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linux/arch/s390/kvm/interrupt.c
Christian Borntraeger 3cd612998f KVM: s390: Fix program check on interrupt delivery handling 
The current interrupt handling on s390 misbehaves on an error case. On s390
each cpu has the prefix area (lowcore) for interrupt delivery. This memory
must always be available. If we fail to access the prefix area for a guest
on interrupt delivery the configuration is completely unusable. There is no
point in sending another program interrupt to an inaccessible lowcore.
Furthermore, we should not bug the host kernel, because this can be triggered
by userspace. I think the guest kernel itself can not trigger the problem, as
SET PREFIX and SIGNAL PROCESSOR SET PREFIX both check that the memory is
available and sane. As this is a userspace bug (e.g. setting the wrong guest
offset, unmapping guest memory) we should kill the userspace process instead
of BUGing the host kernel.
In the long term we probably should notify the userspace process about this
problem.

Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Avi Kivity <avi@qumranet.com>
2008-07-27 11:36:05 +03:00

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/*
* interrupt.c - handling kvm guest interrupts
*
* Copyright IBM Corp. 2008
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License (version 2 only)
* as published by the Free Software Foundation.
*
* Author(s): Carsten Otte <cotte@de.ibm.com>
*/
#include <asm/lowcore.h>
#include <asm/uaccess.h>
#include <linux/kvm_host.h>
#include <linux/signal.h>
#include "kvm-s390.h"
#include "gaccess.h"
static int psw_extint_disabled(struct kvm_vcpu *vcpu)
{
return !(vcpu->arch.sie_block->gpsw.mask & PSW_MASK_EXT);
}
static int psw_interrupts_disabled(struct kvm_vcpu *vcpu)
{
if ((vcpu->arch.sie_block->gpsw.mask & PSW_MASK_PER) ||
(vcpu->arch.sie_block->gpsw.mask & PSW_MASK_IO) ||
(vcpu->arch.sie_block->gpsw.mask & PSW_MASK_EXT))
return 0;
return 1;
}
static int __interrupt_is_deliverable(struct kvm_vcpu *vcpu,
struct kvm_s390_interrupt_info *inti)
{
switch (inti->type) {
case KVM_S390_INT_EMERGENCY:
if (psw_extint_disabled(vcpu))
return 0;
if (vcpu->arch.sie_block->gcr[0] & 0x4000ul)
return 1;
return 0;
case KVM_S390_INT_SERVICE:
if (psw_extint_disabled(vcpu))
return 0;
if (vcpu->arch.sie_block->gcr[0] & 0x200ul)
return 1;
return 0;
case KVM_S390_INT_VIRTIO:
if (psw_extint_disabled(vcpu))
return 0;
if (vcpu->arch.sie_block->gcr[0] & 0x200ul)
return 1;
return 0;
case KVM_S390_PROGRAM_INT:
case KVM_S390_SIGP_STOP:
case KVM_S390_SIGP_SET_PREFIX:
case KVM_S390_RESTART:
return 1;
default:
BUG();
}
return 0;
}
static void __set_cpu_idle(struct kvm_vcpu *vcpu)
{
BUG_ON(vcpu->vcpu_id > KVM_MAX_VCPUS - 1);
atomic_set_mask(CPUSTAT_WAIT, &vcpu->arch.sie_block->cpuflags);
set_bit(vcpu->vcpu_id, vcpu->arch.local_int.float_int->idle_mask);
}
static void __unset_cpu_idle(struct kvm_vcpu *vcpu)
{
BUG_ON(vcpu->vcpu_id > KVM_MAX_VCPUS - 1);
atomic_clear_mask(CPUSTAT_WAIT, &vcpu->arch.sie_block->cpuflags);
clear_bit(vcpu->vcpu_id, vcpu->arch.local_int.float_int->idle_mask);
}
static void __reset_intercept_indicators(struct kvm_vcpu *vcpu)
{
atomic_clear_mask(CPUSTAT_ECALL_PEND |
CPUSTAT_IO_INT | CPUSTAT_EXT_INT | CPUSTAT_STOP_INT,
&vcpu->arch.sie_block->cpuflags);
vcpu->arch.sie_block->lctl = 0x0000;
}
static void __set_cpuflag(struct kvm_vcpu *vcpu, u32 flag)
{
atomic_set_mask(flag, &vcpu->arch.sie_block->cpuflags);
}
static void __set_intercept_indicator(struct kvm_vcpu *vcpu,
struct kvm_s390_interrupt_info *inti)
{
switch (inti->type) {
case KVM_S390_INT_EMERGENCY:
case KVM_S390_INT_SERVICE:
case KVM_S390_INT_VIRTIO:
if (psw_extint_disabled(vcpu))
__set_cpuflag(vcpu, CPUSTAT_EXT_INT);
else
vcpu->arch.sie_block->lctl |= LCTL_CR0;
break;
case KVM_S390_SIGP_STOP:
__set_cpuflag(vcpu, CPUSTAT_STOP_INT);
break;
default:
BUG();
}
}
static void __do_deliver_interrupt(struct kvm_vcpu *vcpu,
struct kvm_s390_interrupt_info *inti)
{
const unsigned short table[] = { 2, 4, 4, 6 };
int rc, exception = 0;
switch (inti->type) {
case KVM_S390_INT_EMERGENCY:
VCPU_EVENT(vcpu, 4, "%s", "interrupt: sigp emerg");
vcpu->stat.deliver_emergency_signal++;
rc = put_guest_u16(vcpu, __LC_EXT_INT_CODE, 0x1201);
if (rc == -EFAULT)
exception = 1;
rc = copy_to_guest(vcpu, __LC_EXT_OLD_PSW,
&vcpu->arch.sie_block->gpsw, sizeof(psw_t));
if (rc == -EFAULT)
exception = 1;
rc = copy_from_guest(vcpu, &vcpu->arch.sie_block->gpsw,
__LC_EXT_NEW_PSW, sizeof(psw_t));
if (rc == -EFAULT)
exception = 1;
break;
case KVM_S390_INT_SERVICE:
VCPU_EVENT(vcpu, 4, "interrupt: sclp parm:%x",
inti->ext.ext_params);
vcpu->stat.deliver_service_signal++;
rc = put_guest_u16(vcpu, __LC_EXT_INT_CODE, 0x2401);
if (rc == -EFAULT)
exception = 1;
rc = copy_to_guest(vcpu, __LC_EXT_OLD_PSW,
&vcpu->arch.sie_block->gpsw, sizeof(psw_t));
if (rc == -EFAULT)
exception = 1;
rc = copy_from_guest(vcpu, &vcpu->arch.sie_block->gpsw,
__LC_EXT_NEW_PSW, sizeof(psw_t));
if (rc == -EFAULT)
exception = 1;
rc = put_guest_u32(vcpu, __LC_EXT_PARAMS, inti->ext.ext_params);
if (rc == -EFAULT)
exception = 1;
break;
case KVM_S390_INT_VIRTIO:
VCPU_EVENT(vcpu, 4, "interrupt: virtio parm:%x,parm64:%lx",
inti->ext.ext_params, inti->ext.ext_params2);
vcpu->stat.deliver_virtio_interrupt++;
rc = put_guest_u16(vcpu, __LC_EXT_INT_CODE, 0x2603);
if (rc == -EFAULT)
exception = 1;
rc = put_guest_u16(vcpu, __LC_CPU_ADDRESS, 0x0d00);
if (rc == -EFAULT)
exception = 1;
rc = copy_to_guest(vcpu, __LC_EXT_OLD_PSW,
&vcpu->arch.sie_block->gpsw, sizeof(psw_t));
if (rc == -EFAULT)
exception = 1;
rc = copy_from_guest(vcpu, &vcpu->arch.sie_block->gpsw,
__LC_EXT_NEW_PSW, sizeof(psw_t));
if (rc == -EFAULT)
exception = 1;
rc = put_guest_u32(vcpu, __LC_EXT_PARAMS, inti->ext.ext_params);
if (rc == -EFAULT)
exception = 1;
rc = put_guest_u64(vcpu, __LC_PFAULT_INTPARM,
inti->ext.ext_params2);
if (rc == -EFAULT)
exception = 1;
break;
case KVM_S390_SIGP_STOP:
VCPU_EVENT(vcpu, 4, "%s", "interrupt: cpu stop");
vcpu->stat.deliver_stop_signal++;
__set_intercept_indicator(vcpu, inti);
break;
case KVM_S390_SIGP_SET_PREFIX:
VCPU_EVENT(vcpu, 4, "interrupt: set prefix to %x",
inti->prefix.address);
vcpu->stat.deliver_prefix_signal++;
vcpu->arch.sie_block->prefix = inti->prefix.address;
vcpu->arch.sie_block->ihcpu = 0xffff;
break;
case KVM_S390_RESTART:
VCPU_EVENT(vcpu, 4, "%s", "interrupt: cpu restart");
vcpu->stat.deliver_restart_signal++;
rc = copy_to_guest(vcpu, offsetof(struct _lowcore,
restart_old_psw), &vcpu->arch.sie_block->gpsw, sizeof(psw_t));
if (rc == -EFAULT)
exception = 1;
rc = copy_from_guest(vcpu, &vcpu->arch.sie_block->gpsw,
offsetof(struct _lowcore, restart_psw), sizeof(psw_t));
if (rc == -EFAULT)
exception = 1;
break;
case KVM_S390_PROGRAM_INT:
VCPU_EVENT(vcpu, 4, "interrupt: pgm check code:%x, ilc:%x",
inti->pgm.code,
table[vcpu->arch.sie_block->ipa >> 14]);
vcpu->stat.deliver_program_int++;
rc = put_guest_u16(vcpu, __LC_PGM_INT_CODE, inti->pgm.code);
if (rc == -EFAULT)
exception = 1;
rc = put_guest_u16(vcpu, __LC_PGM_ILC,
table[vcpu->arch.sie_block->ipa >> 14]);
if (rc == -EFAULT)
exception = 1;
rc = copy_to_guest(vcpu, __LC_PGM_OLD_PSW,
&vcpu->arch.sie_block->gpsw, sizeof(psw_t));
if (rc == -EFAULT)
exception = 1;
rc = copy_from_guest(vcpu, &vcpu->arch.sie_block->gpsw,
__LC_PGM_NEW_PSW, sizeof(psw_t));
if (rc == -EFAULT)
exception = 1;
break;
default:
BUG();
}
if (exception) {
printk("kvm: The guest lowcore is not mapped during interrupt "
"delivery, killing userspace\n");
do_exit(SIGKILL);
}
}
static int __try_deliver_ckc_interrupt(struct kvm_vcpu *vcpu)
{
int rc, exception = 0;
if (psw_extint_disabled(vcpu))
return 0;
if (!(vcpu->arch.sie_block->gcr[0] & 0x800ul))
return 0;
rc = put_guest_u16(vcpu, __LC_EXT_INT_CODE, 0x1004);
if (rc == -EFAULT)
exception = 1;
rc = copy_to_guest(vcpu, __LC_EXT_OLD_PSW,
&vcpu->arch.sie_block->gpsw, sizeof(psw_t));
if (rc == -EFAULT)
exception = 1;
rc = copy_from_guest(vcpu, &vcpu->arch.sie_block->gpsw,
__LC_EXT_NEW_PSW, sizeof(psw_t));
if (rc == -EFAULT)
exception = 1;
if (exception) {
printk("kvm: The guest lowcore is not mapped during interrupt "
"delivery, killing userspace\n");
do_exit(SIGKILL);
}
return 1;
}
int kvm_cpu_has_interrupt(struct kvm_vcpu *vcpu)
{
struct kvm_s390_local_interrupt *li = &vcpu->arch.local_int;
struct kvm_s390_float_interrupt *fi = vcpu->arch.local_int.float_int;
struct kvm_s390_interrupt_info *inti;
int rc = 0;
if (atomic_read(&li->active)) {
spin_lock_bh(&li->lock);
list_for_each_entry(inti, &li->list, list)
if (__interrupt_is_deliverable(vcpu, inti)) {
rc = 1;
break;
}
spin_unlock_bh(&li->lock);
}
if ((!rc) && atomic_read(&fi->active)) {
spin_lock_bh(&fi->lock);
list_for_each_entry(inti, &fi->list, list)
if (__interrupt_is_deliverable(vcpu, inti)) {
rc = 1;
break;
}
spin_unlock_bh(&fi->lock);
}
if ((!rc) && (vcpu->arch.sie_block->ckc <
get_clock() + vcpu->arch.sie_block->epoch)) {
if ((!psw_extint_disabled(vcpu)) &&
(vcpu->arch.sie_block->gcr[0] & 0x800ul))
rc = 1;
}
return rc;
}
int kvm_cpu_has_pending_timer(struct kvm_vcpu *vcpu)
{
return 0;
}
int kvm_s390_handle_wait(struct kvm_vcpu *vcpu)
{
u64 now, sltime;
DECLARE_WAITQUEUE(wait, current);
vcpu->stat.exit_wait_state++;
if (kvm_cpu_has_interrupt(vcpu))
return 0;
__set_cpu_idle(vcpu);
spin_lock_bh(&vcpu->arch.local_int.lock);
vcpu->arch.local_int.timer_due = 0;
spin_unlock_bh(&vcpu->arch.local_int.lock);
if (psw_interrupts_disabled(vcpu)) {
VCPU_EVENT(vcpu, 3, "%s", "disabled wait");
__unset_cpu_idle(vcpu);
return -ENOTSUPP; /* disabled wait */
}
if (psw_extint_disabled(vcpu) ||
(!(vcpu->arch.sie_block->gcr[0] & 0x800ul))) {
VCPU_EVENT(vcpu, 3, "%s", "enabled wait w/o timer");
goto no_timer;
}
now = get_clock() + vcpu->arch.sie_block->epoch;
if (vcpu->arch.sie_block->ckc < now) {
__unset_cpu_idle(vcpu);
return 0;
}
sltime = (vcpu->arch.sie_block->ckc - now) / (0xf4240000ul / HZ) + 1;
vcpu->arch.ckc_timer.expires = jiffies + sltime;
add_timer(&vcpu->arch.ckc_timer);
VCPU_EVENT(vcpu, 5, "enabled wait timer:%lx jiffies", sltime);
no_timer:
spin_lock_bh(&vcpu->arch.local_int.float_int->lock);
spin_lock_bh(&vcpu->arch.local_int.lock);
add_wait_queue(&vcpu->arch.local_int.wq, &wait);
while (list_empty(&vcpu->arch.local_int.list) &&
list_empty(&vcpu->arch.local_int.float_int->list) &&
(!vcpu->arch.local_int.timer_due) &&
!signal_pending(current)) {
set_current_state(TASK_INTERRUPTIBLE);
spin_unlock_bh(&vcpu->arch.local_int.lock);
spin_unlock_bh(&vcpu->arch.local_int.float_int->lock);
vcpu_put(vcpu);
schedule();
vcpu_load(vcpu);
spin_lock_bh(&vcpu->arch.local_int.float_int->lock);
spin_lock_bh(&vcpu->arch.local_int.lock);
}
__unset_cpu_idle(vcpu);
__set_current_state(TASK_RUNNING);
remove_wait_queue(&vcpu->wq, &wait);
spin_unlock_bh(&vcpu->arch.local_int.lock);
spin_unlock_bh(&vcpu->arch.local_int.float_int->lock);
del_timer(&vcpu->arch.ckc_timer);
return 0;
}
void kvm_s390_idle_wakeup(unsigned long data)
{
struct kvm_vcpu *vcpu = (struct kvm_vcpu *)data;
spin_lock_bh(&vcpu->arch.local_int.lock);
vcpu->arch.local_int.timer_due = 1;
if (waitqueue_active(&vcpu->arch.local_int.wq))
wake_up_interruptible(&vcpu->arch.local_int.wq);
spin_unlock_bh(&vcpu->arch.local_int.lock);
}
void kvm_s390_deliver_pending_interrupts(struct kvm_vcpu *vcpu)
{
struct kvm_s390_local_interrupt *li = &vcpu->arch.local_int;
struct kvm_s390_float_interrupt *fi = vcpu->arch.local_int.float_int;
struct kvm_s390_interrupt_info *n, *inti = NULL;
int deliver;
__reset_intercept_indicators(vcpu);
if (atomic_read(&li->active)) {
do {
deliver = 0;
spin_lock_bh(&li->lock);
list_for_each_entry_safe(inti, n, &li->list, list) {
if (__interrupt_is_deliverable(vcpu, inti)) {
list_del(&inti->list);
deliver = 1;
break;
}
__set_intercept_indicator(vcpu, inti);
}
if (list_empty(&li->list))
atomic_set(&li->active, 0);
spin_unlock_bh(&li->lock);
if (deliver) {
__do_deliver_interrupt(vcpu, inti);
kfree(inti);
}
} while (deliver);
}
if ((vcpu->arch.sie_block->ckc <
get_clock() + vcpu->arch.sie_block->epoch))
__try_deliver_ckc_interrupt(vcpu);
if (atomic_read(&fi->active)) {
do {
deliver = 0;
spin_lock_bh(&fi->lock);
list_for_each_entry_safe(inti, n, &fi->list, list) {
if (__interrupt_is_deliverable(vcpu, inti)) {
list_del(&inti->list);
deliver = 1;
break;
}
__set_intercept_indicator(vcpu, inti);
}
if (list_empty(&fi->list))
atomic_set(&fi->active, 0);
spin_unlock_bh(&fi->lock);
if (deliver) {
__do_deliver_interrupt(vcpu, inti);
kfree(inti);
}
} while (deliver);
}
}
int kvm_s390_inject_program_int(struct kvm_vcpu *vcpu, u16 code)
{
struct kvm_s390_local_interrupt *li = &vcpu->arch.local_int;
struct kvm_s390_interrupt_info *inti;
inti = kzalloc(sizeof(*inti), GFP_KERNEL);
if (!inti)
return -ENOMEM;
inti->type = KVM_S390_PROGRAM_INT;;
inti->pgm.code = code;
VCPU_EVENT(vcpu, 3, "inject: program check %d (from kernel)", code);
spin_lock_bh(&li->lock);
list_add(&inti->list, &li->list);
atomic_set(&li->active, 1);
BUG_ON(waitqueue_active(&li->wq));
spin_unlock_bh(&li->lock);
return 0;
}
int kvm_s390_inject_vm(struct kvm *kvm,
struct kvm_s390_interrupt *s390int)
{
struct kvm_s390_local_interrupt *li;
struct kvm_s390_float_interrupt *fi;
struct kvm_s390_interrupt_info *inti;
int sigcpu;
inti = kzalloc(sizeof(*inti), GFP_KERNEL);
if (!inti)
return -ENOMEM;
switch (s390int->type) {
case KVM_S390_INT_VIRTIO:
VM_EVENT(kvm, 5, "inject: virtio parm:%x,parm64:%lx",
s390int->parm, s390int->parm64);
inti->type = s390int->type;
inti->ext.ext_params = s390int->parm;
inti->ext.ext_params2 = s390int->parm64;
break;
case KVM_S390_INT_SERVICE:
VM_EVENT(kvm, 5, "inject: sclp parm:%x", s390int->parm);
inti->type = s390int->type;
inti->ext.ext_params = s390int->parm;
break;
case KVM_S390_PROGRAM_INT:
case KVM_S390_SIGP_STOP:
case KVM_S390_INT_EMERGENCY:
default:
kfree(inti);
return -EINVAL;
}
mutex_lock(&kvm->lock);
fi = &kvm->arch.float_int;
spin_lock_bh(&fi->lock);
list_add_tail(&inti->list, &fi->list);
atomic_set(&fi->active, 1);
sigcpu = find_first_bit(fi->idle_mask, KVM_MAX_VCPUS);
if (sigcpu == KVM_MAX_VCPUS) {
do {
sigcpu = fi->next_rr_cpu++;
if (sigcpu == KVM_MAX_VCPUS)
sigcpu = fi->next_rr_cpu = 0;
} while (fi->local_int[sigcpu] == NULL);
}
li = fi->local_int[sigcpu];
spin_lock_bh(&li->lock);
atomic_set_mask(CPUSTAT_EXT_INT, li->cpuflags);
if (waitqueue_active(&li->wq))
wake_up_interruptible(&li->wq);
spin_unlock_bh(&li->lock);
spin_unlock_bh(&fi->lock);
mutex_unlock(&kvm->lock);
return 0;
}
int kvm_s390_inject_vcpu(struct kvm_vcpu *vcpu,
struct kvm_s390_interrupt *s390int)
{
struct kvm_s390_local_interrupt *li;
struct kvm_s390_interrupt_info *inti;
inti = kzalloc(sizeof(*inti), GFP_KERNEL);
if (!inti)
return -ENOMEM;
switch (s390int->type) {
case KVM_S390_PROGRAM_INT:
if (s390int->parm & 0xffff0000) {
kfree(inti);
return -EINVAL;
}
inti->type = s390int->type;
inti->pgm.code = s390int->parm;
VCPU_EVENT(vcpu, 3, "inject: program check %d (from user)",
s390int->parm);
break;
case KVM_S390_SIGP_STOP:
case KVM_S390_RESTART:
case KVM_S390_SIGP_SET_PREFIX:
case KVM_S390_INT_EMERGENCY:
VCPU_EVENT(vcpu, 3, "inject: type %x", s390int->type);
inti->type = s390int->type;
break;
case KVM_S390_INT_VIRTIO:
case KVM_S390_INT_SERVICE:
default:
kfree(inti);
return -EINVAL;
}
mutex_lock(&vcpu->kvm->lock);
li = &vcpu->arch.local_int;
spin_lock_bh(&li->lock);
if (inti->type == KVM_S390_PROGRAM_INT)
list_add(&inti->list, &li->list);
else
list_add_tail(&inti->list, &li->list);
atomic_set(&li->active, 1);
if (inti->type == KVM_S390_SIGP_STOP)
li->action_bits |= ACTION_STOP_ON_STOP;
atomic_set_mask(CPUSTAT_EXT_INT, li->cpuflags);
if (waitqueue_active(&li->wq))
wake_up_interruptible(&vcpu->arch.local_int.wq);
spin_unlock_bh(&li->lock);
mutex_unlock(&vcpu->kvm->lock);
return 0;
}
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