powerpc/powernv/npu: Add compound IOMMU groups

At the moment the powernv platform registers an IOMMU group for each
PE. There is an exception though: an NVLink bridge which is attached
to the corresponding GPU's IOMMU group making it a master.

Now we have POWER9 systems with GPUs connected to each other directly
bypassing PCI. At the moment we do not control state of these links so
we have to put such interconnected GPUs to one IOMMU group which means
that the old scheme with one GPU as a master won't work - there will
be up to 3 GPUs in such group.

This introduces a npu_comp struct which represents a compound IOMMU
group made of multiple PEs - PCI PEs (for GPUs) and NPU PEs (for
NVLink bridges). This converts the existing NVLink1 code to use the
new scheme. >From now on, each PE must have a valid
iommu_table_group_ops which will either be called directly (for a
single PE group) or indirectly from a compound group handlers.

This moves IOMMU group registration for NVLink-connected GPUs to
npu-dma.c. For POWER8, this stores a new compound group pointer in the
PE (so a GPU is still a master); for POWER9 the new group pointer is
stored in an NPU (which is allocated per a PCI host controller).

Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
[mpe: Initialise npdev to NULL in pnv_try_setup_npu_table_group()]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

1 files changed, 266 insertions, 25 deletions

diff --git a/arch/powerpc/platforms/powernv/npu-dma.c b/arch/powerpc/platforms/powernv/npu-dma.c
index ec52b970cefa..102983207734 100644
--- a/arch/powerpc/platforms/powernv/npu-dma.c
+++ b/arch/powerpc/platforms/powernv/npu-dma.c
@@ -327,31 +327,6 @@ static struct iommu_table_group_ops pnv_pci_npu_ops = {
 	.unset_window = pnv_npu_unset_window,
 	.take_ownership = pnv_npu_take_ownership,
 };
-
-struct pnv_ioda_pe *pnv_pci_npu_setup_iommu(struct pnv_ioda_pe *npe)
-{
-	struct pnv_phb *phb = npe->phb;
-	struct pci_bus *pbus = phb->hose->bus;
-	struct pci_dev *npdev, *gpdev = NULL, *gptmp;
-	struct pnv_ioda_pe *gpe = get_gpu_pci_dev_and_pe(npe, &gpdev);
-
-	if (!gpe || !gpdev)
-		return NULL;
-
-	npe->table_group.ops = &pnv_pci_npu_ops;
-
-	list_for_each_entry(npdev, &pbus->devices, bus_list) {
-		gptmp = pnv_pci_get_gpu_dev(npdev);
-
-		if (gptmp != gpdev)
-			continue;
-
-		pe_info(gpe, "Attached NPU %s\n", dev_name(&npdev->dev));
-		iommu_group_add_device(gpe->table_group.group, &npdev->dev);
-	}
-
-	return gpe;
-}
 #endif /* !CONFIG_IOMMU_API */
 
 /*
@@ -359,6 +334,17 @@ struct pnv_ioda_pe *pnv_pci_npu_setup_iommu(struct pnv_ioda_pe *npe)
  */
 /* Maximum possible number of ATSD MMIO registers per NPU */
 #define NV_NMMU_ATSD_REGS 8
+#define NV_NPU_MAX_PE_NUM	16
+
+/*
+ * A compound NPU IOMMU group which might consist of 1 GPU + 2xNPUs (POWER8) or
+ * up to 3 x (GPU + 2xNPUs) (POWER9).
+ */
+struct npu_comp {
+	struct iommu_table_group table_group;
+	int pe_num;
+	struct pnv_ioda_pe *pe[NV_NPU_MAX_PE_NUM];
+};
 
 /* An NPU descriptor, valid for POWER9 only */
 struct npu {
@@ -371,8 +357,263 @@ struct npu {
 
 	/* Do we need to explicitly flush the nest mmu? */
 	bool nmmu_flush;
+
+	struct npu_comp npucomp;
 };
 
+#ifdef CONFIG_IOMMU_API
+static long pnv_npu_peers_create_table_userspace(
+		struct iommu_table_group *table_group,
+		int num, __u32 page_shift, __u64 window_size, __u32 levels,
+		struct iommu_table **ptbl)
+{
+	struct npu_comp *npucomp = container_of(table_group, struct npu_comp,
+			table_group);
+
+	if (!npucomp->pe_num || !npucomp->pe[0] ||
+			!npucomp->pe[0]->table_group.ops ||
+			!npucomp->pe[0]->table_group.ops->create_table)
+		return -EFAULT;
+
+	return npucomp->pe[0]->table_group.ops->create_table(
+			&npucomp->pe[0]->table_group, num, page_shift,
+			window_size, levels, ptbl);
+}
+
+static long pnv_npu_peers_set_window(struct iommu_table_group *table_group,
+		int num, struct iommu_table *tbl)
+{
+	int i, j;
+	long ret = 0;
+	struct npu_comp *npucomp = container_of(table_group, struct npu_comp,
+			table_group);
+
+	for (i = 0; i < npucomp->pe_num; ++i) {
+		struct pnv_ioda_pe *pe = npucomp->pe[i];
+
+		if (!pe->table_group.ops->set_window)
+			continue;
+
+		ret = pe->table_group.ops->set_window(&pe->table_group,
+				num, tbl);
+		if (ret)
+			break;
+	}
+
+	if (ret) {
+		for (j = 0; j < i; ++j) {
+			struct pnv_ioda_pe *pe = npucomp->pe[j];
+
+			if (!pe->table_group.ops->unset_window)
+				continue;
+
+			ret = pe->table_group.ops->unset_window(
+					&pe->table_group, num);
+			if (ret)
+				break;
+		}
+	} else {
+		table_group->tables[num] = iommu_tce_table_get(tbl);
+	}
+
+	return ret;
+}
+
+static long pnv_npu_peers_unset_window(struct iommu_table_group *table_group,
+		int num)
+{
+	int i, j;
+	long ret = 0;
+	struct npu_comp *npucomp = container_of(table_group, struct npu_comp,
+			table_group);
+
+	for (i = 0; i < npucomp->pe_num; ++i) {
+		struct pnv_ioda_pe *pe = npucomp->pe[i];
+
+		WARN_ON(npucomp->table_group.tables[num] !=
+				table_group->tables[num]);
+		if (!npucomp->table_group.tables[num])
+			continue;
+
+		if (!pe->table_group.ops->unset_window)
+			continue;
+
+		ret = pe->table_group.ops->unset_window(&pe->table_group, num);
+		if (ret)
+			break;
+	}
+
+	if (ret) {
+		for (j = 0; j < i; ++j) {
+			struct pnv_ioda_pe *pe = npucomp->pe[j];
+
+			if (!npucomp->table_group.tables[num])
+				continue;
+
+			if (!pe->table_group.ops->set_window)
+				continue;
+
+			ret = pe->table_group.ops->set_window(&pe->table_group,
+					num, table_group->tables[num]);
+			if (ret)
+				break;
+		}
+	} else if (table_group->tables[num]) {
+		iommu_tce_table_put(table_group->tables[num]);
+		table_group->tables[num] = NULL;
+	}
+
+	return ret;
+}
+
+static void pnv_npu_peers_take_ownership(struct iommu_table_group *table_group)
+{
+	int i;
+	struct npu_comp *npucomp = container_of(table_group, struct npu_comp,
+			table_group);
+
+	for (i = 0; i < npucomp->pe_num; ++i) {
+		struct pnv_ioda_pe *pe = npucomp->pe[i];
+
+		if (!pe->table_group.ops->take_ownership)
+			continue;
+		pe->table_group.ops->take_ownership(&pe->table_group);
+	}
+}
+
+static void pnv_npu_peers_release_ownership(
+		struct iommu_table_group *table_group)
+{
+	int i;
+	struct npu_comp *npucomp = container_of(table_group, struct npu_comp,
+			table_group);
+
+	for (i = 0; i < npucomp->pe_num; ++i) {
+		struct pnv_ioda_pe *pe = npucomp->pe[i];
+
+		if (!pe->table_group.ops->release_ownership)
+			continue;
+		pe->table_group.ops->release_ownership(&pe->table_group);
+	}
+}
+
+static struct iommu_table_group_ops pnv_npu_peers_ops = {
+	.get_table_size = pnv_pci_ioda2_get_table_size,
+	.create_table = pnv_npu_peers_create_table_userspace,
+	.set_window = pnv_npu_peers_set_window,
+	.unset_window = pnv_npu_peers_unset_window,
+	.take_ownership = pnv_npu_peers_take_ownership,
+	.release_ownership = pnv_npu_peers_release_ownership,
+};
+
+static void pnv_comp_attach_table_group(struct npu_comp *npucomp,
+		struct pnv_ioda_pe *pe)
+{
+	if (WARN_ON(npucomp->pe_num == NV_NPU_MAX_PE_NUM))
+		return;
+
+	npucomp->pe[npucomp->pe_num] = pe;
+	++npucomp->pe_num;
+}
+
+struct iommu_table_group *pnv_try_setup_npu_table_group(struct pnv_ioda_pe *pe)
+{
+	struct iommu_table_group *table_group;
+	struct npu_comp *npucomp;
+	struct pci_dev *gpdev = NULL;
+	struct pci_controller *hose;
+	struct pci_dev *npdev = NULL;
+
+	list_for_each_entry(gpdev, &pe->pbus->devices, bus_list) {
+		npdev = pnv_pci_get_npu_dev(gpdev, 0);
+		if (npdev)
+			break;
+	}
+
+	if (!npdev)
+		/* It is not an NPU attached device, skip */
+		return NULL;
+
+	hose = pci_bus_to_host(npdev->bus);
+
+	if (hose->npu) {
+		table_group = &hose->npu->npucomp.table_group;
+
+		if (!table_group->group) {
+			table_group->ops = &pnv_npu_peers_ops;
+			iommu_register_group(table_group,
+					hose->global_number,
+					pe->pe_number);
+		}
+	} else {
+		/* Create a group for 1 GPU and attached NPUs for POWER8 */
+		pe->npucomp = kzalloc(sizeof(pe->npucomp), GFP_KERNEL);
+		table_group = &pe->npucomp->table_group;
+		table_group->ops = &pnv_npu_peers_ops;
+		iommu_register_group(table_group, hose->global_number,
+				pe->pe_number);
+	}
+
+	/* Steal capabilities from a GPU PE */
+	table_group->max_dynamic_windows_supported =
+		pe->table_group.max_dynamic_windows_supported;
+	table_group->tce32_start = pe->table_group.tce32_start;
+	table_group->tce32_size = pe->table_group.tce32_size;
+	table_group->max_levels = pe->table_group.max_levels;
+	if (!table_group->pgsizes)
+		table_group->pgsizes = pe->table_group.pgsizes;
+
+	npucomp = container_of(table_group, struct npu_comp, table_group);
+	pnv_comp_attach_table_group(npucomp, pe);
+
+	return table_group;
+}
+
+struct iommu_table_group *pnv_npu_compound_attach(struct pnv_ioda_pe *pe)
+{
+	struct iommu_table_group *table_group;
+	struct npu_comp *npucomp;
+	struct pci_dev *gpdev = NULL;
+	struct pci_dev *npdev;
+	struct pnv_ioda_pe *gpe = get_gpu_pci_dev_and_pe(pe, &gpdev);
+
+	WARN_ON(!(pe->flags & PNV_IODA_PE_DEV));
+	if (!gpe)
+		return NULL;
+
+	/*
+	 * IODA2 bridges get this set up from pci_controller_ops::setup_bridge
+	 * but NPU bridges do not have this hook defined so we do it here.
+	 * We do not setup other table group parameters as they won't be used
+	 * anyway - NVLink bridges are subordinate PEs.
+	 */
+	pe->table_group.ops = &pnv_pci_npu_ops;
+
+	table_group = iommu_group_get_iommudata(
+			iommu_group_get(&gpdev->dev));
+
+	/*
+	 * On P9 NPU PHB and PCI PHB support different page sizes,
+	 * keep only matching. We expect here that NVLink bridge PE pgsizes is
+	 * initialized by the caller.
+	 */
+	table_group->pgsizes &= pe->table_group.pgsizes;
+	npucomp = container_of(table_group, struct npu_comp, table_group);
+	pnv_comp_attach_table_group(npucomp, pe);
+
+	list_for_each_entry(npdev, &pe->phb->hose->bus->devices, bus_list) {
+		struct pci_dev *gpdevtmp = pnv_pci_get_gpu_dev(npdev);
+
+		if (gpdevtmp != gpdev)
+			continue;
+
+		iommu_add_device(table_group, &npdev->dev);
+	}
+
+	return table_group;
+}
+#endif /* CONFIG_IOMMU_API */
+
 /* Maximum number of nvlinks per npu */
 #define NV_MAX_LINKS 6