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Filename Latest commit message Latest commit date
David Rientjes abbd42939d KVM: SVM: Periodically schedule when unregistering regions on destroy
commit 7be74942f184fdfba34ddd19a0d995deb34d4a03 upstream.

There may be many encrypted regions that need to be unregistered when a
SEV VM is destroyed.  This can lead to soft lockups.  For example, on a
host running 4.15:

watchdog: BUG: soft lockup - CPU#206 stuck for 11s! [t_virtual_machi:194348]
CPU: 206 PID: 194348 Comm: t_virtual_machi
RIP: 0010:free_unref_page_list+0x105/0x170
...
Call Trace:
 [<0>] release_pages+0x159/0x3d0
 [<0>] sev_unpin_memory+0x2c/0x50 [kvm_amd]
 [<0>] __unregister_enc_region_locked+0x2f/0x70 [kvm_amd]
 [<0>] svm_vm_destroy+0xa9/0x200 [kvm_amd]
 [<0>] kvm_arch_destroy_vm+0x47/0x200
 [<0>] kvm_put_kvm+0x1a8/0x2f0
 [<0>] kvm_vm_release+0x25/0x30
 [<0>] do_exit+0x335/0xc10
 [<0>] do_group_exit+0x3f/0xa0
 [<0>] get_signal+0x1bc/0x670
 [<0>] do_signal+0x31/0x130

Although the CLFLUSH is no longer issued on every encrypted region to be
unregistered, there are no other changes that can prevent soft lockups for
very large SEV VMs in the latest kernel.

Periodically schedule if necessary.  This still holds kvm->lock across the
resched, but since this only happens when the VM is destroyed this is
assumed to be acceptable.

Signed-off-by: David Rientjes <rientjes@google.com>
Message-Id: <alpine.DEB.2.23.453.2008251255240.2987727@chino.kir.corp.google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
[iwamatsu: adjust filename.]
Reference: CVE-2020-36311
Signed-off-by: Nobuhiro Iwamatsu (CIP) <nobuhiro1.iwamatsu@toshiba.co.jp>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-07-11 12:52:07 +02:00
arch KVM: SVM: Periodically schedule when unregistering regions on destroy 2021-07-11 12:52:07 +02:00
block blk-mq: Swap two calls in blk_mq_exit_queue() 2021-05-19 10:08:30 +02:00
certs certs: Move load_system_certificate_list to a common function 2021-06-30 08:47:55 -04:00
crypto crypto: rng - fix crypto_rng_reset() refcounting when !CRYPTO_STATS 2021-05-11 14:04:15 +02:00
Documentation mm/slub: clarify verification reporting 2021-06-23 14:41:30 +02:00
drivers RDMA/mlx5: Block FDB rules when not in switchdev mode 2021-07-07 08:22:58 -04:00
fs nilfs2: fix memory leak in nilfs_sysfs_delete_device_group 2021-06-30 08:47:50 -04:00
include certs: Add EFI_CERT_X509_GUID support for dbx entries 2021-06-30 08:47:55 -04:00
init kbuild: add CONFIG_LD_IS_LLD 2021-06-30 08:47:44 -04:00
ipc
kernel mm, futex: fix shared futex pgoff on shmem huge page 2021-06-30 08:47:55 -04:00
lib lib/lz4: explicitly support in-place decompression 2021-06-10 13:37:16 +02:00
LICENSES
mm mm, futex: fix shared futex pgoff on shmem huge page 2021-06-30 08:47:55 -04:00
net net/packet: annotate accesses to po->ifindex 2021-06-30 08:47:48 -04:00
samples samples: vfio-mdev: fix error handing in mdpy_fb_probe() 2021-06-10 13:37:03 +02:00
scripts recordmcount: Correct st_shndx handling 2021-06-30 08:47:49 -04:00
security x86/efi: remove unused variables 2021-07-07 08:22:58 -04:00
sound ASoC: rt5659: Fix the lost powers for the HDA header 2021-06-23 14:41:27 +02:00
tools KVM: selftests: Fix kvm_check_cap() assertion 2021-06-30 08:47:49 -04:00
usr
virt KVM: do not allow mapping valid but non-reference-counted pages 2021-06-30 08:47:50 -04:00
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Makefile Linux 5.4.130 2021-07-07 08:29:57 -04:00
README

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.