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David Hildenbrand 38968bcdcc virtio-mem: s390 support
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>
History 2024-11-07 10:26:24 +01:00
arch s390/physmem_info: Query diag500(STORAGE LIMIT) to support QEMU/KVM memory devices 2024-11-07 10:26:24 +01:00
block block-6.12-20241004 2024-10-04 10:43:44 -07:00
certs sign-file,extract-cert: use pkcs11 provider for OPENSSL MAJOR >= 3 2024-09-20 19:52:48 +03:00
crypto move asm/unaligned.h to linux/unaligned.h 2024-10-02 17:23:23 -04:00
Documentation Documentation: s390-diag.rst: Document diag500(STORAGE LIMIT) subfunction 2024-11-07 10:26:24 +01:00
drivers virtio-mem: s390 support 2024-11-07 10:26:24 +01:00
fs bcachefs fixes for 6.12-rc2 2024-10-05 15:18:04 -07:00
include Power management fixes for 6.12-rc2 2024-10-04 11:57:15 -07:00
init cfi: encode cfi normalized integers + kasan/gcov bug in Kconfig 2024-09-26 21:27:27 +02:00
io_uring io_uring/net: harden multishot termination case for recv 2024-09-30 08:26:59 -06:00
ipc struct fd layout change (and conversion to accessor helpers) 2024-09-23 09:35:36 -07:00
kernel Various fixes for tracing: 2024-10-04 12:11:06 -07:00
lib slab fixes for 6.12-rc1 2024-10-04 12:05:39 -07:00
LICENSES LICENSES: add 0BSD license text 2024-09-01 20:43:24 -07:00
mm mm, slab: suppress warnings in test_leak_destroy kunit test 2024-10-02 16:28:46 +02:00
net Including fixes from ieee802154, bluetooth and netfilter. 2024-10-03 09:44:00 -07:00
rust rust: kunit: use C-string literals to clean warning 2024-10-01 23:46:42 +02:00
samples [tree-wide] finally take no_llseek out 2024-09-27 08:18:43 -07:00
scripts kbuild: deb-pkg: Remove blank first line from maint scripts 2024-10-07 02:36:38 +09:00
security hardening fixes for v6.12-rc2 2024-10-05 10:19:14 -07:00
sound sound fixes for 6.12-rc2 2024-10-04 11:29:46 -07:00
tools ARM64: 2024-10-06 10:53:28 -07:00
usr initramfs: shorten cmd_initfs in usr/Makefile 2024-07-16 01:07:52 +09:00
virt x86: 2024-09-28 09:20:14 -07:00
.clang-format clang-format: Update with v6.11-rc1's for_each macro list 2024-08-02 13:20:31 +02:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.editorconfig .editorconfig: remove trim_trailing_whitespace option 2024-06-13 16:47:52 +02:00
.get_maintainer.ignore Add Jeff Kirsher to .get_maintainer.ignore 2024-03-08 11:36:54 +00:00
.gitattributes .gitattributes: set diff driver for Rust source code files 2023-05-31 17:48:25 +02:00
.gitignore Kbuild updates for v6.12 2024-09-24 13:02:06 -07:00
.mailmap Summary 2024-09-24 11:08:40 -07:00
.rustfmt.toml rust: add .rustfmt.toml 2022-09-28 09:02:20 +02:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS MAINTAINERS: Mark powerpc spufs as orphaned 2024-08-19 21:27:56 +10:00
Kbuild Kbuild updates for v6.1 2022-10-10 12:00:45 -07:00
Kconfig kbuild: ensure full rebuild when the compiler is updated 2020-05-12 13:28:33 +09:00
MAINTAINERS MAINTAINERS: Update and add s390 crypto related entries 2024-10-29 11:17:18 +01:00
Makefile Linux 6.12-rc2 2024-10-06 15:32:27 -07:00
README README: Fix spelling 2024-03-18 03:36:32 -06:00

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the reStructuredText markup notation.

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.