WSL2-Linux-Kernel/arch/arm/kvm/mmu.c

/*
 * Copyright (C) 2012 - Virtual Open Systems and Columbia University
 * Author: Christoffer Dall <c.dall@virtualopensystems.com>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License, version 2, as
 * published by the Free Software Foundation.
 *
 * 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, write to the Free Software
 * Foundation, 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
 */

#include <linux/mman.h>
#include <linux/kvm_host.h>
#include <linux/io.h>
#include <asm/idmap.h>
#include <asm/pgalloc.h>
#include <asm/kvm_arm.h>
#include <asm/kvm_mmu.h>
#include <asm/mach/map.h>

extern char  __hyp_idmap_text_start[], __hyp_idmap_text_end[];

static DEFINE_MUTEX(kvm_hyp_pgd_mutex);

static void kvm_set_pte(pte_t *pte, pte_t new_pte)
{
	pte_val(*pte) = new_pte;
	/*
	 * flush_pmd_entry just takes a void pointer and cleans the necessary
	 * cache entries, so we can reuse the function for ptes.
	 */
	flush_pmd_entry(pte);
}

static void free_ptes(pmd_t *pmd, unsigned long addr)
{
	pte_t *pte;
	unsigned int i;

	for (i = 0; i < PTRS_PER_PMD; i++, addr += PMD_SIZE) {
		if (!pmd_none(*pmd) && pmd_table(*pmd)) {
			pte = pte_offset_kernel(pmd, addr);
			pte_free_kernel(NULL, pte);
		}
		pmd++;
	}
}

/**
 * free_hyp_pmds - free a Hyp-mode level-2 tables and child level-3 tables
 *
 * Assumes this is a page table used strictly in Hyp-mode and therefore contains
 * only mappings in the kernel memory area, which is above PAGE_OFFSET.
 */
void free_hyp_pmds(void)
{
	pgd_t *pgd;
	pud_t *pud;
	pmd_t *pmd;
	unsigned long addr;

	mutex_lock(&kvm_hyp_pgd_mutex);
	for (addr = PAGE_OFFSET; addr != 0; addr += PGDIR_SIZE) {
		pgd = hyp_pgd + pgd_index(addr);
		pud = pud_offset(pgd, addr);

		if (pud_none(*pud))
			continue;
		BUG_ON(pud_bad(*pud));

		pmd = pmd_offset(pud, addr);
		free_ptes(pmd, addr);
		pmd_free(NULL, pmd);
		pud_clear(pud);
	}
	mutex_unlock(&kvm_hyp_pgd_mutex);
}

static void create_hyp_pte_mappings(pmd_t *pmd, unsigned long start,
				    unsigned long end)
{
	pte_t *pte;
	unsigned long addr;
	struct page *page;

	for (addr = start & PAGE_MASK; addr < end; addr += PAGE_SIZE) {
		pte = pte_offset_kernel(pmd, addr);
		BUG_ON(!virt_addr_valid(addr));
		page = virt_to_page(addr);
		kvm_set_pte(pte, mk_pte(page, PAGE_HYP));
	}
}

static void create_hyp_io_pte_mappings(pmd_t *pmd, unsigned long start,
				       unsigned long end,
				       unsigned long *pfn_base)
{
	pte_t *pte;
	unsigned long addr;

	for (addr = start & PAGE_MASK; addr < end; addr += PAGE_SIZE) {
		pte = pte_offset_kernel(pmd, addr);
		BUG_ON(pfn_valid(*pfn_base));
		kvm_set_pte(pte, pfn_pte(*pfn_base, PAGE_HYP_DEVICE));
		(*pfn_base)++;
	}
}

static int create_hyp_pmd_mappings(pud_t *pud, unsigned long start,
				   unsigned long end, unsigned long *pfn_base)
{
	pmd_t *pmd;
	pte_t *pte;
	unsigned long addr, next;

	for (addr = start; addr < end; addr = next) {
		pmd = pmd_offset(pud, addr);

		BUG_ON(pmd_sect(*pmd));

		if (pmd_none(*pmd)) {
			pte = pte_alloc_one_kernel(NULL, addr);
			if (!pte) {
				kvm_err("Cannot allocate Hyp pte\n");
				return -ENOMEM;
			}
			pmd_populate_kernel(NULL, pmd, pte);
		}

		next = pmd_addr_end(addr, end);

		/*
		 * If pfn_base is NULL, we map kernel pages into HYP with the
		 * virtual address. Otherwise, this is considered an I/O
		 * mapping and we map the physical region starting at
		 * *pfn_base to [start, end[.
		 */
		if (!pfn_base)
			create_hyp_pte_mappings(pmd, addr, next);
		else
			create_hyp_io_pte_mappings(pmd, addr, next, pfn_base);
	}

	return 0;
}

static int __create_hyp_mappings(void *from, void *to, unsigned long *pfn_base)
{
	unsigned long start = (unsigned long)from;
	unsigned long end = (unsigned long)to;
	pgd_t *pgd;
	pud_t *pud;
	pmd_t *pmd;
	unsigned long addr, next;
	int err = 0;

	BUG_ON(start > end);
	if (start < PAGE_OFFSET)
		return -EINVAL;

	mutex_lock(&kvm_hyp_pgd_mutex);
	for (addr = start; addr < end; addr = next) {
		pgd = hyp_pgd + pgd_index(addr);
		pud = pud_offset(pgd, addr);

		if (pud_none_or_clear_bad(pud)) {
			pmd = pmd_alloc_one(NULL, addr);
			if (!pmd) {
				kvm_err("Cannot allocate Hyp pmd\n");
				err = -ENOMEM;
				goto out;
			}
			pud_populate(NULL, pud, pmd);
		}

		next = pgd_addr_end(addr, end);
		err = create_hyp_pmd_mappings(pud, addr, next, pfn_base);
		if (err)
			goto out;
	}
out:
	mutex_unlock(&kvm_hyp_pgd_mutex);
	return err;
}

/**
 * create_hyp_mappings - map a kernel virtual address range in Hyp mode
 * @from:	The virtual kernel start address of the range
 * @to:		The virtual kernel end address of the range (exclusive)
 *
 * The same virtual address as the kernel virtual address is also used in
 * Hyp-mode mapping to the same underlying physical pages.
 *
 * Note: Wrapping around zero in the "to" address is not supported.
 */
int create_hyp_mappings(void *from, void *to)
{
	return __create_hyp_mappings(from, to, NULL);
}

/**
 * create_hyp_io_mappings - map a physical IO range in Hyp mode
 * @from:	The virtual HYP start address of the range
 * @to:		The virtual HYP end address of the range (exclusive)
 * @addr:	The physical start address which gets mapped
 */
int create_hyp_io_mappings(void *from, void *to, phys_addr_t addr)
{
	unsigned long pfn = __phys_to_pfn(addr);
	return __create_hyp_mappings(from, to, &pfn);
}

int kvm_handle_guest_abort(struct kvm_vcpu *vcpu, struct kvm_run *run)
{
	return -EINVAL;
}

phys_addr_t kvm_mmu_get_httbr(void)
{
	VM_BUG_ON(!virt_addr_valid(hyp_pgd));
	return virt_to_phys(hyp_pgd);
}

int kvm_mmu_init(void)
{
	return hyp_pgd ? 0 : -ENOMEM;
}

/**
 * kvm_clear_idmap - remove all idmaps from the hyp pgd
 *
 * Free the underlying pmds for all pgds in range and clear the pgds (but
 * don't free them) afterwards.
 */
void kvm_clear_hyp_idmap(void)
{
	unsigned long addr, end;
	unsigned long next;
	pgd_t *pgd = hyp_pgd;
	pud_t *pud;
	pmd_t *pmd;

	addr = virt_to_phys(__hyp_idmap_text_start);
	end = virt_to_phys(__hyp_idmap_text_end);

	pgd += pgd_index(addr);
	do {
		next = pgd_addr_end(addr, end);
		if (pgd_none_or_clear_bad(pgd))
			continue;
		pud = pud_offset(pgd, addr);
		pmd = pmd_offset(pud, addr);

		pud_clear(pud);
		clean_pmd_entry(pmd);
		pmd_free(NULL, (pmd_t *)((unsigned long)pmd & PAGE_MASK));
	} while (pgd++, addr = next, addr < end);
}