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kernel_optimize_test/arch/s390/kvm/intercept.c
Christian Borntraeger 46b708ea87 KVM: s390: use simple switch statement as multiplexer 
We currently do some magic shifting (by exploiting that exit codes
are always a multiple of 4) and a table lookup to jump into the
exit handlers. This causes some calculations and checks, just to
do an potentially expensive function call.

Changing that to a switch statement gives the compiler the chance
to inline and dynamically decide between jump tables or inline
compare and branches. In addition it makes the code more readable.

bloat-o-meter gives me a small reduction in code size:

add/remove: 0/7 grow/shrink: 1/1 up/down: 986/-1334 (-348)
function                                     old     new   delta
kvm_handle_sie_intercept                      72    1058    +986
handle_prog                                  704     696      -8
handle_noop                                   54       -     -54
handle_partial_execution                      60       -     -60
intercept_funcs                              120       -    -120
handle_instruction                           198       -    -198
handle_validity                              210       -    -210
handle_stop                                  316       -    -316
handle_external_interrupt                    368       -    -368

Right now my gcc does conditional branches instead of jump tables.
The inlining seems to give us enough cycles as some micro-benchmarking
shows minimal improvements, but still in noise.

Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Reviewed-by: Cornelia Huck <cornelia.huck@de.ibm.com>
2015-10-29 15:59:11 +01:00

364 lines
9.3 KiB
C
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/*
* in-kernel handling for sie intercepts
*
* Copyright IBM Corp. 2008, 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): 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 <asm/asm-offsets.h>
#include <asm/irq.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,
};
void kvm_s390_rewind_psw(struct kvm_vcpu *vcpu, int ilc)
{
struct kvm_s390_sie_block *sie_block = vcpu->arch.sie_block;
/* Use the length of the EXECUTE instruction if necessary */
if (sie_block->icptstatus & 1) {
ilc = (sie_block->icptstatus >> 4) & 0x6;
if (!ilc)
ilc = 4;
}
sie_block->gpsw.addr = __rewind_psw(sie_block->gpsw, ilc);
}
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;
default:
break; /* nothing */
}
return 0;
}
static int handle_stop(struct kvm_vcpu *vcpu)
{
struct kvm_s390_local_interrupt *li = &vcpu->arch.local_int;
int rc = 0;
uint8_t flags, stop_pending;
vcpu->stat.exit_stop_request++;
/* delay the stop if any non-stop irq is pending */
if (kvm_s390_vcpu_has_irq(vcpu, 1))
return 0;
/* avoid races with the injection/SIGP STOP code */
spin_lock(&li->lock);
flags = li->irq.stop.flags;
stop_pending = kvm_s390_is_stop_irq_pending(vcpu);
spin_unlock(&li->lock);
trace_kvm_s390_stop_request(stop_pending, flags);
if (!stop_pending)
return 0;
if (flags & KVM_S390_STOP_FLAG_STORE_STATUS) {
rc = kvm_s390_vcpu_store_status(vcpu,
KVM_S390_STORE_STATUS_NOADDR);
if (rc)
return rc;
}
if (!kvm_s390_user_cpu_state_ctrl(vcpu->kvm))
kvm_s390_vcpu_stop(vcpu);
return -EOPNOTSUPP;
}
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_VECTOR_PROCESSING:
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;
}
}
/*
* restore ITDB to program-interruption TDB in guest lowcore
* and set TX abort indication if required
*/
static int handle_itdb(struct kvm_vcpu *vcpu)
{
struct kvm_s390_itdb *itdb;
int rc;
if (!IS_TE_ENABLED(vcpu) || !IS_ITDB_VALID(vcpu))
return 0;
if (current->thread.per_flags & PER_FLAG_NO_TE)
return 0;
itdb = (struct kvm_s390_itdb *)vcpu->arch.sie_block->itdba;
rc = write_guest_lc(vcpu, __LC_PGM_TDB, itdb, sizeof(*itdb));
if (rc)
return rc;
memset(itdb, 0, sizeof(*itdb));
return 0;
}
#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;
psw_t psw;
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;
}
trace_kvm_s390_intercept_prog(vcpu, vcpu->arch.sie_block->iprcc);
if (vcpu->arch.sie_block->iprcc == PGM_SPECIFICATION) {
rc = read_guest_lc(vcpu, __LC_PGM_NEW_PSW, &psw, sizeof(psw_t));
if (rc)
return rc;
/* Avoid endless loops of specification exceptions */
if (!is_valid_psw(&psw))
return -EOPNOTSUPP;
}
rc = handle_itdb(vcpu);
if (rc)
return rc;
__extract_prog_irq(vcpu, &pgm_info);
return kvm_s390_inject_prog_irq(vcpu, &pgm_info);
}
/**
* handle_external_interrupt - used for external interruption interceptions
*
* This interception only occurs if the CPUSTAT_EXT_INT bit was set, or if
* the new PSW does not have external interrupts disabled. In the first case,
* we've got to deliver the interrupt manually, and in the second case, we
* drop to userspace to handle the situation there.
*/
static int handle_external_interrupt(struct kvm_vcpu *vcpu)
{
u16 eic = vcpu->arch.sie_block->eic;
struct kvm_s390_irq irq;
psw_t newpsw;
int rc;
vcpu->stat.exit_external_interrupt++;
rc = read_guest_lc(vcpu, __LC_EXT_NEW_PSW, &newpsw, sizeof(psw_t));
if (rc)
return rc;
/* We can not handle clock comparator or timer interrupt with bad PSW */
if ((eic == EXT_IRQ_CLK_COMP || eic == EXT_IRQ_CPU_TIMER) &&
(newpsw.mask & PSW_MASK_EXT))
return -EOPNOTSUPP;
switch (eic) {
case EXT_IRQ_CLK_COMP:
irq.type = KVM_S390_INT_CLOCK_COMP;
break;
case EXT_IRQ_CPU_TIMER:
irq.type = KVM_S390_INT_CPU_TIMER;
break;
case EXT_IRQ_EXTERNAL_CALL:
irq.type = KVM_S390_INT_EXTERNAL_CALL;
irq.u.extcall.code = vcpu->arch.sie_block->extcpuaddr;
rc = kvm_s390_inject_vcpu(vcpu, &irq);
/* ignore if another external call is already pending */
if (rc == -EBUSY)
return 0;
return rc;
default:
return -EOPNOTSUPP;
}
return kvm_s390_inject_vcpu(vcpu, &irq);
}
/**
* Handle MOVE PAGE partial execution interception.
*
* This interception can only happen for guests with DAT disabled and
* addresses that are currently not mapped in the host. Thus we try to
* set up the mappings for the corresponding user pages here (or throw
* addressing exceptions in case of illegal guest addresses).
*/
static int handle_mvpg_pei(struct kvm_vcpu *vcpu)
{
unsigned long srcaddr, dstaddr;
int reg1, reg2, rc;
kvm_s390_get_regs_rre(vcpu, &reg1, &reg2);
/* Make sure that the source is paged-in */
rc = guest_translate_address(vcpu, vcpu->run->s.regs.gprs[reg2],
reg2, &srcaddr, 0);
if (rc)
return kvm_s390_inject_prog_cond(vcpu, rc);
rc = kvm_arch_fault_in_page(vcpu, srcaddr, 0);
if (rc != 0)
return rc;
/* Make sure that the destination is paged-in */
rc = guest_translate_address(vcpu, vcpu->run->s.regs.gprs[reg1],
reg1, &dstaddr, 1);
if (rc)
return kvm_s390_inject_prog_cond(vcpu, rc);
rc = kvm_arch_fault_in_page(vcpu, dstaddr, 1);
if (rc != 0)
return rc;
kvm_s390_rewind_psw(vcpu, 4);
return 0;
}
static int handle_partial_execution(struct kvm_vcpu *vcpu)
{
if (vcpu->arch.sie_block->ipa == 0xb254) /* MVPG */
return handle_mvpg_pei(vcpu);
if (vcpu->arch.sie_block->ipa >> 8 == 0xae) /* SIGP */
return kvm_s390_handle_sigp_pei(vcpu);
return -EOPNOTSUPP;
}
int kvm_handle_sie_intercept(struct kvm_vcpu *vcpu)
{
switch (vcpu->arch.sie_block->icptcode) {
case 0x00:
case 0x10:
case 0x18:
return handle_noop(vcpu);
case 0x04:
return handle_instruction(vcpu);
case 0x08:
return handle_prog(vcpu);
case 0x14:
return handle_external_interrupt(vcpu);
case 0x1c:
return kvm_s390_handle_wait(vcpu);
case 0x20:
return handle_validity(vcpu);
case 0x28:
return handle_stop(vcpu);
case 0x38:
return handle_partial_execution(vcpu);
default:
return -EOPNOTSUPP;
}
}
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