processor.c

// SPDX-License-Identifier: GPL-2.0

#include <assert.h>
#include <linux/compiler.h>

#include <asm/kvm.h>
#include "kvm_util.h"
#include "processor.h"
#include "ucall_common.h"

#define LOONGARCH_PAGE_TABLE_PHYS_MIN		0x200000
#define LOONGARCH_GUEST_STACK_VADDR_MIN		0x200000

static vm_paddr_t invalid_pgtable[4];
static vm_vaddr_t exception_handlers;

static uint64_t virt_pte_index(struct kvm_vm *vm, vm_vaddr_t gva, int level)
{
	unsigned int shift;
	uint64_t mask;

	shift = level * (vm->page_shift - 3) + vm->page_shift;
	mask = (1UL << (vm->page_shift - 3)) - 1;
	return (gva >> shift) & mask;
}

static uint64_t pte_addr(struct kvm_vm *vm, uint64_t entry)
{
	return entry &  ~((0x1UL << vm->page_shift) - 1);
}

static uint64_t ptrs_per_pte(struct kvm_vm *vm)
{
	return 1 << (vm->page_shift - 3);
}

static void virt_set_pgtable(struct kvm_vm *vm, vm_paddr_t table, vm_paddr_t child)
{
	uint64_t *ptep;
	int i, ptrs_per_pte;

	ptep = addr_gpa2hva(vm, table);
	ptrs_per_pte = 1 << (vm->page_shift - 3);
	for (i = 0; i < ptrs_per_pte; i++)
		WRITE_ONCE(*(ptep + i), child);
}

void virt_arch_pgd_alloc(struct kvm_vm *vm)
{
	int i;
	vm_paddr_t child, table;

	if (vm->pgd_created)
		return;

	child = table = 0;
	for (i = 0; i < vm->pgtable_levels; i++) {
		invalid_pgtable[i] = child;
		table = vm_phy_page_alloc(vm, LOONGARCH_PAGE_TABLE_PHYS_MIN,
				vm->memslots[MEM_REGION_PT]);
		TEST_ASSERT(table, "Fail to allocate page tale at level %d\n", i);
		virt_set_pgtable(vm, table, child);
		child = table;
	}
	vm->pgd = table;
	vm->pgd_created = true;
}

static int virt_pte_none(uint64_t *ptep, int level)
{
	return *ptep == invalid_pgtable[level];
}

static uint64_t *virt_populate_pte(struct kvm_vm *vm, vm_vaddr_t gva, int alloc)
{
	int level;
	uint64_t *ptep;
	vm_paddr_t child;

	if (!vm->pgd_created)
		goto unmapped_gva;

	child = vm->pgd;
	level = vm->pgtable_levels - 1;
	while (level > 0) {
		ptep = addr_gpa2hva(vm, child) + virt_pte_index(vm, gva, level) * 8;
		if (virt_pte_none(ptep, level)) {
			if (alloc) {
				child = vm_alloc_page_table(vm);
				virt_set_pgtable(vm, child, invalid_pgtable[level - 1]);
				WRITE_ONCE(*ptep, child);
			} else
				goto unmapped_gva;

		} else
			child = pte_addr(vm, *ptep);
		level--;
	}

	ptep = addr_gpa2hva(vm, child) + virt_pte_index(vm, gva, level) * 8;
	return ptep;

unmapped_gva:
	TEST_FAIL("No mapping for vm virtual address, gva: 0x%lx", gva);
	exit(EXIT_FAILURE);
}

vm_paddr_t addr_arch_gva2gpa(struct kvm_vm *vm, vm_vaddr_t gva)
{
	uint64_t *ptep;

	ptep = virt_populate_pte(vm, gva, 0);
	TEST_ASSERT(*ptep != 0, "Virtual address vaddr: 0x%lx not mapped\n", gva);

	return pte_addr(vm, *ptep) + (gva & (vm->page_size - 1));
}

void virt_arch_pg_map(struct kvm_vm *vm, uint64_t vaddr, uint64_t paddr)
{
	uint32_t prot_bits;
	uint64_t *ptep;

	TEST_ASSERT((vaddr % vm->page_size) == 0,
			"Virtual address not on page boundary,\n"
			"vaddr: 0x%lx vm->page_size: 0x%x", vaddr, vm->page_size);
	TEST_ASSERT(sparsebit_is_set(vm->vpages_valid,
			(vaddr >> vm->page_shift)),
			"Invalid virtual address, vaddr: 0x%lx", vaddr);
	TEST_ASSERT((paddr % vm->page_size) == 0,
			"Physical address not on page boundary,\n"
			"paddr: 0x%lx vm->page_size: 0x%x", paddr, vm->page_size);
	TEST_ASSERT((paddr >> vm->page_shift) <= vm->max_gfn,
			"Physical address beyond maximum supported,\n"
			"paddr: 0x%lx vm->max_gfn: 0x%lx vm->page_size: 0x%x",
			paddr, vm->max_gfn, vm->page_size);

	ptep = virt_populate_pte(vm, vaddr, 1);
	prot_bits = _PAGE_PRESENT | __READABLE | __WRITEABLE | _CACHE_CC | _PAGE_USER;
	WRITE_ONCE(*ptep, paddr | prot_bits);
}

static void pte_dump(FILE *stream, struct kvm_vm *vm, uint8_t indent, uint64_t page, int level)
{
	uint64_t pte, *ptep;
	static const char * const type[] = { "pte", "pmd", "pud", "pgd"};

	if (level < 0)
		return;

	for (pte = page; pte < page + ptrs_per_pte(vm) * 8; pte += 8) {
		ptep = addr_gpa2hva(vm, pte);
		if (virt_pte_none(ptep, level))
			continue;
		fprintf(stream, "%*s%s: %lx: %lx at %p\n",
				indent, "", type[level], pte, *ptep, ptep);
		pte_dump(stream, vm, indent + 1, pte_addr(vm, *ptep), level--);
	}
}

void virt_arch_dump(FILE *stream, struct kvm_vm *vm, uint8_t indent)
{
	int level;

	if (!vm->pgd_created)
		return;

	level = vm->pgtable_levels - 1;
	pte_dump(stream, vm, indent, vm->pgd, level);
}

void vcpu_arch_dump(FILE *stream, struct kvm_vcpu *vcpu, uint8_t indent)
{
}

void assert_on_unhandled_exception(struct kvm_vcpu *vcpu)
{
	struct ucall uc;

	if (get_ucall(vcpu, &uc) != UCALL_UNHANDLED)
		return;

	TEST_FAIL("Unexpected exception (pc:0x%lx, estat:0x%lx, badv:0x%lx)",
			uc.args[0], uc.args[1], uc.args[2]);
}

void route_exception(struct ex_regs *regs)
{
	int vector;
	unsigned long pc, estat, badv;
	struct handlers *handlers;

	handlers = (struct handlers *)exception_handlers;
	vector = (regs->estat & CSR_ESTAT_EXC) >> CSR_ESTAT_EXC_SHIFT;
	if (handlers && handlers->exception_handlers[vector])
		return handlers->exception_handlers[vector](regs);

	pc = regs->pc;
	badv  = regs->badv;
	estat = regs->estat;
	ucall(UCALL_UNHANDLED, 3, pc, estat, badv);
	while (1) ;
}

void vm_init_descriptor_tables(struct kvm_vm *vm)
{
	void *addr;

	vm->handlers = __vm_vaddr_alloc(vm, sizeof(struct handlers),
			LOONGARCH_GUEST_STACK_VADDR_MIN, MEM_REGION_DATA);

	addr = addr_gva2hva(vm, vm->handlers);
	memset(addr, 0, vm->page_size);
	exception_handlers = vm->handlers;
	sync_global_to_guest(vm, exception_handlers);
}

void vm_install_exception_handler(struct kvm_vm *vm, int vector, handler_fn handler)
{
	struct handlers *handlers = addr_gva2hva(vm, vm->handlers);

	assert(vector < VECTOR_NUM);
	handlers->exception_handlers[vector] = handler;
}

uint32_t guest_get_vcpuid(void)
{
	return csr_read(LOONGARCH_CSR_CPUID);
}

void vcpu_args_set(struct kvm_vcpu *vcpu, unsigned int num, ...)
{
	int i;
	va_list ap;
	struct kvm_regs regs;

	TEST_ASSERT(num >= 1 && num <= 8, "Unsupported number of args,\n"
		    "num: %u\n", num);

	vcpu_regs_get(vcpu, &regs);

	va_start(ap, num);
	for (i = 0; i < num; i++)
		regs.gpr[i + 4] = va_arg(ap, uint64_t);
	va_end(ap);

	vcpu_regs_set(vcpu, &regs);
}

static void loongarch_set_reg(struct kvm_vcpu *vcpu, uint64_t id, uint64_t val)
{
	__vcpu_set_reg(vcpu, id, val);
}

static void loongarch_get_csr(struct kvm_vcpu *vcpu, uint64_t id, void *addr)
{
	uint64_t csrid;

	csrid = KVM_REG_LOONGARCH_CSR | KVM_REG_SIZE_U64 | 8 * id;
	__vcpu_get_reg(vcpu, csrid, addr);
}

static void loongarch_set_csr(struct kvm_vcpu *vcpu, uint64_t id, uint64_t val)
{
	uint64_t csrid;

	csrid = KVM_REG_LOONGARCH_CSR | KVM_REG_SIZE_U64 | 8 * id;
	__vcpu_set_reg(vcpu, csrid, val);
}

static void loongarch_vcpu_setup(struct kvm_vcpu *vcpu)
{
	int width;
	unsigned long val;
	struct kvm_vm *vm = vcpu->vm;

	switch (vm->mode) {
	case VM_MODE_P36V47_16K:
	case VM_MODE_P47V47_16K:
		break;

	default:
		TEST_FAIL("Unknown guest mode, mode: 0x%x", vm->mode);
	}

	/* kernel mode and page enable mode */
	val = PLV_KERN | CSR_CRMD_PG;
	loongarch_set_csr(vcpu, LOONGARCH_CSR_CRMD, val);
	loongarch_set_csr(vcpu, LOONGARCH_CSR_PRMD, val);
	loongarch_set_csr(vcpu, LOONGARCH_CSR_EUEN, 1);
	loongarch_set_csr(vcpu, LOONGARCH_CSR_ECFG, 0);
	loongarch_set_csr(vcpu, LOONGARCH_CSR_TCFG, 0);
	loongarch_set_csr(vcpu, LOONGARCH_CSR_ASID, 1);

	/* time count start from 0 */
	val = 0;
	loongarch_set_reg(vcpu, KVM_REG_LOONGARCH_COUNTER, val);

	width = vm->page_shift - 3;

	switch (vm->pgtable_levels) {
	case 4:
		/* pud page shift and width */
		val = (vm->page_shift + width * 2) << 20 | (width << 25);
		/* fall throuth */
	case 3:
		/* pmd page shift and width */
		val |= (vm->page_shift + width) << 10 | (width << 15);
		/* pte page shift and width */
		val |= vm->page_shift | width << 5;
		break;
	default:
		TEST_FAIL("Got %u page table levels, expected 3 or 4", vm->pgtable_levels);
	}

	loongarch_set_csr(vcpu, LOONGARCH_CSR_PWCTL0, val);

	/* PGD page shift and width */
	val = (vm->page_shift + width * (vm->pgtable_levels - 1)) | width << 6;
	loongarch_set_csr(vcpu, LOONGARCH_CSR_PWCTL1, val);
	loongarch_set_csr(vcpu, LOONGARCH_CSR_PGDL, vm->pgd);

	/*
	 * Refill exception runs on real mode
	 * Entry address should be physical address
	 */
	val = addr_gva2gpa(vm, (unsigned long)handle_tlb_refill);
	loongarch_set_csr(vcpu, LOONGARCH_CSR_TLBRENTRY, val);

	/*
	 * General exception runs on page-enabled mode
	 * Entry address should be virtual address
	 */
	val = (unsigned long)handle_exception;
	loongarch_set_csr(vcpu, LOONGARCH_CSR_EENTRY, val);

	loongarch_get_csr(vcpu, LOONGARCH_CSR_TLBIDX, &val);
	val &= ~CSR_TLBIDX_SIZEM;
	val |= PS_DEFAULT_SIZE << CSR_TLBIDX_SIZE;
	loongarch_set_csr(vcpu, LOONGARCH_CSR_TLBIDX, val);

	loongarch_set_csr(vcpu, LOONGARCH_CSR_STLBPGSIZE, PS_DEFAULT_SIZE);

	/* LOONGARCH_CSR_KS1 is used for exception stack */
	val = __vm_vaddr_alloc(vm, vm->page_size,
			LOONGARCH_GUEST_STACK_VADDR_MIN, MEM_REGION_DATA);
	TEST_ASSERT(val != 0,  "No memory for exception stack");
	val = val + vm->page_size;
	loongarch_set_csr(vcpu, LOONGARCH_CSR_KS1, val);

	loongarch_get_csr(vcpu, LOONGARCH_CSR_TLBREHI, &val);
	val &= ~CSR_TLBREHI_PS;
	val |= PS_DEFAULT_SIZE << CSR_TLBREHI_PS_SHIFT;
	loongarch_set_csr(vcpu, LOONGARCH_CSR_TLBREHI, val);

	loongarch_set_csr(vcpu, LOONGARCH_CSR_CPUID, vcpu->id);
	loongarch_set_csr(vcpu, LOONGARCH_CSR_TMID,  vcpu->id);
}

struct kvm_vcpu *vm_arch_vcpu_add(struct kvm_vm *vm, uint32_t vcpu_id)
{
	size_t stack_size;
	uint64_t stack_vaddr;
	struct kvm_regs regs;
	struct kvm_vcpu *vcpu;

	vcpu = __vm_vcpu_add(vm, vcpu_id);
	stack_size = vm->page_size;
	stack_vaddr = __vm_vaddr_alloc(vm, stack_size,
			LOONGARCH_GUEST_STACK_VADDR_MIN, MEM_REGION_DATA);
	TEST_ASSERT(stack_vaddr != 0,  "No memory for vm stack");

	loongarch_vcpu_setup(vcpu);
	/* Setup guest general purpose registers */
	vcpu_regs_get(vcpu, &regs);
	regs.gpr[3] = stack_vaddr + stack_size;
	vcpu_regs_set(vcpu, &regs);

	return vcpu;
}

void vcpu_arch_set_entry_point(struct kvm_vcpu *vcpu, void *guest_code)
{
	struct kvm_regs regs;

	/* Setup guest PC register */
	vcpu_regs_get(vcpu, &regs);
	regs.pc = (uint64_t)guest_code;
	vcpu_regs_set(vcpu, &regs);
}