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linux/arch/s390/kvm/sigp.c
Carsten Otte f50146bd7b KVM: s390: Fix prefix register checking in arch/s390/kvm/sigp.c 
This patch corrects the checking of the new address for the prefix register.
On s390, the prefix register is used to address the cpu's lowcore (address
0...8k). This check is supposed to verify that the memory is readable and
present.
copy_from_guest is a helper function, that can be used to read from guest
memory. It applies prefixing, adds the start address of the guest memory in
user, and then calls copy_from_user. Previous code was obviously broken for
two reasons:
- prefixing should not be applied here. The current prefix register is
  going to be updated soon, and the address we're looking for will be
  0..8k after we've updated the register
- we're adding the guest origin (gmsor) twice: once in subject code
  and once in copy_from_guest

With kuli, we did not hit this problem because (a) we were lucky with
previous prefix register content, and (b) our guest memory was mmaped
very low into user address space.

Cc: stable@kernel.org
Signed-off-by: Carsten Otte <cotte@de.ibm.com>
Reported-by: Alexander Graf <agraf@suse.de>
Signed-off-by: Avi Kivity <avi@redhat.com>
2009-12-03 09:32:26 +02:00

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/*
* sigp.c - handlinge interprocessor communication
*
* Copyright IBM Corp. 2008,2009
*
* 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>
* Christian Borntraeger <borntraeger@de.ibm.com>
* Christian Ehrhardt <ehrhardt@de.ibm.com>
*/
#include <linux/kvm.h>
#include <linux/kvm_host.h>
#include "gaccess.h"
#include "kvm-s390.h"
/* sigp order codes */
#define SIGP_SENSE 0x01
#define SIGP_EXTERNAL_CALL 0x02
#define SIGP_EMERGENCY 0x03
#define SIGP_START 0x04
#define SIGP_STOP 0x05
#define SIGP_RESTART 0x06
#define SIGP_STOP_STORE_STATUS 0x09
#define SIGP_INITIAL_CPU_RESET 0x0b
#define SIGP_CPU_RESET 0x0c
#define SIGP_SET_PREFIX 0x0d
#define SIGP_STORE_STATUS_ADDR 0x0e
#define SIGP_SET_ARCH 0x12
/* cpu status bits */
#define SIGP_STAT_EQUIPMENT_CHECK 0x80000000UL
#define SIGP_STAT_INCORRECT_STATE 0x00000200UL
#define SIGP_STAT_INVALID_PARAMETER 0x00000100UL
#define SIGP_STAT_EXT_CALL_PENDING 0x00000080UL
#define SIGP_STAT_STOPPED 0x00000040UL
#define SIGP_STAT_OPERATOR_INTERV 0x00000020UL
#define SIGP_STAT_CHECK_STOP 0x00000010UL
#define SIGP_STAT_INOPERATIVE 0x00000004UL
#define SIGP_STAT_INVALID_ORDER 0x00000002UL
#define SIGP_STAT_RECEIVER_CHECK 0x00000001UL
static int __sigp_sense(struct kvm_vcpu *vcpu, u16 cpu_addr,
unsigned long *reg)
{
struct kvm_s390_float_interrupt *fi = &vcpu->kvm->arch.float_int;
int rc;
if (cpu_addr >= KVM_MAX_VCPUS)
return 3; /* not operational */
spin_lock(&fi->lock);
if (fi->local_int[cpu_addr] == NULL)
rc = 3; /* not operational */
else if (atomic_read(fi->local_int[cpu_addr]->cpuflags)
& CPUSTAT_RUNNING) {
*reg &= 0xffffffff00000000UL;
rc = 1; /* status stored */
} else {
*reg &= 0xffffffff00000000UL;
*reg |= SIGP_STAT_STOPPED;
rc = 1; /* status stored */
}
spin_unlock(&fi->lock);
VCPU_EVENT(vcpu, 4, "sensed status of cpu %x rc %x", cpu_addr, rc);
return rc;
}
static int __sigp_emergency(struct kvm_vcpu *vcpu, u16 cpu_addr)
{
struct kvm_s390_float_interrupt *fi = &vcpu->kvm->arch.float_int;
struct kvm_s390_local_interrupt *li;
struct kvm_s390_interrupt_info *inti;
int rc;
if (cpu_addr >= KVM_MAX_VCPUS)
return 3; /* not operational */
inti = kzalloc(sizeof(*inti), GFP_KERNEL);
if (!inti)
return -ENOMEM;
inti->type = KVM_S390_INT_EMERGENCY;
spin_lock(&fi->lock);
li = fi->local_int[cpu_addr];
if (li == NULL) {
rc = 3; /* not operational */
kfree(inti);
goto unlock;
}
spin_lock_bh(&li->lock);
list_add_tail(&inti->list, &li->list);
atomic_set(&li->active, 1);
atomic_set_mask(CPUSTAT_EXT_INT, li->cpuflags);
if (waitqueue_active(&li->wq))
wake_up_interruptible(&li->wq);
spin_unlock_bh(&li->lock);
rc = 0; /* order accepted */
unlock:
spin_unlock(&fi->lock);
VCPU_EVENT(vcpu, 4, "sent sigp emerg to cpu %x", cpu_addr);
return rc;
}
static int __inject_sigp_stop(struct kvm_s390_local_interrupt *li, int action)
{
struct kvm_s390_interrupt_info *inti;
inti = kzalloc(sizeof(*inti), GFP_KERNEL);
if (!inti)
return -ENOMEM;
inti->type = KVM_S390_SIGP_STOP;
spin_lock_bh(&li->lock);
list_add_tail(&inti->list, &li->list);
atomic_set(&li->active, 1);
atomic_set_mask(CPUSTAT_STOP_INT, li->cpuflags);
li->action_bits |= action;
if (waitqueue_active(&li->wq))
wake_up_interruptible(&li->wq);
spin_unlock_bh(&li->lock);
return 0; /* order accepted */
}
static int __sigp_stop(struct kvm_vcpu *vcpu, u16 cpu_addr, int action)
{
struct kvm_s390_float_interrupt *fi = &vcpu->kvm->arch.float_int;
struct kvm_s390_local_interrupt *li;
int rc;
if (cpu_addr >= KVM_MAX_VCPUS)
return 3; /* not operational */
spin_lock(&fi->lock);
li = fi->local_int[cpu_addr];
if (li == NULL) {
rc = 3; /* not operational */
goto unlock;
}
rc = __inject_sigp_stop(li, action);
unlock:
spin_unlock(&fi->lock);
VCPU_EVENT(vcpu, 4, "sent sigp stop to cpu %x", cpu_addr);
return rc;
}
int kvm_s390_inject_sigp_stop(struct kvm_vcpu *vcpu, int action)
{
struct kvm_s390_local_interrupt *li = &vcpu->arch.local_int;
return __inject_sigp_stop(li, action);
}
static int __sigp_set_arch(struct kvm_vcpu *vcpu, u32 parameter)
{
int rc;
switch (parameter & 0xff) {
case 0:
rc = 3; /* not operational */
break;
case 1:
case 2:
rc = 0; /* order accepted */
break;
default:
rc = -ENOTSUPP;
}
return rc;
}
static int __sigp_set_prefix(struct kvm_vcpu *vcpu, u16 cpu_addr, u32 address,
unsigned long *reg)
{
struct kvm_s390_float_interrupt *fi = &vcpu->kvm->arch.float_int;
struct kvm_s390_local_interrupt *li = NULL;
struct kvm_s390_interrupt_info *inti;
int rc;
u8 tmp;
/* make sure that the new value is valid memory */
address = address & 0x7fffe000u;
if ((copy_from_user(&tmp, (void __user *)
(address + vcpu->arch.sie_block->gmsor) , 1)) ||
(copy_from_user(&tmp, (void __user *)(address +
vcpu->arch.sie_block->gmsor + PAGE_SIZE), 1))) {
*reg |= SIGP_STAT_INVALID_PARAMETER;
return 1; /* invalid parameter */
}
inti = kzalloc(sizeof(*inti), GFP_KERNEL);
if (!inti)
return 2; /* busy */
spin_lock(&fi->lock);
if (cpu_addr < KVM_MAX_VCPUS)
li = fi->local_int[cpu_addr];
if (li == NULL) {
rc = 1; /* incorrect state */
*reg &= SIGP_STAT_INCORRECT_STATE;
kfree(inti);
goto out_fi;
}
spin_lock_bh(&li->lock);
/* cpu must be in stopped state */
if (atomic_read(li->cpuflags) & CPUSTAT_RUNNING) {
rc = 1; /* incorrect state */
*reg &= SIGP_STAT_INCORRECT_STATE;
kfree(inti);
goto out_li;
}
inti->type = KVM_S390_SIGP_SET_PREFIX;
inti->prefix.address = address;
list_add_tail(&inti->list, &li->list);
atomic_set(&li->active, 1);
if (waitqueue_active(&li->wq))
wake_up_interruptible(&li->wq);
rc = 0; /* order accepted */
VCPU_EVENT(vcpu, 4, "set prefix of cpu %02x to %x", cpu_addr, address);
out_li:
spin_unlock_bh(&li->lock);
out_fi:
spin_unlock(&fi->lock);
return rc;
}
int kvm_s390_handle_sigp(struct kvm_vcpu *vcpu)
{
int r1 = (vcpu->arch.sie_block->ipa & 0x00f0) >> 4;
int r3 = vcpu->arch.sie_block->ipa & 0x000f;
int base2 = vcpu->arch.sie_block->ipb >> 28;
int disp2 = ((vcpu->arch.sie_block->ipb & 0x0fff0000) >> 16);
u32 parameter;
u16 cpu_addr = vcpu->arch.guest_gprs[r3];
u8 order_code;
int rc;
/* sigp in userspace can exit */
if (vcpu->arch.sie_block->gpsw.mask & PSW_MASK_PSTATE)
return kvm_s390_inject_program_int(vcpu,
PGM_PRIVILEGED_OPERATION);
order_code = disp2;
if (base2)
order_code += vcpu->arch.guest_gprs[base2];
if (r1 % 2)
parameter = vcpu->arch.guest_gprs[r1];
else
parameter = vcpu->arch.guest_gprs[r1 + 1];
switch (order_code) {
case SIGP_SENSE:
vcpu->stat.instruction_sigp_sense++;
rc = __sigp_sense(vcpu, cpu_addr,
&vcpu->arch.guest_gprs[r1]);
break;
case SIGP_EMERGENCY:
vcpu->stat.instruction_sigp_emergency++;
rc = __sigp_emergency(vcpu, cpu_addr);
break;
case SIGP_STOP:
vcpu->stat.instruction_sigp_stop++;
rc = __sigp_stop(vcpu, cpu_addr, ACTION_STOP_ON_STOP);
break;
case SIGP_STOP_STORE_STATUS:
vcpu->stat.instruction_sigp_stop++;
rc = __sigp_stop(vcpu, cpu_addr, ACTION_STORE_ON_STOP);
break;
case SIGP_SET_ARCH:
vcpu->stat.instruction_sigp_arch++;
rc = __sigp_set_arch(vcpu, parameter);
break;
case SIGP_SET_PREFIX:
vcpu->stat.instruction_sigp_prefix++;
rc = __sigp_set_prefix(vcpu, cpu_addr, parameter,
&vcpu->arch.guest_gprs[r1]);
break;
case SIGP_RESTART:
vcpu->stat.instruction_sigp_restart++;
/* user space must know about restart */
default:
return -ENOTSUPP;
}
if (rc < 0)
return rc;
vcpu->arch.sie_block->gpsw.mask &= ~(3ul << 44);
vcpu->arch.sie_block->gpsw.mask |= (rc & 3ul) << 44;
return 0;
}
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