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https://github.com/AuxXxilium/linux_dsm_epyc7002.git
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0d640732db
When we emulate an MMIO instruction, we advance the CPU state within decode_hsr(), before emulating the instruction effects. Having this logic in decode_hsr() is opaque, and advancing the state before emulation is problematic. It gets in the way of applying consistent single-step logic, and it prevents us from being able to fail an MMIO instruction with a synchronous exception. Clean this up by only advancing the CPU state *after* the effects of the instruction are emulated. Cc: Peter Maydell <peter.maydell@linaro.org> Reviewed-by: Alex Bennée <alex.bennee@linaro.org> Reviewed-by: Christoffer Dall <christoffer.dall@arm.com> Signed-off-by: Mark Rutland <mark.rutland@arm.com> Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
219 lines
4.9 KiB
C
219 lines
4.9 KiB
C
/*
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* Copyright (C) 2012 - Virtual Open Systems and Columbia University
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* Author: Christoffer Dall <c.dall@virtualopensystems.com>
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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, as
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* published by the Free Software Foundation.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
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*/
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#include <linux/kvm_host.h>
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#include <asm/kvm_mmio.h>
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#include <asm/kvm_emulate.h>
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#include <trace/events/kvm.h>
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#include "trace.h"
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void kvm_mmio_write_buf(void *buf, unsigned int len, unsigned long data)
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{
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void *datap = NULL;
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union {
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u8 byte;
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u16 hword;
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u32 word;
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u64 dword;
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} tmp;
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switch (len) {
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case 1:
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tmp.byte = data;
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datap = &tmp.byte;
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break;
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case 2:
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tmp.hword = data;
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datap = &tmp.hword;
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break;
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case 4:
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tmp.word = data;
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datap = &tmp.word;
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break;
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case 8:
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tmp.dword = data;
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datap = &tmp.dword;
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break;
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}
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memcpy(buf, datap, len);
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}
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unsigned long kvm_mmio_read_buf(const void *buf, unsigned int len)
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{
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unsigned long data = 0;
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union {
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u16 hword;
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u32 word;
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u64 dword;
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} tmp;
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switch (len) {
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case 1:
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data = *(u8 *)buf;
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break;
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case 2:
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memcpy(&tmp.hword, buf, len);
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data = tmp.hword;
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break;
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case 4:
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memcpy(&tmp.word, buf, len);
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data = tmp.word;
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break;
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case 8:
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memcpy(&tmp.dword, buf, len);
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data = tmp.dword;
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break;
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}
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return data;
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}
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/**
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* kvm_handle_mmio_return -- Handle MMIO loads after user space emulation
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* or in-kernel IO emulation
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*
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* @vcpu: The VCPU pointer
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* @run: The VCPU run struct containing the mmio data
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*/
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int kvm_handle_mmio_return(struct kvm_vcpu *vcpu, struct kvm_run *run)
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{
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unsigned long data;
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unsigned int len;
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int mask;
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if (!run->mmio.is_write) {
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len = run->mmio.len;
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if (len > sizeof(unsigned long))
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return -EINVAL;
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data = kvm_mmio_read_buf(run->mmio.data, len);
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if (vcpu->arch.mmio_decode.sign_extend &&
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len < sizeof(unsigned long)) {
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mask = 1U << ((len * 8) - 1);
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data = (data ^ mask) - mask;
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}
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trace_kvm_mmio(KVM_TRACE_MMIO_READ, len, run->mmio.phys_addr,
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&data);
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data = vcpu_data_host_to_guest(vcpu, data, len);
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vcpu_set_reg(vcpu, vcpu->arch.mmio_decode.rt, data);
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}
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/*
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* The MMIO instruction is emulated and should not be re-executed
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* in the guest.
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*/
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kvm_skip_instr(vcpu, kvm_vcpu_trap_il_is32bit(vcpu));
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return 0;
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}
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static int decode_hsr(struct kvm_vcpu *vcpu, bool *is_write, int *len)
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{
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unsigned long rt;
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int access_size;
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bool sign_extend;
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if (kvm_vcpu_dabt_iss1tw(vcpu)) {
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/* page table accesses IO mem: tell guest to fix its TTBR */
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kvm_inject_dabt(vcpu, kvm_vcpu_get_hfar(vcpu));
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return 1;
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}
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access_size = kvm_vcpu_dabt_get_as(vcpu);
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if (unlikely(access_size < 0))
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return access_size;
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*is_write = kvm_vcpu_dabt_iswrite(vcpu);
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sign_extend = kvm_vcpu_dabt_issext(vcpu);
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rt = kvm_vcpu_dabt_get_rd(vcpu);
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*len = access_size;
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vcpu->arch.mmio_decode.sign_extend = sign_extend;
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vcpu->arch.mmio_decode.rt = rt;
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return 0;
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}
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int io_mem_abort(struct kvm_vcpu *vcpu, struct kvm_run *run,
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phys_addr_t fault_ipa)
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{
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unsigned long data;
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unsigned long rt;
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int ret;
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bool is_write;
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int len;
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u8 data_buf[8];
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/*
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* Prepare MMIO operation. First decode the syndrome data we get
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* from the CPU. Then try if some in-kernel emulation feels
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* responsible, otherwise let user space do its magic.
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*/
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if (kvm_vcpu_dabt_isvalid(vcpu)) {
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ret = decode_hsr(vcpu, &is_write, &len);
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if (ret)
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return ret;
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} else {
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kvm_err("load/store instruction decoding not implemented\n");
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return -ENOSYS;
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}
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rt = vcpu->arch.mmio_decode.rt;
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if (is_write) {
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data = vcpu_data_guest_to_host(vcpu, vcpu_get_reg(vcpu, rt),
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len);
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trace_kvm_mmio(KVM_TRACE_MMIO_WRITE, len, fault_ipa, &data);
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kvm_mmio_write_buf(data_buf, len, data);
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ret = kvm_io_bus_write(vcpu, KVM_MMIO_BUS, fault_ipa, len,
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data_buf);
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} else {
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trace_kvm_mmio(KVM_TRACE_MMIO_READ_UNSATISFIED, len,
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fault_ipa, NULL);
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ret = kvm_io_bus_read(vcpu, KVM_MMIO_BUS, fault_ipa, len,
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data_buf);
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}
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/* Now prepare kvm_run for the potential return to userland. */
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run->mmio.is_write = is_write;
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run->mmio.phys_addr = fault_ipa;
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run->mmio.len = len;
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if (!ret) {
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/* We handled the access successfully in the kernel. */
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if (!is_write)
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memcpy(run->mmio.data, data_buf, len);
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vcpu->stat.mmio_exit_kernel++;
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kvm_handle_mmio_return(vcpu, run);
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return 1;
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}
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if (is_write)
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memcpy(run->mmio.data, data_buf, len);
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vcpu->stat.mmio_exit_user++;
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run->exit_reason = KVM_EXIT_MMIO;
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return 0;
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}
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