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kernel_optimize_test/arch/s390/kvm/sigp.c
Eric Farman 0e6c0f3f40 KVM: s390: Clarify SIGP orders versus STOP/RESTART 
commit 812de04661c4daa7ac385c0dfd62594540538034 upstream.

With KVM_CAP_S390_USER_SIGP, there are only five Signal Processor
orders (CONDITIONAL EMERGENCY SIGNAL, EMERGENCY SIGNAL, EXTERNAL CALL,
SENSE, and SENSE RUNNING STATUS) which are intended for frequent use
and thus are processed in-kernel. The remainder are sent to userspace
with the KVM_CAP_S390_USER_SIGP capability. Of those, three orders
(RESTART, STOP, and STOP AND STORE STATUS) have the potential to
inject work back into the kernel, and thus are asynchronous.

Let's look for those pending IRQs when processing one of the in-kernel
SIGP orders, and return BUSY (CC2) if one is in process. This is in
agreement with the Principles of Operation, which states that only one
order can be "active" on a CPU at a time.

Cc: stable@vger.kernel.org
Suggested-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Eric Farman <farman@linux.ibm.com>
Reviewed-by: Christian Borntraeger <borntraeger@linux.ibm.com>
Acked-by: David Hildenbrand <david@redhat.com>
Link: https://lore.kernel.org/r/20211213210550.856213-2-farman@linux.ibm.com
[borntraeger@linux.ibm.com: add stable tag]
Signed-off-by: Christian Borntraeger <borntraeger@linux.ibm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2022-01-20 09:17:50 +01:00

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// SPDX-License-Identifier: GPL-2.0
/*
* handling interprocessor communication
*
* Copyright IBM Corp. 2008, 2013
*
* Author(s): Carsten Otte <cotte@de.ibm.com>
* Christian Borntraeger <borntraeger@de.ibm.com>
* Christian Ehrhardt <ehrhardt@de.ibm.com>
*/
#include <linux/kvm.h>
#include <linux/kvm_host.h>
#include <linux/slab.h>
#include <asm/sigp.h>
#include "gaccess.h"
#include "kvm-s390.h"
#include "trace.h"
static int __sigp_sense(struct kvm_vcpu *vcpu, struct kvm_vcpu *dst_vcpu,
u64 *reg)
{
const bool stopped = kvm_s390_test_cpuflags(dst_vcpu, CPUSTAT_STOPPED);
int rc;
int ext_call_pending;
ext_call_pending = kvm_s390_ext_call_pending(dst_vcpu);
if (!stopped && !ext_call_pending)
rc = SIGP_CC_ORDER_CODE_ACCEPTED;
else {
*reg &= 0xffffffff00000000UL;
if (ext_call_pending)
*reg |= SIGP_STATUS_EXT_CALL_PENDING;
if (stopped)
*reg |= SIGP_STATUS_STOPPED;
rc = SIGP_CC_STATUS_STORED;
}
VCPU_EVENT(vcpu, 4, "sensed status of cpu %x rc %x", dst_vcpu->vcpu_id,
rc);
return rc;
}
static int __inject_sigp_emergency(struct kvm_vcpu *vcpu,
struct kvm_vcpu *dst_vcpu)
{
struct kvm_s390_irq irq = {
.type = KVM_S390_INT_EMERGENCY,
.u.emerg.code = vcpu->vcpu_id,
};
int rc = 0;
rc = kvm_s390_inject_vcpu(dst_vcpu, &irq);
if (!rc)
VCPU_EVENT(vcpu, 4, "sent sigp emerg to cpu %x",
dst_vcpu->vcpu_id);
return rc ? rc : SIGP_CC_ORDER_CODE_ACCEPTED;
}
static int __sigp_emergency(struct kvm_vcpu *vcpu, struct kvm_vcpu *dst_vcpu)
{
return __inject_sigp_emergency(vcpu, dst_vcpu);
}
static int __sigp_conditional_emergency(struct kvm_vcpu *vcpu,
struct kvm_vcpu *dst_vcpu,
u16 asn, u64 *reg)
{
const u64 psw_int_mask = PSW_MASK_IO | PSW_MASK_EXT;
u16 p_asn, s_asn;
psw_t *psw;
bool idle;
idle = is_vcpu_idle(vcpu);
psw = &dst_vcpu->arch.sie_block->gpsw;
p_asn = dst_vcpu->arch.sie_block->gcr[4] & 0xffff; /* Primary ASN */
s_asn = dst_vcpu->arch.sie_block->gcr[3] & 0xffff; /* Secondary ASN */
/* Inject the emergency signal? */
if (!is_vcpu_stopped(vcpu)
|| (psw->mask & psw_int_mask) != psw_int_mask
|| (idle && psw->addr != 0)
|| (!idle && (asn == p_asn || asn == s_asn))) {
return __inject_sigp_emergency(vcpu, dst_vcpu);
} else {
*reg &= 0xffffffff00000000UL;
*reg |= SIGP_STATUS_INCORRECT_STATE;
return SIGP_CC_STATUS_STORED;
}
}
static int __sigp_external_call(struct kvm_vcpu *vcpu,
struct kvm_vcpu *dst_vcpu, u64 *reg)
{
struct kvm_s390_irq irq = {
.type = KVM_S390_INT_EXTERNAL_CALL,
.u.extcall.code = vcpu->vcpu_id,
};
int rc;
rc = kvm_s390_inject_vcpu(dst_vcpu, &irq);
if (rc == -EBUSY) {
*reg &= 0xffffffff00000000UL;
*reg |= SIGP_STATUS_EXT_CALL_PENDING;
return SIGP_CC_STATUS_STORED;
} else if (rc == 0) {
VCPU_EVENT(vcpu, 4, "sent sigp ext call to cpu %x",
dst_vcpu->vcpu_id);
}
return rc ? rc : SIGP_CC_ORDER_CODE_ACCEPTED;
}
static int __sigp_stop(struct kvm_vcpu *vcpu, struct kvm_vcpu *dst_vcpu)
{
struct kvm_s390_irq irq = {
.type = KVM_S390_SIGP_STOP,
};
int rc;
rc = kvm_s390_inject_vcpu(dst_vcpu, &irq);
if (rc == -EBUSY)
rc = SIGP_CC_BUSY;
else if (rc == 0)
VCPU_EVENT(vcpu, 4, "sent sigp stop to cpu %x",
dst_vcpu->vcpu_id);
return rc;
}
static int __sigp_stop_and_store_status(struct kvm_vcpu *vcpu,
struct kvm_vcpu *dst_vcpu, u64 *reg)
{
struct kvm_s390_irq irq = {
.type = KVM_S390_SIGP_STOP,
.u.stop.flags = KVM_S390_STOP_FLAG_STORE_STATUS,
};
int rc;
rc = kvm_s390_inject_vcpu(dst_vcpu, &irq);
if (rc == -EBUSY)
rc = SIGP_CC_BUSY;
else if (rc == 0)
VCPU_EVENT(vcpu, 4, "sent sigp stop and store status to cpu %x",
dst_vcpu->vcpu_id);
return rc;
}
static int __sigp_set_arch(struct kvm_vcpu *vcpu, u32 parameter,
u64 *status_reg)
{
unsigned int i;
struct kvm_vcpu *v;
bool all_stopped = true;
kvm_for_each_vcpu(i, v, vcpu->kvm) {
if (v == vcpu)
continue;
if (!is_vcpu_stopped(v))
all_stopped = false;
}
*status_reg &= 0xffffffff00000000UL;
/* Reject set arch order, with czam we're always in z/Arch mode. */
*status_reg |= (all_stopped ? SIGP_STATUS_INVALID_PARAMETER :
SIGP_STATUS_INCORRECT_STATE);
return SIGP_CC_STATUS_STORED;
}
static int __sigp_set_prefix(struct kvm_vcpu *vcpu, struct kvm_vcpu *dst_vcpu,
u32 address, u64 *reg)
{
struct kvm_s390_irq irq = {
.type = KVM_S390_SIGP_SET_PREFIX,
.u.prefix.address = address & 0x7fffe000u,
};
int rc;
/*
* Make sure the new value is valid memory. We only need to check the
* first page, since address is 8k aligned and memory pieces are always
* at least 1MB aligned and have at least a size of 1MB.
*/
if (kvm_is_error_gpa(vcpu->kvm, irq.u.prefix.address)) {
*reg &= 0xffffffff00000000UL;
*reg |= SIGP_STATUS_INVALID_PARAMETER;
return SIGP_CC_STATUS_STORED;
}
rc = kvm_s390_inject_vcpu(dst_vcpu, &irq);
if (rc == -EBUSY) {
*reg &= 0xffffffff00000000UL;
*reg |= SIGP_STATUS_INCORRECT_STATE;
return SIGP_CC_STATUS_STORED;
}
return rc;
}
static int __sigp_store_status_at_addr(struct kvm_vcpu *vcpu,
struct kvm_vcpu *dst_vcpu,
u32 addr, u64 *reg)
{
int rc;
if (!kvm_s390_test_cpuflags(dst_vcpu, CPUSTAT_STOPPED)) {
*reg &= 0xffffffff00000000UL;
*reg |= SIGP_STATUS_INCORRECT_STATE;
return SIGP_CC_STATUS_STORED;
}
addr &= 0x7ffffe00;
rc = kvm_s390_store_status_unloaded(dst_vcpu, addr);
if (rc == -EFAULT) {
*reg &= 0xffffffff00000000UL;
*reg |= SIGP_STATUS_INVALID_PARAMETER;
rc = SIGP_CC_STATUS_STORED;
}
return rc;
}
static int __sigp_sense_running(struct kvm_vcpu *vcpu,
struct kvm_vcpu *dst_vcpu, u64 *reg)
{
int rc;
if (!test_kvm_facility(vcpu->kvm, 9)) {
*reg &= 0xffffffff00000000UL;
*reg |= SIGP_STATUS_INVALID_ORDER;
return SIGP_CC_STATUS_STORED;
}
if (kvm_s390_test_cpuflags(dst_vcpu, CPUSTAT_RUNNING)) {
/* running */
rc = SIGP_CC_ORDER_CODE_ACCEPTED;
} else {
/* not running */
*reg &= 0xffffffff00000000UL;
*reg |= SIGP_STATUS_NOT_RUNNING;
rc = SIGP_CC_STATUS_STORED;
}
VCPU_EVENT(vcpu, 4, "sensed running status of cpu %x rc %x",
dst_vcpu->vcpu_id, rc);
return rc;
}
static int __prepare_sigp_re_start(struct kvm_vcpu *vcpu,
struct kvm_vcpu *dst_vcpu, u8 order_code)
{
struct kvm_s390_local_interrupt *li = &dst_vcpu->arch.local_int;
/* handle (RE)START in user space */
int rc = -EOPNOTSUPP;
/* make sure we don't race with STOP irq injection */
spin_lock(&li->lock);
if (kvm_s390_is_stop_irq_pending(dst_vcpu))
rc = SIGP_CC_BUSY;
spin_unlock(&li->lock);
return rc;
}
static int __prepare_sigp_cpu_reset(struct kvm_vcpu *vcpu,
struct kvm_vcpu *dst_vcpu, u8 order_code)
{
/* handle (INITIAL) CPU RESET in user space */
return -EOPNOTSUPP;
}
static int __prepare_sigp_unknown(struct kvm_vcpu *vcpu,
struct kvm_vcpu *dst_vcpu)
{
/* handle unknown orders in user space */
return -EOPNOTSUPP;
}
static int handle_sigp_dst(struct kvm_vcpu *vcpu, u8 order_code,
u16 cpu_addr, u32 parameter, u64 *status_reg)
{
int rc;
struct kvm_vcpu *dst_vcpu = kvm_get_vcpu_by_id(vcpu->kvm, cpu_addr);
if (!dst_vcpu)
return SIGP_CC_NOT_OPERATIONAL;
/*
* SIGP RESTART, SIGP STOP, and SIGP STOP AND STORE STATUS orders
* are processed asynchronously. Until the affected VCPU finishes
* its work and calls back into KVM to clear the (RESTART or STOP)
* interrupt, we need to return any new non-reset orders "busy".
*
* This is important because a single VCPU could issue:
* 1) SIGP STOP $DESTINATION
* 2) SIGP SENSE $DESTINATION
*
* If the SIGP SENSE would not be rejected as "busy", it could
* return an incorrect answer as to whether the VCPU is STOPPED
* or OPERATING.
*/
if (order_code != SIGP_INITIAL_CPU_RESET &&
order_code != SIGP_CPU_RESET) {
/*
* Lockless check. Both SIGP STOP and SIGP (RE)START
* properly synchronize everything while processing
* their orders, while the guest cannot observe a
* difference when issuing other orders from two
* different VCPUs.
*/
if (kvm_s390_is_stop_irq_pending(dst_vcpu) ||
kvm_s390_is_restart_irq_pending(dst_vcpu))
return SIGP_CC_BUSY;
}
switch (order_code) {
case SIGP_SENSE:
vcpu->stat.instruction_sigp_sense++;
rc = __sigp_sense(vcpu, dst_vcpu, status_reg);
break;
case SIGP_EXTERNAL_CALL:
vcpu->stat.instruction_sigp_external_call++;
rc = __sigp_external_call(vcpu, dst_vcpu, status_reg);
break;
case SIGP_EMERGENCY_SIGNAL:
vcpu->stat.instruction_sigp_emergency++;
rc = __sigp_emergency(vcpu, dst_vcpu);
break;
case SIGP_STOP:
vcpu->stat.instruction_sigp_stop++;
rc = __sigp_stop(vcpu, dst_vcpu);
break;
case SIGP_STOP_AND_STORE_STATUS:
vcpu->stat.instruction_sigp_stop_store_status++;
rc = __sigp_stop_and_store_status(vcpu, dst_vcpu, status_reg);
break;
case SIGP_STORE_STATUS_AT_ADDRESS:
vcpu->stat.instruction_sigp_store_status++;
rc = __sigp_store_status_at_addr(vcpu, dst_vcpu, parameter,
status_reg);
break;
case SIGP_SET_PREFIX:
vcpu->stat.instruction_sigp_prefix++;
rc = __sigp_set_prefix(vcpu, dst_vcpu, parameter, status_reg);
break;
case SIGP_COND_EMERGENCY_SIGNAL:
vcpu->stat.instruction_sigp_cond_emergency++;
rc = __sigp_conditional_emergency(vcpu, dst_vcpu, parameter,
status_reg);
break;
case SIGP_SENSE_RUNNING:
vcpu->stat.instruction_sigp_sense_running++;
rc = __sigp_sense_running(vcpu, dst_vcpu, status_reg);
break;
case SIGP_START:
vcpu->stat.instruction_sigp_start++;
rc = __prepare_sigp_re_start(vcpu, dst_vcpu, order_code);
break;
case SIGP_RESTART:
vcpu->stat.instruction_sigp_restart++;
rc = __prepare_sigp_re_start(vcpu, dst_vcpu, order_code);
break;
case SIGP_INITIAL_CPU_RESET:
vcpu->stat.instruction_sigp_init_cpu_reset++;
rc = __prepare_sigp_cpu_reset(vcpu, dst_vcpu, order_code);
break;
case SIGP_CPU_RESET:
vcpu->stat.instruction_sigp_cpu_reset++;
rc = __prepare_sigp_cpu_reset(vcpu, dst_vcpu, order_code);
break;
default:
vcpu->stat.instruction_sigp_unknown++;
rc = __prepare_sigp_unknown(vcpu, dst_vcpu);
}
if (rc == -EOPNOTSUPP)
VCPU_EVENT(vcpu, 4,
"sigp order %u -> cpu %x: handled in user space",
order_code, dst_vcpu->vcpu_id);
return rc;
}
static int handle_sigp_order_in_user_space(struct kvm_vcpu *vcpu, u8 order_code,
u16 cpu_addr)
{
if (!vcpu->kvm->arch.user_sigp)
return 0;
switch (order_code) {
case SIGP_SENSE:
case SIGP_EXTERNAL_CALL:
case SIGP_EMERGENCY_SIGNAL:
case SIGP_COND_EMERGENCY_SIGNAL:
case SIGP_SENSE_RUNNING:
return 0;
/* update counters as we're directly dropping to user space */
case SIGP_STOP:
vcpu->stat.instruction_sigp_stop++;
break;
case SIGP_STOP_AND_STORE_STATUS:
vcpu->stat.instruction_sigp_stop_store_status++;
break;
case SIGP_STORE_STATUS_AT_ADDRESS:
vcpu->stat.instruction_sigp_store_status++;
break;
case SIGP_STORE_ADDITIONAL_STATUS:
vcpu->stat.instruction_sigp_store_adtl_status++;
break;
case SIGP_SET_PREFIX:
vcpu->stat.instruction_sigp_prefix++;
break;
case SIGP_START:
vcpu->stat.instruction_sigp_start++;
break;
case SIGP_RESTART:
vcpu->stat.instruction_sigp_restart++;
break;
case SIGP_INITIAL_CPU_RESET:
vcpu->stat.instruction_sigp_init_cpu_reset++;
break;
case SIGP_CPU_RESET:
vcpu->stat.instruction_sigp_cpu_reset++;
break;
default:
vcpu->stat.instruction_sigp_unknown++;
}
VCPU_EVENT(vcpu, 3, "SIGP: order %u for CPU %d handled in userspace",
order_code, cpu_addr);
return 1;
}
int kvm_s390_handle_sigp(struct kvm_vcpu *vcpu)
{
int r1 = (vcpu->arch.sie_block->ipa & 0x00f0) >> 4;
int r3 = vcpu->arch.sie_block->ipa & 0x000f;
u32 parameter;
u16 cpu_addr = vcpu->run->s.regs.gprs[r3];
u8 order_code;
int rc;
/* sigp in userspace can exit */
if (vcpu->arch.sie_block->gpsw.mask & PSW_MASK_PSTATE)
return kvm_s390_inject_program_int(vcpu, PGM_PRIVILEGED_OP);
order_code = kvm_s390_get_base_disp_rs(vcpu, NULL);
if (handle_sigp_order_in_user_space(vcpu, order_code, cpu_addr))
return -EOPNOTSUPP;
if (r1 % 2)
parameter = vcpu->run->s.regs.gprs[r1];
else
parameter = vcpu->run->s.regs.gprs[r1 + 1];
trace_kvm_s390_handle_sigp(vcpu, order_code, cpu_addr, parameter);
switch (order_code) {
case SIGP_SET_ARCHITECTURE:
vcpu->stat.instruction_sigp_arch++;
rc = __sigp_set_arch(vcpu, parameter,
&vcpu->run->s.regs.gprs[r1]);
break;
default:
rc = handle_sigp_dst(vcpu, order_code, cpu_addr,
parameter,
&vcpu->run->s.regs.gprs[r1]);
}
if (rc < 0)
return rc;
kvm_s390_set_psw_cc(vcpu, rc);
return 0;
}
/*
* Handle SIGP partial execution interception.
*
* This interception will occur at the source cpu when a source cpu sends an
* external call to a target cpu and the target cpu has the WAIT bit set in
* its cpuflags. Interception will occurr after the interrupt indicator bits at
* the target cpu have been set. All error cases will lead to instruction
* interception, therefore nothing is to be checked or prepared.
*/
int kvm_s390_handle_sigp_pei(struct kvm_vcpu *vcpu)
{
int r3 = vcpu->arch.sie_block->ipa & 0x000f;
u16 cpu_addr = vcpu->run->s.regs.gprs[r3];
struct kvm_vcpu *dest_vcpu;
u8 order_code = kvm_s390_get_base_disp_rs(vcpu, NULL);
trace_kvm_s390_handle_sigp_pei(vcpu, order_code, cpu_addr);
if (order_code == SIGP_EXTERNAL_CALL) {
dest_vcpu = kvm_get_vcpu_by_id(vcpu->kvm, cpu_addr);
BUG_ON(dest_vcpu == NULL);
kvm_s390_vcpu_wakeup(dest_vcpu);
kvm_s390_set_psw_cc(vcpu, SIGP_CC_ORDER_CODE_ACCEPTED);
return 0;
}
return -EOPNOTSUPP;
}
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