linux/arch/s390/kvm/intercept.c
Christian Borntraeger 0eaeafa10f [S390] s390-kvm: leave sie context on work. Removes preemption requirement
From: Martin Schwidefsky <schwidefsky@de.ibm.com>

This patch fixes a bug with cpu bound guest on kvm-s390. Sometimes it
was impossible to deliver a signal to a spinning guest. We used
preemption as a circumvention. The preemption notifiers called
vcpu_load, which checked for pending signals and triggered a host
intercept. But even with preemption, a sigkill was not delivered
immediately.

This patch changes the low level host interrupt handler to check for the
SIE  instruction, if TIF_WORK is set. In that case we change the
instruction pointer of the return PSW to rerun the vcpu_run loop. The kvm
code sees an intercept reason 0 if that happens. This patch adds accounting
for these types of intercept as well.

The advantages:
- works with and without preemption
- signals are delivered immediately
- much better host latencies without preemption

Acked-by: Carsten Otte <cotte@de.ibm.com>
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2008-05-07 09:23:01 +02:00

220 lines
5.1 KiB
C

/*
* intercept.c - in-kernel handling for sie intercepts
*
* Copyright IBM Corp. 2008
*
* 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"
static int handle_lctg(struct kvm_vcpu *vcpu)
{
int reg1 = (vcpu->arch.sie_block->ipa & 0x00f0) >> 4;
int reg3 = vcpu->arch.sie_block->ipa & 0x000f;
int base2 = vcpu->arch.sie_block->ipb >> 28;
int disp2 = ((vcpu->arch.sie_block->ipb & 0x0fff0000) >> 16) +
((vcpu->arch.sie_block->ipb & 0xff00) << 4);
u64 useraddr;
int reg, rc;
vcpu->stat.instruction_lctg++;
if ((vcpu->arch.sie_block->ipb & 0xff) != 0x2f)
return -ENOTSUPP;
useraddr = disp2;
if (base2)
useraddr += vcpu->arch.guest_gprs[base2];
reg = reg1;
VCPU_EVENT(vcpu, 5, "lctg r1:%x, r3:%x,b2:%x,d2:%x", reg1, reg3, base2,
disp2);
do {
rc = get_guest_u64(vcpu, useraddr,
&vcpu->arch.sie_block->gcr[reg]);
if (rc == -EFAULT) {
kvm_s390_inject_program_int(vcpu, PGM_ADDRESSING);
break;
}
useraddr += 8;
if (reg == reg3)
break;
reg = (reg + 1) % 16;
} while (1);
return 0;
}
static int handle_lctl(struct kvm_vcpu *vcpu)
{
int reg1 = (vcpu->arch.sie_block->ipa & 0x00f0) >> 4;
int reg3 = vcpu->arch.sie_block->ipa & 0x000f;
int base2 = vcpu->arch.sie_block->ipb >> 28;
int disp2 = ((vcpu->arch.sie_block->ipb & 0x0fff0000) >> 16);
u64 useraddr;
u32 val = 0;
int reg, rc;
vcpu->stat.instruction_lctl++;
useraddr = disp2;
if (base2)
useraddr += vcpu->arch.guest_gprs[base2];
VCPU_EVENT(vcpu, 5, "lctl r1:%x, r3:%x,b2:%x,d2:%x", reg1, reg3, base2,
disp2);
reg = reg1;
do {
rc = get_guest_u32(vcpu, useraddr, &val);
if (rc == -EFAULT) {
kvm_s390_inject_program_int(vcpu, PGM_ADDRESSING);
break;
}
vcpu->arch.sie_block->gcr[reg] &= 0xffffffff00000000ul;
vcpu->arch.sie_block->gcr[reg] |= val;
useraddr += 4;
if (reg == reg3)
break;
reg = (reg + 1) % 16;
} while (1);
return 0;
}
static intercept_handler_t instruction_handlers[256] = {
[0x83] = kvm_s390_handle_diag,
[0xae] = kvm_s390_handle_sigp,
[0xb2] = kvm_s390_handle_priv,
[0xb7] = handle_lctl,
[0xeb] = handle_lctg,
};
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;
vcpu->stat.exit_stop_request++;
atomic_clear_mask(CPUSTAT_RUNNING, &vcpu->arch.sie_block->cpuflags);
spin_lock_bh(&vcpu->arch.local_int.lock);
if (vcpu->arch.local_int.action_bits & ACTION_STORE_ON_STOP) {
vcpu->arch.local_int.action_bits &= ~ACTION_STORE_ON_STOP;
rc = __kvm_s390_vcpu_store_status(vcpu,
KVM_S390_STORE_STATUS_NOADDR);
if (rc >= 0)
rc = -ENOTSUPP;
}
if (vcpu->arch.local_int.action_bits & ACTION_STOP_ON_STOP) {
vcpu->arch.local_int.action_bits &= ~ACTION_STOP_ON_STOP;
VCPU_EVENT(vcpu, 3, "%s", "cpu stopped");
rc = -ENOTSUPP;
} else
rc = 0;
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++;
if (viwhy == 0x37) {
fault_in_pages_writeable((char __user *)
vcpu->kvm->arch.guest_origin +
vcpu->arch.sie_block->prefix,
PAGE_SIZE);
return 0;
}
VCPU_EVENT(vcpu, 2, "unhandled validity intercept code %d",
viwhy);
return -ENOTSUPP;
}
static int handle_instruction(struct kvm_vcpu *vcpu)
{
intercept_handler_t handler;
vcpu->stat.exit_instruction++;
handler = instruction_handlers[vcpu->arch.sie_block->ipa >> 8];
if (handler)
return handler(vcpu);
return -ENOTSUPP;
}
static int handle_prog(struct kvm_vcpu *vcpu)
{
vcpu->stat.exit_program_interruption++;
return kvm_s390_inject_program_int(vcpu, vcpu->arch.sie_block->iprcc);
}
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 == -ENOTSUPP)
vcpu->arch.sie_block->icptcode = 0x04;
if (rc)
return rc;
return rc2;
}
static const intercept_handler_t intercept_funcs[0x48 >> 2] = {
[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,
[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 > 0x48)
return -ENOTSUPP;
func = intercept_funcs[code >> 2];
if (func)
return func(vcpu);
return -ENOTSUPP;
}