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android_kernel_samsung_msm8976/arch/s390/kvm/intercept.c
Heiko Carstens dc5008b9bf s390/kvm: remove explicit -EFAULT return code checking on guest access 
Let's change to the paradigm that every return code from guest memory
access functions that is not zero translates to -EFAULT and do not
explictly compare.
Explictly comparing the return value with -EFAULT has already shown to
be a bit fragile. In addition this is closer to the handling of
copy_to/from_user functions, which imho is in general a good idea.

Also shorten the return code handling in interrupt.c a bit.

Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Acked-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
2013-03-07 16:21:21 -03:00

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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 int handle_lctlg(struct kvm_vcpu *vcpu)
{
int reg1 = (vcpu->arch.sie_block->ipa & 0x00f0) >> 4;
int reg3 = vcpu->arch.sie_block->ipa & 0x000f;
u64 useraddr;
int reg, rc;
vcpu->stat.instruction_lctlg++;
useraddr = kvm_s390_get_base_disp_rsy(vcpu);
if (useraddr & 7)
return kvm_s390_inject_program_int(vcpu, PGM_SPECIFICATION);
reg = reg1;
VCPU_EVENT(vcpu, 5, "lctlg r1:%x, r3:%x, addr:%llx", reg1, reg3,
useraddr);
trace_kvm_s390_handle_lctl(vcpu, 1, reg1, reg3, useraddr);
do {
rc = get_guest_u64(vcpu, useraddr,
&vcpu->arch.sie_block->gcr[reg]);
if (rc) {
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;
u64 useraddr;
u32 val = 0;
int reg, rc;
vcpu->stat.instruction_lctl++;
useraddr = kvm_s390_get_base_disp_rs(vcpu);
if (useraddr & 3)
return kvm_s390_inject_program_int(vcpu, PGM_SPECIFICATION);
VCPU_EVENT(vcpu, 5, "lctl r1:%x, r3:%x, addr:%llx", reg1, reg3,
useraddr);
trace_kvm_s390_handle_lctl(vcpu, 0, reg1, reg3, useraddr);
reg = reg1;
do {
rc = get_guest_u32(vcpu, useraddr, &val);
if (rc) {
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 const intercept_handler_t eb_handlers[256] = {
[0x2f] = handle_lctlg,
[0x8a] = kvm_s390_handle_priv_eb,
};
static int handle_eb(struct kvm_vcpu *vcpu)
{
intercept_handler_t handler;
handler = eb_handlers[vcpu->arch.sie_block->ipb & 0xff];
if (handler)
return handler(vcpu);
return -EOPNOTSUPP;
}
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,
[0xb7] = handle_lctl,
[0xb9] = kvm_s390_handle_b9,
[0xe5] = kvm_s390_handle_e5,
[0xeb] = 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_RELOADVCPU_ON_STOP) {
vcpu->arch.local_int.action_bits &= ~ACTION_RELOADVCPU_ON_STOP;
rc = SIE_INTERCEPT_RERUNVCPU;
vcpu->run->exit_reason = KVM_EXIT_INTR;
}
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)
{
unsigned long vmaddr;
int viwhy = vcpu->arch.sie_block->ipb >> 16;
int rc;
vcpu->stat.exit_validity++;
trace_kvm_s390_intercept_validity(vcpu, viwhy);
if (viwhy == 0x37) {
vmaddr = gmap_fault(vcpu->arch.sie_block->prefix,
vcpu->arch.gmap);
if (IS_ERR_VALUE(vmaddr)) {
rc = -EOPNOTSUPP;
goto out;
}
rc = fault_in_pages_writeable((char __user *) vmaddr,
PAGE_SIZE);
if (rc) {
/* user will receive sigsegv, exit to user */
rc = -EOPNOTSUPP;
goto out;
}
vmaddr = gmap_fault(vcpu->arch.sie_block->prefix + PAGE_SIZE,
vcpu->arch.gmap);
if (IS_ERR_VALUE(vmaddr)) {
rc = -EOPNOTSUPP;
goto out;
}
rc = fault_in_pages_writeable((char __user *) vmaddr,
PAGE_SIZE);
if (rc) {
/* user will receive sigsegv, exit to user */
rc = -EOPNOTSUPP;
goto out;
}
} else
rc = -EOPNOTSUPP;
out:
if (rc)
VCPU_EVENT(vcpu, 2, "unhandled validity intercept code %d",
viwhy);
return rc;
}
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 int handle_prog(struct kvm_vcpu *vcpu)
{
vcpu->stat.exit_program_interruption++;
trace_kvm_s390_intercept_prog(vcpu, vcpu->arch.sie_block->iprcc);
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 == -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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