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linux-next/arch/x86/kvm/i8259.c
Marios Pomonis 14e32321f3 KVM: x86: Refactor picdev_write() to prevent Spectre-v1/L1TF attacks
This fixes a Spectre-v1/L1TF vulnerability in picdev_write().
It replaces index computations based on the (attacked-controlled) port
number with constants through a minor refactoring.

Fixes: 85f455f7dd ("KVM: Add support for in-kernel PIC emulation")

Signed-off-by: Nick Finco <nifi@google.com>
Signed-off-by: Marios Pomonis <pomonis@google.com>
Reviewed-by: Andrew Honig <ahonig@google.com>
Cc: stable@vger.kernel.org
Reviewed-by: Jim Mattson <jmattson@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2020-01-27 19:59:37 +01:00

656 lines
14 KiB
C

/*
* 8259 interrupt controller emulation
*
* Copyright (c) 2003-2004 Fabrice Bellard
* Copyright (c) 2007 Intel Corporation
* Copyright 2009 Red Hat, Inc. and/or its affiliates.
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
* Authors:
* Yaozu (Eddie) Dong <Eddie.dong@intel.com>
* Port from Qemu.
*/
#include <linux/mm.h>
#include <linux/slab.h>
#include <linux/bitops.h>
#include "irq.h"
#include <linux/kvm_host.h>
#include "trace.h"
#define pr_pic_unimpl(fmt, ...) \
pr_err_ratelimited("kvm: pic: " fmt, ## __VA_ARGS__)
static void pic_irq_request(struct kvm *kvm, int level);
static void pic_lock(struct kvm_pic *s)
__acquires(&s->lock)
{
spin_lock(&s->lock);
}
static void pic_unlock(struct kvm_pic *s)
__releases(&s->lock)
{
bool wakeup = s->wakeup_needed;
struct kvm_vcpu *vcpu;
int i;
s->wakeup_needed = false;
spin_unlock(&s->lock);
if (wakeup) {
kvm_for_each_vcpu(i, vcpu, s->kvm) {
if (kvm_apic_accept_pic_intr(vcpu)) {
kvm_make_request(KVM_REQ_EVENT, vcpu);
kvm_vcpu_kick(vcpu);
return;
}
}
}
}
static void pic_clear_isr(struct kvm_kpic_state *s, int irq)
{
s->isr &= ~(1 << irq);
if (s != &s->pics_state->pics[0])
irq += 8;
/*
* We are dropping lock while calling ack notifiers since ack
* notifier callbacks for assigned devices call into PIC recursively.
* Other interrupt may be delivered to PIC while lock is dropped but
* it should be safe since PIC state is already updated at this stage.
*/
pic_unlock(s->pics_state);
kvm_notify_acked_irq(s->pics_state->kvm, SELECT_PIC(irq), irq);
pic_lock(s->pics_state);
}
/*
* set irq level. If an edge is detected, then the IRR is set to 1
*/
static inline int pic_set_irq1(struct kvm_kpic_state *s, int irq, int level)
{
int mask, ret = 1;
mask = 1 << irq;
if (s->elcr & mask) /* level triggered */
if (level) {
ret = !(s->irr & mask);
s->irr |= mask;
s->last_irr |= mask;
} else {
s->irr &= ~mask;
s->last_irr &= ~mask;
}
else /* edge triggered */
if (level) {
if ((s->last_irr & mask) == 0) {
ret = !(s->irr & mask);
s->irr |= mask;
}
s->last_irr |= mask;
} else
s->last_irr &= ~mask;
return (s->imr & mask) ? -1 : ret;
}
/*
* return the highest priority found in mask (highest = smallest
* number). Return 8 if no irq
*/
static inline int get_priority(struct kvm_kpic_state *s, int mask)
{
int priority;
if (mask == 0)
return 8;
priority = 0;
while ((mask & (1 << ((priority + s->priority_add) & 7))) == 0)
priority++;
return priority;
}
/*
* return the pic wanted interrupt. return -1 if none
*/
static int pic_get_irq(struct kvm_kpic_state *s)
{
int mask, cur_priority, priority;
mask = s->irr & ~s->imr;
priority = get_priority(s, mask);
if (priority == 8)
return -1;
/*
* compute current priority. If special fully nested mode on the
* master, the IRQ coming from the slave is not taken into account
* for the priority computation.
*/
mask = s->isr;
if (s->special_fully_nested_mode && s == &s->pics_state->pics[0])
mask &= ~(1 << 2);
cur_priority = get_priority(s, mask);
if (priority < cur_priority)
/*
* higher priority found: an irq should be generated
*/
return (priority + s->priority_add) & 7;
else
return -1;
}
/*
* raise irq to CPU if necessary. must be called every time the active
* irq may change
*/
static void pic_update_irq(struct kvm_pic *s)
{
int irq2, irq;
irq2 = pic_get_irq(&s->pics[1]);
if (irq2 >= 0) {
/*
* if irq request by slave pic, signal master PIC
*/
pic_set_irq1(&s->pics[0], 2, 1);
pic_set_irq1(&s->pics[0], 2, 0);
}
irq = pic_get_irq(&s->pics[0]);
pic_irq_request(s->kvm, irq >= 0);
}
void kvm_pic_update_irq(struct kvm_pic *s)
{
pic_lock(s);
pic_update_irq(s);
pic_unlock(s);
}
int kvm_pic_set_irq(struct kvm_pic *s, int irq, int irq_source_id, int level)
{
int ret, irq_level;
BUG_ON(irq < 0 || irq >= PIC_NUM_PINS);
pic_lock(s);
irq_level = __kvm_irq_line_state(&s->irq_states[irq],
irq_source_id, level);
ret = pic_set_irq1(&s->pics[irq >> 3], irq & 7, irq_level);
pic_update_irq(s);
trace_kvm_pic_set_irq(irq >> 3, irq & 7, s->pics[irq >> 3].elcr,
s->pics[irq >> 3].imr, ret == 0);
pic_unlock(s);
return ret;
}
void kvm_pic_clear_all(struct kvm_pic *s, int irq_source_id)
{
int i;
pic_lock(s);
for (i = 0; i < PIC_NUM_PINS; i++)
__clear_bit(irq_source_id, &s->irq_states[i]);
pic_unlock(s);
}
/*
* acknowledge interrupt 'irq'
*/
static inline void pic_intack(struct kvm_kpic_state *s, int irq)
{
s->isr |= 1 << irq;
/*
* We don't clear a level sensitive interrupt here
*/
if (!(s->elcr & (1 << irq)))
s->irr &= ~(1 << irq);
if (s->auto_eoi) {
if (s->rotate_on_auto_eoi)
s->priority_add = (irq + 1) & 7;
pic_clear_isr(s, irq);
}
}
int kvm_pic_read_irq(struct kvm *kvm)
{
int irq, irq2, intno;
struct kvm_pic *s = kvm->arch.vpic;
s->output = 0;
pic_lock(s);
irq = pic_get_irq(&s->pics[0]);
if (irq >= 0) {
pic_intack(&s->pics[0], irq);
if (irq == 2) {
irq2 = pic_get_irq(&s->pics[1]);
if (irq2 >= 0)
pic_intack(&s->pics[1], irq2);
else
/*
* spurious IRQ on slave controller
*/
irq2 = 7;
intno = s->pics[1].irq_base + irq2;
irq = irq2 + 8;
} else
intno = s->pics[0].irq_base + irq;
} else {
/*
* spurious IRQ on host controller
*/
irq = 7;
intno = s->pics[0].irq_base + irq;
}
pic_update_irq(s);
pic_unlock(s);
return intno;
}
static void kvm_pic_reset(struct kvm_kpic_state *s)
{
int irq, i;
struct kvm_vcpu *vcpu;
u8 edge_irr = s->irr & ~s->elcr;
bool found = false;
s->last_irr = 0;
s->irr &= s->elcr;
s->imr = 0;
s->priority_add = 0;
s->special_mask = 0;
s->read_reg_select = 0;
if (!s->init4) {
s->special_fully_nested_mode = 0;
s->auto_eoi = 0;
}
s->init_state = 1;
kvm_for_each_vcpu(i, vcpu, s->pics_state->kvm)
if (kvm_apic_accept_pic_intr(vcpu)) {
found = true;
break;
}
if (!found)
return;
for (irq = 0; irq < PIC_NUM_PINS/2; irq++)
if (edge_irr & (1 << irq))
pic_clear_isr(s, irq);
}
static void pic_ioport_write(void *opaque, u32 addr, u32 val)
{
struct kvm_kpic_state *s = opaque;
int priority, cmd, irq;
addr &= 1;
if (addr == 0) {
if (val & 0x10) {
s->init4 = val & 1;
if (val & 0x02)
pr_pic_unimpl("single mode not supported");
if (val & 0x08)
pr_pic_unimpl(
"level sensitive irq not supported");
kvm_pic_reset(s);
} else if (val & 0x08) {
if (val & 0x04)
s->poll = 1;
if (val & 0x02)
s->read_reg_select = val & 1;
if (val & 0x40)
s->special_mask = (val >> 5) & 1;
} else {
cmd = val >> 5;
switch (cmd) {
case 0:
case 4:
s->rotate_on_auto_eoi = cmd >> 2;
break;
case 1: /* end of interrupt */
case 5:
priority = get_priority(s, s->isr);
if (priority != 8) {
irq = (priority + s->priority_add) & 7;
if (cmd == 5)
s->priority_add = (irq + 1) & 7;
pic_clear_isr(s, irq);
pic_update_irq(s->pics_state);
}
break;
case 3:
irq = val & 7;
pic_clear_isr(s, irq);
pic_update_irq(s->pics_state);
break;
case 6:
s->priority_add = (val + 1) & 7;
pic_update_irq(s->pics_state);
break;
case 7:
irq = val & 7;
s->priority_add = (irq + 1) & 7;
pic_clear_isr(s, irq);
pic_update_irq(s->pics_state);
break;
default:
break; /* no operation */
}
}
} else
switch (s->init_state) {
case 0: { /* normal mode */
u8 imr_diff = s->imr ^ val,
off = (s == &s->pics_state->pics[0]) ? 0 : 8;
s->imr = val;
for (irq = 0; irq < PIC_NUM_PINS/2; irq++)
if (imr_diff & (1 << irq))
kvm_fire_mask_notifiers(
s->pics_state->kvm,
SELECT_PIC(irq + off),
irq + off,
!!(s->imr & (1 << irq)));
pic_update_irq(s->pics_state);
break;
}
case 1:
s->irq_base = val & 0xf8;
s->init_state = 2;
break;
case 2:
if (s->init4)
s->init_state = 3;
else
s->init_state = 0;
break;
case 3:
s->special_fully_nested_mode = (val >> 4) & 1;
s->auto_eoi = (val >> 1) & 1;
s->init_state = 0;
break;
}
}
static u32 pic_poll_read(struct kvm_kpic_state *s, u32 addr1)
{
int ret;
ret = pic_get_irq(s);
if (ret >= 0) {
if (addr1 >> 7) {
s->pics_state->pics[0].isr &= ~(1 << 2);
s->pics_state->pics[0].irr &= ~(1 << 2);
}
s->irr &= ~(1 << ret);
pic_clear_isr(s, ret);
if (addr1 >> 7 || ret != 2)
pic_update_irq(s->pics_state);
} else {
ret = 0x07;
pic_update_irq(s->pics_state);
}
return ret;
}
static u32 pic_ioport_read(void *opaque, u32 addr)
{
struct kvm_kpic_state *s = opaque;
int ret;
if (s->poll) {
ret = pic_poll_read(s, addr);
s->poll = 0;
} else
if ((addr & 1) == 0)
if (s->read_reg_select)
ret = s->isr;
else
ret = s->irr;
else
ret = s->imr;
return ret;
}
static void elcr_ioport_write(void *opaque, u32 addr, u32 val)
{
struct kvm_kpic_state *s = opaque;
s->elcr = val & s->elcr_mask;
}
static u32 elcr_ioport_read(void *opaque, u32 addr1)
{
struct kvm_kpic_state *s = opaque;
return s->elcr;
}
static int picdev_write(struct kvm_pic *s,
gpa_t addr, int len, const void *val)
{
unsigned char data = *(unsigned char *)val;
if (len != 1) {
pr_pic_unimpl("non byte write\n");
return 0;
}
switch (addr) {
case 0x20:
case 0x21:
pic_lock(s);
pic_ioport_write(&s->pics[0], addr, data);
pic_unlock(s);
break;
case 0xa0:
case 0xa1:
pic_lock(s);
pic_ioport_write(&s->pics[1], addr, data);
pic_unlock(s);
break;
case 0x4d0:
case 0x4d1:
pic_lock(s);
elcr_ioport_write(&s->pics[addr & 1], addr, data);
pic_unlock(s);
break;
default:
return -EOPNOTSUPP;
}
return 0;
}
static int picdev_read(struct kvm_pic *s,
gpa_t addr, int len, void *val)
{
unsigned char *data = (unsigned char *)val;
if (len != 1) {
memset(val, 0, len);
pr_pic_unimpl("non byte read\n");
return 0;
}
switch (addr) {
case 0x20:
case 0x21:
case 0xa0:
case 0xa1:
pic_lock(s);
*data = pic_ioport_read(&s->pics[addr >> 7], addr);
pic_unlock(s);
break;
case 0x4d0:
case 0x4d1:
pic_lock(s);
*data = elcr_ioport_read(&s->pics[addr & 1], addr);
pic_unlock(s);
break;
default:
return -EOPNOTSUPP;
}
return 0;
}
static int picdev_master_write(struct kvm_vcpu *vcpu, struct kvm_io_device *dev,
gpa_t addr, int len, const void *val)
{
return picdev_write(container_of(dev, struct kvm_pic, dev_master),
addr, len, val);
}
static int picdev_master_read(struct kvm_vcpu *vcpu, struct kvm_io_device *dev,
gpa_t addr, int len, void *val)
{
return picdev_read(container_of(dev, struct kvm_pic, dev_master),
addr, len, val);
}
static int picdev_slave_write(struct kvm_vcpu *vcpu, struct kvm_io_device *dev,
gpa_t addr, int len, const void *val)
{
return picdev_write(container_of(dev, struct kvm_pic, dev_slave),
addr, len, val);
}
static int picdev_slave_read(struct kvm_vcpu *vcpu, struct kvm_io_device *dev,
gpa_t addr, int len, void *val)
{
return picdev_read(container_of(dev, struct kvm_pic, dev_slave),
addr, len, val);
}
static int picdev_eclr_write(struct kvm_vcpu *vcpu, struct kvm_io_device *dev,
gpa_t addr, int len, const void *val)
{
return picdev_write(container_of(dev, struct kvm_pic, dev_eclr),
addr, len, val);
}
static int picdev_eclr_read(struct kvm_vcpu *vcpu, struct kvm_io_device *dev,
gpa_t addr, int len, void *val)
{
return picdev_read(container_of(dev, struct kvm_pic, dev_eclr),
addr, len, val);
}
/*
* callback when PIC0 irq status changed
*/
static void pic_irq_request(struct kvm *kvm, int level)
{
struct kvm_pic *s = kvm->arch.vpic;
if (!s->output)
s->wakeup_needed = true;
s->output = level;
}
static const struct kvm_io_device_ops picdev_master_ops = {
.read = picdev_master_read,
.write = picdev_master_write,
};
static const struct kvm_io_device_ops picdev_slave_ops = {
.read = picdev_slave_read,
.write = picdev_slave_write,
};
static const struct kvm_io_device_ops picdev_eclr_ops = {
.read = picdev_eclr_read,
.write = picdev_eclr_write,
};
int kvm_pic_init(struct kvm *kvm)
{
struct kvm_pic *s;
int ret;
s = kzalloc(sizeof(struct kvm_pic), GFP_KERNEL_ACCOUNT);
if (!s)
return -ENOMEM;
spin_lock_init(&s->lock);
s->kvm = kvm;
s->pics[0].elcr_mask = 0xf8;
s->pics[1].elcr_mask = 0xde;
s->pics[0].pics_state = s;
s->pics[1].pics_state = s;
/*
* Initialize PIO device
*/
kvm_iodevice_init(&s->dev_master, &picdev_master_ops);
kvm_iodevice_init(&s->dev_slave, &picdev_slave_ops);
kvm_iodevice_init(&s->dev_eclr, &picdev_eclr_ops);
mutex_lock(&kvm->slots_lock);
ret = kvm_io_bus_register_dev(kvm, KVM_PIO_BUS, 0x20, 2,
&s->dev_master);
if (ret < 0)
goto fail_unlock;
ret = kvm_io_bus_register_dev(kvm, KVM_PIO_BUS, 0xa0, 2, &s->dev_slave);
if (ret < 0)
goto fail_unreg_2;
ret = kvm_io_bus_register_dev(kvm, KVM_PIO_BUS, 0x4d0, 2, &s->dev_eclr);
if (ret < 0)
goto fail_unreg_1;
mutex_unlock(&kvm->slots_lock);
kvm->arch.vpic = s;
return 0;
fail_unreg_1:
kvm_io_bus_unregister_dev(kvm, KVM_PIO_BUS, &s->dev_slave);
fail_unreg_2:
kvm_io_bus_unregister_dev(kvm, KVM_PIO_BUS, &s->dev_master);
fail_unlock:
mutex_unlock(&kvm->slots_lock);
kfree(s);
return ret;
}
void kvm_pic_destroy(struct kvm *kvm)
{
struct kvm_pic *vpic = kvm->arch.vpic;
if (!vpic)
return;
mutex_lock(&kvm->slots_lock);
kvm_io_bus_unregister_dev(vpic->kvm, KVM_PIO_BUS, &vpic->dev_master);
kvm_io_bus_unregister_dev(vpic->kvm, KVM_PIO_BUS, &vpic->dev_slave);
kvm_io_bus_unregister_dev(vpic->kvm, KVM_PIO_BUS, &vpic->dev_eclr);
mutex_unlock(&kvm->slots_lock);
kvm->arch.vpic = NULL;
kfree(vpic);
}