diff options
| author | Aaron Lewis <aaronlewis@google.com> | 2021-05-10 17:48:33 +0300 |
|---|---|---|
| committer | Paolo Bonzini <pbonzini@redhat.com> | 2021-06-25 01:00:48 +0300 |
| commit | 19238e75bd8ed8ffe784bf5b37586e77b2093742 (patch) | |
| tree | 13d0d58c59af12f70c7ae7b3f83a4c6a0e755a29 /arch/x86/kvm | |
| parent | 27de925044e18eb056d6157305c841b1408621b5 (diff) | |
| download | linux-19238e75bd8ed8ffe784bf5b37586e77b2093742.tar.xz | |
kvm: x86: Allow userspace to handle emulation errors
Add a fallback mechanism to the in-kernel instruction emulator that
allows userspace the opportunity to process an instruction the emulator
was unable to. When the in-kernel instruction emulator fails to process
an instruction it will either inject a #UD into the guest or exit to
userspace with exit reason KVM_INTERNAL_ERROR. This is because it does
not know how to proceed in an appropriate manner. This feature lets
userspace get involved to see if it can figure out a better path
forward.
Signed-off-by: Aaron Lewis <aaronlewis@google.com>
Reviewed-by: David Edmondson <david.edmondson@oracle.com>
Message-Id: <20210510144834.658457-2-aaronlewis@google.com>
Reviewed-by: Jim Mattson <jmattson@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'arch/x86/kvm')
| -rw-r--r-- | arch/x86/kvm/x86.c | 40 |
1 files changed, 36 insertions, 4 deletions
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index a7c7b2b28de7..17468d983fbd 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -4010,6 +4010,7 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext) #endif case KVM_CAP_VM_COPY_ENC_CONTEXT_FROM: case KVM_CAP_SREGS2: + case KVM_CAP_EXIT_ON_EMULATION_FAILURE: r = 1; break; case KVM_CAP_EXIT_HYPERCALL: @@ -5649,6 +5650,13 @@ split_irqchip_unlock: kvm->arch.hypercall_exit_enabled = cap->args[0]; r = 0; break; + case KVM_CAP_EXIT_ON_EMULATION_FAILURE: + r = -EINVAL; + if (cap->args[0] & ~1) + break; + kvm->arch.exit_on_emulation_error = cap->args[0]; + r = 0; + break; default: r = -EINVAL; break; @@ -7444,8 +7452,33 @@ void kvm_inject_realmode_interrupt(struct kvm_vcpu *vcpu, int irq, int inc_eip) } EXPORT_SYMBOL_GPL(kvm_inject_realmode_interrupt); +static void prepare_emulation_failure_exit(struct kvm_vcpu *vcpu) +{ + struct x86_emulate_ctxt *ctxt = vcpu->arch.emulate_ctxt; + u32 insn_size = ctxt->fetch.end - ctxt->fetch.data; + struct kvm_run *run = vcpu->run; + + run->exit_reason = KVM_EXIT_INTERNAL_ERROR; + run->emulation_failure.suberror = KVM_INTERNAL_ERROR_EMULATION; + run->emulation_failure.ndata = 0; + run->emulation_failure.flags = 0; + + if (insn_size) { + run->emulation_failure.ndata = 3; + run->emulation_failure.flags |= + KVM_INTERNAL_ERROR_EMULATION_FLAG_INSTRUCTION_BYTES; + run->emulation_failure.insn_size = insn_size; + memset(run->emulation_failure.insn_bytes, 0x90, + sizeof(run->emulation_failure.insn_bytes)); + memcpy(run->emulation_failure.insn_bytes, + ctxt->fetch.data, insn_size); + } +} + static int handle_emulation_failure(struct kvm_vcpu *vcpu, int emulation_type) { + struct kvm *kvm = vcpu->kvm; + ++vcpu->stat.insn_emulation_fail; trace_kvm_emulate_insn_failed(vcpu); @@ -7454,10 +7487,9 @@ static int handle_emulation_failure(struct kvm_vcpu *vcpu, int emulation_type) return 1; } - if (emulation_type & EMULTYPE_SKIP) { - vcpu->run->exit_reason = KVM_EXIT_INTERNAL_ERROR; - vcpu->run->internal.suberror = KVM_INTERNAL_ERROR_EMULATION; - vcpu->run->internal.ndata = 0; + if (kvm->arch.exit_on_emulation_error || + (emulation_type & EMULTYPE_SKIP)) { + prepare_emulation_failure_exit(vcpu); return 0; } |