src/load.c

#include "hf/load.h"

#include <assert.h>
#include <stdbool.h>

#include "hf/api.h"
#include "hf/boot_params.h"
#include "hf/dlog.h"
#include "hf/memiter.h"
#include "hf/mm.h"
#include "hf/std.h"
#include "hf/vm.h"

/**
 * Copies data to an unmapped location by mapping it for write, copying the
 * data, then unmapping it.
 */
static bool copy_to_unmapped(paddr_t to, const void *from, size_t size)
{
	paddr_t to_end = pa_add(to, size);
	void *ptr;

	ptr = mm_identity_map(to, to_end, MM_MODE_W);
	if (!ptr) {
		return false;
	}

	memcpy(ptr, from, size);

	mm_unmap(to, to_end, 0);

	return true;
}

/**
 * Moves the kernel of the primary VM to its final destination.
 */
static bool relocate(const char *from, size_t size)
{
	/* TODO: This is a hack. We must read the alignment from the binary. */
	extern char bin_end[];
	size_t tmp = (size_t)&bin_end[0];
	paddr_t dest = pa_init((tmp + 0x80000 - 1) & ~(0x80000 - 1));
	dlog("bin_end is at %p, copying to %p\n", &bin_end[0], pa_addr(dest));
	return copy_to_unmapped(dest, from, size);
}

/**
 * Looks for a file in the given cpio archive. The filename is not
 * null-terminated, so we use a memory iterator to represent it. The file, if
 * found, is returned in the "it" argument.
 */
static bool memiter_find_file(const struct memiter *cpio,
			      const struct memiter *filename,
			      struct memiter *it)
{
	const char *fname;
	const void *fcontents;
	size_t fsize;
	struct memiter iter = *cpio;

	while (cpio_next(&iter, &fname, &fcontents, &fsize)) {
		if (memiter_iseq(filename, fname)) {
			memiter_init(it, fcontents, fsize);
			return true;
		}
	}

	return false;
}

/**
 * Looks for a file in the given cpio archive. The file, if found, is returned
 * in the "it" argument.
 */
static bool find_file(const struct memiter *cpio, const char *name,
		      struct memiter *it)
{
	const char *fname;
	const void *fcontents;
	size_t fsize;
	struct memiter iter = *cpio;

	while (cpio_next(&iter, &fname, &fcontents, &fsize)) {
		if (!strcmp(fname, name)) {
			memiter_init(it, fcontents, fsize);
			return true;
		}
	}

	return false;
}

/**
 * Loads the primary VM.
 */
// TODO: kernel_arg is a size_t???
bool load_primary(const struct memiter *cpio, size_t kernel_arg,
		  struct memiter *initrd)
{
	struct memiter it;

	if (!find_file(cpio, "vmlinuz", &it)) {
		dlog("Unable to find vmlinuz\n");
		return false;
	}

	if (!relocate(it.next, it.limit - it.next)) {
		dlog("Unable to relocate kernel for primary vm.\n");
		return false;
	}

	if (!find_file(cpio, "initrd.img", initrd)) {
		dlog("Unable to find initrd.img\n");
		return false;
	}

	{
		uintpaddr_t tmp = (uintpaddr_t)&load_primary;
		tmp = (tmp + 0x80000 - 1) & ~(0x80000 - 1);
		if (!vm_init(&primary_vm, 0, MAX_CPUS)) {
			dlog("Unable to initialise primary vm\n");
			return false;
		}

		/* Map the 1TB of memory. */
		/* TODO: We should do a whitelist rather than a blacklist. */
		if (!mm_vm_identity_map(
			    &primary_vm.ptable, pa_init(0),
			    pa_init(UINT64_C(1024) * 1024 * 1024 * 1024),
			    MM_MODE_R | MM_MODE_W | MM_MODE_X |
				    MM_MODE_NOINVALIDATE,
			    NULL)) {
			dlog("Unable to initialise memory for primary vm\n");
			return false;
		}

		if (!mm_ptable_unmap_hypervisor(&primary_vm.ptable,
						MM_MODE_NOINVALIDATE)) {
			dlog("Unable to unmap hypervisor from primary vm\n");
			return false;
		}

		vm_start_vcpu(&primary_vm, 0, ipa_init(tmp), kernel_arg);
	}

	return true;
}

/**
 * Try to find a memory range of the given size within the given ranges, and
 * remove it from them. Return true on success, or false if no large enough
 * contiguous range is found.
 */
bool carve_out_mem_range(struct mem_range *mem_ranges, size_t mem_ranges_count,
			 uint64_t size_to_find, paddr_t *found_begin,
			 paddr_t *found_end)
{
	size_t i;

	/* TODO(b/116191358): Consider being cleverer about how we pack VMs
	 * together, with a non-greedy algorithm. */
	for (i = 0; i < mem_ranges_count; ++i) {
		if (size_to_find <=
		    pa_addr(mem_ranges[i].end) - pa_addr(mem_ranges[i].begin)) {
			/* This range is big enough, take some of it from the
			 * end and reduce its size accordingly. */
			*found_end = mem_ranges[i].end;
			*found_begin = pa_init(pa_addr(mem_ranges[i].end) -
					       size_to_find);
			mem_ranges[i].end = *found_begin;
			return true;
		}
	}
	return false;
}

/**
 * Given arrays of memory ranges before and after memory was removed for
 * secondary VMs, add the difference to the reserved ranges of the given update.
 * Return true on success, or false if there would be more than MAX_MEM_RANGES
 * reserved ranges after adding the new ones.
 * `before` and `after` must be arrays of exactly `mem_ranges_count` elements.
 */
bool update_reserved_ranges(struct boot_params_update *update,
			    const struct mem_range *before,
			    const struct mem_range *after,
			    size_t mem_ranges_count)
{
	size_t i;

	for (i = 0; i < mem_ranges_count; ++i) {
		if (pa_addr(after[i].begin) > pa_addr(before[i].begin)) {
			if (update->reserved_ranges_count >= MAX_MEM_RANGES) {
				dlog("Too many reserved ranges after loading "
				     "secondary VMs.\n");
				return false;
			}
			update->reserved_ranges[update->reserved_ranges_count]
				.begin = before[i].begin;
			update->reserved_ranges[update->reserved_ranges_count]
				.end = after[i].begin;
			update->reserved_ranges_count++;
		}
		if (pa_addr(after[i].end) < pa_addr(before[i].end)) {
			if (update->reserved_ranges_count >= MAX_MEM_RANGES) {
				dlog("Too many reserved ranges after loading "
				     "secondary VMs.\n");
				return false;
			}
			update->reserved_ranges[update->reserved_ranges_count]
				.begin = after[i].end;
			update->reserved_ranges[update->reserved_ranges_count]
				.end = before[i].end;
			update->reserved_ranges_count++;
		}
	}

	return true;
}

/**
 * Loads all secondary VMs into the memory ranges from the given params.
 * Memory reserved for the VMs is added to the `reserved_ranges` of `update`.
 */
bool load_secondary(const struct memiter *cpio,
		    const struct boot_params *params,
		    struct boot_params_update *update)
{
	struct memiter it;
	struct memiter str;
	uint64_t mem;
	uint64_t cpu;
	uint32_t count;
	struct mem_range mem_ranges_available[MAX_MEM_RANGES];
	size_t i;

	static_assert(
		sizeof(mem_ranges_available) == sizeof(params->mem_ranges),
		"mem_range arrays must be the same size for memcpy.");
	static_assert(sizeof(mem_ranges_available) < 500,
		      "This will use too much stack, either make "
		      "MAX_MEM_RANGES smaller or change this.");
	memcpy(mem_ranges_available, params->mem_ranges,
	       sizeof(mem_ranges_available));

	if (!find_file(cpio, "vms.txt", &it)) {
		dlog("vms.txt is missing\n");
		return true;
	}

	/* Round the last addresses down to the page size. */
	for (i = 0; i < params->mem_ranges_count; ++i) {
		mem_ranges_available[i].end =
			pa_init(pa_addr(mem_ranges_available[i].end) &
				~(PAGE_SIZE - 1));
	}

	for (count = 0;
	     memiter_parse_uint(&it, &mem) && memiter_parse_uint(&it, &cpu) &&
	     memiter_parse_str(&it, &str) && count < MAX_VMS;
	     count++) {
		struct memiter kernel;
		paddr_t secondary_mem_begin;
		paddr_t secondary_mem_end;
		ipaddr_t secondary_entry;

		if (!memiter_find_file(cpio, &str, &kernel)) {
			dlog("Unable to load kernel for vm %u\n", count);
			continue;
		}

		/* Round up to page size. */
		mem = (mem + PAGE_SIZE - 1) & ~(PAGE_SIZE - 1);

		if (mem < kernel.limit - kernel.next) {
			dlog("Kernel is larger than available memory for vm "
			     "%u\n",
			     count);
			continue;
		}

		if (!carve_out_mem_range(
			    mem_ranges_available, params->mem_ranges_count, mem,
			    &secondary_mem_begin, &secondary_mem_end)) {
			dlog("Not enough memory for vm %u (%u bytes)\n", count,
			     mem);
			continue;
		}

		if (!copy_to_unmapped(secondary_mem_begin, kernel.next,
				      kernel.limit - kernel.next)) {
			dlog("Unable to copy kernel for vm %u\n", count);
			continue;
		}

		if (!vm_init(&secondary_vm[count], count + 1, cpu)) {
			dlog("Unable to initialise vm %u\n", count);
			continue;
		}

		/* TODO: Remove this. */
		/* Grant VM access to uart. */
		mm_vm_identity_map_page(&secondary_vm[count].ptable,
					pa_init(PL011_BASE),
					MM_MODE_R | MM_MODE_W | MM_MODE_D |
						MM_MODE_NOINVALIDATE,
					NULL);

		/* Grant the VM access to the memory. */
		if (!mm_vm_identity_map(&secondary_vm[count].ptable,
					secondary_mem_begin, secondary_mem_end,
					MM_MODE_R | MM_MODE_W | MM_MODE_X |
						MM_MODE_NOINVALIDATE,
					&secondary_entry)) {
			dlog("Unable to initialise memory for vm %u\n", count);
			continue;
		}

		/* Deny the primary VM access to this memory. */
		if (!mm_vm_unmap(&primary_vm.ptable, secondary_mem_begin,
				 secondary_mem_end, MM_MODE_NOINVALIDATE)) {
			dlog("Unable to unmap secondary VM from primary VM\n");
			return false;
		}

		dlog("Loaded VM%u with %u vcpus, entry at 0x%x\n", count, cpu,
		     pa_addr(secondary_mem_begin));

		vm_start_vcpu(&secondary_vm[count], 0, secondary_entry, 0);
	}

	secondary_vm_count = count;

	/* Add newly reserved areas to update params by looking at the
	 * difference between the available ranges from the original params and
	 * the updated mem_ranges_available. We assume that the number and order
	 * of available ranges is the same, i.e. we don't remove any ranges
	 * above only make them smaller. */
	return update_reserved_ranges(update, params->mem_ranges,
				      mem_ranges_available,
				      params->mem_ranges_count);
}