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When L1 IOAPIC redirection-table is written, a request of KVM_REQ_SCAN_IOAPIC is set on all vCPUs. This is done such that all vCPUs will now recalc their IOAPIC handled vectors and load it to their EOI-exitmap. However, it could be that one of the vCPUs is currently running L2. In this case, load_eoi_exitmap() will be called which would write to vmcs02->eoi_exit_bitmap, which is wrong because vmcs02->eoi_exit_bitmap should always be equal to vmcs12->eoi_exit_bitmap. Furthermore, at this point KVM_REQ_SCAN_IOAPIC was already consumed and therefore we will never update vmcs01->eoi_exit_bitmap. This could lead to remote_irr of some IOAPIC level-triggered entry to remain set forever. Fix this issue by delaying the load of EOI-exitmap to when vCPU is running L1. One may wonder why not just delay entire KVM_REQ_SCAN_IOAPIC processing to when vCPU is running L1. This is done in order to handle correctly the case where LAPIC & IO-APIC of L1 is pass-throughed into L2. In this case, vmcs12->virtual_interrupt_delivery should be 0. In current nVMX implementation, that results in vmcs02->virtual_interrupt_delivery to also be 0. Thus, vmcs02->eoi_exit_bitmap is not used. Therefore, every L2 EOI cause a #VMExit into L0 (either on MSR_WRITE to x2APIC MSR or APIC_ACCESS/APIC_WRITE/EPT_MISCONFIG to APIC MMIO page). In order for such L2 EOI to be broadcasted, if needed, from LAPIC to IO-APIC, vcpu->arch.ioapic_handled_vectors must be updated while L2 is running. Therefore, patch makes sure to delay only the loading of EOI-exitmap but not the update of vcpu->arch.ioapic_handled_vectors. Reviewed-by: Arbel Moshe <arbel.moshe@oracle.com> Reviewed-by: Krish Sadhukhan <krish.sadhukhan@oracle.com> Signed-off-by: Liran Alon <liran.alon@oracle.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Linux kernel ============ This file was moved to Documentation/admin-guide/README.rst Please notice that there are several guides for kernel developers and users. These guides can be rendered in a number of formats, like HTML and PDF. In order to build the documentation, use ``make htmldocs`` or ``make pdfdocs``. There are various text files in the Documentation/ subdirectory, several of them using the Restructured Text markup notation. See Documentation/00-INDEX for a list of what is contained in each file. Please read the Documentation/process/changes.rst file, as it contains the requirements for building and running the kernel, and information about the problems which may result by upgrading your kernel.