powerpc/powernv: Add indirect levels to it_userspace

We want to support sparse memory and therefore huge chunks of DMA windows
do not need to be mapped. If a DMA window big enough to require 2 or more
indirect levels, and a DMA window is used to map all RAM (which is
a default case for 64bit window), we can actually save some memory by
not allocation TCE for regions which we are not going to map anyway.

The hardware tables alreary support indirect levels but we also keep
host-physical-to-userspace translation array which is allocated by
vmalloc() and is a flat array which might use quite some memory.

This converts it_userspace from vmalloc'ed array to a multi level table.

As the format becomes platform dependend, this replaces the direct access
to it_usespace with a iommu_table_ops::useraddrptr hook which returns
a pointer to the userspace copy of a TCE; future extension will return
NULL if the level was not allocated.

This should not change non-KVM handling of TCE tables and it_userspace
will not be allocated for non-KVM tables.

Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

1 files changed, 17 insertions, 6 deletions

diff --git a/arch/powerpc/platforms/powernv/pci-ioda.c b/arch/powerpc/platforms/powernv/pci-ioda.c
index 4abf1175626e..fc38f06ee41d 100644
--- a/arch/powerpc/platforms/powernv/pci-ioda.c
+++ b/arch/powerpc/platforms/powernv/pci-ioda.c
@@ -2036,6 +2036,7 @@ static struct iommu_table_ops pnv_ioda1_iommu_ops = {
 #ifdef CONFIG_IOMMU_API
 	.exchange = pnv_ioda1_tce_xchg,
 	.exchange_rm = pnv_ioda1_tce_xchg_rm,
+	.useraddrptr = pnv_tce_useraddrptr,
 #endif
 	.clear = pnv_ioda1_tce_free,
 	.get = pnv_tce_get,
@@ -2200,6 +2201,7 @@ static struct iommu_table_ops pnv_ioda2_iommu_ops = {
 #ifdef CONFIG_IOMMU_API
 	.exchange = pnv_ioda2_tce_xchg,
 	.exchange_rm = pnv_ioda2_tce_xchg_rm,
+	.useraddrptr = pnv_tce_useraddrptr,
 #endif
 	.clear = pnv_ioda2_tce_free,
 	.get = pnv_tce_get,
@@ -2455,7 +2457,7 @@ void pnv_pci_ioda2_set_bypass(struct pnv_ioda_pe *pe, bool enable)
 
 static long pnv_pci_ioda2_create_table(struct iommu_table_group *table_group,
 		int num, __u32 page_shift, __u64 window_size, __u32 levels,
-		struct iommu_table **ptbl)
+		bool alloc_userspace_copy, struct iommu_table **ptbl)
 {
 	struct pnv_ioda_pe *pe = container_of(table_group, struct pnv_ioda_pe,
 			table_group);
@@ -2472,7 +2474,7 @@ static long pnv_pci_ioda2_create_table(struct iommu_table_group *table_group,
 
 	ret = pnv_pci_ioda2_table_alloc_pages(nid,
 			bus_offset, page_shift, window_size,
-			levels, tbl);
+			levels, alloc_userspace_copy, tbl);
 	if (ret) {
 		iommu_tce_table_put(tbl);
 		return ret;
@@ -2505,7 +2507,7 @@ static long pnv_pci_ioda2_setup_default_config(struct pnv_ioda_pe *pe)
 	rc = pnv_pci_ioda2_create_table(&pe->table_group, 0,
 			IOMMU_PAGE_SHIFT_4K,
 			window_size,
-			POWERNV_IOMMU_DEFAULT_LEVELS, &tbl);
+			POWERNV_IOMMU_DEFAULT_LEVELS, false, &tbl);
 	if (rc) {
 		pe_err(pe, "Failed to create 32-bit TCE table, err %ld",
 				rc);
@@ -2592,7 +2594,16 @@ static unsigned long pnv_pci_ioda2_get_table_size(__u32 page_shift,
 				tce_table_size, direct_table_size);
 	}
 
-	return bytes;
+	return bytes + bytes; /* one for HW table, one for userspace copy */
+}
+
+static long pnv_pci_ioda2_create_table_userspace(
+		struct iommu_table_group *table_group,
+		int num, __u32 page_shift, __u64 window_size, __u32 levels,
+		struct iommu_table **ptbl)
+{
+	return pnv_pci_ioda2_create_table(table_group,
+			num, page_shift, window_size, levels, true, ptbl);
 }
 
 static void pnv_ioda2_take_ownership(struct iommu_table_group *table_group)
@@ -2621,7 +2632,7 @@ static void pnv_ioda2_release_ownership(struct iommu_table_group *table_group)
 
 static struct iommu_table_group_ops pnv_pci_ioda2_ops = {
 	.get_table_size = pnv_pci_ioda2_get_table_size,
-	.create_table = pnv_pci_ioda2_create_table,
+	.create_table = pnv_pci_ioda2_create_table_userspace,
 	.set_window = pnv_pci_ioda2_set_window,
 	.unset_window = pnv_pci_ioda2_unset_window,
 	.take_ownership = pnv_ioda2_take_ownership,
@@ -2726,7 +2737,7 @@ static void pnv_ioda2_npu_take_ownership(struct iommu_table_group *table_group)
 
 static struct iommu_table_group_ops pnv_pci_ioda2_npu_ops = {
 	.get_table_size = pnv_pci_ioda2_get_table_size,
-	.create_table = pnv_pci_ioda2_create_table,
+	.create_table = pnv_pci_ioda2_create_table_userspace,
 	.set_window = pnv_pci_ioda2_npu_set_window,
 	.unset_window = pnv_pci_ioda2_npu_unset_window,
 	.take_ownership = pnv_ioda2_npu_take_ownership,