forked from Minki/linux
0eaeafa10f
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>
220 lines
5.1 KiB
C
220 lines
5.1 KiB
C
/*
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* intercept.c - in-kernel handling for sie intercepts
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*
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* Copyright IBM Corp. 2008
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License (version 2 only)
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* as published by the Free Software Foundation.
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*
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* Author(s): Carsten Otte <cotte@de.ibm.com>
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* Christian Borntraeger <borntraeger@de.ibm.com>
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*/
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#include <linux/kvm_host.h>
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#include <linux/errno.h>
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#include <linux/pagemap.h>
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#include <asm/kvm_host.h>
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#include "kvm-s390.h"
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#include "gaccess.h"
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static int handle_lctg(struct kvm_vcpu *vcpu)
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{
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int reg1 = (vcpu->arch.sie_block->ipa & 0x00f0) >> 4;
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int reg3 = vcpu->arch.sie_block->ipa & 0x000f;
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int base2 = vcpu->arch.sie_block->ipb >> 28;
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int disp2 = ((vcpu->arch.sie_block->ipb & 0x0fff0000) >> 16) +
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((vcpu->arch.sie_block->ipb & 0xff00) << 4);
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u64 useraddr;
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int reg, rc;
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vcpu->stat.instruction_lctg++;
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if ((vcpu->arch.sie_block->ipb & 0xff) != 0x2f)
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return -ENOTSUPP;
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useraddr = disp2;
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if (base2)
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useraddr += vcpu->arch.guest_gprs[base2];
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reg = reg1;
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VCPU_EVENT(vcpu, 5, "lctg r1:%x, r3:%x,b2:%x,d2:%x", reg1, reg3, base2,
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disp2);
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do {
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rc = get_guest_u64(vcpu, useraddr,
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&vcpu->arch.sie_block->gcr[reg]);
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if (rc == -EFAULT) {
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kvm_s390_inject_program_int(vcpu, PGM_ADDRESSING);
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break;
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}
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useraddr += 8;
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if (reg == reg3)
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break;
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reg = (reg + 1) % 16;
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} while (1);
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return 0;
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}
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static int handle_lctl(struct kvm_vcpu *vcpu)
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{
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int reg1 = (vcpu->arch.sie_block->ipa & 0x00f0) >> 4;
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int reg3 = vcpu->arch.sie_block->ipa & 0x000f;
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int base2 = vcpu->arch.sie_block->ipb >> 28;
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int disp2 = ((vcpu->arch.sie_block->ipb & 0x0fff0000) >> 16);
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u64 useraddr;
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u32 val = 0;
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int reg, rc;
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vcpu->stat.instruction_lctl++;
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useraddr = disp2;
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if (base2)
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useraddr += vcpu->arch.guest_gprs[base2];
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VCPU_EVENT(vcpu, 5, "lctl r1:%x, r3:%x,b2:%x,d2:%x", reg1, reg3, base2,
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disp2);
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reg = reg1;
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do {
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rc = get_guest_u32(vcpu, useraddr, &val);
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if (rc == -EFAULT) {
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kvm_s390_inject_program_int(vcpu, PGM_ADDRESSING);
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break;
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}
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vcpu->arch.sie_block->gcr[reg] &= 0xffffffff00000000ul;
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vcpu->arch.sie_block->gcr[reg] |= val;
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useraddr += 4;
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if (reg == reg3)
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break;
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reg = (reg + 1) % 16;
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} while (1);
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return 0;
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}
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static intercept_handler_t instruction_handlers[256] = {
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[0x83] = kvm_s390_handle_diag,
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[0xae] = kvm_s390_handle_sigp,
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[0xb2] = kvm_s390_handle_priv,
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[0xb7] = handle_lctl,
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[0xeb] = handle_lctg,
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};
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static int handle_noop(struct kvm_vcpu *vcpu)
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{
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switch (vcpu->arch.sie_block->icptcode) {
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case 0x0:
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vcpu->stat.exit_null++;
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break;
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case 0x10:
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vcpu->stat.exit_external_request++;
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break;
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case 0x14:
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vcpu->stat.exit_external_interrupt++;
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break;
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default:
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break; /* nothing */
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}
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return 0;
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}
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static int handle_stop(struct kvm_vcpu *vcpu)
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{
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int rc;
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vcpu->stat.exit_stop_request++;
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atomic_clear_mask(CPUSTAT_RUNNING, &vcpu->arch.sie_block->cpuflags);
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spin_lock_bh(&vcpu->arch.local_int.lock);
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if (vcpu->arch.local_int.action_bits & ACTION_STORE_ON_STOP) {
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vcpu->arch.local_int.action_bits &= ~ACTION_STORE_ON_STOP;
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rc = __kvm_s390_vcpu_store_status(vcpu,
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KVM_S390_STORE_STATUS_NOADDR);
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if (rc >= 0)
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rc = -ENOTSUPP;
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}
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if (vcpu->arch.local_int.action_bits & ACTION_STOP_ON_STOP) {
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vcpu->arch.local_int.action_bits &= ~ACTION_STOP_ON_STOP;
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VCPU_EVENT(vcpu, 3, "%s", "cpu stopped");
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rc = -ENOTSUPP;
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} else
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rc = 0;
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spin_unlock_bh(&vcpu->arch.local_int.lock);
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return rc;
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}
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static int handle_validity(struct kvm_vcpu *vcpu)
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{
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int viwhy = vcpu->arch.sie_block->ipb >> 16;
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vcpu->stat.exit_validity++;
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if (viwhy == 0x37) {
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fault_in_pages_writeable((char __user *)
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vcpu->kvm->arch.guest_origin +
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vcpu->arch.sie_block->prefix,
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PAGE_SIZE);
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return 0;
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}
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VCPU_EVENT(vcpu, 2, "unhandled validity intercept code %d",
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viwhy);
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return -ENOTSUPP;
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}
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static int handle_instruction(struct kvm_vcpu *vcpu)
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{
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intercept_handler_t handler;
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vcpu->stat.exit_instruction++;
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handler = instruction_handlers[vcpu->arch.sie_block->ipa >> 8];
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if (handler)
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return handler(vcpu);
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return -ENOTSUPP;
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}
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static int handle_prog(struct kvm_vcpu *vcpu)
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{
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vcpu->stat.exit_program_interruption++;
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return kvm_s390_inject_program_int(vcpu, vcpu->arch.sie_block->iprcc);
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}
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static int handle_instruction_and_prog(struct kvm_vcpu *vcpu)
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{
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int rc, rc2;
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vcpu->stat.exit_instr_and_program++;
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rc = handle_instruction(vcpu);
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rc2 = handle_prog(vcpu);
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if (rc == -ENOTSUPP)
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vcpu->arch.sie_block->icptcode = 0x04;
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if (rc)
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return rc;
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return rc2;
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}
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static const intercept_handler_t intercept_funcs[0x48 >> 2] = {
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[0x00 >> 2] = handle_noop,
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[0x04 >> 2] = handle_instruction,
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[0x08 >> 2] = handle_prog,
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[0x0C >> 2] = handle_instruction_and_prog,
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[0x10 >> 2] = handle_noop,
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[0x14 >> 2] = handle_noop,
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[0x1C >> 2] = kvm_s390_handle_wait,
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[0x20 >> 2] = handle_validity,
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[0x28 >> 2] = handle_stop,
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};
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int kvm_handle_sie_intercept(struct kvm_vcpu *vcpu)
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{
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intercept_handler_t func;
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u8 code = vcpu->arch.sie_block->icptcode;
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if (code & 3 || code > 0x48)
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return -ENOTSUPP;
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func = intercept_funcs[code >> 2];
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if (func)
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return func(vcpu);
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return -ENOTSUPP;
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}
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