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Oliver Upton 5994bc9e05 KVM: arm64: Limit stage2_apply_range() batch size to largest block
Presently stage2_apply_range() works on a batch of memory addressed by a
stage 2 root table entry for the VM. Depending on the IPA limit of the
VM and PAGE_SIZE of the host, this could address a massive range of
memory. Some examples:

  4 level, 4K paging -> 512 GB batch size

  3 level, 64K paging -> 4TB batch size

Unsurprisingly, working on such a large range of memory can lead to soft
lockups. When running dirty_log_perf_test:

  ./dirty_log_perf_test -m -2 -s anonymous_thp -b 4G -v 48

  watchdog: BUG: soft lockup - CPU#0 stuck for 45s! [dirty_log_perf_:16703]
  Modules linked in: vfat fat cdc_ether usbnet mii xhci_pci xhci_hcd sha3_generic gq(O)
  CPU: 0 PID: 16703 Comm: dirty_log_perf_ Tainted: G           O       6.0.0-smp-DEV #1
  pstate: 80400009 (Nzcv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--)
  pc : dcache_clean_inval_poc+0x24/0x38
  lr : clean_dcache_guest_page+0x28/0x4c
  sp : ffff800021763990
  pmr_save: 000000e0
  x29: ffff800021763990 x28: 0000000000000005 x27: 0000000000000de0
  x26: 0000000000000001 x25: 00400830b13bc77f x24: ffffad4f91ead9c0
  x23: 0000000000000000 x22: ffff8000082ad9c8 x21: 0000fffafa7bc000
  x20: ffffad4f9066ce50 x19: 0000000000000003 x18: ffffad4f92402000
  x17: 000000000000011b x16: 000000000000011b x15: 0000000000000124
  x14: ffff07ff8301d280 x13: 0000000000000000 x12: 00000000ffffffff
  x11: 0000000000010001 x10: fffffc0000000000 x9 : ffffad4f9069e580
  x8 : 000000000000000c x7 : 0000000000000000 x6 : 000000000000003f
  x5 : ffff07ffa2076980 x4 : 0000000000000001 x3 : 000000000000003f
  x2 : 0000000000000040 x1 : ffff0830313bd000 x0 : ffff0830313bcc40
  Call trace:
   dcache_clean_inval_poc+0x24/0x38
   stage2_unmap_walker+0x138/0x1ec
   __kvm_pgtable_walk+0x130/0x1d4
   __kvm_pgtable_walk+0x170/0x1d4
   __kvm_pgtable_walk+0x170/0x1d4
   __kvm_pgtable_walk+0x170/0x1d4
   kvm_pgtable_stage2_unmap+0xc4/0xf8
   kvm_arch_flush_shadow_memslot+0xa4/0x10c
   kvm_set_memslot+0xb8/0x454
   __kvm_set_memory_region+0x194/0x244
   kvm_vm_ioctl_set_memory_region+0x58/0x7c
   kvm_vm_ioctl+0x49c/0x560
   __arm64_sys_ioctl+0x9c/0xd4
   invoke_syscall+0x4c/0x124
   el0_svc_common+0xc8/0x194
   do_el0_svc+0x38/0xc0
   el0_svc+0x2c/0xa4
   el0t_64_sync_handler+0x84/0xf0
   el0t_64_sync+0x1a0/0x1a4

Use the largest supported block mapping for the configured page size as
the batch granularity. In so doing the walker is guaranteed to visit a
leaf only once.

Signed-off-by: Oliver Upton <oliver.upton@linux.dev>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20221007234151.461779-3-oliver.upton@linux.dev
2022-10-09 02:33:49 +01:00
arch KVM: arm64: Limit stage2_apply_range() batch size to largest block 2022-10-09 02:33:49 +01:00
block block-6.0-2022-08-26 2022-08-26 11:05:54 -07:00
certs Kbuild updates for v5.20 2022-08-10 10:40:41 -07:00
crypto crypto: blake2b: effectively disable frame size warning 2022-08-10 17:59:11 -07:00
Documentation KVM: Document weakly ordered architecture requirements for dirty ring 2022-09-29 10:23:08 +01:00
drivers arm64/sysreg: Standardise naming of ID_AA64MMFR0_EL1.ASIDBits 2022-09-09 10:59:02 +01:00
fs Seventeen hotfixes. Mostly memory management things. Ten patches are 2022-08-28 14:49:59 -07:00
include KVM: Add KVM_CAP_DIRTY_LOG_RING_ACQ_REL capability and config option 2022-09-29 10:23:08 +01:00
init arm64 fixes for -rc3 2022-08-26 11:32:53 -07:00
io_uring io_uring/net: save address for sendzc async execution 2022-08-25 07:52:30 -06:00
ipc Updates to various subsystems which I help look after. lib, ocfs2, 2022-08-07 10:03:24 -07:00
kernel Seventeen hotfixes. Mostly memory management things. Ten patches are 2022-08-28 14:49:59 -07:00
lib bitmap fixes for v6.0-rc3 2022-08-28 14:36:27 -07:00
LICENSES LICENSES/LGPL-2.1: Add LGPL-2.1-or-later as valid identifiers 2021-12-16 14:33:10 +01:00
mm mm/mprotect: only reference swap pfn page if type match 2022-08-28 14:02:46 -07:00
net Including fixes from ipsec and netfilter (with one broken Fixes tag). 2022-08-25 14:03:58 -07:00
samples Tracing updates for 5.20 / 6.0 2022-08-05 09:41:12 -07:00
scripts asm goto: eradicate CC_HAS_ASM_GOTO 2022-08-21 10:06:28 -07:00
security hardening fixes for v6.0-rc2 2022-08-19 13:56:14 -07:00
sound sound fixes for 6.0-rc2 2022-08-19 09:46:11 -07:00
tools Merge branch kvm-arm64/misc-6.1 into kvmarm-master/next 2022-10-01 10:19:36 +01:00
usr Not a lot of material this cycle. Many singleton patches against various 2022-05-27 11:22:03 -07:00
virt KVM: Add KVM_CAP_DIRTY_LOG_RING_ACQ_REL capability and config option 2022-09-29 10:23:08 +01:00
.clang-format PCI/DOE: Add DOE mailbox support functions 2022-07-19 15:38:04 -07:00
.cocciconfig
.get_maintainer.ignore get_maintainer: add Alan to .get_maintainer.ignore 2022-08-20 15:17:44 -07:00
.gitattributes .gitattributes: use 'dts' diff driver for dts files 2019-12-04 19:44:11 -08:00
.gitignore kbuild: split the second line of *.mod into *.usyms 2022-05-08 03:16:59 +09:00
.mailmap .mailmap: update Luca Ceresoli's e-mail address 2022-08-28 14:02:46 -07:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS drm for 5.20/6.0 2022-08-03 19:52:08 -07:00
Kbuild kbuild: rename hostprogs-y/always to hostprogs/always-y 2020-02-04 01:53:07 +09:00
Kconfig kbuild: ensure full rebuild when the compiler is updated 2020-05-12 13:28:33 +09:00
MAINTAINERS KVM: arm64: Advertise new kvmarm mailing list 2022-10-01 10:17:39 +01:00
Makefile Linux 6.0-rc3 2022-08-28 15:05:29 -07:00
README Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -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 Restructured Text 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.