This series specifies and implements an API aimed at saving and restoring the state of the in-kernel emulated ITS device. The ITS is programmed through registers and tables. Those later tables are allocated by the guest. Their base address is programmed in registers or table entries before the ITS is enabled. The ITS is free to use some of them to flush its internal caches. This is likely to be used when entering low power state. Therefore, for save/restore use case, it looks natural to use this guest RAM allocated space to save the table related data. However, currently,The ITS in-kernel emulated device does not use all of those tables and for those it uses, it does not always sync them with its cached data. Additional sync must happen for: - the collection table - the device table - the per-device translation tables - the LPI pending tables. The LPI configration table and the command queues do not need extra syncs. So the bulk of the work in this series consists in the table save/restore rather than register save/restore. An alternative to flushing the tables into guest RAM could have been to flush them into a separate user-space buffer. However the drawback of this alternative is that the virtualizer would allocate dedicated buffers to store the data that should normally be laid out in guest RAM. It would also be obliged to re-compute their size from register/table content. So saving the tables in guest RAM better fit the ITS programming model and optimizes the memory usage. The drawback of this solution is it brings additional challenges at user-space level to make sure the guest RAM is frozen after table sync. The code is functional while saving/restoring a guest using virtio-net-pci. However many points deserve additional tests. I share the series at that stage to get the documentation reviewed and main principles discussed. The series applies on top of Vijaya's series: - [PATCH v10 0/8] arm/arm64: vgic: Implement API for vGICv3 live migration http://www.spinics.net/lists/arm-kernel/msg546383.html Best Regards Eric Git: complete series available at https://github.com/eauger/linux/tree/v4.10-rc3-its-mig-rfc-v1 * Testing: - on Cavium using a virtio-net-pci guest and virsh save/restore commands Eric Auger (13): KVM: arm/arm64: Add vITS save/restore API documentation arm/arm64: vgic: turn vgic_find_mmio_region into public KVM: arm64: ITS: KVM_DEV_ARM_VGIC_GRP_ITS_REGS group KVM: arm64: ITS: Implement vgic_its_has_attr_regs and attr_regs_access KVM: arm64: ITS: Implement vgic_mmio_uaccess_write_its_creadr KVM: arm64: ITS: Expose ITT_Entry_Size in GITS_TYPER KVM: arm64: ITS: Change entry_size and indirect bit in BASER KVM: arm64: ITS: On MAPD interpret and store itt_addr and size KVM: arm64: ITS: KVM_DEV_ARM_VGIC_GRP_ITS_TABLES group KVM: arm64: ITS: vgic_its_alloc_itte/device KVM: arm64: ITS: Collection table save/restore KVM: arm64: ITS: Device and translation table flush KVM: arm64: ITS: Pending table save/restore Documentation/virtual/kvm/devices/arm-vgic-its.txt | 70 +++ arch/arm/include/uapi/asm/kvm.h | 2 + arch/arm64/include/uapi/asm/kvm.h | 2 + include/kvm/arm_vgic.h | 3 + include/linux/irqchip/arm-gic-v3.h | 1 + virt/kvm/arm/vgic/vgic-its.c | 655 +++++++++++++++++++-- virt/kvm/arm/vgic/vgic-mmio.c | 3 +- virt/kvm/arm/vgic/vgic-mmio.h | 14 +- 8 files changed, 705 insertions(+), 45 deletions(-) -- 2.5.5 -- 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
