summaryrefslogtreecommitdiffstats
path: root/arch/s390/kvm/guestdbg.c
diff options
context:
space:
mode:
authorDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-07 18:49:45 +0000
committerDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-07 18:49:45 +0000
commit2c3c1048746a4622d8c89a29670120dc8fab93c4 (patch)
tree848558de17fb3008cdf4d861b01ac7781903ce39 /arch/s390/kvm/guestdbg.c
parentInitial commit. (diff)
downloadlinux-2c3c1048746a4622d8c89a29670120dc8fab93c4.tar.xz
linux-2c3c1048746a4622d8c89a29670120dc8fab93c4.zip
Adding upstream version 6.1.76.upstream/6.1.76
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'arch/s390/kvm/guestdbg.c')
-rw-r--r--arch/s390/kvm/guestdbg.c626
1 files changed, 626 insertions, 0 deletions
diff --git a/arch/s390/kvm/guestdbg.c b/arch/s390/kvm/guestdbg.c
new file mode 100644
index 000000000..3765c4223
--- /dev/null
+++ b/arch/s390/kvm/guestdbg.c
@@ -0,0 +1,626 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * kvm guest debug support
+ *
+ * Copyright IBM Corp. 2014
+ *
+ * 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] &= ~CR0_CLOCK_COMPARATOR_SUBMASK;
+ 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_ACCOUNT);
+ 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;
+ 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;
+
+ bp_data = memdup_user(dbg->arch.hw_bp,
+ sizeof(*bp_data) * dbg->arch.nr_hw_bp);
+ if (IS_ERR(bp_data))
+ return PTR_ERR(bp_data);
+
+ 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;
+ }
+ }
+
+ if (nr_wp > 0) {
+ wp_info = kmalloc_array(nr_wp,
+ sizeof(*wp_info),
+ GFP_KERNEL_ACCOUNT);
+ if (!wp_info) {
+ ret = -ENOMEM;
+ goto error;
+ }
+ }
+ if (nr_bp > 0) {
+ bp_info = kmalloc_array(nr_bp,
+ sizeof(*bp_info),
+ GFP_KERNEL_ACCOUNT);
+ 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_ACCOUNT);
+ 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_CODE_MASK (PER_EVENT_MASK >> 24)
+#define PER_CODE_BRANCH (PER_EVENT_BRANCH >> 24)
+#define PER_CODE_IFETCH (PER_EVENT_IFETCH >> 24)
+#define PER_CODE_STORE (PER_EVENT_STORE >> 24)
+#define PER_CODE_STORE_REAL (PER_EVENT_STORE_REAL >> 24)
+
+#define per_bp_event(code) \
+ (code & (PER_CODE_IFETCH | PER_CODE_BRANCH))
+#define per_write_wp_event(code) \
+ (code & (PER_CODE_STORE | PER_CODE_STORE_REAL))
+
+static int debug_exit_required(struct kvm_vcpu *vcpu, u8 perc,
+ unsigned long peraddr)
+{
+ 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;
+
+ 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;
+}
+
+static int per_fetched_addr(struct kvm_vcpu *vcpu, unsigned long *addr)
+{
+ u8 exec_ilen = 0;
+ u16 opcode[3];
+ int rc;
+
+ if (vcpu->arch.sie_block->icptcode == ICPT_PROGI) {
+ /* PER address references the fetched or the execute instr */
+ *addr = vcpu->arch.sie_block->peraddr;
+ /*
+ * Manually detect if we have an EXECUTE instruction. As
+ * instructions are always 2 byte aligned we can read the
+ * first two bytes unconditionally
+ */
+ rc = read_guest_instr(vcpu, *addr, &opcode, 2);
+ if (rc)
+ return rc;
+ if (opcode[0] >> 8 == 0x44)
+ exec_ilen = 4;
+ if ((opcode[0] & 0xff0f) == 0xc600)
+ exec_ilen = 6;
+ } else {
+ /* instr was suppressed, calculate the responsible instr */
+ *addr = __rewind_psw(vcpu->arch.sie_block->gpsw,
+ kvm_s390_get_ilen(vcpu));
+ if (vcpu->arch.sie_block->icptstatus & 0x01) {
+ exec_ilen = (vcpu->arch.sie_block->icptstatus & 0x60) >> 4;
+ if (!exec_ilen)
+ exec_ilen = 4;
+ }
+ }
+
+ if (exec_ilen) {
+ /* read the complete EXECUTE instr to detect the fetched addr */
+ rc = read_guest_instr(vcpu, *addr, &opcode, exec_ilen);
+ if (rc)
+ return rc;
+ if (exec_ilen == 6) {
+ /* EXECUTE RELATIVE LONG - RIL-b format */
+ s32 rl = *((s32 *) (opcode + 1));
+
+ /* rl is a _signed_ 32 bit value specifying halfwords */
+ *addr += (u64)(s64) rl * 2;
+ } else {
+ /* EXECUTE - RX-a format */
+ u32 base = (opcode[1] & 0xf000) >> 12;
+ u32 disp = opcode[1] & 0x0fff;
+ u32 index = opcode[0] & 0x000f;
+
+ *addr = base ? vcpu->run->s.regs.gprs[base] : 0;
+ *addr += index ? vcpu->run->s.regs.gprs[index] : 0;
+ *addr += disp;
+ }
+ *addr = kvm_s390_logical_to_effective(vcpu, *addr);
+ }
+ return 0;
+}
+
+#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 u64 cr10 = vcpu->arch.sie_block->gcr[10];
+ const u64 cr11 = vcpu->arch.sie_block->gcr[11];
+ const u8 ilen = kvm_s390_get_ilen(vcpu);
+ struct kvm_s390_pgm_info pgm_info = {
+ .code = PGM_PER,
+ .per_code = PER_CODE_IFETCH,
+ .per_address = __rewind_psw(vcpu->arch.sie_block->gpsw, ilen),
+ };
+ unsigned long fetched_addr;
+ int rc;
+
+ /*
+ * 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).
+ */
+ if (!guestdbg_enabled(vcpu))
+ return kvm_s390_inject_prog_irq(vcpu, &pgm_info);
+
+ if (debug_exit_required(vcpu, pgm_info.per_code, pgm_info.per_address))
+ vcpu->guest_debug |= KVM_GUESTDBG_EXIT_PENDING;
+
+ if (!guest_per_enabled(vcpu) ||
+ !(vcpu->arch.sie_block->gcr[9] & PER_EVENT_IFETCH))
+ return 0;
+
+ rc = per_fetched_addr(vcpu, &fetched_addr);
+ if (rc < 0)
+ return rc;
+ if (rc)
+ /* instruction-fetching exceptions */
+ return kvm_s390_inject_program_int(vcpu, PGM_ADDRESSING);
+
+ if (in_addr_range(fetched_addr, cr10, cr11))
+ return kvm_s390_inject_prog_irq(vcpu, &pgm_info);
+ return 0;
+}
+
+static int filter_guest_per_event(struct kvm_vcpu *vcpu)
+{
+ const u8 perc = vcpu->arch.sie_block->perc;
+ 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 */
+ u8 guest_perc = perc & (cr9 >> 24) & PER_CODE_MASK;
+ unsigned long fetched_addr;
+ int rc;
+
+ if (!guest_per_enabled(vcpu))
+ guest_perc = 0;
+
+ /* filter "successful-branching" events */
+ if (guest_perc & PER_CODE_BRANCH &&
+ cr9 & PER_CONTROL_BRANCH_ADDRESS &&
+ !in_addr_range(addr, cr10, cr11))
+ guest_perc &= ~PER_CODE_BRANCH;
+
+ /* filter "instruction-fetching" events */
+ if (guest_perc & PER_CODE_IFETCH) {
+ rc = per_fetched_addr(vcpu, &fetched_addr);
+ if (rc < 0)
+ return rc;
+ /*
+ * Don't inject an irq on exceptions. This would make handling
+ * on icpt code 8 very complex (as PSW was already rewound).
+ */
+ if (rc || !in_addr_range(fetched_addr, cr10, cr11))
+ guest_perc &= ~PER_CODE_IFETCH;
+ }
+
+ /* All other PER events will be given to the guest */
+ /* TODO: Check altered address/address space */
+
+ vcpu->arch.sie_block->perc = guest_perc;
+
+ if (!guest_perc)
+ vcpu->arch.sie_block->iprcc &= ~PGM_PER;
+ return 0;
+}
+
+#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)
+
+int kvm_s390_handle_per_event(struct kvm_vcpu *vcpu)
+{
+ int rc, new_as;
+
+ if (debug_exit_required(vcpu, vcpu->arch.sie_block->perc,
+ vcpu->arch.sie_block->peraddr))
+ vcpu->guest_debug |= KVM_GUESTDBG_EXIT_PENDING;
+
+ rc = filter_guest_per_event(vcpu);
+ if (rc)
+ return rc;
+
+ /*
+ * 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_BITS_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_BITS_AS_PRIMARY && !old_as_is_home(vcpu) &&
+ (pssec(vcpu) || old_ssec(vcpu)))
+ vcpu->arch.sie_block->iprcc = PGM_SPACE_SWITCH;
+ }
+ return 0;
+}