2 files changed, 261 insertions, 0 deletions

diff --git a/usr.sbin/bhyve/e820.c b/usr.sbin/bhyve/e820.c
new file mode 100644
index 000000000000..746d34d6521c
--- /dev/null
+++ b/usr.sbin/bhyve/e820.c
@@ -0,0 +1,233 @@
+/*-
+ * SPDX-License-Identifier: BSD-2-Clause
+ *
+ * Copyright (c) 2021 Beckhoff Automation GmbH & Co. KG
+ * Author: Corvin Köhne <c.koehne@beckhoff.com>
+ */
+
+#include <sys/types.h>
+#include <sys/queue.h>
+
+#include <machine/vmm.h>
+
+#include <assert.h>
+#include <err.h>
+#include <errno.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include "e820.h"
+#include "qemu_fwcfg.h"
+
+#define E820_FWCFG_FILE_NAME "etc/e820"
+
+#define KB (1024UL)
+#define MB (1024 * KB)
+#define GB (1024 * MB)
+
+struct e820_element {
+	TAILQ_ENTRY(e820_element) chain;
+	uint64_t base;
+	uint64_t end;
+	enum e820_memory_type type;
+};
+static TAILQ_HEAD(e820_table, e820_element) e820_table = TAILQ_HEAD_INITIALIZER(
+    e820_table);
+
+static struct e820_element *
+e820_element_alloc(uint64_t base, uint64_t end, enum e820_memory_type type)
+{
+	struct e820_element *element;
+
+	element = calloc(1, sizeof(*element));
+	if (element == NULL) {
+		return (NULL);
+	}
+
+	element->base = base;
+	element->end = end;
+	element->type = type;
+
+	return (element);
+}
+
+struct qemu_fwcfg_item *
+e820_get_fwcfg_item(void)
+{
+	struct qemu_fwcfg_item *fwcfg_item;
+	struct e820_element *element;
+	struct e820_entry *entries;
+	int count, i;
+
+	count = 0;
+	TAILQ_FOREACH(element, &e820_table, chain) {
+		++count;
+	}
+	if (count == 0) {
+		warnx("%s: E820 table empty", __func__);
+		return (NULL);
+	}
+
+	fwcfg_item = calloc(1, sizeof(struct qemu_fwcfg_item));
+	if (fwcfg_item == NULL) {
+		return (NULL);
+	}
+
+	fwcfg_item->size = count * sizeof(struct e820_entry);
+	fwcfg_item->data = calloc(count, sizeof(struct e820_entry));
+	if (fwcfg_item->data == NULL) {
+		free(fwcfg_item);
+		return (NULL);
+	}
+
+	i = 0;
+	entries = (struct e820_entry *)fwcfg_item->data;
+	TAILQ_FOREACH(element, &e820_table, chain) {
+		struct e820_entry *entry = &entries[i];
+
+		entry->base = element->base;
+		entry->length = element->end - element->base;
+		entry->type = element->type;
+
+		++i;
+	}
+
+	return (fwcfg_item);
+}
+
+static int
+e820_add_entry(const uint64_t base, const uint64_t end,
+    const enum e820_memory_type type)
+{
+	struct e820_element *new_element;
+	struct e820_element *element;
+	struct e820_element *ram_element;
+
+	assert(end >= base);
+
+	new_element = e820_element_alloc(base, end, type);
+	if (new_element == NULL) {
+		return (ENOMEM);
+	}
+
+	/*
+	 * E820 table should always be sorted in ascending order. Therefore,
+	 * search for a range whose end is larger than the base parameter.
+	 */
+	TAILQ_FOREACH(element, &e820_table, chain) {
+		if (element->end > base) {
+			break;
+		}
+	}
+
+	/*
+	 * System memory requires special handling.
+	 */
+	if (type == E820_TYPE_MEMORY) {
+		/*
+		 * base is larger than of any existing element. Add new system
+		 * memory at the end of the table.
+		 */
+		if (element == NULL) {
+			TAILQ_INSERT_TAIL(&e820_table, new_element, chain);
+			return (0);
+		}
+
+		/*
+		 * System memory shouldn't overlap with any existing element.
+		 */
+		assert(end >= element->base);
+
+		TAILQ_INSERT_BEFORE(element, new_element, chain);
+
+		return (0);
+	}
+
+	assert(element != NULL);
+	/* Non system memory should be allocated inside system memory. */
+	assert(element->type == E820_TYPE_MEMORY);
+	/* New element should fit into existing system memory element. */
+	assert(base >= element->base && end <= element->end);
+
+	if (base == element->base) {
+		/*
+		 * New element at system memory base boundary. Add new
+		 * element before current and adjust the base of the old
+		 * element.
+		 *
+		 * Old table:
+		 * 	[ 0x1000, 0x4000] RAM		<-- element
+		 * New table:
+		 * 	[ 0x1000, 0x2000] Reserved
+		 * 	[ 0x2000, 0x4000] RAM		<-- element
+		 */
+		TAILQ_INSERT_BEFORE(element, new_element, chain);
+		element->base = end;
+	} else if (end == element->end) {
+		/*
+		 * New element at system memory end boundary. Add new
+		 * element after current and adjust the end of the
+		 * current element.
+		 *
+		 * Old table:
+		 * 	[ 0x1000, 0x4000] RAM		<-- element
+		 * New table:
+		 * 	[ 0x1000, 0x3000] RAM		<-- element
+		 * 	[ 0x3000, 0x4000] Reserved
+		 */
+		TAILQ_INSERT_AFTER(&e820_table, element, new_element, chain);
+		element->end = base;
+	} else {
+		/*
+		 * New element inside system memory entry. Split it by
+		 * adding a system memory element and the new element
+		 * before current.
+		 *
+		 * Old table:
+		 * 	[ 0x1000, 0x4000] RAM		<-- element
+		 * New table:
+		 * 	[ 0x1000, 0x2000] RAM
+		 * 	[ 0x2000, 0x3000] Reserved
+		 * 	[ 0x3000, 0x4000] RAM		<-- element
+		 */
+		ram_element = e820_element_alloc(element->base, base,
+		    E820_TYPE_MEMORY);
+		if (ram_element == NULL) {
+			return (ENOMEM);
+		}
+		TAILQ_INSERT_BEFORE(element, ram_element, chain);
+		TAILQ_INSERT_BEFORE(element, new_element, chain);
+		element->base = end;
+	}
+
+	return (0);
+}
+
+int
+e820_init(struct vmctx *const ctx)
+{
+	uint64_t lowmem_size, highmem_size;
+	int error;
+
+	TAILQ_INIT(&e820_table);
+
+	lowmem_size = vm_get_lowmem_size(ctx);
+	error = e820_add_entry(0, lowmem_size, E820_TYPE_MEMORY);
+	if (error) {
+		warnx("%s: Could not add lowmem", __func__);
+		return (error);
+	}
+
+	highmem_size = vm_get_highmem_size(ctx);
+	if (highmem_size != 0) {
+		error = e820_add_entry(4 * GB, 4 * GB + highmem_size,
+		    E820_TYPE_MEMORY);
+		if (error) {
+			warnx("%s: Could not add highmem", __func__);
+			return (error);
+		}
+	}
+
+	return (0);
+}
diff --git a/usr.sbin/bhyve/e820.h b/usr.sbin/bhyve/e820.h
new file mode 100644
index 000000000000..6843ad5dc736
--- /dev/null
+++ b/usr.sbin/bhyve/e820.h
@@ -0,0 +1,28 @@
+/*-
+ * SPDX-License-Identifier: BSD-2-Clause
+ *
+ * Copyright (c) 2021 Beckhoff Automation GmbH & Co. KG
+ * Author: Corvin Köhne <c.koehne@beckhoff.com>
+ */
+
+#pragma once
+
+#include <vmmapi.h>
+
+#include "qemu_fwcfg.h"
+
+enum e820_memory_type {
+	E820_TYPE_MEMORY = 1,
+	E820_TYPE_RESERVED = 2,
+	E820_TYPE_ACPI = 3,
+	E820_TYPE_NVS = 4
+};
+
+struct e820_entry {
+	uint64_t base;
+	uint64_t length;
+	uint32_t type;
+} __packed;
+
+struct qemu_fwcfg_item *e820_get_fwcfg_item(void);
+int e820_init(struct vmctx *const ctx);