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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_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
*/
int kvm_handle_mmio_return(struct kvm_vcpu *vcpu)
{
unsigned long data;
unsigned int len;
int mask;
/* Detect an already handled MMIO return */
if (unlikely(!vcpu->mmio_needed))
return 1;
vcpu->mmio_needed = 0;
if (!kvm_vcpu_dabt_iswrite(vcpu)) {
struct kvm_run *run = vcpu->run;
len = kvm_vcpu_dabt_get_as(vcpu);
data = kvm_mmio_read_buf(run->mmio.data, len);
if (kvm_vcpu_dabt_issext(vcpu) &&
len < sizeof(unsigned long)) {
mask = 1U << ((len * 8) - 1);
data = (data ^ mask) - mask;
}
if (!kvm_vcpu_dabt_issf(vcpu))
data = data & 0xffffffff;
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, kvm_vcpu_dabt_get_rd(vcpu), data);
}
/*
* The MMIO instruction is emulated and should not be re-executed
* in the guest.
*/
kvm_incr_pc(vcpu);
return 1;
}
int io_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa)
{
struct kvm_run *run = vcpu->run;
unsigned long data;
unsigned long rt;
int ret;
bool is_write;
int len;
u8 data_buf[8];
/*
* No valid syndrome? Ask userspace for help if it has
* volunteered to do so, and bail out otherwise.
*
* In the protected VM case, there isn't much userspace can do
* though, so directly deliver an exception to the guest.
*/
if (!kvm_vcpu_dabt_isvalid(vcpu)) {
trace_kvm_mmio_nisv(*vcpu_pc(vcpu), kvm_vcpu_get_esr(vcpu),
kvm_vcpu_get_hfar(vcpu), fault_ipa);
if (vcpu_is_protected(vcpu)) {
kvm_inject_dabt(vcpu, kvm_vcpu_get_hfar(vcpu));
return 1;
}
if (test_bit(KVM_ARCH_FLAG_RETURN_NISV_IO_ABORT_TO_USER,
&vcpu->kvm->arch.flags)) {
run->exit_reason = KVM_EXIT_ARM_NISV;
run->arm_nisv.esr_iss = kvm_vcpu_dabt_iss_nisv_sanitized(vcpu);
run->arm_nisv.fault_ipa = fault_ipa;
return 0;
}
return -ENOSYS;
}
/*
* 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.
*/
is_write = kvm_vcpu_dabt_iswrite(vcpu);
len = kvm_vcpu_dabt_get_as(vcpu);
rt = kvm_vcpu_dabt_get_rd(vcpu);
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);
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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