blob: aeb11276a54e042d9f342d1d335f0a4a8a19bc18 [file] [log] [blame]
/*
* Copyright 2018 The Hafnium Authors.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* https://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#include "hf/cpu.h"
#include <stdalign.h>
#include "hf/arch/cpu.h"
#include "hf/api.h"
#include "hf/check.h"
#include "hf/dlog.h"
#include "hf/spci.h"
#include "hf/std.h"
#include "hf/vm.h"
#include "vmapi/hf/call.h"
#define STACK_SIZE PAGE_SIZE
/**
* The stacks to be used by the CPUs.
*
* Align to page boundaries to ensure that cache lines are not shared between a
* CPU's stack and data that can be accessed from other CPUs. If this did
* happen, there may be coherency problems when the stack is being used before
* caching is enabled.
*/
alignas(PAGE_SIZE) static char callstacks[MAX_CPUS][STACK_SIZE];
/* NOLINTNEXTLINE(misc-redundant-expression) */
static_assert((STACK_SIZE % PAGE_SIZE) == 0, "Keep each stack page aligned.");
static_assert((PAGE_SIZE % STACK_ALIGN) == 0,
"Page alignment is too weak for the stack.");
/**
* Internal buffer used to store SPCI messages from a VM Tx. Its usage prevents
* TOCTOU issues while Hafnium performs actions on information that would
* otherwise be re-writable by the VM.
*
* Each buffer is owned by a single cpu. The buffer can only be used for
* spci_msg_send. The information stored in the buffer is only valid during the
* spci_msg_send request is performed.
*/
alignas(PAGE_SIZE) uint8_t cpu_message_buffer[MAX_CPUS][PAGE_SIZE];
uint8_t *cpu_get_buffer(cpu_id_t cpu_id)
{
CHECK(cpu_id < MAX_CPUS);
return cpu_message_buffer[cpu_id];
}
uint32_t cpu_get_buffer_size(cpu_id_t cpu_id)
{
CHECK(cpu_id < MAX_CPUS);
return sizeof(cpu_message_buffer[cpu_id]);
}
/* State of all supported CPUs. The stack of the first one is initialized. */
struct cpu cpus[MAX_CPUS] = {
{
.is_on = 1,
.stack_bottom = &callstacks[0][STACK_SIZE],
},
};
static uint32_t cpu_count = 1;
void cpu_module_init(const cpu_id_t *cpu_ids, size_t count)
{
uint32_t i;
uint32_t j;
cpu_id_t boot_cpu_id = cpus[0].id;
bool found_boot_cpu = false;
cpu_count = count;
/*
* Initialize CPUs with the IDs from the configuration passed in. The
* CPUs after the boot CPU are initialized in reverse order. The boot
* CPU is initialized when it is found or in place of the last CPU if it
* is not found.
*/
j = cpu_count;
for (i = 0; i < cpu_count; ++i) {
struct cpu *c;
cpu_id_t id = cpu_ids[i];
if (found_boot_cpu || id != boot_cpu_id) {
--j;
c = &cpus[j];
c->stack_bottom = &callstacks[j][STACK_SIZE];
} else {
found_boot_cpu = true;
c = &cpus[0];
CHECK(c->stack_bottom == &callstacks[0][STACK_SIZE]);
}
sl_init(&c->lock);
c->id = id;
}
if (!found_boot_cpu) {
/* Boot CPU was initialized but with wrong ID. */
dlog("Boot CPU's ID not found in config.\n");
cpus[0].id = boot_cpu_id;
}
}
size_t cpu_index(struct cpu *c)
{
return c - cpus;
}
/**
* Turns CPU on and returns the previous state.
*/
bool cpu_on(struct cpu *c, ipaddr_t entry, uintreg_t arg)
{
bool prev;
sl_lock(&c->lock);
prev = c->is_on;
c->is_on = true;
sl_unlock(&c->lock);
if (!prev) {
struct vm *vm = vm_find(HF_PRIMARY_VM_ID);
struct vcpu *vcpu = vm_get_vcpu(vm, cpu_index(c));
struct vcpu_locked vcpu_locked;
vcpu_locked = vcpu_lock(vcpu);
vcpu_on(vcpu_locked, entry, arg);
vcpu_unlock(&vcpu_locked);
}
return prev;
}
/**
* Prepares the CPU for turning itself off.
*/
void cpu_off(struct cpu *c)
{
sl_lock(&c->lock);
c->is_on = false;
sl_unlock(&c->lock);
}
/**
* Searches for a CPU based on its id.
*/
struct cpu *cpu_find(cpu_id_t id)
{
size_t i;
for (i = 0; i < cpu_count; i++) {
if (cpus[i].id == id) {
return &cpus[i];
}
}
return NULL;
}
/**
* Locks the given vCPU and updates `locked` to hold the newly locked vCPU.
*/
struct vcpu_locked vcpu_lock(struct vcpu *vcpu)
{
struct vcpu_locked locked = {
.vcpu = vcpu,
};
sl_lock(&vcpu->lock);
return locked;
}
/**
* Unlocks a vCPU previously locked with vpu_lock, and updates `locked` to
* reflect the fact that the vCPU is no longer locked.
*/
void vcpu_unlock(struct vcpu_locked *locked)
{
sl_unlock(&locked->vcpu->lock);
locked->vcpu = NULL;
}
void vcpu_init(struct vcpu *vcpu, struct vm *vm)
{
memset_s(vcpu, sizeof(*vcpu), 0, sizeof(*vcpu));
sl_init(&vcpu->lock);
vcpu->regs_available = true;
vcpu->vm = vm;
vcpu->state = VCPU_STATE_OFF;
}
/**
* Initialise the registers for the given vCPU and set the state to
* VCPU_STATE_READY. The caller must hold the vCPU lock while calling this.
*/
void vcpu_on(struct vcpu_locked vcpu, ipaddr_t entry, uintreg_t arg)
{
arch_regs_set_pc_arg(&vcpu.vcpu->regs, entry, arg);
vcpu.vcpu->state = VCPU_STATE_READY;
}
spci_vcpu_index_t vcpu_index(const struct vcpu *vcpu)
{
size_t index = vcpu - vcpu->vm->vcpus;
CHECK(index < UINT16_MAX);
return index;
}
/**
* Check whether the given vcpu_state is an off state, for the purpose of
* turning vCPUs on and off. Note that aborted still counts as on in this
* context.
*/
bool vcpu_is_off(struct vcpu_locked vcpu)
{
switch (vcpu.vcpu->state) {
case VCPU_STATE_OFF:
return true;
case VCPU_STATE_READY:
case VCPU_STATE_RUNNING:
case VCPU_STATE_BLOCKED_MAILBOX:
case VCPU_STATE_BLOCKED_INTERRUPT:
case VCPU_STATE_ABORTED:
/*
* Aborted still counts as ON for the purposes of PSCI,
* because according to the PSCI specification (section
* 5.7.1) a core is only considered to be off if it has
* been turned off with a CPU_OFF call or hasn't yet
* been turned on with a CPU_ON call.
*/
return false;
}
}
/**
* Starts a vCPU of a secondary VM.
*
* Returns true if the secondary was reset and started, or false if it was
* already on and so nothing was done.
*/
bool vcpu_secondary_reset_and_start(struct vcpu *vcpu, ipaddr_t entry,
uintreg_t arg)
{
struct vcpu_locked vcpu_locked;
struct vm *vm = vcpu->vm;
bool vcpu_was_off;
CHECK(vm->id != HF_PRIMARY_VM_ID);
vcpu_locked = vcpu_lock(vcpu);
vcpu_was_off = vcpu_is_off(vcpu_locked);
if (vcpu_was_off) {
/*
* Set vCPU registers to a clean state ready for boot. As this
* is a secondary which can migrate between pCPUs, the ID of the
* vCPU is defined as the index and does not match the ID of the
* pCPU it is running on.
*/
arch_regs_reset(&vcpu->regs, false, vm->id, vcpu_index(vcpu),
vm->ptable.root);
vcpu_on(vcpu_locked, entry, arg);
}
vcpu_unlock(&vcpu_locked);
return vcpu_was_off;
}
/**
* Handles a page fault. It does so by determining if it's a legitimate or
* spurious fault, and recovering from the latter.
*
* Returns true if the caller should resume the current vcpu, or false if its VM
* should be aborted.
*/
bool vcpu_handle_page_fault(const struct vcpu *current,
struct vcpu_fault_info *f)
{
struct vm *vm = current->vm;
uint32_t mode;
uint32_t mask = f->mode | MM_MODE_INVALID;
bool resume;
sl_lock(&vm->lock);
/*
* Check if this is a legitimate fault, i.e., if the page table doesn't
* allow the access attemped by the VM.
*
* Otherwise, this is a spurious fault, likely because another CPU is
* updating the page table. It is responsible for issuing global TLB
* invalidations while holding the VM lock, so we don't need to do
* anything else to recover from it. (Acquiring/releasing the lock
* ensured that the invalidations have completed.)
*/
resume = mm_vm_get_mode(&vm->ptable, f->ipaddr, ipa_add(f->ipaddr, 1),
&mode) &&
(mode & mask) == f->mode;
sl_unlock(&vm->lock);
if (!resume) {
dlog("Stage-2 page fault: pc=%#x, vmid=%u, vcpu=%u, "
"vaddr=%#x, ipaddr=%#x, mode=%#x\n",
f->pc, vm->id, vcpu_index(current), f->vaddr, f->ipaddr,
f->mode);
}
return resume;
}