We intercept #BP while in guest debugging mode. As VM exits due to intercepted exceptions do not necessarily come with valid idt_vectoring, we have to update event_exit_inst_len explicitly in such cases. At least in the absence of migration, this ensures that re-injections of #BP will find and use the correct instruction length. Signed-off-by: Jan Kiszka <jan.kiszka@xxxxxxxxxxx> --- Changes in v2: - added comments arch/x86/kvm/vmx.c | 13 +++++++++++++ 1 files changed, 13 insertions(+), 0 deletions(-) diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c index f82b072..14873b9 100644 --- a/arch/x86/kvm/vmx.c +++ b/arch/x86/kvm/vmx.c @@ -2775,6 +2775,12 @@ static int handle_rmode_exception(struct kvm_vcpu *vcpu, kvm_queue_exception(vcpu, vec); return 1; case BP_VECTOR: + /* + * Update instruction length as we may reinject the exception + * from user space while in guest debugging mode. + */ + to_vmx(vcpu)->vcpu.arch.event_exit_inst_len = + vmcs_read32(VM_EXIT_INSTRUCTION_LEN); if (vcpu->guest_debug & KVM_GUESTDBG_USE_SW_BP) return 0; /* fall through */ @@ -2897,6 +2903,13 @@ static int handle_exception(struct kvm_vcpu *vcpu) kvm_run->debug.arch.dr7 = vmcs_readl(GUEST_DR7); /* fall through */ case BP_VECTOR: + /* + * Update instruction length as we may reinject #BP from + * user space while in guest debugging mode. Reading it for + * #DB as well causes no harm, it is not used in that case. + */ + vmx->vcpu.arch.event_exit_inst_len = + vmcs_read32(VM_EXIT_INSTRUCTION_LEN); kvm_run->exit_reason = KVM_EXIT_DEBUG; kvm_run->debug.arch.pc = vmcs_readl(GUEST_CS_BASE) + rip; kvm_run->debug.arch.exception = ex_no; -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
