1 files changed, 481 insertions, 0 deletions

diff --git a/arch/s390/kvm/guestdbg.c b/arch/s390/kvm/guestdbg.c
new file mode 100644
index 000000000000..757ccef62fd5
--- /dev/null
+++ b/arch/s390/kvm/guestdbg.c
@@ -0,0 +1,481 @@
+/*
+ * 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(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;
+	}
+
+	ret = copy_from_user(bp_data, dbg->arch.hw_bp, size);
+	if (ret)
+		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(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)
+
+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 alterated address/address space */
+
+	vcpu->arch.sie_block->perc = guest_perc >> 24;
+
+	if (!guest_perc)
+		vcpu->arch.sie_block->iprcc &= ~PGM_PER;
+}
+
+void kvm_s390_handle_per_event(struct kvm_vcpu *vcpu)
+{
+	if (debug_exit_required(vcpu))
+		vcpu->guest_debug |= KVM_GUESTDBG_EXIT_PENDING;
+
+	filter_guest_per_event(vcpu);
+}