diff options
Diffstat (limited to 'arch/arm64/kvm/mmio.c')
| -rw-r--r-- | arch/arm64/kvm/mmio.c | 196 |
1 files changed, 196 insertions, 0 deletions
diff --git a/arch/arm64/kvm/mmio.c b/arch/arm64/kvm/mmio.c new file mode 100644 index 000000000..3dd38a151 --- /dev/null +++ b/arch/arm64/kvm/mmio.c @@ -0,0 +1,196 @@ +// 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; +} |