accel/habanalabs/gaudi2: move HMMU page tables to device memory

Currently the HMMU page tables reside in the host memory,
which will cause host access from the device for every page walk.
This can affect PCIe bandwidth in certain scenarios.

To prevent that problem, HMMU page tables will be moved to the device
memory so the miss transaction will read the hops from there instead of
going to the host.

Signed-off-by: Farah Kassabri <fkassabri@habana.ai>
Reviewed-by: Oded Gabbay <ogabbay@kernel.org>
Signed-off-by: Oded Gabbay <ogabbay@kernel.org>

1 files changed, 338 insertions, 0 deletions

diff --git a/drivers/accel/habanalabs/common/mmu/mmu_v2.c b/drivers/accel/habanalabs/common/mmu/mmu_v2.c
new file mode 100644
index 000000000000..4bc0268fff1c
--- /dev/null
+++ b/drivers/accel/habanalabs/common/mmu/mmu_v2.c
@@ -0,0 +1,338 @@
+// SPDX-License-Identifier: GPL-2.0
+
+/*
+ * Copyright 2016-2020 HabanaLabs, Ltd.
+ * All Rights Reserved.
+ */
+
+#include "../habanalabs.h"
+#include "../../include/hw_ip/mmu/mmu_general.h"
+#include "../../include/hw_ip/mmu/mmu_v2_0.h"
+
+#include <linux/slab.h>
+
+/**
+ * hl_mmu_v2_ctx_init() - initialize a context for using the MMU module.
+ * @ctx: pointer to the context structure to initialize.
+ *
+ * Initialize a mutex to protect the concurrent mapping flow, a hash to hold all
+ * page tables hops related to this context.
+ * Return: 0 on success, non-zero otherwise.
+ */
+static int hl_mmu_v2_ctx_init(struct hl_ctx *ctx)
+{
+	hash_init(ctx->mmu_shadow_hash);
+
+	return 0;
+}
+
+/*
+ * hl_mmu_v2_ctx_fini - disable a ctx from using the mmu module
+ *
+ * @ctx: pointer to the context structure
+ *
+ * This function does the following:
+ * - Free any pgts which were not freed yet
+ * - Free the mutex
+ * - Free DRAM default page mapping hops
+ */
+static void hl_mmu_v2_ctx_fini(struct hl_ctx *ctx)
+{
+	struct hl_device *hdev = ctx->hdev;
+	struct pgt_info *pgt_info;
+	struct hlist_node *tmp;
+	int i;
+
+	if (!hash_empty(ctx->mmu_shadow_hash))
+		dev_err(hdev->dev, "ctx %d is freed while it has pgts in use\n",
+			ctx->asid);
+
+	hash_for_each_safe(ctx->mmu_shadow_hash, i, tmp, pgt_info, node) {
+		dev_err_ratelimited(hdev->dev,
+			"pgt_info of addr 0x%llx of asid %d was not destroyed, num_ptes: %d\n",
+			pgt_info->phys_addr, ctx->asid, pgt_info->num_of_ptes);
+		hl_mmu_dr_free_pgt_node(ctx, pgt_info);
+	}
+}
+
+static int hl_mmu_v2_unmap(struct hl_ctx *ctx,	u64 virt_addr, bool is_dram_addr)
+{
+	u64 hop_addr[MMU_ARCH_6_HOPS] = { 0 }, hop_pte_addr[MMU_ARCH_6_HOPS] = { 0 }, curr_pte,
+							scrambled_virt_addr;
+	struct asic_fixed_properties *prop = &ctx->hdev->asic_prop;
+	struct hl_device *hdev = ctx->hdev;
+	struct hl_mmu_properties *mmu_prop;
+	bool is_huge = false;
+	int i, hop_last;
+
+	/* device resident in V2 are allowed only for HMMU */
+	if (!is_dram_addr)
+		return -EINVAL;
+
+	mmu_prop = &prop->dmmu;
+
+	hop_last = mmu_prop->num_hops - 1;
+
+	scrambled_virt_addr = hdev->asic_funcs->scramble_addr(hdev, virt_addr);
+
+	hop_addr[0] = hl_mmu_dr_get_hop0_addr(ctx);
+	hop_pte_addr[0] = hl_mmu_get_hop_pte_phys_addr(ctx, mmu_prop, 0,
+					hop_addr[0], scrambled_virt_addr);
+	if (hop_pte_addr[0] == U64_MAX)
+		return -EFAULT;
+
+	curr_pte = *(u64 *) (uintptr_t) hop_pte_addr[0];
+
+	for (i = 1 ; i < mmu_prop->num_hops ; i++) {
+		hop_addr[i] = hl_mmu_get_next_hop_addr(ctx, curr_pte);
+		if (hop_addr[i] == ULLONG_MAX)
+			goto not_mapped;
+
+		hop_pte_addr[i] = hl_mmu_get_hop_pte_phys_addr(ctx, mmu_prop, i,
+					hop_addr[i], scrambled_virt_addr);
+		if (hop_pte_addr[i] == U64_MAX)
+			return -EFAULT;
+
+		curr_pte = *(u64 *) (uintptr_t) hop_pte_addr[i];
+
+		if ((i <= hop_last) && (curr_pte & mmu_prop->last_mask)) {
+			hop_last = i;
+			is_huge = true;
+			break;
+		}
+	}
+
+	if (is_dram_addr && !is_huge) {
+		dev_err(hdev->dev, "DRAM unmapping should use huge pages only\n");
+		return -EFAULT;
+	}
+
+	if (!(curr_pte & PAGE_PRESENT_MASK))
+		goto not_mapped;
+
+	for (i = hop_last ; i > 0 ; i--) {
+		hl_mmu_dr_clear_pte(ctx, hop_pte_addr[i]);
+		if (hl_mmu_dr_put_pte(ctx, hop_addr[i]))
+			goto mapped;
+	}
+	hl_mmu_dr_clear_pte(ctx, hop_pte_addr[0]);
+
+mapped:
+	return 0;
+
+not_mapped:
+	dev_err(hdev->dev, "virt addr 0x%llx is not mapped to phys addr\n",
+		virt_addr);
+
+	return -EINVAL;
+}
+
+static int hl_mmu_v2_map(struct hl_ctx *ctx, u64 virt_addr, u64 phys_addr,
+							u32 page_size, bool is_dram_addr)
+{
+	u64 hop_addr[MMU_ARCH_6_HOPS] = { 0 }, hop_pte_addr[MMU_ARCH_6_HOPS] = { 0 },
+			curr_pte = 0, scrambled_virt_addr, scrambled_phys_addr;
+	struct asic_fixed_properties *prop = &ctx->hdev->asic_prop;
+	bool hop_new[MMU_ARCH_6_HOPS] = { false };
+	struct hl_device *hdev = ctx->hdev;
+	struct hl_mmu_properties *mmu_prop;
+	int rc, i, hop_last;
+
+	/* device resident in V2 are allowed only for HMMU */
+	if (!is_dram_addr)
+		return -EINVAL;
+
+	mmu_prop = &prop->dmmu;
+
+	hop_last = mmu_prop->num_hops - 1;
+
+	scrambled_virt_addr = hdev->asic_funcs->scramble_addr(hdev, virt_addr);
+	scrambled_phys_addr = hdev->asic_funcs->scramble_addr(hdev, phys_addr);
+
+	/* First hop is preallocated therefore it is treated differently  */
+	hop_addr[0] = hl_mmu_dr_get_hop0_addr(ctx);
+	hop_pte_addr[0] = hl_mmu_get_hop_pte_phys_addr(ctx, mmu_prop, 0,
+						hop_addr[0], scrambled_virt_addr);
+	curr_pte = *(u64 *) (uintptr_t) hop_pte_addr[0];
+
+	/* Handle hop1 to hop_last */
+	for (i = 1 ; i <= hop_last ; i++) {
+		hop_addr[i] = hl_mmu_dr_get_alloc_next_hop_addr(ctx, curr_pte, &hop_new[i]);
+		if (hop_addr[i] == ULLONG_MAX) {
+			rc = -ENOMEM;
+			goto err;
+		}
+
+		hop_pte_addr[i] = hl_mmu_get_hop_pte_phys_addr(ctx, mmu_prop, i,
+					hop_addr[i], scrambled_virt_addr);
+		if (hop_pte_addr[i] == U64_MAX) {
+			rc = -EINVAL;
+			goto err;
+		}
+
+		if (!hop_pte_addr[i]) {
+			rc = -EINVAL;
+			goto err;
+		}
+
+		curr_pte = *(u64 *) (uintptr_t) hop_pte_addr[i];
+	}
+
+	if (curr_pte & PAGE_PRESENT_MASK) {
+		dev_err(hdev->dev,
+			"mapping already exists for virt_addr 0x%llx\n",
+				virt_addr);
+
+		for (i = 0 ; i <= hop_last ; i++)
+			dev_dbg(hdev->dev, "hop%d pte: 0x%llx (0x%llx)\n",
+				i, *(u64 *) (uintptr_t) hop_pte_addr[i],
+				hop_pte_addr[i]);
+
+		rc = -EINVAL;
+		goto err;
+	}
+
+	curr_pte = (scrambled_phys_addr & HOP_PHYS_ADDR_MASK)
+					| mmu_prop->last_mask | PAGE_PRESENT_MASK;
+
+	/* Write the PTEs */
+	hl_mmu_dr_write_final_pte(ctx, hop_pte_addr[hop_last], curr_pte);
+
+	/* for each new hop, add its address to the table of previous-hop */
+	for (i = 1 ; i <= hop_last ; i++) {
+		if (hop_new[i]) {
+			curr_pte = (hop_addr[i] & HOP_PHYS_ADDR_MASK) | PAGE_PRESENT_MASK;
+			hl_mmu_dr_write_pte(ctx, hop_pte_addr[i - 1], curr_pte);
+
+			if (i - 1)
+				hl_mmu_dr_get_pte(ctx, hop_addr[i - 1]);
+		}
+	}
+	hl_mmu_dr_get_pte(ctx, hop_addr[hop_last]);
+
+	return 0;
+
+err:
+	for (i = 1 ; i <= hop_last ; i++)
+		if (hop_new[i] && (hop_addr[i] != U64_MAX))
+			hl_mmu_dr_free_hop(ctx, hop_addr[i]);
+
+	return rc;
+}
+
+/*
+ * hl_mmu_v2_swap_out - marks all mapping of the given ctx as swapped out
+ *
+ * @ctx: pointer to the context structure
+ *
+ */
+static void hl_mmu_v2_swap_out(struct hl_ctx *ctx)
+{
+
+}
+
+/*
+ * hl_mmu_v2_swap_in - marks all mapping of the given ctx as swapped in
+ *
+ * @ctx: pointer to the context structure
+ *
+ */
+static void hl_mmu_v2_swap_in(struct hl_ctx *ctx)
+{
+
+}
+
+static int hl_mmu_v2_get_tlb_info(struct hl_ctx *ctx, u64 virt_addr, struct hl_mmu_hop_info *hops)
+{
+	struct asic_fixed_properties *prop = &ctx->hdev->asic_prop;
+	struct hl_device *hdev = ctx->hdev;
+	struct hl_mmu_properties *mmu_prop;
+	bool is_dram_addr;
+	int i;
+
+	is_dram_addr = hl_mem_area_inside_range(virt_addr, prop->dmmu.page_size,
+						prop->dmmu.start_addr,
+						prop->dmmu.end_addr);
+
+	/* device resident in V2 are allowed only for HMMU */
+	if (!is_dram_addr)
+		return -EINVAL;
+
+	mmu_prop = &prop->dmmu;
+	hops->range_type = HL_VA_RANGE_TYPE_DRAM;
+
+	hops->scrambled_vaddr = hdev->asic_funcs->scramble_addr(hdev, virt_addr);
+
+	hops->hop_info[0].hop_addr = hl_mmu_dr_get_phys_hop0_addr(ctx);
+	hops->hop_info[0].hop_pte_addr = hl_mmu_get_hop_pte_phys_addr(ctx, mmu_prop, 0,
+						hops->hop_info[0].hop_addr,
+							hops->scrambled_vaddr);
+	if (hops->hop_info[0].hop_pte_addr == U64_MAX)
+		return -EFAULT;
+
+	hops->hop_info[0].hop_pte_val = hdev->asic_funcs->read_pte(hdev,
+						hops->hop_info[0].hop_pte_addr);
+	if (hops->hop_info[0].hop_pte_val == U64_MAX)
+		return -EFAULT;
+
+	for (i = 1 ; i < mmu_prop->num_hops ; i++) {
+		hops->hop_info[i].hop_addr =
+			hl_mmu_get_next_hop_addr(ctx, hops->hop_info[i - 1].hop_pte_val);
+		if (hops->hop_info[i].hop_addr == ULLONG_MAX)
+			return -EFAULT;
+
+		hops->hop_info[i].hop_pte_addr =
+				hl_mmu_get_hop_pte_phys_addr(ctx, mmu_prop, i,
+						hops->hop_info[i].hop_addr,
+						hops->scrambled_vaddr);
+		if (hops->hop_info[i].hop_pte_addr == U64_MAX)
+			return -EFAULT;
+
+		hops->hop_info[i].hop_pte_val =
+				hdev->asic_funcs->read_pte(hdev,
+					hops->hop_info[i].hop_pte_addr);
+
+		if (!(hops->hop_info[i].hop_pte_val & PAGE_PRESENT_MASK))
+			return -EFAULT;
+
+		if (hops->hop_info[i].hop_pte_val & mmu_prop->last_mask)
+			break;
+	}
+
+	/* if passed over all hops then no last hop was found */
+	if (i == mmu_prop->num_hops)
+		return -EFAULT;
+
+	if (!(hops->hop_info[i].hop_pte_val & PAGE_PRESENT_MASK))
+		return -EFAULT;
+
+	if (hops->scrambled_vaddr != virt_addr)
+		hops->unscrambled_paddr = hdev->asic_funcs->descramble_addr
+				(hdev, hops->hop_info[i].hop_pte_val);
+	else
+		hops->unscrambled_paddr = hops->hop_info[i].hop_pte_val;
+
+	hops->used_hops = i + 1;
+
+	return 0;
+}
+
+/*
+ * hl_mmu_v2_prepare - prepare mmu_if for working with mmu v2
+ *
+ * @hdev: pointer to the device structure
+ * @mmu_if: pointer to the mmu interface structure
+ */
+void hl_mmu_v2_set_funcs(struct hl_device *hdev, struct hl_mmu_funcs *mmu)
+{
+	mmu->init = hl_mmu_dr_init;
+	mmu->fini = hl_mmu_dr_fini;
+	mmu->ctx_init = hl_mmu_v2_ctx_init;
+	mmu->ctx_fini = hl_mmu_v2_ctx_fini;
+	mmu->map = hl_mmu_v2_map;
+	mmu->unmap = hl_mmu_v2_unmap;
+	mmu->flush = hl_mmu_dr_flush;
+	mmu->swap_out = hl_mmu_v2_swap_out;
+	mmu->swap_in = hl_mmu_v2_swap_in;
+	mmu->get_tlb_info = hl_mmu_v2_get_tlb_info;
+}