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linux_dsm_epyc7002/arch/s390/kvm/intercept.c
David Hildenbrand 27291e2165 KVM: s390: hardware support for guest debugging 
This patch adds support to debug the guest using the PER facility on s390.
Single-stepping, hardware breakpoints and hardware watchpoints are supported. In
order to use the PER facility of the guest without it noticing it, the control
registers of the guest have to be patched and access to them has to be
intercepted(stctl, stctg, lctl, lctlg).

All PER program interrupts have to be intercepted and only the relevant PER
interrupts for the guest have to be given back. Special care has to be taken
about repeated exits on the same hardware breakpoint. The intervention of the
host in the guests PER configuration is not fully transparent. PER instruction
nullification can not be used by the guest and too many storage alteration
events may be reported to the guest (if it is activated for special address
ranges only) when the host concurrently debugging it.

Signed-off-by: David Hildenbrand <dahi@linux.vnet.ibm.com>
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
2014-04-22 13:24:51 +02:00

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/*
* in-kernel handling for sie intercepts
*
* 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>
*/
#include <linux/kvm_host.h>
#include <linux/errno.h>
#include <linux/pagemap.h>
#include <asm/kvm_host.h>
#include "kvm-s390.h"
#include "gaccess.h"
#include "trace.h"
#include "trace-s390.h"
static const intercept_handler_t instruction_handlers[256] = {
[0x01] = kvm_s390_handle_01,
[0x82] = kvm_s390_handle_lpsw,
[0x83] = kvm_s390_handle_diag,
[0xae] = kvm_s390_handle_sigp,
[0xb2] = kvm_s390_handle_b2,
[0xb6] = kvm_s390_handle_stctl,
[0xb7] = kvm_s390_handle_lctl,
[0xb9] = kvm_s390_handle_b9,
[0xe5] = kvm_s390_handle_e5,
[0xeb] = kvm_s390_handle_eb,
};
static int handle_noop(struct kvm_vcpu *vcpu)
{
switch (vcpu->arch.sie_block->icptcode) {
case 0x0:
vcpu->stat.exit_null++;
break;
case 0x10:
vcpu->stat.exit_external_request++;
break;
case 0x14:
vcpu->stat.exit_external_interrupt++;
break;
default:
break; /* nothing */
}
return 0;
}
static int handle_stop(struct kvm_vcpu *vcpu)
{
int rc = 0;
vcpu->stat.exit_stop_request++;
spin_lock_bh(&vcpu->arch.local_int.lock);
trace_kvm_s390_stop_request(vcpu->arch.local_int.action_bits);
if (vcpu->arch.local_int.action_bits & ACTION_STOP_ON_STOP) {
atomic_set_mask(CPUSTAT_STOPPED,
&vcpu->arch.sie_block->cpuflags);
vcpu->arch.local_int.action_bits &= ~ACTION_STOP_ON_STOP;
VCPU_EVENT(vcpu, 3, "%s", "cpu stopped");
rc = -EOPNOTSUPP;
}
if (vcpu->arch.local_int.action_bits & ACTION_STORE_ON_STOP) {
vcpu->arch.local_int.action_bits &= ~ACTION_STORE_ON_STOP;
/* store status must be called unlocked. Since local_int.lock
* only protects local_int.* and not guest memory we can give
* up the lock here */
spin_unlock_bh(&vcpu->arch.local_int.lock);
rc = kvm_s390_vcpu_store_status(vcpu,
KVM_S390_STORE_STATUS_NOADDR);
if (rc >= 0)
rc = -EOPNOTSUPP;
} else
spin_unlock_bh(&vcpu->arch.local_int.lock);
return rc;
}
static int handle_validity(struct kvm_vcpu *vcpu)
{
int viwhy = vcpu->arch.sie_block->ipb >> 16;
vcpu->stat.exit_validity++;
trace_kvm_s390_intercept_validity(vcpu, viwhy);
WARN_ONCE(true, "kvm: unhandled validity intercept 0x%x\n", viwhy);
return -EOPNOTSUPP;
}
static int handle_instruction(struct kvm_vcpu *vcpu)
{
intercept_handler_t handler;
vcpu->stat.exit_instruction++;
trace_kvm_s390_intercept_instruction(vcpu,
vcpu->arch.sie_block->ipa,
vcpu->arch.sie_block->ipb);
handler = instruction_handlers[vcpu->arch.sie_block->ipa >> 8];
if (handler)
return handler(vcpu);
return -EOPNOTSUPP;
}
static void __extract_prog_irq(struct kvm_vcpu *vcpu,
struct kvm_s390_pgm_info *pgm_info)
{
memset(pgm_info, 0, sizeof(struct kvm_s390_pgm_info));
pgm_info->code = vcpu->arch.sie_block->iprcc;
switch (vcpu->arch.sie_block->iprcc & ~PGM_PER) {
case PGM_AFX_TRANSLATION:
case PGM_ASX_TRANSLATION:
case PGM_EX_TRANSLATION:
case PGM_LFX_TRANSLATION:
case PGM_LSTE_SEQUENCE:
case PGM_LSX_TRANSLATION:
case PGM_LX_TRANSLATION:
case PGM_PRIMARY_AUTHORITY:
case PGM_SECONDARY_AUTHORITY:
case PGM_SPACE_SWITCH:
pgm_info->trans_exc_code = vcpu->arch.sie_block->tecmc;
break;
case PGM_ALEN_TRANSLATION:
case PGM_ALE_SEQUENCE:
case PGM_ASTE_INSTANCE:
case PGM_ASTE_SEQUENCE:
case PGM_ASTE_VALIDITY:
case PGM_EXTENDED_AUTHORITY:
pgm_info->exc_access_id = vcpu->arch.sie_block->eai;
break;
case PGM_ASCE_TYPE:
case PGM_PAGE_TRANSLATION:
case PGM_REGION_FIRST_TRANS:
case PGM_REGION_SECOND_TRANS:
case PGM_REGION_THIRD_TRANS:
case PGM_SEGMENT_TRANSLATION:
pgm_info->trans_exc_code = vcpu->arch.sie_block->tecmc;
pgm_info->exc_access_id = vcpu->arch.sie_block->eai;
pgm_info->op_access_id = vcpu->arch.sie_block->oai;
break;
case PGM_MONITOR:
pgm_info->mon_class_nr = vcpu->arch.sie_block->mcn;
pgm_info->mon_code = vcpu->arch.sie_block->tecmc;
break;
case PGM_DATA:
pgm_info->data_exc_code = vcpu->arch.sie_block->dxc;
break;
case PGM_PROTECTION:
pgm_info->trans_exc_code = vcpu->arch.sie_block->tecmc;
pgm_info->exc_access_id = vcpu->arch.sie_block->eai;
break;
default:
break;
}
if (vcpu->arch.sie_block->iprcc & PGM_PER) {
pgm_info->per_code = vcpu->arch.sie_block->perc;
pgm_info->per_atmid = vcpu->arch.sie_block->peratmid;
pgm_info->per_address = vcpu->arch.sie_block->peraddr;
pgm_info->per_access_id = vcpu->arch.sie_block->peraid;
}
}
#define per_event(vcpu) (vcpu->arch.sie_block->iprcc & PGM_PER)
static int handle_prog(struct kvm_vcpu *vcpu)
{
struct kvm_s390_pgm_info pgm_info;
struct kvm_s390_itdb *itdb;
int rc;
vcpu->stat.exit_program_interruption++;
if (guestdbg_enabled(vcpu) && per_event(vcpu)) {
kvm_s390_handle_per_event(vcpu);
/* the interrupt might have been filtered out completely */
if (vcpu->arch.sie_block->iprcc == 0)
return 0;
}
/* Restore ITDB to Program-Interruption TDB in guest memory */
if (!IS_TE_ENABLED(vcpu) || !IS_ITDB_VALID(vcpu))
goto skip_itdb;
if (current->thread.per_flags & PER_FLAG_NO_TE)
goto skip_itdb;
itdb = (struct kvm_s390_itdb *)vcpu->arch.sie_block->itdba;
rc = write_guest_lc(vcpu, TDB_ADDR, itdb, sizeof(*itdb));
if (rc)
return rc;
memset(itdb, 0, sizeof(*itdb));
skip_itdb:
trace_kvm_s390_intercept_prog(vcpu, vcpu->arch.sie_block->iprcc);
__extract_prog_irq(vcpu, &pgm_info);
return kvm_s390_inject_prog_irq(vcpu, &pgm_info);
}
static int handle_instruction_and_prog(struct kvm_vcpu *vcpu)
{
int rc, rc2;
vcpu->stat.exit_instr_and_program++;
rc = handle_instruction(vcpu);
rc2 = handle_prog(vcpu);
if (rc == -EOPNOTSUPP)
vcpu->arch.sie_block->icptcode = 0x04;
if (rc)
return rc;
return rc2;
}
static const intercept_handler_t intercept_funcs[] = {
[0x00 >> 2] = handle_noop,
[0x04 >> 2] = handle_instruction,
[0x08 >> 2] = handle_prog,
[0x0C >> 2] = handle_instruction_and_prog,
[0x10 >> 2] = handle_noop,
[0x14 >> 2] = handle_noop,
[0x18 >> 2] = handle_noop,
[0x1C >> 2] = kvm_s390_handle_wait,
[0x20 >> 2] = handle_validity,
[0x28 >> 2] = handle_stop,
};
int kvm_handle_sie_intercept(struct kvm_vcpu *vcpu)
{
intercept_handler_t func;
u8 code = vcpu->arch.sie_block->icptcode;
if (code & 3 || (code >> 2) >= ARRAY_SIZE(intercept_funcs))
return -EOPNOTSUPP;
func = intercept_funcs[code >> 2];
if (func)
return func(vcpu);
return -EOPNOTSUPP;
}
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