arm64: mm: limit linear region to 51 bits for KVM in nVHE mode

[linux-2.6-microblaze.git] / arch / arm64 / mm / init.c

// SPDX-License-Identifier: GPL-2.0-only
/*
 * Based on arch/arm/mm/init.c
 *
 * Copyright (C) 1995-2005 Russell King
 * Copyright (C) 2012 ARM Ltd.
 */

#include <linux/kernel.h>
#include <linux/export.h>
#include <linux/errno.h>
#include <linux/swap.h>
#include <linux/init.h>
#include <linux/cache.h>
#include <linux/mman.h>
#include <linux/nodemask.h>
#include <linux/initrd.h>
#include <linux/gfp.h>
#include <linux/memblock.h>
#include <linux/sort.h>
#include <linux/of.h>
#include <linux/of_fdt.h>
#include <linux/dma-direct.h>
#include <linux/dma-map-ops.h>
#include <linux/efi.h>
#include <linux/swiotlb.h>
#include <linux/vmalloc.h>
#include <linux/mm.h>
#include <linux/kexec.h>
#include <linux/crash_dump.h>
#include <linux/hugetlb.h>
#include <linux/acpi_iort.h>

#include <asm/boot.h>
#include <asm/fixmap.h>
#include <asm/kasan.h>
#include <asm/kernel-pgtable.h>
#include <asm/kvm_host.h>
#include <asm/memory.h>
#include <asm/numa.h>
#include <asm/sections.h>
#include <asm/setup.h>
#include <linux/sizes.h>
#include <asm/tlb.h>
#include <asm/alternative.h>
#include <asm/xen/swiotlb-xen.h>

/*
 * We need to be able to catch inadvertent references to memstart_addr
 * that occur (potentially in generic code) before arm64_memblock_init()
 * executes, which assigns it its actual value. So use a default value
 * that cannot be mistaken for a real physical address.
 */
s64 memstart_addr __ro_after_init = -1;
EXPORT_SYMBOL(memstart_addr);

/*
 * If the corresponding config options are enabled, we create both ZONE_DMA
 * and ZONE_DMA32. By default ZONE_DMA covers the 32-bit addressable memory
 * unless restricted on specific platforms (e.g. 30-bit on Raspberry Pi 4).
 * In such case, ZONE_DMA32 covers the rest of the 32-bit addressable memory,
 * otherwise it is empty.
 */
phys_addr_t arm64_dma_phys_limit __ro_after_init;

#ifdef CONFIG_KEXEC_CORE
/*
 * reserve_crashkernel() - reserves memory for crash kernel
 *
 * This function reserves memory area given in "crashkernel=" kernel command
 * line parameter. The memory reserved is used by dump capture kernel when
 * primary kernel is crashing.
 */
static void __init reserve_crashkernel(void)
{
        unsigned long long crash_base, crash_size;
        int ret;

        ret = parse_crashkernel(boot_command_line, memblock_phys_mem_size(),
                                &crash_size, &crash_base);
        /* no crashkernel= or invalid value specified */
        if (ret || !crash_size)
                return;

        crash_size = PAGE_ALIGN(crash_size);

        if (crash_base == 0) {
                /* Current arm64 boot protocol requires 2MB alignment */
                crash_base = memblock_find_in_range(0, arm64_dma_phys_limit,
                                crash_size, SZ_2M);
                if (crash_base == 0) {
                        pr_warn("cannot allocate crashkernel (size:0x%llx)\n",
                                crash_size);
                        return;
                }
        } else {
                /* User specifies base address explicitly. */
                if (!memblock_is_region_memory(crash_base, crash_size)) {
                        pr_warn("cannot reserve crashkernel: region is not memory\n");
                        return;
                }

                if (memblock_is_region_reserved(crash_base, crash_size)) {
                        pr_warn("cannot reserve crashkernel: region overlaps reserved memory\n");
                        return;
                }

                if (!IS_ALIGNED(crash_base, SZ_2M)) {
                        pr_warn("cannot reserve crashkernel: base address is not 2MB aligned\n");
                        return;
                }
        }
        memblock_reserve(crash_base, crash_size);

        pr_info("crashkernel reserved: 0x%016llx - 0x%016llx (%lld MB)\n",
                crash_base, crash_base + crash_size, crash_size >> 20);

        crashk_res.start = crash_base;
        crashk_res.end = crash_base + crash_size - 1;
}
#else
static void __init reserve_crashkernel(void)
{
}
#endif /* CONFIG_KEXEC_CORE */

#ifdef CONFIG_CRASH_DUMP
static int __init early_init_dt_scan_elfcorehdr(unsigned long node,
                const char *uname, int depth, void *data)
{
        const __be32 *reg;
        int len;

        if (depth != 1 || strcmp(uname, "chosen") != 0)
                return 0;

        reg = of_get_flat_dt_prop(node, "linux,elfcorehdr", &len);
        if (!reg || (len < (dt_root_addr_cells + dt_root_size_cells)))
                return 1;

        elfcorehdr_addr = dt_mem_next_cell(dt_root_addr_cells, &reg);
        elfcorehdr_size = dt_mem_next_cell(dt_root_size_cells, &reg);

        return 1;
}

/*
 * reserve_elfcorehdr() - reserves memory for elf core header
 *
 * This function reserves the memory occupied by an elf core header
 * described in the device tree. This region contains all the
 * information about primary kernel's core image and is used by a dump
 * capture kernel to access the system memory on primary kernel.
 */
static void __init reserve_elfcorehdr(void)
{
        of_scan_flat_dt(early_init_dt_scan_elfcorehdr, NULL);

        if (!elfcorehdr_size)
                return;

        if (memblock_is_region_reserved(elfcorehdr_addr, elfcorehdr_size)) {
                pr_warn("elfcorehdr is overlapped\n");
                return;
        }

        memblock_reserve(elfcorehdr_addr, elfcorehdr_size);

        pr_info("Reserving %lldKB of memory at 0x%llx for elfcorehdr\n",
                elfcorehdr_size >> 10, elfcorehdr_addr);
}
#else
static void __init reserve_elfcorehdr(void)
{
}
#endif /* CONFIG_CRASH_DUMP */

/*
 * Return the maximum physical address for a zone accessible by the given bits
 * limit. If DRAM starts above 32-bit, expand the zone to the maximum
 * available memory, otherwise cap it at 32-bit.
 */
static phys_addr_t __init max_zone_phys(unsigned int zone_bits)
{
        phys_addr_t zone_mask = DMA_BIT_MASK(zone_bits);
        phys_addr_t phys_start = memblock_start_of_DRAM();

        if (phys_start > U32_MAX)
                zone_mask = PHYS_ADDR_MAX;
        else if (phys_start > zone_mask)
                zone_mask = U32_MAX;

        return min(zone_mask, memblock_end_of_DRAM() - 1) + 1;
}

static void __init zone_sizes_init(unsigned long min, unsigned long max)
{
        unsigned long max_zone_pfns[MAX_NR_ZONES]  = {0};
        unsigned int __maybe_unused acpi_zone_dma_bits;
        unsigned int __maybe_unused dt_zone_dma_bits;
        phys_addr_t __maybe_unused dma32_phys_limit = max_zone_phys(32);

#ifdef CONFIG_ZONE_DMA
        acpi_zone_dma_bits = fls64(acpi_iort_dma_get_max_cpu_address());
        dt_zone_dma_bits = fls64(of_dma_get_max_cpu_address(NULL));
        zone_dma_bits = min3(32U, dt_zone_dma_bits, acpi_zone_dma_bits);
        arm64_dma_phys_limit = max_zone_phys(zone_dma_bits);
        max_zone_pfns[ZONE_DMA] = PFN_DOWN(arm64_dma_phys_limit);
#endif
#ifdef CONFIG_ZONE_DMA32
        max_zone_pfns[ZONE_DMA32] = PFN_DOWN(dma32_phys_limit);
        if (!arm64_dma_phys_limit)
                arm64_dma_phys_limit = dma32_phys_limit;
#endif
        if (!arm64_dma_phys_limit)
                arm64_dma_phys_limit = PHYS_MASK + 1;
        max_zone_pfns[ZONE_NORMAL] = max;

        free_area_init(max_zone_pfns);
}

int pfn_is_map_memory(unsigned long pfn)
{
        phys_addr_t addr = PFN_PHYS(pfn);

        /* avoid false positives for bogus PFNs, see comment in pfn_valid() */
        if (PHYS_PFN(addr) != pfn)
                return 0;

        return memblock_is_map_memory(addr);
}
EXPORT_SYMBOL(pfn_is_map_memory);

static phys_addr_t memory_limit = PHYS_ADDR_MAX;

/*
 * Limit the memory size that was specified via FDT.
 */
static int __init early_mem(char *p)
{
        if (!p)
                return 1;

        memory_limit = memparse(p, &p) & PAGE_MASK;
        pr_notice("Memory limited to %lldMB\n", memory_limit >> 20);

        return 0;
}
early_param("mem", early_mem);

static int __init early_init_dt_scan_usablemem(unsigned long node,
                const char *uname, int depth, void *data)
{
        struct memblock_region *usablemem = data;
        const __be32 *reg;
        int len;

        if (depth != 1 || strcmp(uname, "chosen") != 0)
                return 0;

        reg = of_get_flat_dt_prop(node, "linux,usable-memory-range", &len);
        if (!reg || (len < (dt_root_addr_cells + dt_root_size_cells)))
                return 1;

        usablemem->base = dt_mem_next_cell(dt_root_addr_cells, &reg);
        usablemem->size = dt_mem_next_cell(dt_root_size_cells, &reg);

        return 1;
}

static void __init fdt_enforce_memory_region(void)
{
        struct memblock_region reg = {
                .size = 0,
        };

        of_scan_flat_dt(early_init_dt_scan_usablemem, &reg);

        if (reg.size)
                memblock_cap_memory_range(reg.base, reg.size);
}

void __init arm64_memblock_init(void)
{
        s64 linear_region_size = PAGE_END - _PAGE_OFFSET(vabits_actual);

        /*
         * Corner case: 52-bit VA capable systems running KVM in nVHE mode may
         * be limited in their ability to support a linear map that exceeds 51
         * bits of VA space, depending on the placement of the ID map. Given
         * that the placement of the ID map may be randomized, let's simply
         * limit the kernel's linear map to 51 bits as well if we detect this
         * configuration.
         */
        if (IS_ENABLED(CONFIG_KVM) && vabits_actual == 52 &&
            is_hyp_mode_available() && !is_kernel_in_hyp_mode()) {
                pr_info("Capping linear region to 51 bits for KVM in nVHE mode on LVA capable hardware.\n");
                linear_region_size = min_t(u64, linear_region_size, BIT(51));
        }

        /* Handle linux,usable-memory-range property */
        fdt_enforce_memory_region();

        /* Remove memory above our supported physical address size */
        memblock_remove(1ULL << PHYS_MASK_SHIFT, ULLONG_MAX);

        /*
         * Select a suitable value for the base of physical memory.
         */
        memstart_addr = round_down(memblock_start_of_DRAM(),
                                   ARM64_MEMSTART_ALIGN);

        if ((memblock_end_of_DRAM() - memstart_addr) > linear_region_size)
                pr_warn("Memory doesn't fit in the linear mapping, VA_BITS too small\n");

        /*
         * Remove the memory that we will not be able to cover with the
         * linear mapping. Take care not to clip the kernel which may be
         * high in memory.
         */
        memblock_remove(max_t(u64, memstart_addr + linear_region_size,
                        __pa_symbol(_end)), ULLONG_MAX);
        if (memstart_addr + linear_region_size < memblock_end_of_DRAM()) {
                /* ensure that memstart_addr remains sufficiently aligned */
                memstart_addr = round_up(memblock_end_of_DRAM() - linear_region_size,
                                         ARM64_MEMSTART_ALIGN);
                memblock_remove(0, memstart_addr);
        }

        /*
         * If we are running with a 52-bit kernel VA config on a system that
         * does not support it, we have to place the available physical
         * memory in the 48-bit addressable part of the linear region, i.e.,
         * we have to move it upward. Since memstart_addr represents the
         * physical address of PAGE_OFFSET, we have to *subtract* from it.
         */
        if (IS_ENABLED(CONFIG_ARM64_VA_BITS_52) && (vabits_actual != 52))
                memstart_addr -= _PAGE_OFFSET(48) - _PAGE_OFFSET(52);

        /*
         * Apply the memory limit if it was set. Since the kernel may be loaded
         * high up in memory, add back the kernel region that must be accessible
         * via the linear mapping.
         */
        if (memory_limit != PHYS_ADDR_MAX) {
                memblock_mem_limit_remove_map(memory_limit);
                memblock_add(__pa_symbol(_text), (u64)(_end - _text));
        }

        if (IS_ENABLED(CONFIG_BLK_DEV_INITRD) && phys_initrd_size) {
                /*
                 * Add back the memory we just removed if it results in the
                 * initrd to become inaccessible via the linear mapping.
                 * Otherwise, this is a no-op
                 */
                u64 base = phys_initrd_start & PAGE_MASK;
                u64 size = PAGE_ALIGN(phys_initrd_start + phys_initrd_size) - base;

                /*
                 * We can only add back the initrd memory if we don't end up
                 * with more memory than we can address via the linear mapping.
                 * It is up to the bootloader to position the kernel and the
                 * initrd reasonably close to each other (i.e., within 32 GB of
                 * each other) so that all granule/#levels combinations can
                 * always access both.
                 */
                if (WARN(base < memblock_start_of_DRAM() ||
                         base + size > memblock_start_of_DRAM() +
                                       linear_region_size,
                        "initrd not fully accessible via the linear mapping -- please check your bootloader ...\n")) {
                        phys_initrd_size = 0;
                } else {
                        memblock_remove(base, size); /* clear MEMBLOCK_ flags */
                        memblock_add(base, size);
                        memblock_reserve(base, size);
                }
        }

        if (IS_ENABLED(CONFIG_RANDOMIZE_BASE)) {
                extern u16 memstart_offset_seed;
                u64 mmfr0 = read_cpuid(ID_AA64MMFR0_EL1);
                int parange = cpuid_feature_extract_unsigned_field(
                                        mmfr0, ID_AA64MMFR0_PARANGE_SHIFT);
                s64 range = linear_region_size -
                            BIT(id_aa64mmfr0_parange_to_phys_shift(parange));

                /*
                 * If the size of the linear region exceeds, by a sufficient
                 * margin, the size of the region that the physical memory can
                 * span, randomize the linear region as well.
                 */
                if (memstart_offset_seed > 0 && range >= (s64)ARM64_MEMSTART_ALIGN) {
                        range /= ARM64_MEMSTART_ALIGN;
                        memstart_addr -= ARM64_MEMSTART_ALIGN *
                                         ((range * memstart_offset_seed) >> 16);
                }
        }

        /*
         * Register the kernel text, kernel data, initrd, and initial
         * pagetables with memblock.
         */
        memblock_reserve(__pa_symbol(_stext), _end - _stext);
        if (IS_ENABLED(CONFIG_BLK_DEV_INITRD) && phys_initrd_size) {
                /* the generic initrd code expects virtual addresses */
                initrd_start = __phys_to_virt(phys_initrd_start);
                initrd_end = initrd_start + phys_initrd_size;
        }

        early_init_fdt_scan_reserved_mem();

        reserve_elfcorehdr();

        high_memory = __va(memblock_end_of_DRAM() - 1) + 1;
}

void __init bootmem_init(void)
{
        unsigned long min, max;

        min = PFN_UP(memblock_start_of_DRAM());
        max = PFN_DOWN(memblock_end_of_DRAM());

        early_memtest(min << PAGE_SHIFT, max << PAGE_SHIFT);

        max_pfn = max_low_pfn = max;
        min_low_pfn = min;

        arch_numa_init();

        /*
         * must be done after arch_numa_init() which calls numa_init() to
         * initialize node_online_map that gets used in hugetlb_cma_reserve()
         * while allocating required CMA size across online nodes.
         */
#if defined(CONFIG_HUGETLB_PAGE) && defined(CONFIG_CMA)
        arm64_hugetlb_cma_reserve();
#endif

        dma_pernuma_cma_reserve();

        kvm_hyp_reserve();

        /*
         * sparse_init() tries to allocate memory from memblock, so must be
         * done after the fixed reservations
         */
        sparse_init();
        zone_sizes_init(min, max);

        /*
         * Reserve the CMA area after arm64_dma_phys_limit was initialised.
         */
        dma_contiguous_reserve(arm64_dma_phys_limit);

        /*
         * request_standard_resources() depends on crashkernel's memory being
         * reserved, so do it here.
         */
        reserve_crashkernel();

        memblock_dump_all();
}

/*
 * mem_init() marks the free areas in the mem_map and tells us how much memory
 * is free.  This is done after various parts of the system have claimed their
 * memory after the kernel image.
 */
void __init mem_init(void)
{
        if (swiotlb_force == SWIOTLB_FORCE ||
            max_pfn > PFN_DOWN(arm64_dma_phys_limit))
                swiotlb_init(1);
        else if (!xen_swiotlb_detect())
                swiotlb_force = SWIOTLB_NO_FORCE;

        set_max_mapnr(max_pfn - PHYS_PFN_OFFSET);

        /* this will put all unused low memory onto the freelists */
        memblock_free_all();

        /*
         * Check boundaries twice: Some fundamental inconsistencies can be
         * detected at build time already.
         */
#ifdef CONFIG_COMPAT
        BUILD_BUG_ON(TASK_SIZE_32 > DEFAULT_MAP_WINDOW_64);
#endif

        /*
         * Selected page table levels should match when derived from
         * scratch using the virtual address range and page size.
         */
        BUILD_BUG_ON(ARM64_HW_PGTABLE_LEVELS(CONFIG_ARM64_VA_BITS) !=
                     CONFIG_PGTABLE_LEVELS);

        if (PAGE_SIZE >= 16384 && get_num_physpages() <= 128) {
                extern int sysctl_overcommit_memory;
                /*
                 * On a machine this small we won't get anywhere without
                 * overcommit, so turn it on by default.
                 */
                sysctl_overcommit_memory = OVERCOMMIT_ALWAYS;
        }
}

void free_initmem(void)
{
        free_reserved_area(lm_alias(__init_begin),
                           lm_alias(__init_end),
                           POISON_FREE_INITMEM, "unused kernel");
        /*
         * Unmap the __init region but leave the VM area in place. This
         * prevents the region from being reused for kernel modules, which
         * is not supported by kallsyms.
         */
        vunmap_range((u64)__init_begin, (u64)__init_end);
}

void dump_mem_limit(void)
{
        if (memory_limit != PHYS_ADDR_MAX) {
                pr_emerg("Memory Limit: %llu MB\n", memory_limit >> 20);
        } else {
                pr_emerg("Memory Limit: none\n");
        }
}