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Now that s390 code is prepared for memory devices that reside above the maximum storage increment exposed through SCLP, everything is in place to unlock virtio-mem support. As virtio-mem in Linux currently supports logically onlining/offlining memory in pageblock granularity, we have an effective hot(un)plug granularity of 1 MiB on s390. As virito-mem adds/removes individual Linux memory blocks (256MB), we will currently never use gigantic pages in the identity mapping. It is worth noting that neither storage keys nor storage attributes (e.g., data / nodat) are touched when onlining memory blocks, which is good because we are not supposed to touch these parts for unplugged device blocks that are logically offline in Linux. We will currently never initialize storage keys for virtio-mem memory -- IOW, storage_key_init_range() is never called. It could be added in the future when plugging device blocks. But as that function essentially does nothing without modifying the code (changing PAGE_DEFAULT_ACC), that's just fine for now. kexec should work as intended and just like on other architectures that support virtio-mem: we will never place kexec binaries on virtio-mem memory, and never indicate virtio-mem memory to the 2nd kernel. The device driver in the 2nd kernel can simply reset the device -- turning all memory unplugged, to then start plugging memory and adding them to Linux, without causing trouble because the memory is already used elsewhere. The special s390 kdump mode, whereby the 2nd kernel creates the ELF core header, won't currently dump virtio-mem memory. The virtio-mem driver has a special kdump mode, from where we can detect memory ranges to dump. Based on this, support for dumping virtio-mem memory can be added in the future fairly easily. Acked-by: Michael S. Tsirkin <mst@redhat.com> Tested-by: Mario Casquero <mcasquer@redhat.com> Signed-off-by: David Hildenbrand <david@redhat.com> Acked-by: Heiko Carstens <hca@linux.ibm.com> Tested-by: Sumanth Korikkar <sumanthk@linux.ibm.com> Acked-by: Christian Borntraeger <borntraeger@linux.ibm.com> Link: https://lore.kernel.org/r/20241025141453.1210600-5-david@redhat.com Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
192 lines
5.5 KiB
Plaintext
192 lines
5.5 KiB
Plaintext
# SPDX-License-Identifier: GPL-2.0-only
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config VIRTIO_ANCHOR
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bool
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config VIRTIO
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tristate
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select VIRTIO_ANCHOR
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help
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This option is selected by any driver which implements the virtio
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bus, such as CONFIG_VIRTIO_PCI, CONFIG_VIRTIO_MMIO, CONFIG_RPMSG
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or CONFIG_S390_GUEST.
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config VIRTIO_PCI_LIB
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tristate
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help
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Modern PCI device implementation. This module implements the
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basic probe and control for devices which are based on modern
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PCI device with possible vendor specific extensions. Any
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module that selects this module must depend on PCI.
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config VIRTIO_PCI_LIB_LEGACY
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tristate
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help
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Legacy PCI device (Virtio PCI Card 0.9.x Draft and older device)
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implementation.
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This module implements the basic probe and control for devices
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which are based on legacy PCI device. Any module that selects this
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module must depend on PCI.
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menuconfig VIRTIO_MENU
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bool "Virtio drivers"
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default y
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if VIRTIO_MENU
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config VIRTIO_HARDEN_NOTIFICATION
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bool "Harden virtio notification"
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depends on BROKEN
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help
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Enable this to harden the device notifications and suppress
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those that happen at a time where notifications are illegal.
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Experimental: Note that several drivers still have issues that
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may cause crashes or hangs when correct handling of
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notifications is enforced; depending on the subset of
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drivers and devices you use, this may or may not work.
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If unsure, say N.
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config VIRTIO_PCI
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tristate "PCI driver for virtio devices"
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depends on PCI
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select VIRTIO_PCI_LIB
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select VIRTIO
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help
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This driver provides support for virtio based paravirtual device
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drivers over PCI. This requires that your VMM has appropriate PCI
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virtio backends. Most QEMU based VMMs should support these devices
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(like KVM or Xen).
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If unsure, say M.
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config VIRTIO_PCI_ADMIN_LEGACY
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bool
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depends on VIRTIO_PCI && (X86 || COMPILE_TEST)
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default y
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config VIRTIO_PCI_LEGACY
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bool "Support for legacy virtio draft 0.9.X and older devices"
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default y
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depends on VIRTIO_PCI
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select VIRTIO_PCI_LIB_LEGACY
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help
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Virtio PCI Card 0.9.X Draft (circa 2014) and older device support.
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This option enables building a transitional driver, supporting
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both devices conforming to Virtio 1 specification, and legacy devices.
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If disabled, you get a slightly smaller, non-transitional driver,
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with no legacy compatibility.
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So look out into your driveway. Do you have a flying car? If
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so, you can happily disable this option and virtio will not
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break. Otherwise, leave it set. Unless you're testing what
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life will be like in The Future.
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If unsure, say Y.
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config VIRTIO_VDPA
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tristate "vDPA driver for virtio devices"
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depends on VDPA
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select VIRTIO
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help
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This driver provides support for virtio based paravirtual
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device driver over vDPA bus. For this to be useful, you need
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an appropriate vDPA device implementation that operates on a
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physical device to allow the datapath of virtio to be
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offloaded to hardware.
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If unsure, say M.
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config VIRTIO_PMEM
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tristate "Support for virtio pmem driver"
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depends on VIRTIO
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depends on LIBNVDIMM
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help
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This driver provides access to virtio-pmem devices, storage devices
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that are mapped into the physical address space - similar to NVDIMMs
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- with a virtio-based flushing interface.
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If unsure, say Y.
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config VIRTIO_BALLOON
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tristate "Virtio balloon driver"
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depends on VIRTIO
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select MEMORY_BALLOON
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select PAGE_REPORTING
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help
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This driver supports increasing and decreasing the amount
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of memory within a KVM guest.
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If unsure, say M.
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config VIRTIO_MEM
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tristate "Virtio mem driver"
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depends on X86_64 || ARM64 || RISCV || S390
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depends on VIRTIO
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depends on MEMORY_HOTPLUG
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depends on MEMORY_HOTREMOVE
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depends on CONTIG_ALLOC
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depends on EXCLUSIVE_SYSTEM_RAM
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help
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This driver provides access to virtio-mem paravirtualized memory
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devices, allowing to hotplug and hotunplug memory.
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This driver currently supports x86-64, arm64, riscv and s390.
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Although it should compile on other architectures that implement
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memory hot(un)plug, architecture-specific and/or common
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code changes may be required for virtio-mem, kdump and kexec to
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work as expected.
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If unsure, say M.
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config VIRTIO_INPUT
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tristate "Virtio input driver"
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depends on VIRTIO
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depends on INPUT
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help
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This driver supports virtio input devices such as
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keyboards, mice and tablets.
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If unsure, say M.
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config VIRTIO_MMIO
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tristate "Platform bus driver for memory mapped virtio devices"
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depends on HAS_IOMEM && HAS_DMA
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select VIRTIO
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help
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This drivers provides support for memory mapped virtio
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platform device driver.
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If unsure, say N.
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config VIRTIO_MMIO_CMDLINE_DEVICES
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bool "Memory mapped virtio devices parameter parsing"
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depends on VIRTIO_MMIO
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help
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Allow virtio-mmio devices instantiation via the kernel command line
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or module parameters. Be aware that using incorrect parameters (base
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address in particular) can crash your system - you have been warned.
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See Documentation/admin-guide/kernel-parameters.rst for details.
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If unsure, say 'N'.
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config VIRTIO_DMA_SHARED_BUFFER
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tristate
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depends on DMA_SHARED_BUFFER
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help
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This option adds a flavor of dma buffers that are backed by
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virtio resources.
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config VIRTIO_DEBUG
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bool "Debug facilities"
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depends on VIRTIO
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help
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Enable this to expose debug facilities over debugfs.
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This allows to debug features, to see what features the device
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advertises and to set filter for features used by driver.
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If unsure, say N.
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endif # VIRTIO_MENU
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