dma_iommu topic branch of my
git.kernel.org repository[3]. And we also get base-commit, and change-id
tags as well as PGP signed mails.

NOTE: Due to the large drop in performance I think we should not merge the DMA
API conversion (patch 4) until we have a more suited IOVA flushing scheme
with similar improvements as the proposed changes.

Best regards,
Niklas

[0] https://lore.kernel.org/linux-iommu/20221109142903.4080275-1-schnelle@linux.ibm.com/
[1] https://lore.kernel.org/linux-iommu/3e402947-61f9-b7e8-1414-fde006257b6f@arm.com/
[2] https://lore.kernel.org/linux-iommu/a8e778da-7b41-a6ba-83c3-c366a426c3da@arm.com/
[3] https://git.kernel.org/pub/scm/linux/kernel/git/niks/linux.git/

Changes sinve v7:
- Add R-b from Matt
- Rebase on v6.3-rc1
- Switched to b4 prep / b4 send adding base-commit, change-id, PGP signatures.
  For the cost of no per-patch change lists.

Changes since v6:
- Rebased on iommu-next branch (Matt)
  - No need for ops->set_platform_dma() anymore
  - Add gfp_t gfp parameters for page allocations
- In patch 4 removed a superflous s390_domain->dma_table assignment
- Added R-bs from Matt

Changes since v5:
- Instead of introducing a new IOMMU domain type utilize a new options
  mechanism that allows IOMMU drivers to tune the DMA IOMMU flushing (Jason,
  Robin)
- The above reworks patches 5 and 6
- Dropped patch 7 as its functionality is no longer needed

Changes since v4:
- Picked up R-b's for patch 1, 2 and 3
- In patch 5 fixed iommu_group_store_type() mistakenly initializing DMA-SQ
  instead of DMA-FQ. This was caused by iommu_dma_init_fq() being called before
  domain->type is set, instead pass the type as paramater. This also closes
  a window where domain->type is still DMA while the FQ is already used. (Gerd)
- Replaced a missed check for IOMMU_DOMAIN_DMA_FQ with the new generic
  __IOMMU_DOMAIN_DMA_LAZY in patch 5
- Made the ISM PCI Function Type a define (Matt)
- Removed stale TODO comment (Matt)

Changes since v3:
- Reword commit message of patch 2 for more clarity
- Correct typo in comment added by patch 2 (Alexandra)
- Adapted signature of .iommu_tlb_sync mapo for sun50i IOMMU driver added in
  v6.2-rc1 (kernel test robot)
- Add R-b from Alexandra for patch 1

Changes since v2:
- Move the IOTLB out-of-resource handling into the IOMMU enabling it also for
  the IOMMU API (patch 2). This also makes this independent from the DMA API
  conversion (Robin, Jason).
- Rename __IOMMU_DOMAIN_DMA_FQ to __IOMMU_DOMAIN_DMA_LAZY when introducing
  single queue flushing mode.
- Make selecting between single and per-CPU flush queues an explicit IOMMU op
  (patch 7)

Changes since RFC v1:
- Patch 1 uses dma_set_mask_and_coherent() (Christoph)
- Patch 3 now documents and allows the use of iommu.strict=0|1 on s390 and
  deprecates s390_iommu=strict while making it an alias.
- Patches 5-7 completely reworked to reuse existing queue logic (Robin)
- Added patch 4 to allow using iommu.strict=0|1 to override
  ops->def_domain_type.

---
Niklas Schnelle (6):
      s390/ism: Set DMA coherent mask
      iommu: Allow .iotlb_sync_map to fail and handle s390's -ENOMEM return
      s390/pci: prepare is_passed_through() for dma-iommu
      s390/pci: Use dma-iommu layer
      iommu/dma: Allow a single FQ in addition to per-CPU FQs
      iommu/dma: Make flush queue sizes and timeout driver configurable

 Documentation/admin-guide/kernel-parameters.txt |   9 +-
 arch/s390/include/asm/pci.h                     |   7 -
 arch/s390/include/asm/pci_clp.h                 |   3 +
 arch/s390/include/asm/pci_dma.h                 | 121 +---
 arch/s390/pci/Makefile                          |   2 +-
 arch/s390/pci/pci.c                             |  22 +-
 arch/s390/pci/pci_bus.c                         |   5 -
 arch/s390/pci/pci_debug.c                       |  12 +-
 arch/s390/pci/pci_dma.c                         | 735 ------------------------
 arch/s390/pci/pci_event.c                       |  17 +-
 arch/s390/pci/pci_sysfs.c                       |  19 +-
 drivers/iommu/Kconfig                           |   4 +-
 drivers/iommu/amd/iommu.c                       |   5 +-
 drivers/iommu/apple-dart.c                      |   5 +-
 drivers/iommu/dma-iommu.c                       | 189 ++++--
 drivers/iommu/dma-iommu.h                       |   4 +-
 drivers/iommu/intel/iommu.c                     |   5 +-
 drivers/iommu/iommu.c                           |  24 +-
 drivers/iommu/msm_iommu.c                       |   5 +-
 drivers/iommu/mtk_iommu.c                       |   5 +-
 drivers/iommu/s390-iommu.c                      | 435 +++++++++++++-
 drivers/iommu/sprd-iommu.c                      |   5 +-
 drivers/iommu/sun50i-iommu.c                    |   4 +-
 drivers/iommu/tegra-gart.c                      |   5 +-
 drivers/s390/net/ism_drv.c                      |   2 +-
 include/linux/iommu.h                           |  29 +-
 26 files changed, 671 insertions(+), 1007 deletions(-)
---
base-commit: fe15c26ee26efa11741a7b632e9f23b01aca4cc6
change-id: 20230310-dma_iommu-5e048c538647

Best regards,
-- 
Niklas Schnelle
Linux on Z Development

IBM Deutschland Research & Development GmbH
Vorsitzender des Aufsichtsrats: Gregor Pillen
Geschäftsführung: David Faller
Sitz der Gesellschaft: Böblingen / Registergericht: Amtsgericht Stuttgart, HRB 243294
IBM Data Privacy Statement - https://www.ibm.com/privacy 

[PATCH v8 1/6] s390/ism: Set DMA coherent mask

[Niklas Schnelle]

A future change will convert the DMA API implementation from the
architecture specific arch/s390/pci/pci_dma.c to using the common code
drivers/iommu/dma-iommu.c which the utilizes the same IOMMU hardware
through the s390-iommu driver. Unlike the s390 specific DMA API this
requires devices to correctly call set the coherent mask to be allowed
to use IOVAs >2^32 in dma_alloc_coherent(). This was however not done
for ISM devices. ISM requires such addresses since currently the DMA
aperture for PCI devices starts at 2^32 and all calls to
dma_alloc_coherent() would thus fail.

Reviewed-by: Alexandra Winter <wintera@linux.ibm.com>
Reviewed-by: Matthew Rosato <mjrosato@linux.ibm.com>
Signed-off-by: Niklas Schnelle <schnelle@linux.ibm.com>
---
 drivers/s390/net/ism_drv.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/s390/net/ism_drv.c b/drivers/s390/net/ism_drv.c
index eb7e13486087..a40e3afeaaa8 100644
--- a/drivers/s390/net/ism_drv.c
+++ b/drivers/s390/net/ism_drv.c
@@ -661,7 +661,7 @@ static int ism_probe(struct pci_dev *pdev, const struct pci_device_id *id)
 	if (ret)
 		goto err_disable;
 
-	ret = dma_set_mask(&pdev->dev, DMA_BIT_MASK(64));
+	ret = dma_set_mask_and_coherent(&pdev->dev, DMA_BIT_MASK(64));
 	if (ret)
 		goto err_resource;
 

-- 
2.37.2

[PATCH v8 2/6] iommu: Allow .iotlb_sync_map to fail and handle s390's -ENOMEM return

[Niklas Schnelle]

On s390 when using a paging hypervisor, .iotlb_sync_map is used to sync
mappings by letting the hypervisor inspect the synced IOVA range and
updating a shadow table. This however means that .iotlb_sync_map can
fail as the hypervisor may run out of resources while doing the sync.
This can be due to the hypervisor being unable to pin guest pages, due
to a limit on mapped addresses such as vfio_iommu_type1.dma_entry_limit
or lack of other resources. Either way such a failure to sync a mapping
should result in a DMA_MAPPING_ERROR.

Now especially when running with batched IOTLB flushes for unmap it may
be that some IOVAs have already been invalidated but not yet synced via
.iotlb_sync_map. Thus if the hypervisor indicates running out of
resources, first do a global flush allowing the hypervisor to free
resources associated with these mappings as well a retry creating the
new mappings and only if that also fails report this error to callers.

Reviewed-by: Lu Baolu <baolu.lu@linux.intel.com>
Reviewed-by: Matthew Rosato <mjrosato@linux.ibm.com>
Signed-off-by: Niklas Schnelle <schnelle@linux.ibm.com>
---
 drivers/iommu/amd/iommu.c    |  5 +++--
 drivers/iommu/apple-dart.c   |  5 +++--
 drivers/iommu/intel/iommu.c  |  5 +++--
 drivers/iommu/iommu.c        | 20 ++++++++++++++++----
 drivers/iommu/msm_iommu.c    |  5 +++--
 drivers/iommu/mtk_iommu.c    |  5 +++--
 drivers/iommu/s390-iommu.c   | 29 ++++++++++++++++++++++++-----
 drivers/iommu/sprd-iommu.c   |  5 +++--
 drivers/iommu/sun50i-iommu.c |  4 +++-
 drivers/iommu/tegra-gart.c   |  5 +++--
 include/linux/iommu.h        |  4 ++--
 11 files changed, 66 insertions(+), 26 deletions(-)

diff --git a/drivers/iommu/amd/iommu.c b/drivers/iommu/amd/iommu.c
index 5a505ba5467e..ff309bd1bb8f 100644
--- a/drivers/iommu/amd/iommu.c
+++ b/drivers/iommu/amd/iommu.c
@@ -2187,14 +2187,15 @@ static int amd_iommu_attach_device(struct iommu_domain *dom,
 	return ret;
 }
 
-static void amd_iommu_iotlb_sync_map(struct iommu_domain *dom,
-				     unsigned long iova, size_t size)
+static int amd_iommu_iotlb_sync_map(struct iommu_domain *dom,
+				    unsigned long iova, size_t size)
 {
 	struct protection_domain *domain = to_pdomain(dom);
 	struct io_pgtable_ops *ops = &domain->iop.iop.ops;
 
 	if (ops->map_pages)
 		domain_flush_np_cache(domain, iova, size);
+	return 0;
 }
 
 static int amd_iommu_map_pages(struct iommu_domain *dom, unsigned long iova,
diff --git a/drivers/iommu/apple-dart.c b/drivers/iommu/apple-dart.c
index 06169d36eab8..cbed1f87eae9 100644
--- a/drivers/iommu/apple-dart.c
+++ b/drivers/iommu/apple-dart.c
@@ -506,10 +506,11 @@ static void apple_dart_iotlb_sync(struct iommu_domain *domain,
 	apple_dart_domain_flush_tlb(to_dart_domain(domain));
 }
 
-static void apple_dart_iotlb_sync_map(struct iommu_domain *domain,
-				      unsigned long iova, size_t size)
+static int apple_dart_iotlb_sync_map(struct iommu_domain *domain,
+				     unsigned long iova, size_t size)
 {
 	apple_dart_domain_flush_tlb(to_dart_domain(domain));
+	return 0;
 }
 
 static phys_addr_t apple_dart_iova_to_phys(struct iommu_domain *domain,
diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c
index 7c2f4bd33582..b795b2f323e3 100644
--- a/drivers/iommu/intel/iommu.c
+++ b/drivers/iommu/intel/iommu.c
@@ -4745,8 +4745,8 @@ static bool risky_device(struct pci_dev *pdev)
 	return false;
 }
 
-static void intel_iommu_iotlb_sync_map(struct iommu_domain *domain,
-				       unsigned long iova, size_t size)
+static int intel_iommu_iotlb_sync_map(struct iommu_domain *domain,
+				      unsigned long iova, size_t size)
 {
 	struct dmar_domain *dmar_domain = to_dmar_domain(domain);
 	unsigned long pages = aligned_nrpages(iova, size);
@@ -4756,6 +4756,7 @@ static void intel_iommu_iotlb_sync_map(struct iommu_domain *domain,
 
 	xa_for_each(&dmar_domain->iommu_array, i, info)
 		__mapping_notify_one(info->iommu, dmar_domain, pfn, pages);
+	return 0;
 }
 
 static void intel_iommu_remove_dev_pasid(struct device *dev, ioasid_t pasid)
diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
index 10db680acaed..ae549b032a16 100644
--- a/drivers/iommu/iommu.c
+++ b/drivers/iommu/iommu.c
@@ -2410,8 +2410,17 @@ int iommu_map(struct iommu_domain *domain, unsigned long iova,
 		return -EINVAL;
 
 	ret = __iommu_map(domain, iova, paddr, size, prot, gfp);
-	if (ret == 0 && ops->iotlb_sync_map)
-		ops->iotlb_sync_map(domain, iova, size);
+	if (ret == 0 && ops->iotlb_sync_map) {
+		ret = ops->iotlb_sync_map(domain, iova, size);
+		if (ret)
+			goto out_err;
+	}
+
+	return ret;
+
+out_err:
+	/* undo mappings already done */
+	iommu_unmap(domain, iova, size);
 
 	return ret;
 }
@@ -2552,8 +2561,11 @@ ssize_t iommu_map_sg(struct iommu_domain *domain, unsigned long iova,
 			sg = sg_next(sg);
 	}
 
-	if (ops->iotlb_sync_map)
-		ops->iotlb_sync_map(domain, iova, mapped);
+	if (ops->iotlb_sync_map) {
+		ret = ops->iotlb_sync_map(domain, iova, mapped);
+		if (ret)
+			goto out_err;
+	}
 	return mapped;
 
 out_err:
diff --git a/drivers/iommu/msm_iommu.c b/drivers/iommu/msm_iommu.c
index 454f6331c889..2033716eac78 100644
--- a/drivers/iommu/msm_iommu.c
+++ b/drivers/iommu/msm_iommu.c
@@ -486,12 +486,13 @@ static int msm_iommu_map(struct iommu_domain *domain, unsigned long iova,
 	return ret;
 }
 
-static void msm_iommu_sync_map(struct iommu_domain *domain, unsigned long iova,
-			       size_t size)
+static int msm_iommu_sync_map(struct iommu_domain *domain, unsigned long iova,
+			      size_t size)
 {
 	struct msm_priv *priv = to_msm_priv(domain);
 
 	__flush_iotlb_range(iova, size, SZ_4K, false, priv);
+	return 0;
 }
 
 static size_t msm_iommu_unmap(struct iommu_domain *domain, unsigned long iova,
diff --git a/drivers/iommu/mtk_iommu.c b/drivers/iommu/mtk_iommu.c
index d5a4955910ff..29769fb5c51e 100644
--- a/drivers/iommu/mtk_iommu.c
+++ b/drivers/iommu/mtk_iommu.c
@@ -750,12 +750,13 @@ static void mtk_iommu_iotlb_sync(struct iommu_domain *domain,
 	mtk_iommu_tlb_flush_range_sync(gather->start, length, dom->bank);
 }
 
-static void mtk_iommu_sync_map(struct iommu_domain *domain, unsigned long iova,
-			       size_t size)
+static int mtk_iommu_sync_map(struct iommu_domain *domain, unsigned long iova,
+			      size_t size)
 {
 	struct mtk_iommu_domain *dom = to_mtk_domain(domain);
 
 	mtk_iommu_tlb_flush_range_sync(iova, size, dom->bank);
+	return 0;
 }
 
 static phys_addr_t mtk_iommu_iova_to_phys(struct iommu_domain *domain,
diff --git a/drivers/iommu/s390-iommu.c b/drivers/iommu/s390-iommu.c
index fbf59a8db29b..17174b35db11 100644
--- a/drivers/iommu/s390-iommu.c
+++ b/drivers/iommu/s390-iommu.c
@@ -205,6 +205,14 @@ static void s390_iommu_release_device(struct device *dev)
 		__s390_iommu_detach_device(zdev);
 }
 
+
+static int zpci_refresh_all(struct zpci_dev *zdev)
+{
+	return zpci_refresh_trans((u64)zdev->fh << 32, zdev->start_dma,
+				  zdev->end_dma - zdev->start_dma + 1);
+
+}
+
 static void s390_iommu_flush_iotlb_all(struct iommu_domain *domain)
 {
 	struct s390_domain *s390_domain = to_s390_domain(domain);
@@ -212,8 +220,7 @@ static void s390_iommu_flush_iotlb_all(struct iommu_domain *domain)
 
 	rcu_read_lock();
 	list_for_each_entry_rcu(zdev, &s390_domain->devices, iommu_list) {
-		zpci_refresh_trans((u64)zdev->fh << 32, zdev->start_dma,
-				   zdev->end_dma - zdev->start_dma + 1);
+		zpci_refresh_all(zdev);
 	}
 	rcu_read_unlock();
 }
@@ -237,20 +244,32 @@ static void s390_iommu_iotlb_sync(struct iommu_domain *domain,
 	rcu_read_unlock();
 }
 
-static void s390_iommu_iotlb_sync_map(struct iommu_domain *domain,
+static int s390_iommu_iotlb_sync_map(struct iommu_domain *domain,
 				      unsigned long iova, size_t size)
 {
 	struct s390_domain *s390_domain = to_s390_domain(domain);
 	struct zpci_dev *zdev;
+	int ret = 0;
 
 	rcu_read_lock();
 	list_for_each_entry_rcu(zdev, &s390_domain->devices, iommu_list) {
 		if (!zdev->tlb_refresh)
 			continue;
-		zpci_refresh_trans((u64)zdev->fh << 32,
-				   iova, size);
+		ret = zpci_refresh_trans((u64)zdev->fh << 32,
+					 iova, size);
+		/*
+		 * let the hypervisor discover invalidated entries
+		 * allowing it to free IOVAs and unpin pages
+		 */
+		if (ret == -ENOMEM) {
+			ret = zpci_refresh_all(zdev);
+			if (ret)
+				break;
+		}
 	}
 	rcu_read_unlock();
+
+	return ret;
 }
 
 static int s390_iommu_validate_trans(struct s390_domain *s390_domain,
diff --git a/drivers/iommu/sprd-iommu.c b/drivers/iommu/sprd-iommu.c
index ae94d74b73f4..74bcae69653c 100644
--- a/drivers/iommu/sprd-iommu.c
+++ b/drivers/iommu/sprd-iommu.c
@@ -315,8 +315,8 @@ static size_t sprd_iommu_unmap(struct iommu_domain *domain, unsigned long iova,
 	return size;
 }
 
-static void sprd_iommu_sync_map(struct iommu_domain *domain,
-				unsigned long iova, size_t size)
+static int sprd_iommu_sync_map(struct iommu_domain *domain,
+			       unsigned long iova, size_t size)
 {
 	struct sprd_iommu_domain *dom = to_sprd_domain(domain);
 	unsigned int reg;
@@ -328,6 +328,7 @@ static void sprd_iommu_sync_map(struct iommu_domain *domain,
 
 	/* clear IOMMU TLB buffer after page table updated */
 	sprd_iommu_write(dom->sdev, reg, 0xffffffff);
+	return 0;
 }
 
 static void sprd_iommu_sync(struct iommu_domain *domain,
diff --git a/drivers/iommu/sun50i-iommu.c b/drivers/iommu/sun50i-iommu.c
index 2d993d0cea7d..60a983f4a494 100644
--- a/drivers/iommu/sun50i-iommu.c
+++ b/drivers/iommu/sun50i-iommu.c
@@ -402,7 +402,7 @@ static void sun50i_iommu_flush_iotlb_all(struct iommu_domain *domain)
 	spin_unlock_irqrestore(&iommu->iommu_lock, flags);
 }
 
-static void sun50i_iommu_iotlb_sync_map(struct iommu_domain *domain,
+static int sun50i_iommu_iotlb_sync_map(struct iommu_domain *domain,
 					unsigned long iova, size_t size)
 {
 	struct sun50i_iommu_domain *sun50i_domain = to_sun50i_domain(domain);
@@ -412,6 +412,8 @@ static void sun50i_iommu_iotlb_sync_map(struct iommu_domain *domain,
 	spin_lock_irqsave(&iommu->iommu_lock, flags);
 	sun50i_iommu_zap_range(iommu, iova, size);
 	spin_unlock_irqrestore(&iommu->iommu_lock, flags);
+
+	return 0;
 }
 
 static void sun50i_iommu_iotlb_sync(struct iommu_domain *domain,
diff --git a/drivers/iommu/tegra-gart.c b/drivers/iommu/tegra-gart.c
index a482ff838b53..44966d7b07ba 100644
--- a/drivers/iommu/tegra-gart.c
+++ b/drivers/iommu/tegra-gart.c
@@ -252,10 +252,11 @@ static int gart_iommu_of_xlate(struct device *dev,
 	return 0;
 }
 
-static void gart_iommu_sync_map(struct iommu_domain *domain, unsigned long iova,
-				size_t size)
+static int gart_iommu_sync_map(struct iommu_domain *domain, unsigned long iova,
+			       size_t size)
 {
 	FLUSH_GART_REGS(gart_handle);
+	return 0;
 }
 
 static void gart_iommu_sync(struct iommu_domain *domain,
diff --git a/include/linux/iommu.h b/include/linux/iommu.h
index 6595454d4f48..932e5532ee33 100644
--- a/include/linux/iommu.h
+++ b/include/linux/iommu.h
@@ -333,8 +333,8 @@ struct iommu_domain_ops {
 			      struct iommu_iotlb_gather *iotlb_gather);
 
 	void (*flush_iotlb_all)(struct iommu_domain *domain);
-	void (*iotlb_sync_map)(struct iommu_domain *domain, unsigned long iova,
-			       size_t size);
+	int (*iotlb_sync_map)(struct iommu_domain *domain, unsigned long iova,
+			      size_t size);
 	void (*iotlb_sync)(struct iommu_domain *domain,
 			   struct iommu_iotlb_gather *iotlb_gather);
 

-- 
2.37.2

[PATCH v8 3/6] s390/pci: prepare is_passed_through() for dma-iommu

[Niklas Schnelle]

With the IOMMU always controlled through the IOMMU driver testing for
zdev->s390_domain is not a valid indication of the device being
passed-through. Instead test if zdev->kzdev is set.

Reviewed-by: Pierre Morel <pmorel@linux.ibm.com>
Reviewed-by: Matthew Rosato <mjrosato@linux.ibm.com>
Signed-off-by: Niklas Schnelle <schnelle@linux.ibm.com>
---
 arch/s390/pci/pci_event.c | 15 +++++++++++----
 1 file changed, 11 insertions(+), 4 deletions(-)

diff --git a/arch/s390/pci/pci_event.c b/arch/s390/pci/pci_event.c
index b9324ca2eb94..4ef5a6a1d618 100644
--- a/arch/s390/pci/pci_event.c
+++ b/arch/s390/pci/pci_event.c
@@ -59,9 +59,16 @@ static inline bool ers_result_indicates_abort(pci_ers_result_t ers_res)
 	}
 }
 
-static bool is_passed_through(struct zpci_dev *zdev)
+static bool is_passed_through(struct pci_dev *pdev)
 {
-	return zdev->s390_domain;
+	struct zpci_dev *zdev = to_zpci(pdev);
+	bool ret;
+
+	mutex_lock(&zdev->kzdev_lock);
+	ret = !!zdev->kzdev;
+	mutex_unlock(&zdev->kzdev_lock);
+
+	return ret;
 }
 
 static bool is_driver_supported(struct pci_driver *driver)
@@ -176,7 +183,7 @@ static pci_ers_result_t zpci_event_attempt_error_recovery(struct pci_dev *pdev)
 	}
 	pdev->error_state = pci_channel_io_frozen;
 
-	if (is_passed_through(to_zpci(pdev))) {
+	if (is_passed_through(pdev)) {
 		pr_info("%s: Cannot be recovered in the host because it is a pass-through device\n",
 			pci_name(pdev));
 		goto out_unlock;
@@ -239,7 +246,7 @@ static void zpci_event_io_failure(struct pci_dev *pdev, pci_channel_state_t es)
 	 * we will inject the error event and let the guest recover the device
 	 * itself.
 	 */
-	if (is_passed_through(to_zpci(pdev)))
+	if (is_passed_through(pdev))
 		goto out;
 	driver = to_pci_driver(pdev->dev.driver);
 	if (driver && driver->err_handler && driver->err_handler->error_detected)

-- 
2.37.2

[PATCH v8 4/6] s390/pci: Use dma-iommu layer

[Niklas Schnelle]

While s390 already has a standard IOMMU driver and previous changes have
added I/O TLB flushing operations this driver is currently only used for
user-space PCI access such as vfio-pci. For the DMA API s390 instead
utilizes its own implementation in arch/s390/pci/pci_dma.c which drives
the same hardware and shares some code but requires a complex and
fragile hand over between DMA API and IOMMU API use of a device and
despite code sharing still leads to significant duplication and
maintenance effort. Let's utilize the common code DMAP API
implementation from drivers/iommu/dma-iommu.c instead allowing us to
get rid of arch/s390/pci/pci_dma.c.

Reviewed-by: Matthew Rosato <mjrosato@linux.ibm.com>
Signed-off-by: Niklas Schnelle <schnelle@linux.ibm.com>
---
 Documentation/admin-guide/kernel-parameters.txt |   9 +-
 arch/s390/include/asm/pci.h                     |   7 -
 arch/s390/include/asm/pci_clp.h                 |   3 +
 arch/s390/include/asm/pci_dma.h                 | 121 +---
 arch/s390/pci/Makefile                          |   2 +-
 arch/s390/pci/pci.c                             |  22 +-
 arch/s390/pci/pci_bus.c                         |   5 -
 arch/s390/pci/pci_debug.c                       |  12 +-
 arch/s390/pci/pci_dma.c                         | 735 ------------------------
 arch/s390/pci/pci_event.c                       |   2 -
 arch/s390/pci/pci_sysfs.c                       |  19 +-
 drivers/iommu/Kconfig                           |   4 +-
 drivers/iommu/s390-iommu.c                      | 390 ++++++++++++-
 13 files changed, 407 insertions(+), 924 deletions(-)

diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index 6221a1d057dd..dd832f2c9495 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -2149,7 +2149,7 @@
 			  forcing Dual Address Cycle for PCI cards supporting
 			  greater than 32-bit addressing.
 
-	iommu.strict=	[ARM64, X86] Configure TLB invalidation behaviour
+	iommu.strict=	[ARM64, X86, S390] Configure TLB invalidation behaviour
 			Format: { "0" | "1" }
 			0 - Lazy mode.
 			  Request that DMA unmap operations use deferred
@@ -5435,9 +5435,10 @@
 	s390_iommu=	[HW,S390]
 			Set s390 IOTLB flushing mode
 		strict
-			With strict flushing every unmap operation will result in
-			an IOTLB flush. Default is lazy flushing before reuse,
-			which is faster.
+			With strict flushing every unmap operation will result
+			in an IOTLB flush. Default is lazy flushing before
+			reuse, which is faster. Deprecated, equivalent to
+			iommu.strict=1.
 
 	s390_iommu_aperture=	[KNL,S390]
 			Specifies the size of the per device DMA address space
diff --git a/arch/s390/include/asm/pci.h b/arch/s390/include/asm/pci.h
index b248694e0024..3f74f1cf37df 100644
--- a/arch/s390/include/asm/pci.h
+++ b/arch/s390/include/asm/pci.h
@@ -159,13 +159,6 @@ struct zpci_dev {
 	unsigned long	*dma_table;
 	int		tlb_refresh;
 
-	spinlock_t	iommu_bitmap_lock;
-	unsigned long	*iommu_bitmap;
-	unsigned long	*lazy_bitmap;
-	unsigned long	iommu_size;
-	unsigned long	iommu_pages;
-	unsigned int	next_bit;
-
 	struct iommu_device iommu_dev;  /* IOMMU core handle */
 
 	char res_name[16];
diff --git a/arch/s390/include/asm/pci_clp.h b/arch/s390/include/asm/pci_clp.h
index d6189ed14f84..f0c677ddd270 100644
--- a/arch/s390/include/asm/pci_clp.h
+++ b/arch/s390/include/asm/pci_clp.h
@@ -50,6 +50,9 @@ struct clp_fh_list_entry {
 #define CLP_UTIL_STR_LEN	64
 #define CLP_PFIP_NR_SEGMENTS	4
 
+/* PCI function type numbers */
+#define PCI_FUNC_TYPE_ISM	0x5	/* ISM device */
+
 extern bool zpci_unique_uid;
 
 struct clp_rsp_slpc_pci {
diff --git a/arch/s390/include/asm/pci_dma.h b/arch/s390/include/asm/pci_dma.h
index 7119c04c51c5..42d7cc4262ca 100644
--- a/arch/s390/include/asm/pci_dma.h
+++ b/arch/s390/include/asm/pci_dma.h
@@ -82,117 +82,16 @@ enum zpci_ioat_dtype {
 #define ZPCI_TABLE_VALID_MASK		0x20
 #define ZPCI_TABLE_PROT_MASK		0x200
 
-static inline unsigned int calc_rtx(dma_addr_t ptr)
-{
-	return ((unsigned long) ptr >> ZPCI_RT_SHIFT) & ZPCI_INDEX_MASK;
-}
-
-static inline unsigned int calc_sx(dma_addr_t ptr)
-{
-	return ((unsigned long) ptr >> ZPCI_ST_SHIFT) & ZPCI_INDEX_MASK;
-}
-
-static inline unsigned int calc_px(dma_addr_t ptr)
-{
-	return ((unsigned long) ptr >> PAGE_SHIFT) & ZPCI_PT_MASK;
-}
-
-static inline void set_pt_pfaa(unsigned long *entry, phys_addr_t pfaa)
-{
-	*entry &= ZPCI_PTE_FLAG_MASK;
-	*entry |= (pfaa & ZPCI_PTE_ADDR_MASK);
-}
-
-static inline void set_rt_sto(unsigned long *entry, phys_addr_t sto)
-{
-	*entry &= ZPCI_RTE_FLAG_MASK;
-	*entry |= (sto & ZPCI_RTE_ADDR_MASK);
-	*entry |= ZPCI_TABLE_TYPE_RTX;
-}
-
-static inline void set_st_pto(unsigned long *entry, phys_addr_t pto)
-{
-	*entry &= ZPCI_STE_FLAG_MASK;
-	*entry |= (pto & ZPCI_STE_ADDR_MASK);
-	*entry |= ZPCI_TABLE_TYPE_SX;
-}
-
-static inline void validate_rt_entry(unsigned long *entry)
-{
-	*entry &= ~ZPCI_TABLE_VALID_MASK;
-	*entry &= ~ZPCI_TABLE_OFFSET_MASK;
-	*entry |= ZPCI_TABLE_VALID;
-	*entry |= ZPCI_TABLE_LEN_RTX;
-}
-
-static inline void validate_st_entry(unsigned long *entry)
-{
-	*entry &= ~ZPCI_TABLE_VALID_MASK;
-	*entry |= ZPCI_TABLE_VALID;
-}
-
-static inline void invalidate_pt_entry(unsigned long *entry)
-{
-	WARN_ON_ONCE((*entry & ZPCI_PTE_VALID_MASK) == ZPCI_PTE_INVALID);
-	*entry &= ~ZPCI_PTE_VALID_MASK;
-	*entry |= ZPCI_PTE_INVALID;
-}
-
-static inline void validate_pt_entry(unsigned long *entry)
-{
-	WARN_ON_ONCE((*entry & ZPCI_PTE_VALID_MASK) == ZPCI_PTE_VALID);
-	*entry &= ~ZPCI_PTE_VALID_MASK;
-	*entry |= ZPCI_PTE_VALID;
-}
-
-static inline void entry_set_protected(unsigned long *entry)
-{
-	*entry &= ~ZPCI_TABLE_PROT_MASK;
-	*entry |= ZPCI_TABLE_PROTECTED;
-}
-
-static inline void entry_clr_protected(unsigned long *entry)
-{
-	*entry &= ~ZPCI_TABLE_PROT_MASK;
-	*entry |= ZPCI_TABLE_UNPROTECTED;
-}
-
-static inline int reg_entry_isvalid(unsigned long entry)
-{
-	return (entry & ZPCI_TABLE_VALID_MASK) == ZPCI_TABLE_VALID;
-}
-
-static inline int pt_entry_isvalid(unsigned long entry)
-{
-	return (entry & ZPCI_PTE_VALID_MASK) == ZPCI_PTE_VALID;
-}
-
-static inline unsigned long *get_rt_sto(unsigned long entry)
-{
-	if ((entry & ZPCI_TABLE_TYPE_MASK) == ZPCI_TABLE_TYPE_RTX)
-		return phys_to_virt(entry & ZPCI_RTE_ADDR_MASK);
-	else
-		return NULL;
-
-}
-
-static inline unsigned long *get_st_pto(unsigned long entry)
-{
-	if ((entry & ZPCI_TABLE_TYPE_MASK) == ZPCI_TABLE_TYPE_SX)
-		return phys_to_virt(entry & ZPCI_STE_ADDR_MASK);
-	else
-		return NULL;
-}
-
-/* Prototypes */
-void dma_free_seg_table(unsigned long);
-unsigned long *dma_alloc_cpu_table(gfp_t gfp);
-void dma_cleanup_tables(unsigned long *);
-unsigned long *dma_walk_cpu_trans(unsigned long *rto, dma_addr_t dma_addr,
-				  gfp_t gfp);
-void dma_update_cpu_trans(unsigned long *entry, phys_addr_t page_addr, int flags);
-
-extern const struct dma_map_ops s390_pci_dma_ops;
+struct zpci_iommu_ctrs {
+	atomic64_t		mapped_pages;
+	atomic64_t		unmapped_pages;
+	atomic64_t		global_rpcits;
+	atomic64_t		sync_map_rpcits;
+	atomic64_t		sync_rpcits;
+};
+
+struct zpci_dev;
 
+struct zpci_iommu_ctrs *zpci_get_iommu_ctrs(struct zpci_dev *zdev);
 
 #endif
diff --git a/arch/s390/pci/Makefile b/arch/s390/pci/Makefile
index 5ae31ca9dd44..0547a10406e7 100644
--- a/arch/s390/pci/Makefile
+++ b/arch/s390/pci/Makefile
@@ -3,7 +3,7 @@
 # Makefile for the s390 PCI subsystem.
 #
 
-obj-$(CONFIG_PCI)	+= pci.o pci_irq.o pci_dma.o pci_clp.o pci_sysfs.o \
+obj-$(CONFIG_PCI)	+= pci.o pci_irq.o pci_clp.o pci_sysfs.o \
 			   pci_event.o pci_debug.o pci_insn.o pci_mmio.o \
 			   pci_bus.o pci_kvm_hook.o
 obj-$(CONFIG_PCI_IOV)	+= pci_iov.o
diff --git a/arch/s390/pci/pci.c b/arch/s390/pci/pci.c
index ef38b1514c77..ec4b41839c22 100644
--- a/arch/s390/pci/pci.c
+++ b/arch/s390/pci/pci.c
@@ -124,7 +124,11 @@ int zpci_register_ioat(struct zpci_dev *zdev, u8 dmaas,
 
 	WARN_ON_ONCE(iota & 0x3fff);
 	fib.pba = base;
-	fib.pal = limit;
+	/* Work around off by one in ISM virt device */
+	if (zdev->pft == PCI_FUNC_TYPE_ISM && limit > base)
+		fib.pal = limit + (1 << 12);
+	else
+		fib.pal = limit;
 	fib.iota = iota | ZPCI_IOTA_RTTO_FLAG;
 	fib.gd = zdev->gisa;
 	cc = zpci_mod_fc(req, &fib, status);
@@ -615,7 +619,6 @@ int pcibios_device_add(struct pci_dev *pdev)
 		pdev->no_vf_scan = 1;
 
 	pdev->dev.groups = zpci_attr_groups;
-	pdev->dev.dma_ops = &s390_pci_dma_ops;
 	zpci_map_resources(pdev);
 
 	for (i = 0; i < PCI_STD_NUM_BARS; i++) {
@@ -789,8 +792,6 @@ int zpci_hot_reset_device(struct zpci_dev *zdev)
 	if (zdev->dma_table)
 		rc = zpci_register_ioat(zdev, 0, zdev->start_dma, zdev->end_dma,
 					virt_to_phys(zdev->dma_table), &status);
-	else
-		rc = zpci_dma_init_device(zdev);
 	if (rc) {
 		zpci_disable_device(zdev);
 		return rc;
@@ -915,11 +916,6 @@ int zpci_deconfigure_device(struct zpci_dev *zdev)
 	if (zdev->zbus->bus)
 		zpci_bus_remove_device(zdev, false);
 
-	if (zdev->dma_table) {
-		rc = zpci_dma_exit_device(zdev);
-		if (rc)
-			return rc;
-	}
 	if (zdev_enabled(zdev)) {
 		rc = zpci_disable_device(zdev);
 		if (rc)
@@ -968,8 +964,6 @@ void zpci_release_device(struct kref *kref)
 	if (zdev->zbus->bus)
 		zpci_bus_remove_device(zdev, false);
 
-	if (zdev->dma_table)
-		zpci_dma_exit_device(zdev);
 	if (zdev_enabled(zdev))
 		zpci_disable_device(zdev);
 
@@ -1159,10 +1153,6 @@ static int __init pci_base_init(void)
 	if (rc)
 		goto out_irq;
 
-	rc = zpci_dma_init();
-	if (rc)
-		goto out_dma;
-
 	rc = clp_scan_pci_devices();
 	if (rc)
 		goto out_find;
@@ -1172,8 +1162,6 @@ static int __init pci_base_init(void)
 	return 0;
 
 out_find:
-	zpci_dma_exit();
-out_dma:
 	zpci_irq_exit();
 out_irq:
 	zpci_mem_exit();
diff --git a/arch/s390/pci/pci_bus.c b/arch/s390/pci/pci_bus.c
index 6a8da1b742ae..b15ad15999f8 100644
--- a/arch/s390/pci/pci_bus.c
+++ b/arch/s390/pci/pci_bus.c
@@ -49,11 +49,6 @@ static int zpci_bus_prepare_device(struct zpci_dev *zdev)
 		rc = zpci_enable_device(zdev);
 		if (rc)
 			return rc;
-		rc = zpci_dma_init_device(zdev);
-		if (rc) {
-			zpci_disable_device(zdev);
-			return rc;
-		}
 	}
 
 	if (!zdev->has_resources) {
diff --git a/arch/s390/pci/pci_debug.c b/arch/s390/pci/pci_debug.c
index ca6bd98eec13..6dde2263c79d 100644
--- a/arch/s390/pci/pci_debug.c
+++ b/arch/s390/pci/pci_debug.c
@@ -53,9 +53,11 @@ static char *pci_fmt3_names[] = {
 };
 
 static char *pci_sw_names[] = {
-	"Allocated pages",
 	"Mapped pages",
 	"Unmapped pages",
+	"Global RPCITs",
+	"Sync Map RPCITs",
+	"Sync RPCITs",
 };
 
 static void pci_fmb_show(struct seq_file *m, char *name[], int length,
@@ -69,10 +71,14 @@ static void pci_fmb_show(struct seq_file *m, char *name[], int length,
 
 static void pci_sw_counter_show(struct seq_file *m)
 {
-	struct zpci_dev *zdev = m->private;
-	atomic64_t *counter = &zdev->allocated_pages;
+	struct zpci_iommu_ctrs  *ctrs = zpci_get_iommu_ctrs(m->private);
+	atomic64_t *counter;
 	int i;
 
+	if (!ctrs)
+		return;
+
+	counter = &ctrs->mapped_pages;
 	for (i = 0; i < ARRAY_SIZE(pci_sw_names); i++, counter++)
 		seq_printf(m, "%26s:\t%llu\n", pci_sw_names[i],
 			   atomic64_read(counter));
diff --git a/arch/s390/pci/pci_dma.c b/arch/s390/pci/pci_dma.c
deleted file mode 100644
index 2d9b01d7ca4c..000000000000
--- a/arch/s390/pci/pci_dma.c
+++ /dev/null
@@ -1,735 +0,0 @@
-// SPDX-License-Identifier: GPL-2.0
-/*
- * Copyright IBM Corp. 2012
- *
- * Author(s):
- *   Jan Glauber <jang@linux.vnet.ibm.com>
- */
-
-#include <linux/kernel.h>
-#include <linux/slab.h>
-#include <linux/export.h>
-#include <linux/iommu-helper.h>
-#include <linux/dma-map-ops.h>
-#include <linux/vmalloc.h>
-#include <linux/pci.h>
-#include <asm/pci_dma.h>
-
-static struct kmem_cache *dma_region_table_cache;
-static struct kmem_cache *dma_page_table_cache;
-static int s390_iommu_strict;
-static u64 s390_iommu_aperture;
-static u32 s390_iommu_aperture_factor = 1;
-
-static int zpci_refresh_global(struct zpci_dev *zdev)
-{
-	return zpci_refresh_trans((u64) zdev->fh << 32, zdev->start_dma,
-				  zdev->iommu_pages * PAGE_SIZE);
-}
-
-unsigned long *dma_alloc_cpu_table(gfp_t gfp)
-{
-	unsigned long *table, *entry;
-
-	table = kmem_cache_alloc(dma_region_table_cache, gfp);
-	if (!table)
-		return NULL;
-
-	for (entry = table; entry < table + ZPCI_TABLE_ENTRIES; entry++)
-		*entry = ZPCI_TABLE_INVALID;
-	return table;
-}
-
-static void dma_free_cpu_table(void *table)
-{
-	kmem_cache_free(dma_region_table_cache, table);
-}
-
-static unsigned long *dma_alloc_page_table(gfp_t gfp)
-{
-	unsigned long *table, *entry;
-
-	table = kmem_cache_alloc(dma_page_table_cache, gfp);
-	if (!table)
-		return NULL;
-
-	for (entry = table; entry < table + ZPCI_PT_ENTRIES; entry++)
-		*entry = ZPCI_PTE_INVALID;
-	return table;
-}
-
-static void dma_free_page_table(void *table)
-{
-	kmem_cache_free(dma_page_table_cache, table);
-}
-
-static unsigned long *dma_get_seg_table_origin(unsigned long *rtep, gfp_t gfp)
-{
-	unsigned long old_rte, rte;
-	unsigned long *sto;
-
-	rte = READ_ONCE(*rtep);
-	if (reg_entry_isvalid(rte)) {
-		sto = get_rt_sto(rte);
-	} else {
-		sto = dma_alloc_cpu_table(gfp);
-		if (!sto)
-			return NULL;
-
-		set_rt_sto(&rte, virt_to_phys(sto));
-		validate_rt_entry(&rte);
-		entry_clr_protected(&rte);
-
-		old_rte = cmpxchg(rtep, ZPCI_TABLE_INVALID, rte);
-		if (old_rte != ZPCI_TABLE_INVALID) {
-			/* Somone else was faster, use theirs */
-			dma_free_cpu_table(sto);
-			sto = get_rt_sto(old_rte);
-		}
-	}
-	return sto;
-}
-
-static unsigned long *dma_get_page_table_origin(unsigned long *step, gfp_t gfp)
-{
-	unsigned long old_ste, ste;
-	unsigned long *pto;
-
-	ste = READ_ONCE(*step);
-	if (reg_entry_isvalid(ste)) {
-		pto = get_st_pto(ste);
-	} else {
-		pto = dma_alloc_page_table(gfp);
-		if (!pto)
-			return NULL;
-		set_st_pto(&ste, virt_to_phys(pto));
-		validate_st_entry(&ste);
-		entry_clr_protected(&ste);
-
-		old_ste = cmpxchg(step, ZPCI_TABLE_INVALID, ste);
-		if (old_ste != ZPCI_TABLE_INVALID) {
-			/* Somone else was faster, use theirs */
-			dma_free_page_table(pto);
-			pto = get_st_pto(old_ste);
-		}
-	}
-	return pto;
-}
-
-unsigned long *dma_walk_cpu_trans(unsigned long *rto, dma_addr_t dma_addr,
-				  gfp_t gfp)
-{
-	unsigned long *sto, *pto;
-	unsigned int rtx, sx, px;
-
-	rtx = calc_rtx(dma_addr);
-	sto = dma_get_seg_table_origin(&rto[rtx], gfp);
-	if (!sto)
-		return NULL;
-
-	sx = calc_sx(dma_addr);
-	pto = dma_get_page_table_origin(&sto[sx], gfp);
-	if (!pto)
-		return NULL;
-
-	px = calc_px(dma_addr);
-	return &pto[px];
-}
-
-void dma_update_cpu_trans(unsigned long *ptep, phys_addr_t page_addr, int flags)
-{
-	unsigned long pte;
-
-	pte = READ_ONCE(*ptep);
-	if (flags & ZPCI_PTE_INVALID) {
-		invalidate_pt_entry(&pte);
-	} else {
-		set_pt_pfaa(&pte, page_addr);
-		validate_pt_entry(&pte);
-	}
-
-	if (flags & ZPCI_TABLE_PROTECTED)
-		entry_set_protected(&pte);
-	else
-		entry_clr_protected(&pte);
-
-	xchg(ptep, pte);
-}
-
-static int __dma_update_trans(struct zpci_dev *zdev, phys_addr_t pa,
-			      dma_addr_t dma_addr, size_t size, int flags)
-{
-	unsigned int nr_pages = PAGE_ALIGN(size) >> PAGE_SHIFT;
-	phys_addr_t page_addr = (pa & PAGE_MASK);
-	unsigned long *entry;
-	int i, rc = 0;
-
-	if (!nr_pages)
-		return -EINVAL;
-
-	if (!zdev->dma_table)
-		return -EINVAL;
-
-	for (i = 0; i < nr_pages; i++) {
-		entry = dma_walk_cpu_trans(zdev->dma_table, dma_addr,
-					   GFP_ATOMIC);
-		if (!entry) {
-			rc = -ENOMEM;
-			goto undo_cpu_trans;
-		}
-		dma_update_cpu_trans(entry, page_addr, flags);
-		page_addr += PAGE_SIZE;
-		dma_addr += PAGE_SIZE;
-	}
-
-undo_cpu_trans:
-	if (rc && ((flags & ZPCI_PTE_VALID_MASK) == ZPCI_PTE_VALID)) {
-		flags = ZPCI_PTE_INVALID;
-		while (i-- > 0) {
-			page_addr -= PAGE_SIZE;
-			dma_addr -= PAGE_SIZE;
-			entry = dma_walk_cpu_trans(zdev->dma_table, dma_addr,
-						   GFP_ATOMIC);
-			if (!entry)
-				break;
-			dma_update_cpu_trans(entry, page_addr, flags);
-		}
-	}
-	return rc;
-}
-
-static int __dma_purge_tlb(struct zpci_dev *zdev, dma_addr_t dma_addr,
-			   size_t size, int flags)
-{
-	unsigned long irqflags;
-	int ret;
-
-	/*
-	 * With zdev->tlb_refresh == 0, rpcit is not required to establish new
-	 * translations when previously invalid translation-table entries are
-	 * validated. With lazy unmap, rpcit is skipped for previously valid
-	 * entries, but a global rpcit is then required before any address can
-	 * be re-used, i.e. after each iommu bitmap wrap-around.
-	 */
-	if ((flags & ZPCI_PTE_VALID_MASK) == ZPCI_PTE_VALID) {
-		if (!zdev->tlb_refresh)
-			return 0;
-	} else {
-		if (!s390_iommu_strict)
-			return 0;
-	}
-
-	ret = zpci_refresh_trans((u64) zdev->fh << 32, dma_addr,
-				 PAGE_ALIGN(size));
-	if (ret == -ENOMEM && !s390_iommu_strict) {
-		/* enable the hypervisor to free some resources */
-		if (zpci_refresh_global(zdev))
-			goto out;
-
-		spin_lock_irqsave(&zdev->iommu_bitmap_lock, irqflags);
-		bitmap_andnot(zdev->iommu_bitmap, zdev->iommu_bitmap,
-			      zdev->lazy_bitmap, zdev->iommu_pages);
-		bitmap_zero(zdev->lazy_bitmap, zdev->iommu_pages);
-		spin_unlock_irqrestore(&zdev->iommu_bitmap_lock, irqflags);
-		ret = 0;
-	}
-out:
-	return ret;
-}
-
-static int dma_update_trans(struct zpci_dev *zdev, phys_addr_t pa,
-			    dma_addr_t dma_addr, size_t size, int flags)
-{
-	int rc;
-
-	rc = __dma_update_trans(zdev, pa, dma_addr, size, flags);
-	if (rc)
-		return rc;
-
-	rc = __dma_purge_tlb(zdev, dma_addr, size, flags);
-	if (rc && ((flags & ZPCI_PTE_VALID_MASK) == ZPCI_PTE_VALID))
-		__dma_update_trans(zdev, pa, dma_addr, size, ZPCI_PTE_INVALID);
-
-	return rc;
-}
-
-void dma_free_seg_table(unsigned long entry)
-{
-	unsigned long *sto = get_rt_sto(entry);
-	int sx;
-
-	for (sx = 0; sx < ZPCI_TABLE_ENTRIES; sx++)
-		if (reg_entry_isvalid(sto[sx]))
-			dma_free_page_table(get_st_pto(sto[sx]));
-
-	dma_free_cpu_table(sto);
-}
-
-void dma_cleanup_tables(unsigned long *table)
-{
-	int rtx;
-
-	if (!table)
-		return;
-
-	for (rtx = 0; rtx < ZPCI_TABLE_ENTRIES; rtx++)
-		if (reg_entry_isvalid(table[rtx]))
-			dma_free_seg_table(table[rtx]);
-
-	dma_free_cpu_table(table);
-}
-
-static unsigned long __dma_alloc_iommu(struct device *dev,
-				       unsigned long start, int size)
-{
-	struct zpci_dev *zdev = to_zpci(to_pci_dev(dev));
-
-	return iommu_area_alloc(zdev->iommu_bitmap, zdev->iommu_pages,
-				start, size, zdev->start_dma >> PAGE_SHIFT,
-				dma_get_seg_boundary_nr_pages(dev, PAGE_SHIFT),
-				0);
-}
-
-static dma_addr_t dma_alloc_address(struct device *dev, int size)
-{
-	struct zpci_dev *zdev = to_zpci(to_pci_dev(dev));
-	unsigned long offset, flags;
-
-	spin_lock_irqsave(&zdev->iommu_bitmap_lock, flags);
-	offset = __dma_alloc_iommu(dev, zdev->next_bit, size);
-	if (offset == -1) {
-		if (!s390_iommu_strict) {
-			/* global flush before DMA addresses are reused */
-			if (zpci_refresh_global(zdev))
-				goto out_error;
-
-			bitmap_andnot(zdev->iommu_bitmap, zdev->iommu_bitmap,
-				      zdev->lazy_bitmap, zdev->iommu_pages);
-			bitmap_zero(zdev->lazy_bitmap, zdev->iommu_pages);
-		}
-		/* wrap-around */
-		offset = __dma_alloc_iommu(dev, 0, size);
-		if (offset == -1)
-			goto out_error;
-	}
-	zdev->next_bit = offset + size;
-	spin_unlock_irqrestore(&zdev->iommu_bitmap_lock, flags);
-
-	return zdev->start_dma + offset * PAGE_SIZE;
-
-out_error:
-	spin_unlock_irqrestore(&zdev->iommu_bitmap_lock, flags);
-	return DMA_MAPPING_ERROR;
-}
-
-static void dma_free_address(struct device *dev, dma_addr_t dma_addr, int size)
-{
-	struct zpci_dev *zdev = to_zpci(to_pci_dev(dev));
-	unsigned long flags, offset;
-
-	offset = (dma_addr - zdev->start_dma) >> PAGE_SHIFT;
-
-	spin_lock_irqsave(&zdev->iommu_bitmap_lock, flags);
-	if (!zdev->iommu_bitmap)
-		goto out;
-
-	if (s390_iommu_strict)
-		bitmap_clear(zdev->iommu_bitmap, offset, size);
-	else
-		bitmap_set(zdev->lazy_bitmap, offset, size);
-
-out:
-	spin_unlock_irqrestore(&zdev->iommu_bitmap_lock, flags);
-}
-
-static inline void zpci_err_dma(unsigned long rc, unsigned long addr)
-{
-	struct {
-		unsigned long rc;
-		unsigned long addr;
-	} __packed data = {rc, addr};
-
-	zpci_err_hex(&data, sizeof(data));
-}
-
-static dma_addr_t s390_dma_map_pages(struct device *dev, struct page *page,
-				     unsigned long offset, size_t size,
-				     enum dma_data_direction direction,
-				     unsigned long attrs)
-{
-	struct zpci_dev *zdev = to_zpci(to_pci_dev(dev));
-	unsigned long pa = page_to_phys(page) + offset;
-	int flags = ZPCI_PTE_VALID;
-	unsigned long nr_pages;
-	dma_addr_t dma_addr;
-	int ret;
-
-	/* This rounds up number of pages based on size and offset */
-	nr_pages = iommu_num_pages(pa, size, PAGE_SIZE);
-	dma_addr = dma_alloc_address(dev, nr_pages);
-	if (dma_addr == DMA_MAPPING_ERROR) {
-		ret = -ENOSPC;
-		goto out_err;
-	}
-
-	/* Use rounded up size */
-	size = nr_pages * PAGE_SIZE;
-
-	if (direction == DMA_NONE || direction == DMA_TO_DEVICE)
-		flags |= ZPCI_TABLE_PROTECTED;
-
-	ret = dma_update_trans(zdev, pa, dma_addr, size, flags);
-	if (ret)
-		goto out_free;
-
-	atomic64_add(nr_pages, &zdev->mapped_pages);
-	return dma_addr + (offset & ~PAGE_MASK);
-
-out_free:
-	dma_free_address(dev, dma_addr, nr_pages);
-out_err:
-	zpci_err("map error:\n");
-	zpci_err_dma(ret, pa);
-	return DMA_MAPPING_ERROR;
-}
-
-static void s390_dma_unmap_pages(struct device *dev, dma_addr_t dma_addr,
-				 size_t size, enum dma_data_direction direction,
-				 unsigned long attrs)
-{
-	struct zpci_dev *zdev = to_zpci(to_pci_dev(dev));
-	int npages, ret;
-
-	npages = iommu_num_pages(dma_addr, size, PAGE_SIZE);
-	dma_addr = dma_addr & PAGE_MASK;
-	ret = dma_update_trans(zdev, 0, dma_addr, npages * PAGE_SIZE,
-			       ZPCI_PTE_INVALID);
-	if (ret) {
-		zpci_err("unmap error:\n");
-		zpci_err_dma(ret, dma_addr);
-		return;
-	}
-
-	atomic64_add(npages, &zdev->unmapped_pages);
-	dma_free_address(dev, dma_addr, npages);
-}
-
-static void *s390_dma_alloc(struct device *dev, size_t size,
-			    dma_addr_t *dma_handle, gfp_t flag,
-			    unsigned long attrs)
-{
-	struct zpci_dev *zdev = to_zpci(to_pci_dev(dev));
-	struct page *page;
-	phys_addr_t pa;
-	dma_addr_t map;
-
-	size = PAGE_ALIGN(size);
-	page = alloc_pages(flag | __GFP_ZERO, get_order(size));
-	if (!page)
-		return NULL;
-
-	pa = page_to_phys(page);
-	map = s390_dma_map_pages(dev, page, 0, size, DMA_BIDIRECTIONAL, 0);
-	if (dma_mapping_error(dev, map)) {
-		__free_pages(page, get_order(size));
-		return NULL;
-	}
-
-	atomic64_add(size / PAGE_SIZE, &zdev->allocated_pages);
-	if (dma_handle)
-		*dma_handle = map;
-	return phys_to_virt(pa);
-}
-
-static void s390_dma_free(struct device *dev, size_t size,
-			  void *vaddr, dma_addr_t dma_handle,
-			  unsigned long attrs)
-{
-	struct zpci_dev *zdev = to_zpci(to_pci_dev(dev));
-
-	size = PAGE_ALIGN(size);
-	atomic64_sub(size / PAGE_SIZE, &zdev->allocated_pages);
-	s390_dma_unmap_pages(dev, dma_handle, size, DMA_BIDIRECTIONAL, 0);
-	free_pages((unsigned long)vaddr, get_order(size));
-}
-
-/* Map a segment into a contiguous dma address area */
-static int __s390_dma_map_sg(struct device *dev, struct scatterlist *sg,
-			     size_t size, dma_addr_t *handle,
-			     enum dma_data_direction dir)
-{
-	unsigned long nr_pages = PAGE_ALIGN(size) >> PAGE_SHIFT;
-	struct zpci_dev *zdev = to_zpci(to_pci_dev(dev));
-	dma_addr_t dma_addr_base, dma_addr;
-	int flags = ZPCI_PTE_VALID;
-	struct scatterlist *s;
-	phys_addr_t pa = 0;
-	int ret;
-
-	dma_addr_base = dma_alloc_address(dev, nr_pages);
-	if (dma_addr_base == DMA_MAPPING_ERROR)
-		return -ENOMEM;
-
-	dma_addr = dma_addr_base;
-	if (dir == DMA_NONE || dir == DMA_TO_DEVICE)
-		flags |= ZPCI_TABLE_PROTECTED;
-
-	for (s = sg; dma_addr < dma_addr_base + size; s = sg_next(s)) {
-		pa = page_to_phys(sg_page(s));
-		ret = __dma_update_trans(zdev, pa, dma_addr,
-					 s->offset + s->length, flags);
-		if (ret)
-			goto unmap;
-
-		dma_addr += s->offset + s->length;
-	}
-	ret = __dma_purge_tlb(zdev, dma_addr_base, size, flags);
-	if (ret)
-		goto unmap;
-
-	*handle = dma_addr_base;
-	atomic64_add(nr_pages, &zdev->mapped_pages);
-
-	return ret;
-
-unmap:
-	dma_update_trans(zdev, 0, dma_addr_base, dma_addr - dma_addr_base,
-			 ZPCI_PTE_INVALID);
-	dma_free_address(dev, dma_addr_base, nr_pages);
-	zpci_err("map error:\n");
-	zpci_err_dma(ret, pa);
-	return ret;
-}
-
-static int s390_dma_map_sg(struct device *dev, struct scatterlist *sg,
-			   int nr_elements, enum dma_data_direction dir,
-			   unsigned long attrs)
-{
-	struct scatterlist *s = sg, *start = sg, *dma = sg;
-	unsigned int max = dma_get_max_seg_size(dev);
-	unsigned int size = s->offset + s->length;
-	unsigned int offset = s->offset;
-	int count = 0, i, ret;
-
-	for (i = 1; i < nr_elements; i++) {
-		s = sg_next(s);
-
-		s->dma_length = 0;
-
-		if (s->offset || (size & ~PAGE_MASK) ||
-		    size + s->length > max) {
-			ret = __s390_dma_map_sg(dev, start, size,
-						&dma->dma_address, dir);
-			if (ret)
-				goto unmap;
-
-			dma->dma_address += offset;
-			dma->dma_length = size - offset;
-
-			size = offset = s->offset;
-			start = s;
-			dma = sg_next(dma);
-			count++;
-		}
-		size += s->length;
-	}
-	ret = __s390_dma_map_sg(dev, start, size, &dma->dma_address, dir);
-	if (ret)
-		goto unmap;
-
-	dma->dma_address += offset;
-	dma->dma_length = size - offset;
-
-	return count + 1;
-unmap:
-	for_each_sg(sg, s, count, i)
-		s390_dma_unmap_pages(dev, sg_dma_address(s), sg_dma_len(s),
-				     dir, attrs);
-
-	return ret;
-}
-
-static void s390_dma_unmap_sg(struct device *dev, struct scatterlist *sg,
-			      int nr_elements, enum dma_data_direction dir,
-			      unsigned long attrs)
-{
-	struct scatterlist *s;
-	int i;
-
-	for_each_sg(sg, s, nr_elements, i) {
-		if (s->dma_length)
-			s390_dma_unmap_pages(dev, s->dma_address, s->dma_length,
-					     dir, attrs);
-		s->dma_address = 0;
-		s->dma_length = 0;
-	}
-}
-	
-int zpci_dma_init_device(struct zpci_dev *zdev)
-{
-	u8 status;
-	int rc;
-
-	/*
-	 * At this point, if the device is part of an IOMMU domain, this would
-	 * be a strong hint towards a bug in the IOMMU API (common) code and/or
-	 * simultaneous access via IOMMU and DMA API. So let's issue a warning.
-	 */
-	WARN_ON(zdev->s390_domain);
-
-	spin_lock_init(&zdev->iommu_bitmap_lock);
-
-	zdev->dma_table = dma_alloc_cpu_table(GFP_KERNEL);
-	if (!zdev->dma_table) {
-		rc = -ENOMEM;
-		goto out;
-	}
-
-	/*
-	 * Restrict the iommu bitmap size to the minimum of the following:
-	 * - s390_iommu_aperture which defaults to high_memory
-	 * - 3-level pagetable address limit minus start_dma offset
-	 * - DMA address range allowed by the hardware (clp query pci fn)
-	 *
-	 * Also set zdev->end_dma to the actual end address of the usable
-	 * range, instead of the theoretical maximum as reported by hardware.
-	 *
-	 * This limits the number of concurrently usable DMA mappings since
-	 * for each DMA mapped memory address we need a DMA address including
-	 * extra DMA addresses for multiple mappings of the same memory address.
-	 */
-	zdev->start_dma = PAGE_ALIGN(zdev->start_dma);
-	zdev->iommu_size = min3(s390_iommu_aperture,
-				ZPCI_TABLE_SIZE_RT - zdev->start_dma,
-				zdev->end_dma - zdev->start_dma + 1);
-	zdev->end_dma = zdev->start_dma + zdev->iommu_size - 1;
-	zdev->iommu_pages = zdev->iommu_size >> PAGE_SHIFT;
-	zdev->iommu_bitmap = vzalloc(zdev->iommu_pages / 8);
-	if (!zdev->iommu_bitmap) {
-		rc = -ENOMEM;
-		goto free_dma_table;
-	}
-	if (!s390_iommu_strict) {
-		zdev->lazy_bitmap = vzalloc(zdev->iommu_pages / 8);
-		if (!zdev->lazy_bitmap) {
-			rc = -ENOMEM;
-			goto free_bitmap;
-		}
-
-	}
-	if (zpci_register_ioat(zdev, 0, zdev->start_dma, zdev->end_dma,
-			       virt_to_phys(zdev->dma_table), &status)) {
-		rc = -EIO;
-		goto free_bitmap;
-	}
-
-	return 0;
-free_bitmap:
-	vfree(zdev->iommu_bitmap);
-	zdev->iommu_bitmap = NULL;
-	vfree(zdev->lazy_bitmap);
-	zdev->lazy_bitmap = NULL;
-free_dma_table:
-	dma_free_cpu_table(zdev->dma_table);
-	zdev->dma_table = NULL;
-out:
-	return rc;
-}
-
-int zpci_dma_exit_device(struct zpci_dev *zdev)
-{
-	int cc = 0;
-
-	/*
-	 * At this point, if the device is part of an IOMMU domain, this would
-	 * be a strong hint towards a bug in the IOMMU API (common) code and/or
-	 * simultaneous access via IOMMU and DMA API. So let's issue a warning.
-	 */
-	WARN_ON(zdev->s390_domain);
-	if (zdev_enabled(zdev))
-		cc = zpci_unregister_ioat(zdev, 0);
-	/*
-	 * cc == 3 indicates the function is gone already. This can happen
-	 * if the function was deconfigured/disabled suddenly and we have not
-	 * received a new handle yet.
-	 */
-	if (cc && cc != 3)
-		return -EIO;
-
-	dma_cleanup_tables(zdev->dma_table);
-	zdev->dma_table = NULL;
-	vfree(zdev->iommu_bitmap);
-	zdev->iommu_bitmap = NULL;
-	vfree(zdev->lazy_bitmap);
-	zdev->lazy_bitmap = NULL;
-	zdev->next_bit = 0;
-	return 0;
-}
-
-static int __init dma_alloc_cpu_table_caches(void)
-{
-	dma_region_table_cache = kmem_cache_create("PCI_DMA_region_tables",
-					ZPCI_TABLE_SIZE, ZPCI_TABLE_ALIGN,
-					0, NULL);
-	if (!dma_region_table_cache)
-		return -ENOMEM;
-
-	dma_page_table_cache = kmem_cache_create("PCI_DMA_page_tables",
-					ZPCI_PT_SIZE, ZPCI_PT_ALIGN,
-					0, NULL);
-	if (!dma_page_table_cache) {
-		kmem_cache_destroy(dma_region_table_cache);
-		return -ENOMEM;
-	}
-	return 0;
-}
-
-int __init zpci_dma_init(void)
-{
-	s390_iommu_aperture = (u64)virt_to_phys(high_memory);
-	if (!s390_iommu_aperture_factor)
-		s390_iommu_aperture = ULONG_MAX;
-	else
-		s390_iommu_aperture *= s390_iommu_aperture_factor;
-
-	return dma_alloc_cpu_table_caches();
-}
-
-void zpci_dma_exit(void)
-{
-	kmem_cache_destroy(dma_page_table_cache);
-	kmem_cache_destroy(dma_region_table_cache);
-}
-
-const struct dma_map_ops s390_pci_dma_ops = {
-	.alloc		= s390_dma_alloc,
-	.free		= s390_dma_free,
-	.map_sg		= s390_dma_map_sg,
-	.unmap_sg	= s390_dma_unmap_sg,
-	.map_page	= s390_dma_map_pages,
-	.unmap_page	= s390_dma_unmap_pages,
-	.mmap		= dma_common_mmap,
-	.get_sgtable	= dma_common_get_sgtable,
-	.alloc_pages	= dma_common_alloc_pages,
-	.free_pages	= dma_common_free_pages,
-	/* dma_supported is unconditionally true without a callback */
-};
-EXPORT_SYMBOL_GPL(s390_pci_dma_ops);
-
-static int __init s390_iommu_setup(char *str)
-{
-	if (!strcmp(str, "strict"))
-		s390_iommu_strict = 1;
-	return 1;
-}
-
-__setup("s390_iommu=", s390_iommu_setup);
-
-static int __init s390_iommu_aperture_setup(char *str)
-{
-	if (kstrtou32(str, 10, &s390_iommu_aperture_factor))
-		s390_iommu_aperture_factor = 1;
-	return 1;
-}
-
-__setup("s390_iommu_aperture=", s390_iommu_aperture_setup);
diff --git a/arch/s390/pci/pci_event.c b/arch/s390/pci/pci_event.c
index 4ef5a6a1d618..4d9773ef9e0a 100644
--- a/arch/s390/pci/pci_event.c
+++ b/arch/s390/pci/pci_event.c
@@ -313,8 +313,6 @@ static void zpci_event_hard_deconfigured(struct zpci_dev *zdev, u32 fh)
 	/* Even though the device is already gone we still
 	 * need to free zPCI resources as part of the disable.
 	 */
-	if (zdev->dma_table)
-		zpci_dma_exit_device(zdev);
 	if (zdev_enabled(zdev))
 		zpci_disable_device(zdev);
 	zdev->state = ZPCI_FN_STATE_STANDBY;
diff --git a/arch/s390/pci/pci_sysfs.c b/arch/s390/pci/pci_sysfs.c
index cae280e5c047..8a7abac51816 100644
--- a/arch/s390/pci/pci_sysfs.c
+++ b/arch/s390/pci/pci_sysfs.c
@@ -56,6 +56,7 @@ static ssize_t recover_store(struct device *dev, struct device_attribute *attr,
 	struct pci_dev *pdev = to_pci_dev(dev);
 	struct zpci_dev *zdev = to_zpci(pdev);
 	int ret = 0;
+	u8 status;
 
 	/* Can't use device_remove_self() here as that would lead us to lock
 	 * the pci_rescan_remove_lock while holding the device' kernfs lock.
@@ -82,12 +83,6 @@ static ssize_t recover_store(struct device *dev, struct device_attribute *attr,
 	pci_lock_rescan_remove();
 	if (pci_dev_is_added(pdev)) {
 		pci_stop_and_remove_bus_device(pdev);
-		if (zdev->dma_table) {
-			ret = zpci_dma_exit_device(zdev);
-			if (ret)
-				goto out;
-		}
-
 		if (zdev_enabled(zdev)) {
 			ret = zpci_disable_device(zdev);
 			/*
@@ -105,14 +100,16 @@ static ssize_t recover_store(struct device *dev, struct device_attribute *attr,
 		ret = zpci_enable_device(zdev);
 		if (ret)
 			goto out;
-		ret = zpci_dma_init_device(zdev);
-		if (ret) {
-			zpci_disable_device(zdev);
-			goto out;
+
+		if (zdev->dma_table) {
+			ret = zpci_register_ioat(zdev, 0, zdev->start_dma, zdev->end_dma,
+						 virt_to_phys(zdev->dma_table), &status);
+			if (ret)
+				zpci_disable_device(zdev);
 		}
-		pci_rescan_bus(zdev->zbus->bus);
 	}
 out:
+	pci_rescan_bus(zdev->zbus->bus);
 	pci_unlock_rescan_remove();
 	if (kn)
 		sysfs_unbreak_active_protection(kn);
diff --git a/drivers/iommu/Kconfig b/drivers/iommu/Kconfig
index 889c7efd050b..7fe48b643831 100644
--- a/drivers/iommu/Kconfig
+++ b/drivers/iommu/Kconfig
@@ -95,7 +95,7 @@ config IOMMU_DEBUGFS
 choice
 	prompt "IOMMU default domain type"
 	depends on IOMMU_API
-	default IOMMU_DEFAULT_DMA_LAZY if X86 || IA64
+	default IOMMU_DEFAULT_DMA_LAZY if X86 || IA64 || S390
 	default IOMMU_DEFAULT_DMA_STRICT
 	help
 	  Choose the type of IOMMU domain used to manage DMA API usage by
@@ -150,7 +150,7 @@ config OF_IOMMU
 
 # IOMMU-agnostic DMA-mapping layer
 config IOMMU_DMA
-	def_bool ARM64 || IA64 || X86
+	def_bool ARM64 || IA64 || X86 || S390
 	select DMA_OPS
 	select IOMMU_API
 	select IOMMU_IOVA
diff --git a/drivers/iommu/s390-iommu.c b/drivers/iommu/s390-iommu.c
index 17174b35db11..161b0be5aba6 100644
--- a/drivers/iommu/s390-iommu.c
+++ b/drivers/iommu/s390-iommu.c
@@ -14,16 +14,300 @@
 #include <linux/rcupdate.h>
 #include <asm/pci_dma.h>
 
+#include "dma-iommu.h"
+
 static const struct iommu_ops s390_iommu_ops;
 
+static struct kmem_cache *dma_region_table_cache;
+static struct kmem_cache *dma_page_table_cache;
+
+static u64 s390_iommu_aperture;
+static u32 s390_iommu_aperture_factor = 1;
+
 struct s390_domain {
 	struct iommu_domain	domain;
 	struct list_head	devices;
+	struct zpci_iommu_ctrs	ctrs;
 	unsigned long		*dma_table;
 	spinlock_t		list_lock;
 	struct rcu_head		rcu;
 };
 
+static inline unsigned int calc_rtx(dma_addr_t ptr)
+{
+	return ((unsigned long)ptr >> ZPCI_RT_SHIFT) & ZPCI_INDEX_MASK;
+}
+
+static inline unsigned int calc_sx(dma_addr_t ptr)
+{
+	return ((unsigned long)ptr >> ZPCI_ST_SHIFT) & ZPCI_INDEX_MASK;
+}
+
+static inline unsigned int calc_px(dma_addr_t ptr)
+{
+	return ((unsigned long)ptr >> PAGE_SHIFT) & ZPCI_PT_MASK;
+}
+
+static inline void set_pt_pfaa(unsigned long *entry, phys_addr_t pfaa)
+{
+	*entry &= ZPCI_PTE_FLAG_MASK;
+	*entry |= (pfaa & ZPCI_PTE_ADDR_MASK);
+}
+
+static inline void set_rt_sto(unsigned long *entry, phys_addr_t sto)
+{
+	*entry &= ZPCI_RTE_FLAG_MASK;
+	*entry |= (sto & ZPCI_RTE_ADDR_MASK);
+	*entry |= ZPCI_TABLE_TYPE_RTX;
+}
+
+static inline void set_st_pto(unsigned long *entry, phys_addr_t pto)
+{
+	*entry &= ZPCI_STE_FLAG_MASK;
+	*entry |= (pto & ZPCI_STE_ADDR_MASK);
+	*entry |= ZPCI_TABLE_TYPE_SX;
+}
+
+static inline void validate_rt_entry(unsigned long *entry)
+{
+	*entry &= ~ZPCI_TABLE_VALID_MASK;
+	*entry &= ~ZPCI_TABLE_OFFSET_MASK;
+	*entry |= ZPCI_TABLE_VALID;
+	*entry |= ZPCI_TABLE_LEN_RTX;
+}
+
+static inline void validate_st_entry(unsigned long *entry)
+{
+	*entry &= ~ZPCI_TABLE_VALID_MASK;
+	*entry |= ZPCI_TABLE_VALID;
+}
+
+static inline void invalidate_pt_entry(unsigned long *entry)
+{
+	WARN_ON_ONCE((*entry & ZPCI_PTE_VALID_MASK) == ZPCI_PTE_INVALID);
+	*entry &= ~ZPCI_PTE_VALID_MASK;
+	*entry |= ZPCI_PTE_INVALID;
+}
+
+static inline void validate_pt_entry(unsigned long *entry)
+{
+	WARN_ON_ONCE((*entry & ZPCI_PTE_VALID_MASK) == ZPCI_PTE_VALID);
+	*entry &= ~ZPCI_PTE_VALID_MASK;
+	*entry |= ZPCI_PTE_VALID;
+}
+
+static inline void entry_set_protected(unsigned long *entry)
+{
+	*entry &= ~ZPCI_TABLE_PROT_MASK;
+	*entry |= ZPCI_TABLE_PROTECTED;
+}
+
+static inline void entry_clr_protected(unsigned long *entry)
+{
+	*entry &= ~ZPCI_TABLE_PROT_MASK;
+	*entry |= ZPCI_TABLE_UNPROTECTED;
+}
+
+static inline int reg_entry_isvalid(unsigned long entry)
+{
+	return (entry & ZPCI_TABLE_VALID_MASK) == ZPCI_TABLE_VALID;
+}
+
+static inline int pt_entry_isvalid(unsigned long entry)
+{
+	return (entry & ZPCI_PTE_VALID_MASK) == ZPCI_PTE_VALID;
+}
+
+static inline unsigned long *get_rt_sto(unsigned long entry)
+{
+	if ((entry & ZPCI_TABLE_TYPE_MASK) == ZPCI_TABLE_TYPE_RTX)
+		return phys_to_virt(entry & ZPCI_RTE_ADDR_MASK);
+	else
+		return NULL;
+}
+
+static inline unsigned long *get_st_pto(unsigned long entry)
+{
+	if ((entry & ZPCI_TABLE_TYPE_MASK) == ZPCI_TABLE_TYPE_SX)
+		return phys_to_virt(entry & ZPCI_STE_ADDR_MASK);
+	else
+		return NULL;
+}
+
+static int __init dma_alloc_cpu_table_caches(void)
+{
+	dma_region_table_cache = kmem_cache_create("PCI_DMA_region_tables",
+						   ZPCI_TABLE_SIZE,
+						   ZPCI_TABLE_ALIGN,
+						   0, NULL);
+	if (!dma_region_table_cache)
+		return -ENOMEM;
+
+	dma_page_table_cache = kmem_cache_create("PCI_DMA_page_tables",
+						 ZPCI_PT_SIZE,
+						 ZPCI_PT_ALIGN,
+						 0, NULL);
+	if (!dma_page_table_cache) {
+		kmem_cache_destroy(dma_region_table_cache);
+		return -ENOMEM;
+	}
+	return 0;
+}
+
+static unsigned long *dma_alloc_cpu_table(gfp_t gfp)
+{
+	unsigned long *table, *entry;
+
+	table = kmem_cache_alloc(dma_region_table_cache, gfp);
+	if (!table)
+		return NULL;
+
+	for (entry = table; entry < table + ZPCI_TABLE_ENTRIES; entry++)
+		*entry = ZPCI_TABLE_INVALID;
+	return table;
+}
+
+static void dma_free_cpu_table(void *table)
+{
+	kmem_cache_free(dma_region_table_cache, table);
+}
+
+static void dma_free_page_table(void *table)
+{
+	kmem_cache_free(dma_page_table_cache, table);
+}
+
+static void dma_free_seg_table(unsigned long entry)
+{
+	unsigned long *sto = get_rt_sto(entry);
+	int sx;
+
+	for (sx = 0; sx < ZPCI_TABLE_ENTRIES; sx++)
+		if (reg_entry_isvalid(sto[sx]))
+			dma_free_page_table(get_st_pto(sto[sx]));
+
+	dma_free_cpu_table(sto);
+}
+
+static void dma_cleanup_tables(unsigned long *table)
+{
+	int rtx;
+
+	if (!table)
+		return;
+
+	for (rtx = 0; rtx < ZPCI_TABLE_ENTRIES; rtx++)
+		if (reg_entry_isvalid(table[rtx]))
+			dma_free_seg_table(table[rtx]);
+
+	dma_free_cpu_table(table);
+}
+
+static unsigned long *dma_alloc_page_table(gfp_t gfp)
+{
+	unsigned long *table, *entry;
+
+	table = kmem_cache_alloc(dma_page_table_cache, gfp);
+	if (!table)
+		return NULL;
+
+	for (entry = table; entry < table + ZPCI_PT_ENTRIES; entry++)
+		*entry = ZPCI_PTE_INVALID;
+	return table;
+}
+
+static unsigned long *dma_get_seg_table_origin(unsigned long *rtep, gfp_t gfp)
+{
+	unsigned long old_rte, rte;
+	unsigned long *sto;
+
+	rte = READ_ONCE(*rtep);
+	if (reg_entry_isvalid(rte)) {
+		sto = get_rt_sto(rte);
+	} else {
+		sto = dma_alloc_cpu_table(gfp);
+		if (!sto)
+			return NULL;
+
+		set_rt_sto(&rte, virt_to_phys(sto));
+		validate_rt_entry(&rte);
+		entry_clr_protected(&rte);
+
+		old_rte = cmpxchg(rtep, ZPCI_TABLE_INVALID, rte);
+		if (old_rte != ZPCI_TABLE_INVALID) {
+			/* Somone else was faster, use theirs */
+			dma_free_cpu_table(sto);
+			sto = get_rt_sto(old_rte);
+		}
+	}
+	return sto;
+}
+
+static unsigned long *dma_get_page_table_origin(unsigned long *step, gfp_t gfp)
+{
+	unsigned long old_ste, ste;
+	unsigned long *pto;
+
+	ste = READ_ONCE(*step);
+	if (reg_entry_isvalid(ste)) {
+		pto = get_st_pto(ste);
+	} else {
+		pto = dma_alloc_page_table(gfp);
+		if (!pto)
+			return NULL;
+		set_st_pto(&ste, virt_to_phys(pto));
+		validate_st_entry(&ste);
+		entry_clr_protected(&ste);
+
+		old_ste = cmpxchg(step, ZPCI_TABLE_INVALID, ste);
+		if (old_ste != ZPCI_TABLE_INVALID) {
+			/* Somone else was faster, use theirs */
+			dma_free_page_table(pto);
+			pto = get_st_pto(old_ste);
+		}
+	}
+	return pto;
+}
+
+static unsigned long *dma_walk_cpu_trans(unsigned long *rto, dma_addr_t dma_addr, gfp_t gfp)
+{
+	unsigned long *sto, *pto;
+	unsigned int rtx, sx, px;
+
+	rtx = calc_rtx(dma_addr);
+	sto = dma_get_seg_table_origin(&rto[rtx], gfp);
+	if (!sto)
+		return NULL;
+
+	sx = calc_sx(dma_addr);
+	pto = dma_get_page_table_origin(&sto[sx], gfp);
+	if (!pto)
+		return NULL;
+
+	px = calc_px(dma_addr);
+	return &pto[px];
+}
+
+static void dma_update_cpu_trans(unsigned long *ptep, phys_addr_t page_addr, int flags)
+{
+	unsigned long pte;
+
+	pte = READ_ONCE(*ptep);
+	if (flags & ZPCI_PTE_INVALID) {
+		invalidate_pt_entry(&pte);
+	} else {
+		set_pt_pfaa(&pte, page_addr);
+		validate_pt_entry(&pte);
+	}
+
+	if (flags & ZPCI_TABLE_PROTECTED)
+		entry_set_protected(&pte);
+	else
+		entry_clr_protected(&pte);
+
+	xchg(ptep, pte);
+}
+
 static struct s390_domain *to_s390_domain(struct iommu_domain *dom)
 {
 	return container_of(dom, struct s390_domain, domain);
@@ -43,9 +327,14 @@ static struct iommu_domain *s390_domain_alloc(unsigned domain_type)
 {
 	struct s390_domain *s390_domain;
 
-	if (domain_type != IOMMU_DOMAIN_UNMANAGED)
+	switch (domain_type) {
+	case IOMMU_DOMAIN_DMA:
+	case IOMMU_DOMAIN_DMA_FQ:
+	case IOMMU_DOMAIN_UNMANAGED:
+		break;
+	default:
 		return NULL;
-
+	}
 	s390_domain = kzalloc(sizeof(*s390_domain), GFP_KERNEL);
 	if (!s390_domain)
 		return NULL;
@@ -84,14 +373,13 @@ static void s390_domain_free(struct iommu_domain *domain)
 	call_rcu(&s390_domain->rcu, s390_iommu_rcu_free_domain);
 }
 
-static void __s390_iommu_detach_device(struct zpci_dev *zdev)
+static void s390_iommu_detach_device(struct iommu_domain *domain,
+				     struct device *dev)
 {
-	struct s390_domain *s390_domain = zdev->s390_domain;
+	struct s390_domain *s390_domain = to_s390_domain(domain);
+	struct zpci_dev *zdev = to_zpci_dev(dev);
 	unsigned long flags;
 
-	if (!s390_domain)
-		return;
-
 	spin_lock_irqsave(&s390_domain->list_lock, flags);
 	list_del_rcu(&zdev->iommu_list);
 	spin_unlock_irqrestore(&s390_domain->list_lock, flags);
@@ -118,9 +406,7 @@ static int s390_iommu_attach_device(struct iommu_domain *domain,
 		return -EINVAL;
 
 	if (zdev->s390_domain)
-		__s390_iommu_detach_device(zdev);
-	else if (zdev->dma_table)
-		zpci_dma_exit_device(zdev);
+		s390_iommu_detach_device(&zdev->s390_domain->domain, dev);
 
 	cc = zpci_register_ioat(zdev, 0, zdev->start_dma, zdev->end_dma,
 				virt_to_phys(s390_domain->dma_table), &status);
@@ -130,7 +416,6 @@ static int s390_iommu_attach_device(struct iommu_domain *domain,
 	 */
 	if (cc && status != ZPCI_PCI_ST_FUNC_NOT_AVAIL)
 		return -EIO;
-	zdev->dma_table = s390_domain->dma_table;
 
 	zdev->dma_table = s390_domain->dma_table;
 	zdev->s390_domain = s390_domain;
@@ -142,14 +427,6 @@ static int s390_iommu_attach_device(struct iommu_domain *domain,
 	return 0;
 }
 
-static void s390_iommu_set_platform_dma(struct device *dev)
-{
-	struct zpci_dev *zdev = to_zpci_dev(dev);
-
-	__s390_iommu_detach_device(zdev);
-	zpci_dma_init_device(zdev);
-}
-
 static void s390_iommu_get_resv_regions(struct device *dev,
 					struct list_head *list)
 {
@@ -202,7 +479,7 @@ static void s390_iommu_release_device(struct device *dev)
 	 * to the device, but keep it attached to other devices in the group.
 	 */
 	if (zdev)
-		__s390_iommu_detach_device(zdev);
+		s390_iommu_detach_device(&zdev->s390_domain->domain, dev);
 }
 
 
@@ -220,6 +497,7 @@ static void s390_iommu_flush_iotlb_all(struct iommu_domain *domain)
 
 	rcu_read_lock();
 	list_for_each_entry_rcu(zdev, &s390_domain->devices, iommu_list) {
+		atomic64_inc(&s390_domain->ctrs.global_rpcits);
 		zpci_refresh_all(zdev);
 	}
 	rcu_read_unlock();
@@ -238,6 +516,7 @@ static void s390_iommu_iotlb_sync(struct iommu_domain *domain,
 
 	rcu_read_lock();
 	list_for_each_entry_rcu(zdev, &s390_domain->devices, iommu_list) {
+		atomic64_inc(&s390_domain->ctrs.sync_rpcits);
 		zpci_refresh_trans((u64)zdev->fh << 32, gather->start,
 				   size);
 	}
@@ -255,6 +534,7 @@ static int s390_iommu_iotlb_sync_map(struct iommu_domain *domain,
 	list_for_each_entry_rcu(zdev, &s390_domain->devices, iommu_list) {
 		if (!zdev->tlb_refresh)
 			continue;
+		atomic64_inc(&s390_domain->ctrs.sync_map_rpcits);
 		ret = zpci_refresh_trans((u64)zdev->fh << 32,
 					 iova, size);
 		/*
@@ -349,16 +629,15 @@ static int s390_iommu_map_pages(struct iommu_domain *domain,
 	if (!IS_ALIGNED(iova | paddr, pgsize))
 		return -EINVAL;
 
-	if (!(prot & IOMMU_READ))
-		return -EINVAL;
-
 	if (!(prot & IOMMU_WRITE))
 		flags |= ZPCI_TABLE_PROTECTED;
 
 	rc = s390_iommu_validate_trans(s390_domain, paddr, iova,
-				       pgcount, flags, gfp);
-	if (!rc)
+				     pgcount, flags, gfp);
+	if (!rc) {
 		*mapped = size;
+		atomic64_add(pgcount, &s390_domain->ctrs.mapped_pages);
+	}
 
 	return rc;
 }
@@ -414,12 +693,27 @@ static size_t s390_iommu_unmap_pages(struct iommu_domain *domain,
 		return 0;
 
 	iommu_iotlb_gather_add_range(gather, iova, size);
+	atomic64_add(pgcount, &s390_domain->ctrs.unmapped_pages);
 
 	return size;
 }
 
+static void s390_iommu_probe_finalize(struct device *dev)
+{
+	iommu_dma_forcedac = true;
+	iommu_setup_dma_ops(dev, 0, U64_MAX);
+}
+
+struct zpci_iommu_ctrs *zpci_get_iommu_ctrs(struct zpci_dev *zdev)
+{
+	if (!zdev || !zdev->s390_domain)
+		return NULL;
+	return &zdev->s390_domain->ctrs;
+}
+
 int zpci_init_iommu(struct zpci_dev *zdev)
 {
+	u64 aperture_size;
 	int rc = 0;
 
 	rc = iommu_device_sysfs_add(&zdev->iommu_dev, NULL, NULL,
@@ -431,6 +725,12 @@ int zpci_init_iommu(struct zpci_dev *zdev)
 	if (rc)
 		goto out_sysfs;
 
+	zdev->start_dma = PAGE_ALIGN(zdev->start_dma);
+	aperture_size = min3(s390_iommu_aperture,
+			     ZPCI_TABLE_SIZE_RT - zdev->start_dma,
+			     zdev->end_dma - zdev->start_dma + 1);
+	zdev->end_dma = zdev->start_dma + aperture_size - 1;
+
 	return 0;
 
 out_sysfs:
@@ -446,13 +746,51 @@ void zpci_destroy_iommu(struct zpci_dev *zdev)
 	iommu_device_sysfs_remove(&zdev->iommu_dev);
 }
 
+static int __init s390_iommu_setup(char *str)
+{
+	if (!strcmp(str, "strict")) {
+		pr_warn("s390_iommu=strict deprecated; use iommu.strict=1 instead\n");
+		iommu_set_dma_strict();
+	}
+	return 1;
+}
+
+__setup("s390_iommu=", s390_iommu_setup);
+
+static int __init s390_iommu_aperture_setup(char *str)
+{
+	if (kstrtou32(str, 10, &s390_iommu_aperture_factor))
+		s390_iommu_aperture_factor = 1;
+	return 1;
+}
+
+__setup("s390_iommu_aperture=", s390_iommu_aperture_setup);
+
+static int __init s390_iommu_init(void)
+{
+	int rc;
+
+	s390_iommu_aperture = (u64)virt_to_phys(high_memory);
+	if (!s390_iommu_aperture_factor)
+		s390_iommu_aperture = ULONG_MAX;
+	else
+		s390_iommu_aperture *= s390_iommu_aperture_factor;
+
+	rc = dma_alloc_cpu_table_caches();
+	if (rc)
+		return rc;
+
+	return rc;
+}
+subsys_initcall(s390_iommu_init);
+
 static const struct iommu_ops s390_iommu_ops = {
 	.capable = s390_iommu_capable,
 	.domain_alloc = s390_domain_alloc,
 	.probe_device = s390_iommu_probe_device,
+	.probe_finalize = s390_iommu_probe_finalize,
 	.release_device = s390_iommu_release_device,
 	.device_group = generic_device_group,
-	.set_platform_dma_ops = s390_iommu_set_platform_dma,
 	.pgsize_bitmap = SZ_4K,
 	.get_resv_regions = s390_iommu_get_resv_regions,
 	.default_domain_ops = &(const struct iommu_domain_ops) {

-- 
2.37.2

[PATCH v8 5/6] iommu/dma: Allow a single FQ in addition to per-CPU FQs

[Niklas Schnelle]

In some virtualized environments, including s390 paged memory guests,
IOTLB flushes are used to update IOMMU shadow tables. Due to this, they
are much more expensive than in typical bare metal environments or
non-paged s390 guests. In addition they may parallelize more poorly in
virtualized environments. This changes the trade off for flushing IOVAs
such that minimizing the number of IOTLB flushes trumps any benefit of
cheaper queuing operations or increased paralellism.

In this scenario per-CPU flush queues pose several problems. Firstly
per-CPU memory is often quite limited prohibiting larger queues.
Secondly collecting IOVAs per-CPU but flushing via a global timeout
reduces the number of IOVAs flushed for each timeout especially on s390
where PCI interrupts may not be bound to a specific CPU.

Let's introduce a single flush queue mode that reuses the same queue
logic but only allocates a single global queue. This mode can be
selected as a flag bit in a new dma_iommu_options struct which can be
modified from its defaults by IOMMU drivers implementing a new
ops.tune_dma_iommu() callback. As a first user the s390 IOMMU driver
selects the single queue mode if IOTLB flushes are needed on map which
indicates shadow table use. With the unchanged small FQ size and
timeouts this setting is worse than per-CPU queues but a follow up patch
will make the FQ size and timeout variable. Together this allows the
common IOVA flushing code to more closely resemble the global flush
behavior used on s390's previous internal DMA API implementation.

Link: https://lore.kernel.org/linux-iommu/3e402947-61f9-b7e8-1414-fde006257b6f@arm.com/
Reviewed-by: Matthew Rosato <mjrosato@linux.ibm.com> #s390
Signed-off-by: Niklas Schnelle <schnelle@linux.ibm.com>
---
 drivers/iommu/dma-iommu.c  | 161 ++++++++++++++++++++++++++++++++++-----------
 drivers/iommu/dma-iommu.h  |   4 +-
 drivers/iommu/iommu.c      |   4 +-
 drivers/iommu/s390-iommu.c |  10 +++
 include/linux/iommu.h      |  21 ++++++
 5 files changed, 157 insertions(+), 43 deletions(-)

diff --git a/drivers/iommu/dma-iommu.c b/drivers/iommu/dma-iommu.c
index 99b2646cb5c7..6f5fd110e0e0 100644
--- a/drivers/iommu/dma-iommu.c
+++ b/drivers/iommu/dma-iommu.c
@@ -49,8 +49,11 @@ struct iommu_dma_cookie {
 		/* Full allocator for IOMMU_DMA_IOVA_COOKIE */
 		struct {
 			struct iova_domain	iovad;
-
-			struct iova_fq __percpu *fq;	/* Flush queue */
+			/* Flush queue */
+			union {
+				struct iova_fq	*single_fq;
+				struct iova_fq	__percpu *percpu_fq;
+			};
 			/* Number of TLB flushes that have been started */
 			atomic64_t		fq_flush_start_cnt;
 			/* Number of TLB flushes that have been finished */
@@ -67,6 +70,8 @@ struct iommu_dma_cookie {
 
 	/* Domain for flush queue callback; NULL if flush queue not in use */
 	struct iommu_domain		*fq_domain;
+	/* Options for dma-iommu use */
+	struct dma_iommu_options	options;
 	struct mutex			mutex;
 };
 
@@ -152,25 +157,44 @@ static void fq_flush_iotlb(struct iommu_dma_cookie *cookie)
 	atomic64_inc(&cookie->fq_flush_finish_cnt);
 }
 
-static void fq_flush_timeout(struct timer_list *t)
+static void fq_flush_percpu(struct iommu_dma_cookie *cookie)
 {
-	struct iommu_dma_cookie *cookie = from_timer(cookie, t, fq_timer);
 	int cpu;
 
-	atomic_set(&cookie->fq_timer_on, 0);
-	fq_flush_iotlb(cookie);
-
 	for_each_possible_cpu(cpu) {
 		unsigned long flags;
 		struct iova_fq *fq;
 
-		fq = per_cpu_ptr(cookie->fq, cpu);
+		fq = per_cpu_ptr(cookie->percpu_fq, cpu);
 		spin_lock_irqsave(&fq->lock, flags);
 		fq_ring_free(cookie, fq);
 		spin_unlock_irqrestore(&fq->lock, flags);
 	}
 }
 
+static void fq_flush_single(struct iommu_dma_cookie *cookie)
+{
+	struct iova_fq *fq = cookie->single_fq;
+	unsigned long flags;
+
+	spin_lock_irqsave(&fq->lock, flags);
+	fq_ring_free(cookie, fq);
+	spin_unlock_irqrestore(&fq->lock, flags);
+}
+
+static void fq_flush_timeout(struct timer_list *t)
+{
+	struct iommu_dma_cookie *cookie = from_timer(cookie, t, fq_timer);
+
+	atomic_set(&cookie->fq_timer_on, 0);
+	fq_flush_iotlb(cookie);
+
+	if (cookie->options.flags & IOMMU_DMA_OPTS_SINGLE_QUEUE)
+		fq_flush_single(cookie);
+	else
+		fq_flush_percpu(cookie);
+}
+
 static void queue_iova(struct iommu_dma_cookie *cookie,
 		unsigned long pfn, unsigned long pages,
 		struct list_head *freelist)
@@ -188,7 +212,11 @@ static void queue_iova(struct iommu_dma_cookie *cookie,
 	 */
 	smp_mb();
 
-	fq = raw_cpu_ptr(cookie->fq);
+	if (cookie->options.flags & IOMMU_DMA_OPTS_SINGLE_QUEUE)
+		fq = cookie->single_fq;
+	else
+		fq = raw_cpu_ptr(cookie->percpu_fq);
+
 	spin_lock_irqsave(&fq->lock, flags);
 
 	/*
@@ -219,58 +247,114 @@ static void queue_iova(struct iommu_dma_cookie *cookie,
 			  jiffies + msecs_to_jiffies(IOVA_FQ_TIMEOUT));
 }
 
-static void iommu_dma_free_fq(struct iommu_dma_cookie *cookie)
+static void iommu_dma_free_fq_single(struct iova_fq *fq)
 {
-	int cpu, idx;
+	int idx;
 
-	if (!cookie->fq)
+	if (!fq)
 		return;
+	fq_ring_for_each(idx, fq)
+		put_pages_list(&fq->entries[idx].freelist);
+	vfree(fq);
+}
+
+static void iommu_dma_free_fq_percpu(struct iova_fq __percpu *percpu_fq)
+{
+	int cpu, idx;
 
-	del_timer_sync(&cookie->fq_timer);
 	/* The IOVAs will be torn down separately, so just free our queued pages */
 	for_each_possible_cpu(cpu) {
-		struct iova_fq *fq = per_cpu_ptr(cookie->fq, cpu);
+		struct iova_fq *fq = per_cpu_ptr(percpu_fq, cpu);
 
 		fq_ring_for_each(idx, fq)
 			put_pages_list(&fq->entries[idx].freelist);
 	}
 
-	free_percpu(cookie->fq);
+	free_percpu(percpu_fq);
+}
+
+static void iommu_dma_free_fq(struct iommu_dma_cookie *cookie)
+{
+	if (!cookie->fq_domain)
+		return;
+
+	del_timer_sync(&cookie->fq_timer);
+	if (cookie->options.flags & IOMMU_DMA_OPTS_SINGLE_QUEUE)
+		iommu_dma_free_fq_single(cookie->single_fq);
+	else
+		iommu_dma_free_fq_percpu(cookie->percpu_fq);
+}
+
+
+static void iommu_dma_init_one_fq(struct iova_fq *fq)
+{
+	int i;
+
+	fq->head = 0;
+	fq->tail = 0;
+
+	spin_lock_init(&fq->lock);
+
+	for (i = 0; i < IOVA_FQ_SIZE; i++)
+		INIT_LIST_HEAD(&fq->entries[i].freelist);
+}
+
+static int iommu_dma_init_fq_single(struct iommu_dma_cookie *cookie)
+{
+	struct iova_fq *queue;
+
+	queue = vzalloc(sizeof(*queue));
+	if (!queue)
+		return -ENOMEM;
+	iommu_dma_init_one_fq(queue);
+	cookie->single_fq = queue;
+
+	return 0;
+}
+
+static int iommu_dma_init_fq_percpu(struct iommu_dma_cookie *cookie)
+{
+	struct iova_fq __percpu *queue;
+	int cpu;
+
+	queue = alloc_percpu(struct iova_fq);
+	if (!queue)
+		return -ENOMEM;
+
+	for_each_possible_cpu(cpu)
+		iommu_dma_init_one_fq(per_cpu_ptr(queue, cpu));
+	cookie->percpu_fq = queue;
+	return 0;
 }
 
 /* sysfs updates are serialised by the mutex of the group owning @domain */
-int iommu_dma_init_fq(struct iommu_domain *domain)
+int iommu_dma_init_fq(struct device *dev, struct iommu_domain *domain)
 {
 	struct iommu_dma_cookie *cookie = domain->iova_cookie;
-	struct iova_fq __percpu *queue;
-	int i, cpu;
+	const struct iommu_ops *ops = dev_iommu_ops(dev);
+	int rc;
 
 	if (cookie->fq_domain)
 		return 0;
 
+	if (ops->tune_dma_iommu)
+		ops->tune_dma_iommu(dev, &cookie->options);
+
 	atomic64_set(&cookie->fq_flush_start_cnt,  0);
 	atomic64_set(&cookie->fq_flush_finish_cnt, 0);
 
-	queue = alloc_percpu(struct iova_fq);
-	if (!queue) {
-		pr_warn("iova flush queue initialization failed\n");
-		return -ENOMEM;
-	}
-
-	for_each_possible_cpu(cpu) {
-		struct iova_fq *fq = per_cpu_ptr(queue, cpu);
-
-		fq->head = 0;
-		fq->tail = 0;
-
-		spin_lock_init(&fq->lock);
+	if (cookie->options.flags & IOMMU_DMA_OPTS_SINGLE_QUEUE)
+		rc = iommu_dma_init_fq_single(cookie);
+	else
+		rc = iommu_dma_init_fq_percpu(cookie);
 
-		for (i = 0; i < IOVA_FQ_SIZE; i++)
-			INIT_LIST_HEAD(&fq->entries[i].freelist);
+	if (rc) {
+		pr_warn("iova flush queue initialization failed\n");
+		/* fall back to strict mode */
+		domain->type = IOMMU_DOMAIN_DMA;
+		return rc;
 	}
 
-	cookie->fq = queue;
-
 	timer_setup(&cookie->fq_timer, fq_flush_timeout, 0);
 	atomic_set(&cookie->fq_timer_on, 0);
 	/*
@@ -297,6 +381,7 @@ static struct iommu_dma_cookie *cookie_alloc(enum iommu_dma_cookie_type type)
 	if (cookie) {
 		INIT_LIST_HEAD(&cookie->msi_page_list);
 		cookie->type = type;
+		cookie->options.flags = IOMMU_DMA_OPTS_PER_CPU_QUEUE;
 	}
 	return cookie;
 }
@@ -585,9 +670,9 @@ static int iommu_dma_init_domain(struct iommu_domain *domain, dma_addr_t base,
 	if (ret)
 		goto done_unlock;
 
-	/* If the FQ fails we can simply fall back to strict mode */
-	if (domain->type == IOMMU_DOMAIN_DMA_FQ && iommu_dma_init_fq(domain))
-		domain->type = IOMMU_DOMAIN_DMA;
+	/* If the FQ fails we fall back to strict mode */
+	if (domain->type == IOMMU_DOMAIN_DMA_FQ)
+		iommu_dma_init_fq(dev, domain);
 
 	ret = iova_reserve_iommu_regions(dev, domain);
 
diff --git a/drivers/iommu/dma-iommu.h b/drivers/iommu/dma-iommu.h
index 942790009292..4f727ab56d3c 100644
--- a/drivers/iommu/dma-iommu.h
+++ b/drivers/iommu/dma-iommu.h
@@ -12,7 +12,7 @@
 int iommu_get_dma_cookie(struct iommu_domain *domain);
 void iommu_put_dma_cookie(struct iommu_domain *domain);
 
-int iommu_dma_init_fq(struct iommu_domain *domain);
+int iommu_dma_init_fq(struct device *dev, struct iommu_domain *domain);
 
 void iommu_dma_get_resv_regions(struct device *dev, struct list_head *list);
 
@@ -20,7 +20,7 @@ extern bool iommu_dma_forcedac;
 
 #else /* CONFIG_IOMMU_DMA */
 
-static inline int iommu_dma_init_fq(struct iommu_domain *domain)
+static inline int iommu_dma_init_fq(struct device *dev, struct iommu_domain *domain)
 {
 	return -EINVAL;
 }
diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
index ae549b032a16..869dd0b6e1f3 100644
--- a/drivers/iommu/iommu.c
+++ b/drivers/iommu/iommu.c
@@ -2920,9 +2920,7 @@ static int iommu_change_dev_def_domain(struct iommu_group *group,
 
 	/* We can bring up a flush queue without tearing down the domain */
 	if (type == IOMMU_DOMAIN_DMA_FQ && prev_dom->type == IOMMU_DOMAIN_DMA) {
-		ret = iommu_dma_init_fq(prev_dom);
-		if (!ret)
-			prev_dom->type = IOMMU_DOMAIN_DMA_FQ;
+		ret = iommu_dma_init_fq(dev, prev_dom);
 		goto out;
 	}
 
diff --git a/drivers/iommu/s390-iommu.c b/drivers/iommu/s390-iommu.c
index 161b0be5aba6..65dd469ad524 100644
--- a/drivers/iommu/s390-iommu.c
+++ b/drivers/iommu/s390-iommu.c
@@ -451,6 +451,15 @@ static void s390_iommu_get_resv_regions(struct device *dev,
 	}
 }
 
+static void s390_iommu_tune_dma_iommu(struct device *dev,
+					     struct dma_iommu_options *options)
+{
+	struct zpci_dev *zdev = to_zpci_dev(dev);
+
+	if (zdev->tlb_refresh)
+		options->flags |= IOMMU_DMA_OPTS_SINGLE_QUEUE;
+}
+
 static struct iommu_device *s390_iommu_probe_device(struct device *dev)
 {
 	struct zpci_dev *zdev;
@@ -793,6 +802,7 @@ static const struct iommu_ops s390_iommu_ops = {
 	.device_group = generic_device_group,
 	.pgsize_bitmap = SZ_4K,
 	.get_resv_regions = s390_iommu_get_resv_regions,
+	.tune_dma_iommu = s390_iommu_tune_dma_iommu,
 	.default_domain_ops = &(const struct iommu_domain_ops) {
 		.attach_dev	= s390_iommu_attach_device,
 		.map_pages	= s390_iommu_map_pages,
diff --git a/include/linux/iommu.h b/include/linux/iommu.h
index 932e5532ee33..2b43a3de2c4f 100644
--- a/include/linux/iommu.h
+++ b/include/linux/iommu.h
@@ -219,6 +219,21 @@ struct iommu_iotlb_gather {
 	bool			queued;
 };
 
+/**
+ * struct dma_iommu_options - Options for dma-iommu
+ *
+ * @flags: Flag bits for enabling/disabling dma-iommu settings
+ *
+ * This structure is intended to provide IOMMU drivers a way to influence the
+ * behavior of the dma-iommu DMA API implementation. This allows optimizing for
+ * example for a virtualized environment with slow IOTLB flushes.
+ */
+struct dma_iommu_options {
+#define IOMMU_DMA_OPTS_PER_CPU_QUEUE	(0L << 0)
+#define IOMMU_DMA_OPTS_SINGLE_QUEUE	(1L << 0)
+	u64	flags;
+};
+
 /**
  * struct iommu_ops - iommu ops and capabilities
  * @capable: check capability
@@ -242,6 +257,9 @@ struct iommu_iotlb_gather {
  *		- IOMMU_DOMAIN_IDENTITY: must use an identity domain
  *		- IOMMU_DOMAIN_DMA: must use a dma domain
  *		- 0: use the default setting
+ * @tune_dma_iommu: Allows the IOMMU driver to modify the default
+ *		    options of the dma-iommu layer for a specific
+ *		    device.
  * @default_domain_ops: the default ops for domains
  * @remove_dev_pasid: Remove any translation configurations of a specific
  *                    pasid, so that any DMA transactions with this pasid
@@ -278,6 +296,9 @@ struct iommu_ops {
 	int (*def_domain_type)(struct device *dev);
 	void (*remove_dev_pasid)(struct device *dev, ioasid_t pasid);
 
+	void (*tune_dma_iommu)(struct device *dev,
+			       struct dma_iommu_options *options);
+
 	const struct iommu_domain_ops *default_domain_ops;
 	unsigned long pgsize_bitmap;
 	struct module *owner;

-- 
2.37.2

[PATCH v8 6/6] iommu/dma: Make flush queue sizes and timeout driver configurable

[Niklas Schnelle]

Flush queues currently use a fixed compile time size of 256 entries.
This being a power of 2 allows the compiler to use shift and mask
instead of more expensive modulo operations. With per-CPU flush queues
larger queue sizes would hit per-CPU allocation limits, with a single
flush queue these limits do not apply however. Also with single queues
being particularly suitable for virtualized environments with expensive
IOTLB flushes these benefit especially from larger queues and thus fewer
flushes.

To this end re-order struct iova_fq so we can use a dynamic array and
introduce the flush queue size and timeouts as new options in the
dma_iommu_options struct. So as not to lose the shift and mask
optimization, check that the variable length is a power of 2 and use
explicit shift and mask instead of letting the compiler optimize this.

In the s390 IOMMU driver a large fixed queue size and timeout is then
set together with single queue mode bringing its performance on s390
paged memory guests on par with the previous s390 specific DMA API
implementation.

Reviewed-by: Matthew Rosato <mjrosato@linux.ibm.com> #s390
Signed-off-by: Niklas Schnelle <schnelle@linux.ibm.com>
---
 drivers/iommu/dma-iommu.c  | 40 +++++++++++++++++++++++++---------------
 drivers/iommu/s390-iommu.c |  8 +++++++-
 include/linux/iommu.h      |  6 +++++-
 3 files changed, 37 insertions(+), 17 deletions(-)

diff --git a/drivers/iommu/dma-iommu.c b/drivers/iommu/dma-iommu.c
index 6f5fd110e0e0..ec71dda87521 100644
--- a/drivers/iommu/dma-iommu.c
+++ b/drivers/iommu/dma-iommu.c
@@ -89,10 +89,10 @@ static int __init iommu_dma_forcedac_setup(char *str)
 early_param("iommu.forcedac", iommu_dma_forcedac_setup);
 
 /* Number of entries per flush queue */
-#define IOVA_FQ_SIZE	256
+#define IOVA_DEFAULT_FQ_SIZE	256
 
 /* Timeout (in ms) after which entries are flushed from the queue */
-#define IOVA_FQ_TIMEOUT	10
+#define IOVA_DEFAULT_FQ_TIMEOUT	10
 
 /* Flush queue entry for deferred flushing */
 struct iova_fq_entry {
@@ -104,18 +104,19 @@ struct iova_fq_entry {
 
 /* Per-CPU flush queue structure */
 struct iova_fq {
-	struct iova_fq_entry entries[IOVA_FQ_SIZE];
-	unsigned int head, tail;
 	spinlock_t lock;
+	unsigned int head, tail;
+	unsigned int mod_mask;
+	struct iova_fq_entry entries[];
 };
 
 #define fq_ring_for_each(i, fq) \
-	for ((i) = (fq)->head; (i) != (fq)->tail; (i) = ((i) + 1) % IOVA_FQ_SIZE)
+	for ((i) = (fq)->head; (i) != (fq)->tail; (i) = ((i) + 1) & (fq)->mod_mask)
 
 static inline bool fq_full(struct iova_fq *fq)
 {
 	assert_spin_locked(&fq->lock);
-	return (((fq->tail + 1) % IOVA_FQ_SIZE) == fq->head);
+	return (((fq->tail + 1) & fq->mod_mask) == fq->head);
 }
 
 static inline unsigned int fq_ring_add(struct iova_fq *fq)
@@ -124,7 +125,7 @@ static inline unsigned int fq_ring_add(struct iova_fq *fq)
 
 	assert_spin_locked(&fq->lock);
 
-	fq->tail = (idx + 1) % IOVA_FQ_SIZE;
+	fq->tail = (idx + 1) & fq->mod_mask;
 
 	return idx;
 }
@@ -146,7 +147,7 @@ static void fq_ring_free(struct iommu_dma_cookie *cookie, struct iova_fq *fq)
 			       fq->entries[idx].iova_pfn,
 			       fq->entries[idx].pages);
 
-		fq->head = (fq->head + 1) % IOVA_FQ_SIZE;
+		fq->head = (fq->head + 1) & fq->mod_mask;
 	}
 }
 
@@ -244,7 +245,7 @@ static void queue_iova(struct iommu_dma_cookie *cookie,
 	if (!atomic_read(&cookie->fq_timer_on) &&
 	    !atomic_xchg(&cookie->fq_timer_on, 1))
 		mod_timer(&cookie->fq_timer,
-			  jiffies + msecs_to_jiffies(IOVA_FQ_TIMEOUT));
+			  jiffies + msecs_to_jiffies(cookie->options.fq_timeout));
 }
 
 static void iommu_dma_free_fq_single(struct iova_fq *fq)
@@ -286,27 +287,29 @@ static void iommu_dma_free_fq(struct iommu_dma_cookie *cookie)
 }
 
 
-static void iommu_dma_init_one_fq(struct iova_fq *fq)
+static void iommu_dma_init_one_fq(struct iova_fq *fq, size_t fq_size)
 {
 	int i;
 
 	fq->head = 0;
 	fq->tail = 0;
+	fq->mod_mask = fq_size - 1;
 
 	spin_lock_init(&fq->lock);
 
-	for (i = 0; i < IOVA_FQ_SIZE; i++)
+	for (i = 0; i < fq_size; i++)
 		INIT_LIST_HEAD(&fq->entries[i].freelist);
 }
 
 static int iommu_dma_init_fq_single(struct iommu_dma_cookie *cookie)
 {
+	size_t fq_size = cookie->options.fq_size;
 	struct iova_fq *queue;
 
-	queue = vzalloc(sizeof(*queue));
+	queue = vzalloc(struct_size(queue, entries, fq_size));
 	if (!queue)
 		return -ENOMEM;
-	iommu_dma_init_one_fq(queue);
+	iommu_dma_init_one_fq(queue, fq_size);
 	cookie->single_fq = queue;
 
 	return 0;
@@ -314,15 +317,17 @@ static int iommu_dma_init_fq_single(struct iommu_dma_cookie *cookie)
 
 static int iommu_dma_init_fq_percpu(struct iommu_dma_cookie *cookie)
 {
+	size_t fq_size = cookie->options.fq_size;
 	struct iova_fq __percpu *queue;
 	int cpu;
 
-	queue = alloc_percpu(struct iova_fq);
+	queue = __alloc_percpu(struct_size(queue, entries, fq_size),
+			       __alignof__(*queue));
 	if (!queue)
 		return -ENOMEM;
 
 	for_each_possible_cpu(cpu)
-		iommu_dma_init_one_fq(per_cpu_ptr(queue, cpu));
+		iommu_dma_init_one_fq(per_cpu_ptr(queue, cpu), fq_size);
 	cookie->percpu_fq = queue;
 	return 0;
 }
@@ -340,6 +345,9 @@ int iommu_dma_init_fq(struct device *dev, struct iommu_domain *domain)
 	if (ops->tune_dma_iommu)
 		ops->tune_dma_iommu(dev, &cookie->options);
 
+	if (WARN_ON_ONCE(!is_power_of_2(cookie->options.fq_size)))
+		cookie->options.fq_size = IOVA_DEFAULT_FQ_SIZE;
+
 	atomic64_set(&cookie->fq_flush_start_cnt,  0);
 	atomic64_set(&cookie->fq_flush_finish_cnt, 0);
 
@@ -382,6 +390,8 @@ static struct iommu_dma_cookie *cookie_alloc(enum iommu_dma_cookie_type type)
 		INIT_LIST_HEAD(&cookie->msi_page_list);
 		cookie->type = type;
 		cookie->options.flags = IOMMU_DMA_OPTS_PER_CPU_QUEUE;
+		cookie->options.fq_size = IOVA_DEFAULT_FQ_SIZE;
+		cookie->options.fq_timeout = IOVA_DEFAULT_FQ_TIMEOUT;
 	}
 	return cookie;
 }
diff --git a/drivers/iommu/s390-iommu.c b/drivers/iommu/s390-iommu.c
index 65dd469ad524..77d204232646 100644
--- a/drivers/iommu/s390-iommu.c
+++ b/drivers/iommu/s390-iommu.c
@@ -451,13 +451,19 @@ static void s390_iommu_get_resv_regions(struct device *dev,
 	}
 }
 
+#define S390_IOMMU_SINGLE_FQ_SIZE      32768
+#define S390_IOMMU_SINGLE_FQ_TIMEOUT   1000
+
 static void s390_iommu_tune_dma_iommu(struct device *dev,
 					     struct dma_iommu_options *options)
 {
 	struct zpci_dev *zdev = to_zpci_dev(dev);
 
-	if (zdev->tlb_refresh)
+	if (zdev->tlb_refresh) {
 		options->flags |= IOMMU_DMA_OPTS_SINGLE_QUEUE;
+		options->fq_size = S390_IOMMU_SINGLE_FQ_SIZE;
+		options->fq_timeout = S390_IOMMU_SINGLE_FQ_TIMEOUT;
+	}
 }
 
 static struct iommu_device *s390_iommu_probe_device(struct device *dev)
diff --git a/include/linux/iommu.h b/include/linux/iommu.h
index 2b43a3de2c4f..1675755b7f7d 100644
--- a/include/linux/iommu.h
+++ b/include/linux/iommu.h
@@ -223,6 +223,8 @@ struct iommu_iotlb_gather {
  * struct dma_iommu_options - Options for dma-iommu
  *
  * @flags: Flag bits for enabling/disabling dma-iommu settings
+ * @fq_size: Size of the IOTLB flush queue(s), must be a power of two
+ * @fq_timeout: Timeout used for queued IOTLB flushes
  *
  * This structure is intended to provide IOMMU drivers a way to influence the
  * behavior of the dma-iommu DMA API implementation. This allows optimizing for
@@ -231,7 +233,9 @@ struct iommu_iotlb_gather {
 struct dma_iommu_options {
 #define IOMMU_DMA_OPTS_PER_CPU_QUEUE	(0L << 0)
 #define IOMMU_DMA_OPTS_SINGLE_QUEUE	(1L << 0)
-	u64	flags;
+	u64		flags;
+	size_t		fq_size;
+	unsigned int	fq_timeout;
 };
 
 /**

-- 
2.37.2

Re: [PATCH v8 2/6] iommu: Allow .iotlb_sync_map to fail and handle s390's -ENOMEM return

[Jernej Škrabec]

Dne petek, 10. marec 2023 ob 17:07:47 CET je Niklas Schnelle napisal(a):
> On s390 when using a paging hypervisor, .iotlb_sync_map is used to sync
> mappings by letting the hypervisor inspect the synced IOVA range and
> updating a shadow table. This however means that .iotlb_sync_map can
> fail as the hypervisor may run out of resources while doing the sync.
> This can be due to the hypervisor being unable to pin guest pages, due
> to a limit on mapped addresses such as vfio_iommu_type1.dma_entry_limit
> or lack of other resources. Either way such a failure to sync a mapping
> should result in a DMA_MAPPING_ERROR.
> 
> Now especially when running with batched IOTLB flushes for unmap it may
> be that some IOVAs have already been invalidated but not yet synced via
> .iotlb_sync_map. Thus if the hypervisor indicates running out of
> resources, first do a global flush allowing the hypervisor to free
> resources associated with these mappings as well a retry creating the
> new mappings and only if that also fails report this error to callers.
> 
> Reviewed-by: Lu Baolu <baolu.lu@linux.intel.com>
> Reviewed-by: Matthew Rosato <mjrosato@linux.ibm.com>
> Signed-off-by: Niklas Schnelle <schnelle@linux.ibm.com>
> ---
>  drivers/iommu/amd/iommu.c    |  5 +++--
>  drivers/iommu/apple-dart.c   |  5 +++--
>  drivers/iommu/intel/iommu.c  |  5 +++--
>  drivers/iommu/iommu.c        | 20 ++++++++++++++++----
>  drivers/iommu/msm_iommu.c    |  5 +++--
>  drivers/iommu/mtk_iommu.c    |  5 +++--
>  drivers/iommu/s390-iommu.c   | 29 ++++++++++++++++++++++++-----
>  drivers/iommu/sprd-iommu.c   |  5 +++--
>  drivers/iommu/sun50i-iommu.c |  4 +++-

For sun50i:
Acked-by: Jernej Skrabec <jernej.skrabec@gmail.com>

Best regards,
Jernej

>  drivers/iommu/tegra-gart.c   |  5 +++--
>  include/linux/iommu.h        |  4 ++--
>  11 files changed, 66 insertions(+), 26 deletions(-)
> 
> diff --git a/drivers/iommu/amd/iommu.c b/drivers/iommu/amd/iommu.c
> index 5a505ba5467e..ff309bd1bb8f 100644
> --- a/drivers/iommu/amd/iommu.c
> +++ b/drivers/iommu/amd/iommu.c
> @@ -2187,14 +2187,15 @@ static int amd_iommu_attach_device(struct
> iommu_domain *dom, return ret;
>  }
> 
> -static void amd_iommu_iotlb_sync_map(struct iommu_domain *dom,
> -				     unsigned long iova, size_t 
size)
> +static int amd_iommu_iotlb_sync_map(struct iommu_domain *dom,
> +				    unsigned long iova, size_t 
size)
>  {
>  	struct protection_domain *domain = to_pdomain(dom);
>  	struct io_pgtable_ops *ops = &domain->iop.iop.ops;
> 
>  	if (ops->map_pages)
>  		domain_flush_np_cache(domain, iova, size);
> +	return 0;
>  }
> 
>  static int amd_iommu_map_pages(struct iommu_domain *dom, unsigned long
> iova, diff --git a/drivers/iommu/apple-dart.c b/drivers/iommu/apple-dart.c
> index 06169d36eab8..cbed1f87eae9 100644
> --- a/drivers/iommu/apple-dart.c
> +++ b/drivers/iommu/apple-dart.c
> @@ -506,10 +506,11 @@ static void apple_dart_iotlb_sync(struct iommu_domain
> *domain, apple_dart_domain_flush_tlb(to_dart_domain(domain));
>  }
> 
> -static void apple_dart_iotlb_sync_map(struct iommu_domain *domain,
> -				      unsigned long iova, size_t 
size)
> +static int apple_dart_iotlb_sync_map(struct iommu_domain *domain,
> +				     unsigned long iova, size_t 
size)
>  {
>  	apple_dart_domain_flush_tlb(to_dart_domain(domain));
> +	return 0;
>  }
> 
>  static phys_addr_t apple_dart_iova_to_phys(struct iommu_domain *domain,
> diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c
> index 7c2f4bd33582..b795b2f323e3 100644
> --- a/drivers/iommu/intel/iommu.c
> +++ b/drivers/iommu/intel/iommu.c
> @@ -4745,8 +4745,8 @@ static bool risky_device(struct pci_dev *pdev)
>  	return false;
>  }
> 
> -static void intel_iommu_iotlb_sync_map(struct iommu_domain *domain,
> -				       unsigned long iova, size_t 
size)
> +static int intel_iommu_iotlb_sync_map(struct iommu_domain *domain,
> +				      unsigned long iova, size_t 
size)
>  {
>  	struct dmar_domain *dmar_domain = to_dmar_domain(domain);
>  	unsigned long pages = aligned_nrpages(iova, size);
> @@ -4756,6 +4756,7 @@ static void intel_iommu_iotlb_sync_map(struct
> iommu_domain *domain,
> 
>  	xa_for_each(&dmar_domain->iommu_array, i, info)
>  		__mapping_notify_one(info->iommu, dmar_domain, pfn, 
pages);
> +	return 0;
>  }
> 
>  static void intel_iommu_remove_dev_pasid(struct device *dev, ioasid_t
> pasid) diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
> index 10db680acaed..ae549b032a16 100644
> --- a/drivers/iommu/iommu.c
> +++ b/drivers/iommu/iommu.c
> @@ -2410,8 +2410,17 @@ int iommu_map(struct iommu_domain *domain, unsigned
> long iova, return -EINVAL;
> 
>  	ret = __iommu_map(domain, iova, paddr, size, prot, gfp);
> -	if (ret == 0 && ops->iotlb_sync_map)
> -		ops->iotlb_sync_map(domain, iova, size);
> +	if (ret == 0 && ops->iotlb_sync_map) {
> +		ret = ops->iotlb_sync_map(domain, iova, size);
> +		if (ret)
> +			goto out_err;
> +	}
> +
> +	return ret;
> +
> +out_err:
> +	/* undo mappings already done */
> +	iommu_unmap(domain, iova, size);
> 
>  	return ret;
>  }
> @@ -2552,8 +2561,11 @@ ssize_t iommu_map_sg(struct iommu_domain *domain,
> unsigned long iova, sg = sg_next(sg);
>  	}
> 
> -	if (ops->iotlb_sync_map)
> -		ops->iotlb_sync_map(domain, iova, mapped);
> +	if (ops->iotlb_sync_map) {
> +		ret = ops->iotlb_sync_map(domain, iova, mapped);
> +		if (ret)
> +			goto out_err;
> +	}
>  	return mapped;
> 
>  out_err:
> diff --git a/drivers/iommu/msm_iommu.c b/drivers/iommu/msm_iommu.c
> index 454f6331c889..2033716eac78 100644
> --- a/drivers/iommu/msm_iommu.c
> +++ b/drivers/iommu/msm_iommu.c
> @@ -486,12 +486,13 @@ static int msm_iommu_map(struct iommu_domain *domain,
> unsigned long iova, return ret;
>  }
> 
> -static void msm_iommu_sync_map(struct iommu_domain *domain, unsigned long
> iova, -			       size_t size)
> +static int msm_iommu_sync_map(struct iommu_domain *domain, unsigned long
> iova, +			      size_t size)
>  {
>  	struct msm_priv *priv = to_msm_priv(domain);
> 
>  	__flush_iotlb_range(iova, size, SZ_4K, false, priv);
> +	return 0;
>  }
> 
>  static size_t msm_iommu_unmap(struct iommu_domain *domain, unsigned long
> iova, diff --git a/drivers/iommu/mtk_iommu.c b/drivers/iommu/mtk_iommu.c
> index d5a4955910ff..29769fb5c51e 100644
> --- a/drivers/iommu/mtk_iommu.c
> +++ b/drivers/iommu/mtk_iommu.c
> @@ -750,12 +750,13 @@ static void mtk_iommu_iotlb_sync(struct iommu_domain
> *domain, mtk_iommu_tlb_flush_range_sync(gather->start, length, dom->bank);
> }
> 
> -static void mtk_iommu_sync_map(struct iommu_domain *domain, unsigned long
> iova, -			       size_t size)
> +static int mtk_iommu_sync_map(struct iommu_domain *domain, unsigned long
> iova, +			      size_t size)
>  {
>  	struct mtk_iommu_domain *dom = to_mtk_domain(domain);
> 
>  	mtk_iommu_tlb_flush_range_sync(iova, size, dom->bank);
> +	return 0;
>  }
> 
>  static phys_addr_t mtk_iommu_iova_to_phys(struct iommu_domain *domain,
> diff --git a/drivers/iommu/s390-iommu.c b/drivers/iommu/s390-iommu.c
> index fbf59a8db29b..17174b35db11 100644
> --- a/drivers/iommu/s390-iommu.c
> +++ b/drivers/iommu/s390-iommu.c
> @@ -205,6 +205,14 @@ static void s390_iommu_release_device(struct device
> *dev) __s390_iommu_detach_device(zdev);
>  }
> 
> +
> +static int zpci_refresh_all(struct zpci_dev *zdev)
> +{
> +	return zpci_refresh_trans((u64)zdev->fh << 32, zdev->start_dma,
> +				  zdev->end_dma - zdev->start_dma 
+ 1);
> +
> +}
> +
>  static void s390_iommu_flush_iotlb_all(struct iommu_domain *domain)
>  {
>  	struct s390_domain *s390_domain = to_s390_domain(domain);
> @@ -212,8 +220,7 @@ static void s390_iommu_flush_iotlb_all(struct
> iommu_domain *domain)
> 
>  	rcu_read_lock();
>  	list_for_each_entry_rcu(zdev, &s390_domain->devices, iommu_list) {
> -		zpci_refresh_trans((u64)zdev->fh << 32, zdev-
>start_dma,
> -				   zdev->end_dma - zdev-
>start_dma + 1);
> +		zpci_refresh_all(zdev);
>  	}
>  	rcu_read_unlock();
>  }
> @@ -237,20 +244,32 @@ static void s390_iommu_iotlb_sync(struct iommu_domain
> *domain, rcu_read_unlock();
>  }
> 
> -static void s390_iommu_iotlb_sync_map(struct iommu_domain *domain,
> +static int s390_iommu_iotlb_sync_map(struct iommu_domain *domain,
>  				      unsigned long iova, size_t 
size)
>  {
>  	struct s390_domain *s390_domain = to_s390_domain(domain);
>  	struct zpci_dev *zdev;
> +	int ret = 0;
> 
>  	rcu_read_lock();
>  	list_for_each_entry_rcu(zdev, &s390_domain->devices, iommu_list) {
>  		if (!zdev->tlb_refresh)
>  			continue;
> -		zpci_refresh_trans((u64)zdev->fh << 32,
> -				   iova, size);
> +		ret = zpci_refresh_trans((u64)zdev->fh << 32,
> +					 iova, size);
> +		/*
> +		 * let the hypervisor discover invalidated entries
> +		 * allowing it to free IOVAs and unpin pages
> +		 */
> +		if (ret == -ENOMEM) {
> +			ret = zpci_refresh_all(zdev);
> +			if (ret)
> +				break;
> +		}
>  	}
>  	rcu_read_unlock();
> +
> +	return ret;
>  }
> 
>  static int s390_iommu_validate_trans(struct s390_domain *s390_domain,
> diff --git a/drivers/iommu/sprd-iommu.c b/drivers/iommu/sprd-iommu.c
> index ae94d74b73f4..74bcae69653c 100644
> --- a/drivers/iommu/sprd-iommu.c
> +++ b/drivers/iommu/sprd-iommu.c
> @@ -315,8 +315,8 @@ static size_t sprd_iommu_unmap(struct iommu_domain
> *domain, unsigned long iova, return size;
>  }
> 
> -static void sprd_iommu_sync_map(struct iommu_domain *domain,
> -				unsigned long iova, size_t size)
> +static int sprd_iommu_sync_map(struct iommu_domain *domain,
> +			       unsigned long iova, size_t size)
>  {
>  	struct sprd_iommu_domain *dom = to_sprd_domain(domain);
>  	unsigned int reg;
> @@ -328,6 +328,7 @@ static void sprd_iommu_sync_map(struct iommu_domain
> *domain,
> 
>  	/* clear IOMMU TLB buffer after page table updated */
>  	sprd_iommu_write(dom->sdev, reg, 0xffffffff);
> +	return 0;
>  }
> 
>  static void sprd_iommu_sync(struct iommu_domain *domain,
> diff --git a/drivers/iommu/sun50i-iommu.c b/drivers/iommu/sun50i-iommu.c
> index 2d993d0cea7d..60a983f4a494 100644
> --- a/drivers/iommu/sun50i-iommu.c
> +++ b/drivers/iommu/sun50i-iommu.c
> @@ -402,7 +402,7 @@ static void sun50i_iommu_flush_iotlb_all(struct
> iommu_domain *domain) spin_unlock_irqrestore(&iommu->iommu_lock, flags);
>  }
> 
> -static void sun50i_iommu_iotlb_sync_map(struct iommu_domain *domain,
> +static int sun50i_iommu_iotlb_sync_map(struct iommu_domain *domain,
>  					unsigned long iova, 
size_t size)
>  {
>  	struct sun50i_iommu_domain *sun50i_domain = 
to_sun50i_domain(domain);
> @@ -412,6 +412,8 @@ static void sun50i_iommu_iotlb_sync_map(struct
> iommu_domain *domain, spin_lock_irqsave(&iommu->iommu_lock, flags);
>  	sun50i_iommu_zap_range(iommu, iova, size);
>  	spin_unlock_irqrestore(&iommu->iommu_lock, flags);
> +
> +	return 0;
>  }
> 
>  static void sun50i_iommu_iotlb_sync(struct iommu_domain *domain,
> diff --git a/drivers/iommu/tegra-gart.c b/drivers/iommu/tegra-gart.c
> index a482ff838b53..44966d7b07ba 100644
> --- a/drivers/iommu/tegra-gart.c
> +++ b/drivers/iommu/tegra-gart.c
> @@ -252,10 +252,11 @@ static int gart_iommu_of_xlate(struct device *dev,
>  	return 0;
>  }
> 
> -static void gart_iommu_sync_map(struct iommu_domain *domain, unsigned long
> iova, -				size_t size)
> +static int gart_iommu_sync_map(struct iommu_domain *domain, unsigned long
> iova, +			       size_t size)
>  {
>  	FLUSH_GART_REGS(gart_handle);
> +	return 0;
>  }
> 
>  static void gart_iommu_sync(struct iommu_domain *domain,
> diff --git a/include/linux/iommu.h b/include/linux/iommu.h
> index 6595454d4f48..932e5532ee33 100644
> --- a/include/linux/iommu.h
> +++ b/include/linux/iommu.h
> @@ -333,8 +333,8 @@ struct iommu_domain_ops {
>  			      struct iommu_iotlb_gather 
*iotlb_gather);
> 
>  	void (*flush_iotlb_all)(struct iommu_domain *domain);
> -	void (*iotlb_sync_map)(struct iommu_domain *domain, unsigned long 
iova,
> -			       size_t size);
> +	int (*iotlb_sync_map)(struct iommu_domain *domain, unsigned long 
iova,
> +			      size_t size);
>  	void (*iotlb_sync)(struct iommu_domain *domain,
>  			   struct iommu_iotlb_gather *iotlb_gather);

Re: [PATCH v8 0/6] iommu/dma: s390 DMA API conversion and optimized IOTLB flushing

[Christoph Hellwig]

On Fri, Mar 10, 2023 at 05:07:45PM +0100, Niklas Schnelle wrote:
> Hi All,
> 
> This patch series converts s390's PCI support from its platform specific DMA
> API implementation in arch/s390/pci/pci_dma.c to the common DMA IOMMU layer.
> The conversion itself is done in patches 3-4 with patch 2 providing the final
> necessary IOMMU driver improvement to handle s390's special IOTLB flush
> out-of-resource indication in virtualized environments. Patches 1-2 may be
> applied independently. The conversion itself only touches the s390 IOMMU driver
> and s390 arch code moving over remaining functions from the s390 DMA API
> implementation. No changes to common code are necessary.

It looks like this still hasn't made it upstream as of 6.4-rc1.  What's
holding this series up?

Re: [PATCH v8 0/6] iommu/dma: s390 DMA API conversion and optimized IOTLB flushing

[Niklas Schnelle]

On Fri, 2023-05-12 at 07:29 -0700, Christoph Hellwig wrote:
> On Fri, Mar 10, 2023 at 05:07:45PM +0100, Niklas Schnelle wrote:
> > Hi All,
> > 
> > This patch series converts s390's PCI support from its platform specific DMA
> > API implementation in arch/s390/pci/pci_dma.c to the common DMA IOMMU layer.
> > The conversion itself is done in patches 3-4 with patch 2 providing the final
> > necessary IOMMU driver improvement to handle s390's special IOTLB flush
> > out-of-resource indication in virtualized environments. Patches 1-2 may be
> > applied independently. The conversion itself only touches the s390 IOMMU driver
> > and s390 arch code moving over remaining functions from the s390 DMA API
> > implementation. No changes to common code are necessary.
> 
> It looks like this still hasn't made it upstream as of 6.4-rc1.  What's
> holding this series up?
> 

I think with all the IOMMUFD work going on this got starved out of
reviewer resources. I didn't have any open todos but I guess there is
still some review needed around how the IOMMU driver tells the dma-
iommu that it expects IOTLB flushes to be slow requiring a larger
single flush queue. There was also a small conflict with commit
49a22aae7d9c ("iommu: Replace device_lock() with group->mutex") that
prevented this from applying to current upstream so I've just now sent
out a v9 rebased on v6.4-rc2.

Thanks,
Niklas