diff options
| author | Liran Alon <liran.alon@oracle.com> | 2018-03-12 13:12:51 +0200 |
|---|---|---|
| committer | Paolo Bonzini <pbonzini@redhat.com> | 2018-03-16 22:01:42 +0100 |
| commit | 9e86948041f2ec6b7868d4849181cb7bb1bdee70 (patch) | |
| tree | 45ed6947b868187d8988e695a0d3a68b61b5914d /arch/x86/kvm | |
| parent | 04789b6664a60474aeb8b07a9a94d923a217690e (diff) | |
KVM: x86: VMX: Intercept #GP to support access to VMware backdoor ports
If KVM enable_vmware_backdoor module parameter is set,
the commit change VMX to now intercept #GP instead of being directly
deliviered from CPU to guest.
It is done to support access to VMware backdoor I/O ports
even if TSS I/O permission denies it.
In that case:
1. A #GP will be raised and intercepted.
2. #GP intercept handler will simulate I/O port access instruction.
3. I/O port access instruction simulation will allow access to VMware
backdoor ports specifically even if TSS I/O permission bitmap denies it.
Note that the above change introduce slight performance hit as now #GPs
are not deliviered directly from CPU to guest but instead
cause #VMExit and instruction emulation.
However, this behavior is introduced only when enable_vmware_backdoor
KVM module parameter is set.
Signed-off-by: Liran Alon <liran.alon@oracle.com>
Reviewed-by: Nikita Leshenko <nikita.leshchenko@oracle.com>
Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Reviewed-by: Radim Krčmář <rkrcmar@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'arch/x86/kvm')
| -rw-r--r-- | arch/x86/kvm/vmx.c | 24 |
1 files changed, 24 insertions, 0 deletions
diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c index cd71b154b7bd..b4d8da6c62c8 100644 --- a/arch/x86/kvm/vmx.c +++ b/arch/x86/kvm/vmx.c @@ -1039,6 +1039,11 @@ static inline bool is_invalid_opcode(u32 intr_info) return is_exception_n(intr_info, UD_VECTOR); } +static inline bool is_gp_fault(u32 intr_info) +{ + return is_exception_n(intr_info, GP_VECTOR); +} + static inline bool is_external_interrupt(u32 intr_info) { return (intr_info & (INTR_INFO_INTR_TYPE_MASK | INTR_INFO_VALID_MASK)) @@ -1875,6 +1880,14 @@ static void update_exception_bitmap(struct kvm_vcpu *vcpu) eb = (1u << PF_VECTOR) | (1u << UD_VECTOR) | (1u << MC_VECTOR) | (1u << DB_VECTOR) | (1u << AC_VECTOR); + /* + * Guest access to VMware backdoor ports could legitimately + * trigger #GP because of TSS I/O permission bitmap. + * We intercept those #GP and allow access to them anyway + * as VMware does. + */ + if (enable_vmware_backdoor) + eb |= (1u << GP_VECTOR); if ((vcpu->guest_debug & (KVM_GUESTDBG_ENABLE | KVM_GUESTDBG_USE_SW_BP)) == (KVM_GUESTDBG_ENABLE | KVM_GUESTDBG_USE_SW_BP)) @@ -6180,6 +6193,17 @@ static int handle_exception(struct kvm_vcpu *vcpu) if (intr_info & INTR_INFO_DELIVER_CODE_MASK) error_code = vmcs_read32(VM_EXIT_INTR_ERROR_CODE); + if (!vmx->rmode.vm86_active && is_gp_fault(intr_info)) { + WARN_ON_ONCE(!enable_vmware_backdoor); + er = emulate_instruction(vcpu, + EMULTYPE_VMWARE | EMULTYPE_NO_UD_ON_FAIL); + if (er == EMULATE_USER_EXIT) + return 0; + else if (er != EMULATE_DONE) + kvm_queue_exception_e(vcpu, GP_VECTOR, error_code); + return 1; + } + /* * The #PF with PFEC.RSVD = 1 indicates the guest is accessing * MMIO, it is better to report an internal error. |