acrn guest 内存分析

记录一下 acrn guest 内存分配原理
dm 的-m参数会调用 vm_setup_memory，将要为user vm 分配的内存大小记录下来，同时调用
hugetlb_setup_memory从 sos 大页中分出对应内存

int hugetlb_setup_memory(struct vmctx *ctx)
{
   
	int level;
	size_t lowmem, fbmem, biosmem, highmem;
	bool has_gap;
	int fd;
	unsigned int seal_flag = F_SEAL_GROW | F_SEAL_SHRINK | F_SEAL_SEAL;
	size_t mem_size_level;

	mem_idx = 0;
	memset(&mmap_mem_regions, 0, sizeof(mmap_mem_regions));
	if (ctx->lowmem == 0) {
   
		pr_err("vm requests 0 memory");
		goto err;
	}

	/* In course of reboot sequence, the memfd is closed. So it
	 * needs to recreate the memfd if it is closed.
	 */
	for (level = HUGETLB_LV1; level < HUGETLB_LV_MAX; level++) {
   
		if (hugetlb_priv[level].fd > 0)
			continue;

		fd = memfd_create("acrn_memfd", hugetlb_priv[level].flags);
		if (fd == -1) {
   
			pr_err("Fail to create memfd for %d.\n",
				level);
			break;
		}
		hugetlb_priv[level].fd = fd;
	}

	if (ALIGN_CHECK(ctx->lowmem, hugetlb_priv[HUGETLB_LV1].pg_size) ||
		ALIGN_CHECK(ctx->highmem, hugetlb_priv[HUGETLB_LV1].pg_size) ||
		ALIGN_CHECK(ctx->biosmem, hugetlb_priv[HUGETLB_LV1].pg_size) ||
		ALIGN_CHECK(ctx->fbmem, hugetlb_priv[HUGETLB_LV1].pg_size)) {
   
		pr_err("Memory size is not aligned to 2M.\n");
		goto err;
	}
	/* all memory should be at least aligned with
	 * hugetlb_priv[HUGETLB_LV1].pg_size */
	ctx->lowmem =
		ALIGN_DOWN(ctx->lowmem, hugetlb_priv[HUGETLB_LV1].pg_size);
	ctx->fbmem =
		ALIGN_DOWN(ctx->fbmem, hugetlb_priv[HUGETLB_LV1].pg_size);
	ctx->biosmem =
		ALIGN_DOWN(ctx->biosmem, hugetlb_priv[HUGETLB_LV1].pg_size);
	ctx->highmem =
		ALIGN_DOWN(ctx->highmem, hugetlb_priv[HUGETLB_LV1].pg_size);

	total_size = ctx->highmem_gpa_base + ctx->highmem;

	/* check & set hugetlb level memory size for lowmem/biosmem/highmem */
	lowmem = ctx->lowmem;
	fbmem = ctx->fbmem;
	biosmem = ctx->biosmem;
	highmem = ctx->highmem;

	for (level = hugetlb_lv_max - 1; level >= HUGETLB_LV1; level--) {
   
		if (hugetlb_priv[level].fd < 0) {
   
			hugetlb_priv[level].lowmem = 0;
			hugetlb_priv[level].highmem = 0;
			hugetlb_priv[level].biosmem = 0;
			hugetlb_priv[level].fbmem = 0;
			continue;
		}
		hugetlb_priv[level].lowmem =
			ALIGN_DOWN(lowmem, hugetlb_priv[level].pg_size);
		hugetlb_priv[level].fbmem =
			ALIGN_DOWN(fbmem, hugetlb_priv[level].pg_size);
		hugetlb_priv[level].biosmem =
			ALIGN_DOWN(biosmem, hugetlb_priv[level].pg_size);
		hugetlb_priv[level].highmem =
			ALIGN_DOWN(highmem, hugetlb_priv[level].pg_size);

		if (level > HUGETLB_LV1) {
   
			hugetlb_priv[level-1].lowmem = lowmem =
				lowmem - hugetlb_priv[level].lowmem;
			hugetlb_priv[level-1].fbmem = fbmem =
				fbmem - hugetlb_priv[l
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