linux/arch/arm64/kvm/mmio.c
Marc Zyngier 06394531b4 KVM: arm64: Generalise VM features into a set of flags
We currently deal with a set of booleans for VM features,
while they could be better represented as set of flags
contained in an unsigned long, similarily to what we are
doing on the CPU side.

Signed-off-by: Marc Zyngier <maz@kernel.org>
[Oliver: Flag-ify the 'ran_once' boolean]
Signed-off-by: Oliver Upton <oupton@google.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20220311174001.605719-2-oupton@google.com
2022-03-18 14:02:33 +00:00

197 lines
4.1 KiB
C

// 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 0;
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 0;
}
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.
*/
if (!kvm_vcpu_dabt_isvalid(vcpu)) {
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;
}
kvm_pr_unimpl("Data abort outside memslots with no valid syndrome info\n");
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;
}