acrn-hypervisor/hypervisor/arch/x86/ept.c

/*
 * Copyright (C) 2018 Intel Corporation. All rights reserved.
 *
 * SPDX-License-Identifier: BSD-3-Clause
 */

#include <hypervisor.h>

#include "guest/instr_emul.h"

#define ACRN_DBG_EPT	6U

static uint64_t find_next_table(uint32_t table_offset, void *table_base)
{
	uint64_t table_entry;
	uint64_t table_present;
	uint64_t sub_table_addr = 0UL;

	/* Read the table entry */
	table_entry = mem_read64(table_base
			+ (table_offset * IA32E_COMM_ENTRY_SIZE));

	/* If bit 7 is set, entry is not a subtable. */
	if ((table_entry & IA32E_PDPTE_PS_BIT) != 0U
	    || (table_entry & IA32E_PDE_PS_BIT) != 0U) {
		return sub_table_addr;
	}

	/* Set table present bits to any of the read/write/execute bits */
	table_present = (IA32E_EPT_R_BIT | IA32E_EPT_W_BIT | IA32E_EPT_X_BIT);

	/* Determine if a valid entry exists */
	if ((table_entry & table_present) == 0UL) {
		/* No entry present */
		return sub_table_addr;
	}

	/* Get address of the sub-table */
	sub_table_addr = table_entry & IA32E_REF_MASK;

	/* Return the next table in the walk */
	return sub_table_addr;
}

/**
 * @pre pml4_addr != NULL
 */
void free_ept_mem(void *pml4_addr)
{
	void *pdpt_addr;
	void *pde_addr;
	void *pte_addr;
	uint32_t pml4_index;
	uint32_t pdpt_index;
	uint32_t pde_idx;

	for (pml4_index = 0U; pml4_index < IA32E_NUM_ENTRIES; pml4_index++) {
		/* Walk from the PML4 table to the PDPT table */
		pdpt_addr = HPA2HVA(find_next_table(pml4_index, pml4_addr));
		if (pdpt_addr == NULL) {
			continue;
		}

		for (pdpt_index = 0U; pdpt_index < IA32E_NUM_ENTRIES;
				pdpt_index++) {
			/* Walk from the PDPT table to the PD table */
			pde_addr = HPA2HVA(find_next_table(pdpt_index,
						pdpt_addr));

			if (pde_addr == NULL) {
				continue;
			}

			for (pde_idx = 0U; pde_idx < IA32E_NUM_ENTRIES;
					pde_idx++) {
				/* Walk from the PD table to the page table */
				pte_addr = HPA2HVA(find_next_table(pde_idx,
						pde_addr));

				/* Free page table entry table */
				if (pte_addr != NULL) {
					free_paging_struct(pte_addr);
				}
			}
			/* Free page directory entry table */
			if (pde_addr != NULL) {
				free_paging_struct(pde_addr);
			}
		}
		free_paging_struct(pdpt_addr);
	}
	free_paging_struct(pml4_addr);
}

void destroy_ept(struct vm *vm)
{
	if (vm->arch_vm.nworld_eptp != NULL)
		free_ept_mem(vm->arch_vm.nworld_eptp);
	if (vm->arch_vm.m2p != NULL)
		free_ept_mem(vm->arch_vm.m2p);
}

uint64_t local_gpa2hpa(struct vm *vm, uint64_t gpa, uint32_t *size)
{
	uint64_t hpa = 0UL;
	uint64_t *pgentry, pg_size = 0UL;

	pgentry = lookup_address((uint64_t *)vm->arch_vm.nworld_eptp,
			gpa, &pg_size, PTT_EPT);
	if (pgentry != NULL) {
		hpa = ((*pgentry & (~(pg_size - 1UL)))
				| (gpa & (pg_size - 1UL)));
		pr_dbg("GPA2HPA: 0x%llx->0x%llx", gpa, hpa);
	} else {
		pr_err("VM %d GPA2HPA: failed for gpa 0x%llx",
				vm->vm_id, gpa);
	}

	if (size != NULL) {
		*size = (uint32_t)pg_size;
	}

	return hpa;
}

/* using return value 0 as failure, make sure guest will not use hpa 0 */
uint64_t gpa2hpa(struct vm *vm, uint64_t gpa)
{
	return local_gpa2hpa(vm, gpa, NULL);
}

uint64_t hpa2gpa(struct vm *vm, uint64_t hpa)
{
	uint64_t *pgentry, pg_size = 0UL;

	pgentry = lookup_address((uint64_t *)vm->arch_vm.m2p,
			hpa, &pg_size, PTT_EPT);
	if (pgentry == NULL) {
		pr_err("VM %d hpa2gpa: failed for hpa 0x%llx",
				vm->vm_id, hpa);
		ASSERT(false, "hpa2gpa not found");
	}
	return ((*pgentry & (~(pg_size - 1UL)))
			| (hpa & (pg_size - 1UL)));
}

bool is_ept_supported(void)
{
	bool status;
	uint64_t tmp64;

	/* Read primary processor based VM control. */
	tmp64 = msr_read(MSR_IA32_VMX_PROCBASED_CTLS);

	/* Check if secondary processor based VM control is available. */
	if ((tmp64 & MMU_MEM_ATTR_BIT_EXECUTE_DISABLE) != 0U) {
		/* Read primary processor based VM control. */
		tmp64 = msr_read(MSR_IA32_VMX_PROCBASED_CTLS2);

		/* Check if EPT is supported. */
		if ((tmp64 & (((uint64_t)VMX_PROCBASED_CTLS2_EPT) << 32)) != 0U) {
			/* EPT is present. */
			status = true;
		} else {
			status = false;
		}

	} else {
		/* Secondary processor based VM control is not present */
		status = false;
	}

	return status;
}

int ept_violation_vmexit_handler(struct vcpu *vcpu)
{
	int status = -EINVAL, ret;
	uint64_t exit_qual;
	uint64_t gpa;
	struct io_request *io_req = &vcpu->req;
	struct mmio_request *mmio_req = &io_req->reqs.mmio;

	/* Handle page fault from guest */
	exit_qual = vcpu->arch_vcpu.exit_qualification;

	io_req->type = REQ_MMIO;
	io_req->processed = REQ_STATE_PENDING;

	/* Specify if read or write operation */
	if ((exit_qual & 0x2UL) != 0UL) {
		/* Write operation */
		mmio_req->direction = REQUEST_WRITE;
		mmio_req->value = 0UL;

		/* XXX: write access while EPT perm RX -> WP */
		if ((exit_qual & 0x38UL) == 0x28UL) {
			io_req->type = REQ_WP;
		}
	} else {
		/* Read operation */
		mmio_req->direction = REQUEST_READ;

		/* TODO: Need to determine how sign extension is determined for
		 * reads
		 */
	}

	/* Get the guest physical address */
	gpa = exec_vmread64(VMX_GUEST_PHYSICAL_ADDR_FULL);

	TRACE_2L(TRACE_VMEXIT_EPT_VIOLATION, exit_qual, gpa);

	/* Adjust IPA appropriately and OR page offset to get full IPA of abort
	 */
	mmio_req->address = gpa;

	ret = decode_instruction(vcpu);
	if (ret > 0) {
		mmio_req->size = (uint64_t)ret;
	} else if (ret == -EFAULT) {
		pr_info("page fault happen during decode_instruction");
		status = 0;
		goto out;
	} else {
		goto out;
	}


	/*
	 * For MMIO write, ask DM to run MMIO emulation after
	 * instruction emulation. For MMIO read, ask DM to run MMIO
	 * emulation at first.
	 */

	/* Determine value being written. */
	if (mmio_req->direction == REQUEST_WRITE) {
		status = emulate_instruction(vcpu);
		if (status != 0) {
			goto out;
		}
	}

	status = emulate_io(vcpu, io_req);

	/* io_req is hypervisor-private. For requests sent to VHM,
	 * io_req->processed will be PENDING till dm_emulate_mmio_post() is
	 * called on vcpu resume. */
	if (status == 0) {
		if (io_req->processed != REQ_STATE_PENDING) {
			status = emulate_mmio_post(vcpu, io_req);
		}
 	}

	return status;

out:
	pr_acrnlog("Guest Linear Address: 0x%016llx",
			exec_vmread(VMX_GUEST_LINEAR_ADDR));

	pr_acrnlog("Guest Physical Address address: 0x%016llx",
			gpa);

	return status;
}

int ept_misconfig_vmexit_handler(__unused struct vcpu *vcpu)
{
	int status;

	status = -EINVAL;

	/* TODO - EPT Violation handler */
	pr_fatal("%s, Guest linear address: 0x%016llx ",
			__func__, exec_vmread(VMX_GUEST_LINEAR_ADDR));

	pr_fatal("%s, Guest physical address: 0x%016llx ",
			__func__, exec_vmread64(VMX_GUEST_PHYSICAL_ADDR_FULL));

	ASSERT(status == 0, "EPT Misconfiguration is not handled.\n");

	TRACE_2L(TRACE_VMEXIT_EPT_MISCONFIGURATION, 0UL, 0UL);

	return status;
}

int ept_mr_add(struct vm *vm, uint64_t hpa_arg,
	uint64_t gpa_arg, uint64_t size, uint32_t prot_arg)
{
	struct mem_map_params map_params;
	uint16_t i;
	struct vcpu *vcpu;
	uint64_t hpa = hpa_arg;
	uint64_t gpa = gpa_arg;
	uint32_t prot = prot_arg;

	/* Setup memory map parameters */
	map_params.page_table_type = PTT_EPT;
	map_params.pml4_base = vm->arch_vm.nworld_eptp;
	map_params.pml4_inverted = vm->arch_vm.m2p;

	/* EPT & VT-d share the same page tables, set SNP bit
	 * to force snooping of PCIe devices if the page
	 * is cachable
	 */
	if ((prot & IA32E_EPT_MT_MASK) != IA32E_EPT_UNCACHED) {
		prot |= IA32E_EPT_SNOOP_CTRL;
	}
	/* TODO: replace map_mem with mmu_add once SOS has add
	 * HC_VM_WRITE_PROTECT_PAGE support.
	 */
	map_mem(&map_params, (void *)hpa,
			(void *)gpa, size, prot);

	foreach_vcpu(i, vm, vcpu) {
		vcpu_make_request(vcpu, ACRN_REQUEST_EPT_FLUSH);
	}

	dev_dbg(ACRN_DBG_EPT, "%s, hpa: 0x%016llx gpa: 0x%016llx ",
			__func__, hpa, gpa);
	dev_dbg(ACRN_DBG_EPT, "size: 0x%016llx prot: 0x%x\n", size, prot);

	return 0;
}

int ept_mr_modify(struct vm *vm, uint64_t *pml4_page,
		uint64_t gpa, uint64_t size,
		uint64_t prot_set, uint64_t prot_clr)
{
	struct vcpu *vcpu;
	uint16_t i;
	int ret;

	ret = mmu_modify_or_del(pml4_page, gpa, size,
			prot_set, prot_clr, PTT_EPT, MR_MODIFY);

	foreach_vcpu(i, vm, vcpu) {
		vcpu_make_request(vcpu, ACRN_REQUEST_EPT_FLUSH);
	}

	return ret;
}

int ept_mr_del(struct vm *vm, uint64_t *pml4_page,
		uint64_t gpa, uint64_t size)
{
	struct vcpu *vcpu;
	uint16_t i;
	int ret;
	uint64_t hpa = gpa2hpa(vm, gpa);

	ret = mmu_modify_or_del(pml4_page, gpa, size,
			0UL, 0UL, PTT_EPT, MR_DEL);
	if (ret < 0) {
		return ret;
	}

	if (hpa != 0UL) {
		ret = mmu_modify_or_del((uint64_t *)vm->arch_vm.m2p,
			hpa, size, 0UL, 0UL, PTT_EPT, MR_DEL);
	}

	foreach_vcpu(i, vm, vcpu) {
		vcpu_make_request(vcpu, ACRN_REQUEST_EPT_FLUSH);
	}

	dev_dbg(ACRN_DBG_EPT, "%s, gpa 0x%llx size 0x%llx\n",
			__func__, gpa, size);

	return 0;
}