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// SPDX-License-Identifier: GPL-2.0-only
/*
* Copyright (C) 2012 - Virtual Open Systems and Columbia University
* Author: Christoffer Dall <c.dall@virtualopensystems.com>
*/
#include <linux/kvm_host.h>
#include <asm/kvm_mmio.h>
#include <asm/kvm_emulate.h>
#include <trace/events/kvm.h>
#include "trace.h"
void kvm_mmio_write_buf(void *buf, unsigned int len, unsigned long data)
{
void *datap = NULL;
union {
u8 byte;
u16 hword;
u32 word;
u64 dword;
} tmp;
switch (len) {
case 1:
tmp.byte = data;
datap = &tmp.byte;
break;
case 2:
tmp.hword = data;
datap = &tmp.hword;
break;
case 4:
tmp.word = data;
datap = &tmp.word;
break;
case 8:
tmp.dword = data;
datap = &tmp.dword;
break;
}
memcpy(buf, datap, len);
}
unsigned long kvm_mmio_read_buf(const void *buf, unsigned int len)
{
unsigned long data = 0;
union {
u16 hword;
u32 word;
u64 dword;
} tmp;
switch (len) {
case 1:
data = *(u8 *)buf;
break;
case 2:
memcpy(&tmp.hword, buf, len);
data = tmp.hword;
break;
case 4:
memcpy(&tmp.word, buf, len);
data = tmp.word;
break;
case 8:
memcpy(&tmp.dword, buf, len);
data = tmp.dword;
break;
}
return data;
}
/**
* kvm_handle_mmio_return -- Handle MMIO loads after user space emulation
* or in-kernel IO emulation
*
* @vcpu: The VCPU pointer
* @run: The VCPU run struct containing the mmio data
*/
int kvm_handle_mmio_return(struct kvm_vcpu *vcpu, struct kvm_run *run)
{
unsigned long data;
unsigned int len;
int mask;
/* Detect an already handled MMIO return */
if (unlikely(!vcpu->mmio_needed))
return 0;
vcpu->mmio_needed = 0;
if (!run->mmio.is_write) {
len = run->mmio.len;
if (len > sizeof(unsigned long))
return -EINVAL;
data = kvm_mmio_read_buf(run->mmio.data, len);
if (vcpu->arch.mmio_decode.sign_extend &&
len < sizeof(unsigned long)) {
mask = 1U << ((len * 8) - 1);
data = (data ^ mask) - mask;
}
trace_kvm_mmio(KVM_TRACE_MMIO_READ, len, run->mmio.phys_addr,
&data);
data = vcpu_data_host_to_guest(vcpu, data, len);
vcpu_set_reg(vcpu, vcpu->arch.mmio_decode.rt, data);
}
/*
* The MMIO instruction is emulated and should not be re-executed
* in the guest.
*/
kvm_skip_instr(vcpu, kvm_vcpu_trap_il_is32bit(vcpu));
return 0;
}
static int decode_hsr(struct kvm_vcpu *vcpu, bool *is_write, int *len)
{
unsigned long rt;
int access_size;
bool sign_extend;
if (kvm_vcpu_dabt_iss1tw(vcpu)) {
/* page table accesses IO mem: tell guest to fix its TTBR */
kvm_inject_dabt(vcpu, kvm_vcpu_get_hfar(vcpu));
return 1;
}
access_size = kvm_vcpu_dabt_get_as(vcpu);
if (unlikely(access_size < 0))
return access_size;
*is_write = kvm_vcpu_dabt_iswrite(vcpu);
sign_extend = kvm_vcpu_dabt_issext(vcpu);
rt = kvm_vcpu_dabt_get_rd(vcpu);
*len = access_size;
vcpu->arch.mmio_decode.sign_extend = sign_extend;
vcpu->arch.mmio_decode.rt = rt;
return 0;
}
int io_mem_abort(struct kvm_vcpu *vcpu, struct kvm_run *run,
phys_addr_t fault_ipa)
{
unsigned long data;
unsigned long rt;
int ret;
bool is_write;
int len;
u8 data_buf[8];
/*
* Prepare MMIO operation. First decode the syndrome data we get
* from the CPU. Then try if some in-kernel emulation feels
* responsible, otherwise let user space do its magic.
*/
if (kvm_vcpu_dabt_isvalid(vcpu)) {
ret = decode_hsr(vcpu, &is_write, &len);
if (ret)
return ret;
} else {
kvm_err("load/store instruction decoding not implemented\n");
return -ENOSYS;
}
rt = vcpu->arch.mmio_decode.rt;
if (is_write) {
data = vcpu_data_guest_to_host(vcpu, vcpu_get_reg(vcpu, rt),
len);
trace_kvm_mmio(KVM_TRACE_MMIO_WRITE, len, fault_ipa, &data);
kvm_mmio_write_buf(data_buf, len, data);
ret = kvm_io_bus_write(vcpu, KVM_MMIO_BUS, fault_ipa, len,
data_buf);
} else {
trace_kvm_mmio(KVM_TRACE_MMIO_READ_UNSATISFIED, len,
fault_ipa, NULL);
ret = kvm_io_bus_read(vcpu, KVM_MMIO_BUS, fault_ipa, len,
data_buf);
}
/* Now prepare kvm_run for the potential return to userland. */
run->mmio.is_write = is_write;
run->mmio.phys_addr = fault_ipa;
run->mmio.len = len;
vcpu->mmio_needed = 1;
if (!ret) {
/* We handled the access successfully in the kernel. */
if (!is_write)
memcpy(run->mmio.data, data_buf, len);
vcpu->stat.mmio_exit_kernel++;
kvm_handle_mmio_return(vcpu, run);
return 1;
}
if (is_write)
memcpy(run->mmio.data, data_buf, len);
vcpu->stat.mmio_exit_user++;
run->exit_reason = KVM_EXIT_MMIO;
return 0;
}
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