[PATCH ats_vtd v5 17/22] atc: generic ATC that can be used by PCIe devices that support SVM

[CLEMENT MATHIEU--DRIF]

From: Clément Mathieu--Drif <clement.mathieu--drif@eviden.com>

As the SVM-capable devices will need to cache translations, we provide
an first implementation.

This cache uses a two-level design based on hash tables.
The first level is indexed by a PASID and the second by a virtual addresse.

Signed-off-by: Clément Mathieu--Drif <clement.mathieu--drif@eviden.com>
---
 util/atc.c       | 211 +++++++++++++++++++++++++++++++++++++++++++++++
 util/atc.h       | 117 ++++++++++++++++++++++++++
 util/meson.build |   1 +
 3 files changed, 329 insertions(+)
 create mode 100644 util/atc.c
 create mode 100644 util/atc.h

diff --git a/util/atc.c b/util/atc.c
new file mode 100644
index 0000000000..584ce045db
--- /dev/null
+++ b/util/atc.c
@@ -0,0 +1,211 @@
+/*
+ * QEMU emulation of an ATC
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include "util/atc.h"
+
+
+#define PAGE_TABLE_ENTRY_SIZE 8
+
+/* a pasid is hashed using the identity function */
+static guint atc_pasid_key_hash(gconstpointer v)
+{
+    return (guint)(uintptr_t)v; /* pasid */
+}
+
+/* pasid equality */
+static gboolean atc_pasid_key_equal(gconstpointer v1, gconstpointer v2)
+{
+    return v1 == v2;
+}
+
+/* Hash function for IOTLB entries */
+static guint atc_addr_key_hash(gconstpointer v)
+{
+    hwaddr addr = (hwaddr)v;
+    return (guint)((addr >> 32) ^ (addr & 0xffffffffU));
+}
+
+/* Equality test for IOTLB entries */
+static gboolean atc_addr_key_equal(gconstpointer v1, gconstpointer v2)
+{
+    return (hwaddr)v1 == (hwaddr)v2;
+}
+
+static void atc_address_space_free(void *as)
+{
+    g_hash_table_unref(as);
+}
+
+/* return log2(val), or UINT8_MAX if val is not a power of 2 */
+static uint8_t ilog2(uint64_t val)
+{
+    uint8_t result = 0;
+    while (val != 1) {
+        if (val & 1) {
+            return UINT8_MAX;
+        }
+
+        val >>= 1;
+        result += 1;
+    }
+    return result;
+}
+
+ATC *atc_new(uint64_t page_size, uint8_t address_width)
+{
+    ATC *atc;
+    uint8_t log_page_size = ilog2(page_size);
+    /* number of bits each used to store all the intermediate indexes */
+    uint64_t addr_lookup_indexes_size;
+
+    if (log_page_size == UINT8_MAX) {
+        return NULL;
+    }
+    /*
+     * We only support page table entries of 8 (PAGE_TABLE_ENTRY_SIZE) bytes
+     * log2(page_size / 8) = log2(page_size) - 3
+     * is the level offset
+     */
+    if (log_page_size <= 3) {
+        return NULL;
+    }
+
+    atc = g_new0(ATC, 1);
+    atc->address_spaces = g_hash_table_new_full(atc_pasid_key_hash,
+                                                atc_pasid_key_equal,
+                                                NULL, atc_address_space_free);
+    atc->level_offset = log_page_size - 3;
+    /* at this point, we know that page_size is a power of 2 */
+    atc->min_addr_mask = page_size - 1;
+    addr_lookup_indexes_size = address_width - log_page_size;
+    if ((addr_lookup_indexes_size % atc->level_offset) != 0) {
+        goto error;
+    }
+    atc->levels = addr_lookup_indexes_size / atc->level_offset;
+    atc->page_size = page_size;
+    return atc;
+
+error:
+    g_free(atc);
+    return NULL;
+}
+
+static inline GHashTable *atc_get_address_space_cache(ATC *atc, uint32_t pasid)
+{
+    return g_hash_table_lookup(atc->address_spaces,
+                               (gconstpointer)(uintptr_t)pasid);
+}
+
+void atc_create_address_space_cache(ATC *atc, uint32_t pasid)
+{
+    GHashTable *as_cache;
+
+    as_cache = atc_get_address_space_cache(atc, pasid);
+    if (!as_cache) {
+        as_cache = g_hash_table_new_full(atc_addr_key_hash,
+                                         atc_addr_key_equal,
+                                         NULL, g_free);
+        g_hash_table_replace(atc->address_spaces,
+                             (gpointer)(uintptr_t)pasid, as_cache);
+    }
+}
+
+void atc_delete_address_space_cache(ATC *atc, uint32_t pasid)
+{
+    g_hash_table_remove(atc->address_spaces, (gpointer)(uintptr_t)pasid);
+}
+
+int atc_update(ATC *atc, IOMMUTLBEntry *entry)
+{
+    IOMMUTLBEntry *value;
+    GHashTable *as_cache = atc_get_address_space_cache(atc, entry->pasid);
+    if (!as_cache) {
+        return -ENODEV;
+    }
+    value = g_memdup2(entry, sizeof(*value));
+    g_hash_table_replace(as_cache, (gpointer)(entry->iova), value);
+    return 0;
+}
+
+IOMMUTLBEntry *atc_lookup(ATC *atc, uint32_t pasid, hwaddr addr)
+{
+    IOMMUTLBEntry *entry;
+    hwaddr mask = atc->min_addr_mask;
+    hwaddr key = addr & (~mask);
+    GHashTable *as_cache = atc_get_address_space_cache(atc, pasid);
+
+    if (!as_cache) {
+        return NULL;
+    }
+
+    /*
+     * Iterate over the possible page sizes and try to find a hit
+     */
+    for (uint8_t level = 0; level < atc->levels; ++level) {
+        entry = g_hash_table_lookup(as_cache, (gconstpointer)key);
+        if (entry && (mask == entry->addr_mask)) {
+            return entry;
+        }
+        mask = (mask << atc->level_offset) | ((1 << atc->level_offset) - 1);
+        key = addr & (~mask);
+    }
+
+    return NULL;
+}
+
+static gboolean atc_invalidate_entry_predicate(gpointer key, gpointer value,
+                                               gpointer user_data)
+{
+    IOMMUTLBEntry *entry = (IOMMUTLBEntry *)value;
+    IOMMUTLBEntry *target = (IOMMUTLBEntry *)user_data;
+    hwaddr target_mask = ~target->addr_mask;
+    hwaddr entry_mask = ~entry->addr_mask;
+    return ((target->iova & target_mask) == (entry->iova & target_mask)) ||
+           ((target->iova & entry_mask) == (entry->iova & entry_mask));
+}
+
+void atc_invalidate(ATC *atc, IOMMUTLBEntry *entry)
+{
+    GHashTable *as_cache = atc_get_address_space_cache(atc, entry->pasid);
+    if (!as_cache) {
+        return;
+    }
+    g_hash_table_foreach_remove(as_cache,
+                                atc_invalidate_entry_predicate,
+                                entry);
+}
+
+void atc_destroy(ATC *atc)
+{
+    g_hash_table_unref(atc->address_spaces);
+}
+
+size_t atc_get_max_number_of_pages(ATC *atc, hwaddr addr, size_t length)
+{
+    hwaddr page_mask = ~(atc->min_addr_mask);
+    size_t result = (length / atc->page_size);
+    if ((((addr & page_mask) + length - 1) & page_mask) !=
+        ((addr + length - 1) & page_mask)) {
+        result += 1;
+    }
+    return result + (length % atc->page_size != 0 ? 1 : 0);
+}
+
+void atc_reset(ATC *atc)
+{
+    g_hash_table_remove_all(atc->address_spaces);
+}
diff --git a/util/atc.h b/util/atc.h
new file mode 100644
index 0000000000..8be95f5cca
--- /dev/null
+++ b/util/atc.h
@@ -0,0 +1,117 @@
+/*
+ * QEMU emulation of an ATC
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, see <http://www.gnu.org/licenses/>.
+ */
+
+#ifndef UTIL_ATC_H
+#define UTIL_ATC_H
+
+#include "qemu/osdep.h"
+#include "exec/memory.h"
+
+typedef struct ATC {
+    GHashTable *address_spaces; /* Key : pasid, value : GHashTable */
+    hwaddr min_addr_mask;
+    uint64_t page_size;
+    uint8_t levels;
+    uint8_t level_offset;
+} ATC;
+
+/*
+ * atc_new: Create an ATC.
+ *
+ * Return an ATC or NULL if the creation failed
+ *
+ * @page_size: #PCIDevice doing the memory access
+ * @address_width: width of the virtual addresses used by the IOMMU (in bits)
+ */
+ATC *atc_new(uint64_t page_size, uint8_t address_width);
+
+/*
+ * atc_update: Insert or update an entry in the cache
+ *
+ * Return 0 if the operation succeeds, a negative error code otherwise
+ *
+ * The insertion will fail if the address space associated with this pasid
+ * has not been created with atc_create_address_space_cache
+ *
+ * @atc: the ATC to update
+ * @entry: the tlb entry to insert into the cache
+ */
+int atc_update(ATC *atc, IOMMUTLBEntry *entry);
+
+/*
+ * atc_create_address_space_cache: delare a new address space
+ * identified by a PASID
+ *
+ * @atc: the ATC to update
+ * @pasid: the pasid of the address space to be created
+ */
+void atc_create_address_space_cache(ATC *atc, uint32_t pasid);
+
+/*
+ * atc_delete_address_space_cache: delete an address space
+ * identified by a PASID
+ *
+ * @atc: the ATC to update
+ * @pasid: the pasid of the address space to be deleted
+ */
+void atc_delete_address_space_cache(ATC *atc, uint32_t pasid);
+
+/*
+ * atc_lookup: query the cache in a given address space
+ *
+ * @atc: the ATC to query
+ * @pasid: the pasid of the address space to query
+ * @addr: the virtual address to translate
+ */
+IOMMUTLBEntry *atc_lookup(ATC *atc, uint32_t pasid, hwaddr addr);
+
+/*
+ * atc_invalidate: invalidate an entry in the cache
+ *
+ * @atc: the ATC to update
+ * @entry: the entry to invalidate
+ */
+void atc_invalidate(ATC *atc, IOMMUTLBEntry *entry);
+
+/*
+ * atc_destroy: delete an ATC
+ *
+ * @atc: the cache to be deleted
+ */
+void atc_destroy(ATC *atc);
+
+/*
+ * atc_get_max_number_of_pages: get the number of pages a memory operation
+ * will access if all the pages concerned have the minimum size.
+ *
+ * This function can be used to determine the size of the result array to be
+ * allocated when issuing an ATS request.
+ *
+ * @atc: the cache
+ * @addr: start address
+ * @length: number of bytes accessed from addr
+ */
+size_t atc_get_max_number_of_pages(ATC *atc, hwaddr addr, size_t length);
+
+/*
+ * atc_reset: invalidates all the entries stored in the ATC
+ *
+ * @atc: the cache
+ */
+void atc_reset(ATC *atc);
+
+#endif
diff --git a/util/meson.build b/util/meson.build
index 72b505df11..2273f8176a 100644
--- a/util/meson.build
+++ b/util/meson.build
@@ -93,6 +93,7 @@ if have_block
   util_ss.add(files('hbitmap.c'))
   util_ss.add(files('hexdump.c'))
   util_ss.add(files('iova-tree.c'))
+  util_ss.add(files('atc.c'))
   util_ss.add(files('iov.c'))
   util_ss.add(files('nvdimm-utils.c'))
   util_ss.add(files('block-helpers.c'))
-- 
2.45.2