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![Marc Zyngier](/assets/img/avatar_default.png)
Admitedly, reading a MMIO register to load PC is very weird. Writing PC to a MMIO register is probably even worse. But the architecture doesn't forbid any of these, and injecting a Prefetch Abort is the wrong thing to do anyway. Remove this check altogether, and let the adventurous guest wander into LaLaLand if they feel compelled to do so. Reported-by: Catalin Marinas <catalin.marinas@arm.com> Acked-by: Catalin Marinas <catalin.marinas@arm.com> Signed-off-by: Marc Zyngier <marc.zyngier@arm.com> Signed-off-by: Christoffer Dall <cdall@cs.columbia.edu>
140 lines
3.6 KiB
C
140 lines
3.6 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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/**
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* kvm_handle_mmio_return -- Handle MMIO loads after user space emulation
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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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* This should only be called after returning from userspace for MMIO load
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* emulation.
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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 *dest;
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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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dest = vcpu_reg(vcpu, vcpu->arch.mmio_decode.rt);
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*dest = 0;
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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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memcpy(dest, run->mmio.data, len);
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trace_kvm_mmio(KVM_TRACE_MMIO_READ, len, run->mmio.phys_addr,
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*((u64 *)run->mmio.data));
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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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*dest = (*dest ^ mask) - mask;
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}
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}
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return 0;
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}
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static int decode_hsr(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa,
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struct kvm_exit_mmio *mmio)
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{
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unsigned long rt, len;
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bool is_write, sign_extend;
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if (kvm_vcpu_dabt_isextabt(vcpu)) {
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/* cache operation on I/O addr, tell guest unsupported */
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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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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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len = kvm_vcpu_dabt_get_as(vcpu);
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if (unlikely(len < 0))
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return len;
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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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mmio->is_write = is_write;
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mmio->phys_addr = fault_ipa;
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mmio->len = len;
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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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/*
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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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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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struct kvm_exit_mmio mmio;
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unsigned long rt;
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int ret;
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/*
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* Prepare MMIO operation. First stash it in a private
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* structure that we can use for in-kernel emulation. If the
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* kernel can't handle it, copy it into run->mmio and let user
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* 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, fault_ipa, &mmio);
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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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trace_kvm_mmio((mmio.is_write) ? KVM_TRACE_MMIO_WRITE :
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KVM_TRACE_MMIO_READ_UNSATISFIED,
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mmio.len, fault_ipa,
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(mmio.is_write) ? *vcpu_reg(vcpu, rt) : 0);
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if (mmio.is_write)
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memcpy(mmio.data, vcpu_reg(vcpu, rt), mmio.len);
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if (vgic_handle_mmio(vcpu, run, &mmio))
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return 1;
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kvm_prepare_mmio(run, &mmio);
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return 0;
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}
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