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Commit c573cd22 authored by Jan Kiszka's avatar Jan Kiszka Committed by Marcelo Tosatti
Browse files

KVM: VMX: Update instruction length on intercepted BP 



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: default avatarJan Kiszka <jan.kiszka@siemens.com>
Cc: stable@kernel.org (2.6.32, 2.6.33)
Signed-off-by: default avatarAvi Kivity <avi@redhat.com>
parent e54cfa97

arch/x86/kvm/vmx.c

+13 −0
Original line number Diff line number Diff line
@@ -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;