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/*
* kvm guest debug support
*
* Copyright IBM Corp. 2014
*
* 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): David Hildenbrand <dahi@linux.vnet.ibm.com>
*/
#include <linux/kvm_host.h>
#include <linux/errno.h>
#include "kvm-s390.h"
#include "gaccess.h"
/*
* Extends the address range given by *start and *stop to include the address
* range starting with estart and the length len. Takes care of overflowing
* intervals and tries to minimize the overall intervall size.
*/
static void extend_address_range(u64 *start, u64 *stop, u64 estart, int len)
{
u64 estop;
if (len > 0)
len--;
else
len = 0;
estop = estart + len;
/* 0-0 range represents "not set" */
if ((*start == 0) && (*stop == 0)) {
*start = estart;
*stop = estop;
} else if (*start <= *stop) {
/* increase the existing range */
if (estart < *start)
*start = estart;
if (estop > *stop)
*stop = estop;
} else {
/* "overflowing" interval, whereby *stop > *start */
if (estart <= *stop) {
if (estop > *stop)
*stop = estop;
} else if (estop > *start) {
if (estart < *start)
*start = estart;
}
/* minimize the range */
else if ((estop - *stop) < (*start - estart))
*stop = estop;
else
*start = estart;
}
}
#define MAX_INST_SIZE 6
static void enable_all_hw_bp(struct kvm_vcpu *vcpu)
{
unsigned long start, len;
u64 *cr9 = &vcpu->arch.sie_block->gcr[9];
u64 *cr10 = &vcpu->arch.sie_block->gcr[10];
u64 *cr11 = &vcpu->arch.sie_block->gcr[11];
int i;
if (vcpu->arch.guestdbg.nr_hw_bp <= 0 ||
vcpu->arch.guestdbg.hw_bp_info == NULL)
return;
/*
* If the guest is not interrested in branching events, we can savely
* limit them to the PER address range.
*/
if (!(*cr9 & PER_EVENT_BRANCH))
*cr9 |= PER_CONTROL_BRANCH_ADDRESS;
*cr9 |= PER_EVENT_IFETCH | PER_EVENT_BRANCH;
for (i = 0; i < vcpu->arch.guestdbg.nr_hw_bp; i++) {
start = vcpu->arch.guestdbg.hw_bp_info[i].addr;
len = vcpu->arch.guestdbg.hw_bp_info[i].len;
/*
* The instruction in front of the desired bp has to
* report instruction-fetching events
*/
if (start < MAX_INST_SIZE) {
len += start;
start = 0;
} else {
start -= MAX_INST_SIZE;
len += MAX_INST_SIZE;
}
extend_address_range(cr10, cr11, start, len);
}
}
static void enable_all_hw_wp(struct kvm_vcpu *vcpu)
{
unsigned long start, len;
u64 *cr9 = &vcpu->arch.sie_block->gcr[9];
u64 *cr10 = &vcpu->arch.sie_block->gcr[10];
u64 *cr11 = &vcpu->arch.sie_block->gcr[11];
int i;
if (vcpu->arch.guestdbg.nr_hw_wp <= 0 ||
vcpu->arch.guestdbg.hw_wp_info == NULL)
return;
/* if host uses storage alternation for special address
* spaces, enable all events and give all to the guest */
if (*cr9 & PER_EVENT_STORE && *cr9 & PER_CONTROL_ALTERATION) {
*cr9 &= ~PER_CONTROL_ALTERATION;
*cr10 = 0;
*cr11 = PSW_ADDR_INSN;
} else {
*cr9 &= ~PER_CONTROL_ALTERATION;
*cr9 |= PER_EVENT_STORE;
for (i = 0; i < vcpu->arch.guestdbg.nr_hw_wp; i++) {
start = vcpu->arch.guestdbg.hw_wp_info[i].addr;
len = vcpu->arch.guestdbg.hw_wp_info[i].len;
extend_address_range(cr10, cr11, start, len);
}
}
}
void kvm_s390_backup_guest_per_regs(struct kvm_vcpu *vcpu)
{
vcpu->arch.guestdbg.cr0 = vcpu->arch.sie_block->gcr[0];
vcpu->arch.guestdbg.cr9 = vcpu->arch.sie_block->gcr[9];
vcpu->arch.guestdbg.cr10 = vcpu->arch.sie_block->gcr[10];
vcpu->arch.guestdbg.cr11 = vcpu->arch.sie_block->gcr[11];
}
void kvm_s390_restore_guest_per_regs(struct kvm_vcpu *vcpu)
{
vcpu->arch.sie_block->gcr[0] = vcpu->arch.guestdbg.cr0;
vcpu->arch.sie_block->gcr[9] = vcpu->arch.guestdbg.cr9;
vcpu->arch.sie_block->gcr[10] = vcpu->arch.guestdbg.cr10;
vcpu->arch.sie_block->gcr[11] = vcpu->arch.guestdbg.cr11;
}
void kvm_s390_patch_guest_per_regs(struct kvm_vcpu *vcpu)
{
/*
* TODO: if guest psw has per enabled, otherwise 0s!
* This reduces the amount of reported events.
* Need to intercept all psw changes!
*/
if (guestdbg_sstep_enabled(vcpu)) {
/* disable timer (clock-comparator) interrupts */
vcpu->arch.sie_block->gcr[0] &= ~0x800ul;
vcpu->arch.sie_block->gcr[9] |= PER_EVENT_IFETCH;
vcpu->arch.sie_block->gcr[10] = 0;
vcpu->arch.sie_block->gcr[11] = PSW_ADDR_INSN;
}
if (guestdbg_hw_bp_enabled(vcpu)) {
enable_all_hw_bp(vcpu);
enable_all_hw_wp(vcpu);
}
/* TODO: Instruction-fetching-nullification not allowed for now */
if (vcpu->arch.sie_block->gcr[9] & PER_EVENT_NULLIFICATION)
vcpu->arch.sie_block->gcr[9] &= ~PER_EVENT_NULLIFICATION;
}
#define MAX_WP_SIZE 100
static int __import_wp_info(struct kvm_vcpu *vcpu,
struct kvm_hw_breakpoint *bp_data,
struct kvm_hw_wp_info_arch *wp_info)
{
int ret = 0;
wp_info->len = bp_data->len;
wp_info->addr = bp_data->addr;
wp_info->phys_addr = bp_data->phys_addr;
wp_info->old_data = NULL;
if (wp_info->len < 0 || wp_info->len > MAX_WP_SIZE)
return -EINVAL;
wp_info->old_data = kmalloc(bp_data->len, GFP_KERNEL);
if (!wp_info->old_data)
return -ENOMEM;
/* try to backup the original value */
ret = read_guest_abs(vcpu, wp_info->phys_addr, wp_info->old_data,
wp_info->len);
if (ret) {
kfree(wp_info->old_data);
wp_info->old_data = NULL;
}
return ret;
}
#define MAX_BP_COUNT 50
int kvm_s390_import_bp_data(struct kvm_vcpu *vcpu,
s
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