diff options
| author |   Liran Alon <liran.alon@oracle.com> | 2018-03-12 13:12:49 +0200 |
|---|---|---|
| committer |   Paolo Bonzini <pbonzini@redhat.com> | 2018-03-16 22:01:41 +0100 |
| commit | e23661712005fd01ad9d2bca6eb4a122b79c8b0b (patch) | |
| tree | bee9a081152fbeb96251e903b2706ffbe164e8f5 /arch | |
| parent | KVM: x86: Always allow access to VMware backdoor I/O ports (diff) | |
| download | linux-dev-e23661712005fd01ad9d2bca6eb4a122b79c8b0b.tar.xz linux-dev-e23661712005fd01ad9d2bca6eb4a122b79c8b0b.zip | |
KVM: x86: Add emulation_type to not raise #UD on emulation failure
Next commits are going introduce support for accessing VMware backdoor
ports even though guest's TSS I/O permissions bitmap doesn't allow
access. This mimic VMware hypervisor behavior.
In order to support this, next commits will change VMX/SVM to
intercept #GP which was raised by such access and handle it by calling
the x86 emulator to emulate instruction. Since commit "KVM: x86:
Always allow access to VMware backdoor I/O ports", the x86 emulator
handles access to these I/O ports by not checking these ports against
the TSS I/O permission bitmap.
However, there could be cases that CPU rasies a #GP on instruction
that fails to be disassembled by the x86 emulator (Because of
incomplete implementation for example).
In those cases, we would like the #GP intercept to just forward #GP
as-is to guest as if there was no intercept to begin with.
However, current emulator code always queues #UD exception in case
emulator fails (including disassembly failures) which is not what is
wanted in this flow.
This commit addresses this issue by adding a new emulation_type flag
that will allow the #GP intercept handler to specify that it wishes
to be aware when instruction emulation fails and doesn't want #UD
exception to be queued.
Signed-off-by: Liran Alon <liran.alon@oracle.com>
Reviewed-by: Nikita Leshenko <nikita.leshchenko@oracle.com>
Reviewed-by: Radim Krčmář <rkrcmar@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'arch')
| -rw-r--r-- | arch/x86/include/asm/kvm_host.h | 1 | ||||
| -rw-r--r-- | arch/x86/kvm/x86.c | 11 |
2 files changed, 9 insertions, 3 deletions
diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h index dc0ae1bbec96..41f32268a9a2 100644 --- a/arch/x86/include/asm/kvm_host.h +++ b/arch/x86/include/asm/kvm_host.h @@ -1193,6 +1193,7 @@ enum emulation_result { #define EMULTYPE_SKIP (1 << 2) #define EMULTYPE_RETRY (1 << 3) #define EMULTYPE_NO_REEXECUTE (1 << 4) +#define EMULTYPE_NO_UD_ON_FAIL (1 << 5) int x86_emulate_instruction(struct kvm_vcpu *vcpu, unsigned long cr2, int emulation_type, void *insn, int insn_len); diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 172f703552ca..df849da5be9c 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -5670,18 +5670,23 @@ int kvm_inject_realmode_interrupt(struct kvm_vcpu *vcpu, int irq, int inc_eip) } EXPORT_SYMBOL_GPL(kvm_inject_realmode_interrupt); -static int handle_emulation_failure(struct kvm_vcpu *vcpu) +static int handle_emulation_failure(struct kvm_vcpu *vcpu, int emulation_type) { int r = EMULATE_DONE; ++vcpu->stat.insn_emulation_fail; trace_kvm_emulate_insn_failed(vcpu); + + if (emulation_type & EMULTYPE_NO_UD_ON_FAIL) + return EMULATE_FAIL; + if (!is_guest_mode(vcpu) && kvm_x86_ops->get_cpl(vcpu) == 0) { vcpu->run->exit_reason = KVM_EXIT_INTERNAL_ERROR; vcpu->run->internal.suberror = KVM_INTERNAL_ERROR_EMULATION; vcpu->run->internal.ndata = 0; r = EMULATE_USER_EXIT; } + kvm_queue_exception(vcpu, UD_VECTOR); return r; @@ -5977,7 +5982,7 @@ int x86_emulate_instruction(struct kvm_vcpu *vcpu, return EMULATE_DONE; if (emulation_type & EMULTYPE_SKIP) return EMULATE_FAIL; - return handle_emulation_failure(vcpu); + return handle_emulation_failure(vcpu, emulation_type); } } @@ -6012,7 +6017,7 @@ restart: emulation_type)) return EMULATE_DONE; - return handle_emulation_failure(vcpu); + return handle_emulation_failure(vcpu, emulation_type); } if (ctxt->have_exception) { |