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linux/arch/s390/kvm/guestdbg.c

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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 interval 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 interested in branching events, we can safely
* 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 = -1UL;
} 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] = -1UL;
}
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,
struct kvm_guest_debug *dbg)
{
int ret = 0, nr_wp = 0, nr_bp = 0, i, size;
struct kvm_hw_breakpoint *bp_data = NULL;
struct kvm_hw_wp_info_arch *wp_info = NULL;
struct kvm_hw_bp_info_arch *bp_info = NULL;
if (dbg->arch.nr_hw_bp <= 0 || !dbg->arch.hw_bp)
return 0;
else if (dbg->arch.nr_hw_bp > MAX_BP_COUNT)
return -EINVAL;
size = dbg->arch.nr_hw_bp * sizeof(struct kvm_hw_breakpoint);
bp_data = kmalloc(size, GFP_KERNEL);
if (!bp_data) {
ret = -ENOMEM;
goto error;
}
if (copy_from_user(bp_data, dbg->arch.hw_bp, size)) {
ret = -EFAULT;
goto error;
}
for (i = 0; i < dbg->arch.nr_hw_bp; i++) {
switch (bp_data[i].type) {
case KVM_HW_WP_WRITE:
nr_wp++;
break;
case KVM_HW_BP:
nr_bp++;
break;
default:
break;
}
}
size = nr_wp * sizeof(struct kvm_hw_wp_info_arch);
if (size > 0) {
wp_info = kmalloc(size, GFP_KERNEL);
if (!wp_info) {
ret = -ENOMEM;
goto error;
}
}
size = nr_bp * sizeof(struct kvm_hw_bp_info_arch);
if (size > 0) {
bp_info = kmalloc(size, GFP_KERNEL);
if (!bp_info) {
ret = -ENOMEM;
goto error;
}
}
for (nr_wp = 0, nr_bp = 0, i = 0; i < dbg->arch.nr_hw_bp; i++) {
switch (bp_data[i].type) {
case KVM_HW_WP_WRITE:
ret = __import_wp_info(vcpu, &bp_data[i],
&wp_info[nr_wp]);
if (ret)
goto error;
nr_wp++;
break;
case KVM_HW_BP:
bp_info[nr_bp].len = bp_data[i].len;
bp_info[nr_bp].addr = bp_data[i].addr;
nr_bp++;
break;
}
}
vcpu->arch.guestdbg.nr_hw_bp = nr_bp;
vcpu->arch.guestdbg.hw_bp_info = bp_info;
vcpu->arch.guestdbg.nr_hw_wp = nr_wp;
vcpu->arch.guestdbg.hw_wp_info = wp_info;
return 0;
error:
kfree(bp_data);
kfree(wp_info);
kfree(bp_info);
return ret;
}
void kvm_s390_clear_bp_data(struct kvm_vcpu *vcpu)
{
int i;
struct kvm_hw_wp_info_arch *hw_wp_info = NULL;
for (i = 0; i < vcpu->arch.guestdbg.nr_hw_wp; i++) {
hw_wp_info = &vcpu->arch.guestdbg.hw_wp_info[i];
kfree(hw_wp_info->old_data);
hw_wp_info->old_data = NULL;
}
kfree(vcpu->arch.guestdbg.hw_wp_info);
vcpu->arch.guestdbg.hw_wp_info = NULL;
kfree(vcpu->arch.guestdbg.hw_bp_info);
vcpu->arch.guestdbg.hw_bp_info = NULL;
vcpu->arch.guestdbg.nr_hw_wp = 0;
vcpu->arch.guestdbg.nr_hw_bp = 0;
}
static inline int in_addr_range(u64 addr, u64 a, u64 b)
{
if (a <= b)
return (addr >= a) && (addr <= b);
else
/* "overflowing" interval */
return (addr <= a) && (addr >= b);
}
#define end_of_range(bp_info) (bp_info->addr + bp_info->len - 1)
static struct kvm_hw_bp_info_arch *find_hw_bp(struct kvm_vcpu *vcpu,
unsigned long addr)
{
struct kvm_hw_bp_info_arch *bp_info = vcpu->arch.guestdbg.hw_bp_info;
int i;
if (vcpu->arch.guestdbg.nr_hw_bp == 0)
return NULL;
for (i = 0; i < vcpu->arch.guestdbg.nr_hw_bp; i++) {
/* addr is directly the start or in the range of a bp */
if (addr == bp_info->addr)
goto found;
if (bp_info->len > 0 &&
in_addr_range(addr, bp_info->addr, end_of_range(bp_info)))
goto found;
bp_info++;
}
return NULL;
found:
return bp_info;
}
static struct kvm_hw_wp_info_arch *any_wp_changed(struct kvm_vcpu *vcpu)
{
int i;
struct kvm_hw_wp_info_arch *wp_info = NULL;
void *temp = NULL;
if (vcpu->arch.guestdbg.nr_hw_wp == 0)
return NULL;
for (i = 0; i < vcpu->arch.guestdbg.nr_hw_wp; i++) {
wp_info = &vcpu->arch.guestdbg.hw_wp_info[i];
if (!wp_info || !wp_info->old_data || wp_info->len <= 0)
continue;
temp = kmalloc(wp_info->len, GFP_KERNEL);
if (!temp)
continue;
/* refetch the wp data and compare it to the old value */
if (!read_guest_abs(vcpu, wp_info->phys_addr, temp,
wp_info->len)) {
if (memcmp(temp, wp_info->old_data, wp_info->len)) {
kfree(temp);
return wp_info;
}
}
kfree(temp);
temp = NULL;
}
return NULL;
}
void kvm_s390_prepare_debug_exit(struct kvm_vcpu *vcpu)
{
vcpu->run->exit_reason = KVM_EXIT_DEBUG;
vcpu->guest_debug &= ~KVM_GUESTDBG_EXIT_PENDING;
}
#define per_bp_event(code) \
(code & (PER_EVENT_IFETCH | PER_EVENT_BRANCH))
#define per_write_wp_event(code) \
(code & (PER_EVENT_STORE | PER_EVENT_STORE_REAL))
static int debug_exit_required(struct kvm_vcpu *vcpu)
{
u32 perc = (vcpu->arch.sie_block->perc << 24);
struct kvm_debug_exit_arch *debug_exit = &vcpu->run->debug.arch;
struct kvm_hw_wp_info_arch *wp_info = NULL;
struct kvm_hw_bp_info_arch *bp_info = NULL;
unsigned long addr = vcpu->arch.sie_block->gpsw.addr;
unsigned long peraddr = vcpu->arch.sie_block->peraddr;
if (guestdbg_hw_bp_enabled(vcpu)) {
if (per_write_wp_event(perc) &&
vcpu->arch.guestdbg.nr_hw_wp > 0) {
wp_info = any_wp_changed(vcpu);
if (wp_info) {
debug_exit->addr = wp_info->addr;
debug_exit->type = KVM_HW_WP_WRITE;
goto exit_required;
}
}
if (per_bp_event(perc) &&
vcpu->arch.guestdbg.nr_hw_bp > 0) {
bp_info = find_hw_bp(vcpu, addr);
/* remove duplicate events if PC==PER address */
if (bp_info && (addr != peraddr)) {
debug_exit->addr = addr;
debug_exit->type = KVM_HW_BP;
vcpu->arch.guestdbg.last_bp = addr;
goto exit_required;
}
/* breakpoint missed */
bp_info = find_hw_bp(vcpu, peraddr);
if (bp_info && vcpu->arch.guestdbg.last_bp != peraddr) {
debug_exit->addr = peraddr;
debug_exit->type = KVM_HW_BP;
goto exit_required;
}
}
}
if (guestdbg_sstep_enabled(vcpu) && per_bp_event(perc)) {
debug_exit->addr = addr;
debug_exit->type = KVM_SINGLESTEP;
goto exit_required;
}
return 0;
exit_required:
return 1;
}
#define guest_per_enabled(vcpu) \
(vcpu->arch.sie_block->gpsw.mask & PSW_MASK_PER)
int kvm_s390_handle_per_ifetch_icpt(struct kvm_vcpu *vcpu)
{
const u8 ilen = kvm_s390_get_ilen(vcpu);
struct kvm_s390_pgm_info pgm_info = {
.code = PGM_PER,
.per_code = PER_EVENT_IFETCH >> 24,
.per_address = __rewind_psw(vcpu->arch.sie_block->gpsw, ilen),
};
/*
* The PSW points to the next instruction, therefore the intercepted
* instruction generated a PER i-fetch event. PER address therefore
* points at the previous PSW address (could be an EXECUTE function).
*/
return kvm_s390_inject_prog_irq(vcpu, &pgm_info);
}
static void filter_guest_per_event(struct kvm_vcpu *vcpu)
{
u32 perc = vcpu->arch.sie_block->perc << 24;
u64 peraddr = vcpu->arch.sie_block->peraddr;
u64 addr = vcpu->arch.sie_block->gpsw.addr;
u64 cr9 = vcpu->arch.sie_block->gcr[9];
u64 cr10 = vcpu->arch.sie_block->gcr[10];
u64 cr11 = vcpu->arch.sie_block->gcr[11];
/* filter all events, demanded by the guest */
u32 guest_perc = perc & cr9 & PER_EVENT_MASK;
if (!guest_per_enabled(vcpu))
guest_perc = 0;
/* filter "successful-branching" events */
if (guest_perc & PER_EVENT_BRANCH &&
cr9 & PER_CONTROL_BRANCH_ADDRESS &&
!in_addr_range(addr, cr10, cr11))
guest_perc &= ~PER_EVENT_BRANCH;
/* filter "instruction-fetching" events */
if (guest_perc & PER_EVENT_IFETCH &&
!in_addr_range(peraddr, cr10, cr11))
guest_perc &= ~PER_EVENT_IFETCH;
/* All other PER events will be given to the guest */
/* TODO: Check altered address/address space */
vcpu->arch.sie_block->perc = guest_perc >> 24;
if (!guest_perc)
vcpu->arch.sie_block->iprcc &= ~PGM_PER;
}
#define pssec(vcpu) (vcpu->arch.sie_block->gcr[1] & _ASCE_SPACE_SWITCH)
#define hssec(vcpu) (vcpu->arch.sie_block->gcr[13] & _ASCE_SPACE_SWITCH)
#define old_ssec(vcpu) ((vcpu->arch.sie_block->tecmc >> 31) & 0x1)
#define old_as_is_home(vcpu) !(vcpu->arch.sie_block->tecmc & 0xffff)
void kvm_s390_handle_per_event(struct kvm_vcpu *vcpu)
{
int new_as;
if (debug_exit_required(vcpu))
vcpu->guest_debug |= KVM_GUESTDBG_EXIT_PENDING;
filter_guest_per_event(vcpu);
/*
* Only RP, SAC, SACF, PT, PTI, PR, PC instructions can trigger
* a space-switch event. PER events enforce space-switch events
* for these instructions. So if no PER event for the guest is left,
* we might have to filter the space-switch element out, too.
*/
if (vcpu->arch.sie_block->iprcc == PGM_SPACE_SWITCH) {
vcpu->arch.sie_block->iprcc = 0;
new_as = psw_bits(vcpu->arch.sie_block->gpsw).as;
/*
* If the AS changed from / to home, we had RP, SAC or SACF
* instruction. Check primary and home space-switch-event
* controls. (theoretically home -> home produced no event)
*/
if (((new_as == PSW_AS_HOME) ^ old_as_is_home(vcpu)) &&
(pssec(vcpu) || hssec(vcpu)))
vcpu->arch.sie_block->iprcc = PGM_SPACE_SWITCH;
/*
* PT, PTI, PR, PC instruction operate on primary AS only. Check
* if the primary-space-switch-event control was or got set.
*/
if (new_as == PSW_AS_PRIMARY && !old_as_is_home(vcpu) &&
(pssec(vcpu) || old_ssec(vcpu)))
vcpu->arch.sie_block->iprcc = PGM_SPACE_SWITCH;
}
}
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