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Vitaly Kuznetsov c8bf64e3fb KVM: nVMX: Always make an attempt to map eVMCS after migration 
commit f5c7e8425f upstream.

When enlightened VMCS is in use and nested state is migrated with
vmx_get_nested_state()/vmx_set_nested_state() KVM can't map evmcs
page right away: evmcs gpa is not 'struct kvm_vmx_nested_state_hdr'
and we can't read it from VP assist page because userspace may decide
to restore HV_X64_MSR_VP_ASSIST_PAGE after restoring nested state
(and QEMU, for example, does exactly that). To make sure eVMCS is
mapped /vmx_set_nested_state() raises KVM_REQ_GET_NESTED_STATE_PAGES
request.

Commit f2c7ef3ba9 ("KVM: nSVM: cancel KVM_REQ_GET_NESTED_STATE_PAGES
on nested vmexit") added KVM_REQ_GET_NESTED_STATE_PAGES clearing to
nested_vmx_vmexit() to make sure MSR permission bitmap is not switched
when an immediate exit from L2 to L1 happens right after migration (caused
by a pending event, for example). Unfortunately, in the exact same
situation we still need to have eVMCS mapped so
nested_sync_vmcs12_to_shadow() reflects changes in VMCS12 to eVMCS.

As a band-aid, restore nested_get_evmcs_page() when clearing
KVM_REQ_GET_NESTED_STATE_PAGES in nested_vmx_vmexit(). The 'fix' is far
from being ideal as we can't easily propagate possible failures and even if
we could, this is most likely already too late to do so. The whole
'KVM_REQ_GET_NESTED_STATE_PAGES' idea for mapping eVMCS after migration
seems to be fragile as we diverge too much from the 'native' path when
vmptr loading happens on vmx_set_nested_state().

Fixes: f2c7ef3ba9 ("KVM: nSVM: cancel KVM_REQ_GET_NESTED_STATE_PAGES on nested vmexit")
Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Message-Id: <20210503150854.1144255-2-vkuznets@redhat.com>
Cc: stable@vger.kernel.org
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-05-19 10:13:16 +02:00
arch KVM: nVMX: Always make an attempt to map eVMCS after migration 2021-05-19 10:13:16 +02:00
block blk-mq: Swap two calls in blk_mq_exit_queue() 2021-05-19 10:13:14 +02:00
certs certs: Fix blacklist flag type confusion 2021-03-04 11:37:59 +01:00
crypto async_xor: increase src_offs when dropping destination page 2021-05-14 09:49:59 +02:00
Documentation kbuild: generate Module.symvers only when vmlinux exists 2021-05-19 10:12:59 +02:00
drivers xen/gntdev: fix gntdev_mmap() error exit path 2021-05-19 10:13:16 +02:00
fs f2fs: compress: fix to assign cc.cluster_idx correctly 2021-05-19 10:13:14 +02:00
include kyber: fix out of bounds access when preempted 2021-05-19 10:13:13 +02:00
init seccomp: Fix CONFIG tests for Seccomp_filters 2021-05-14 09:50:24 +02:00
ipc ipc: adjust proc_ipc_sem_dointvec definition to match prototype 2020-09-05 12:14:29 -07:00
kernel kernel/resource: make walk_mem_res() find all busy IORESOURCE_MEM resources 2021-05-19 10:13:09 +02:00
lib kasan: fix unit tests with CONFIG_UBSAN_LOCAL_BOUNDS enabled 2021-05-19 10:13:11 +02:00
LICENSES LICENSES/deprecated: add Zlib license text 2020-09-16 14:33:49 +02:00
mm mm/hugetlb: fix F_SEAL_FUTURE_WRITE 2021-05-19 10:13:11 +02:00
net mptcp: fix splat when closing unaccepted socket 2021-05-19 10:13:10 +02:00
samples samples/bpf: Fix broken tracex1 due to kprobe argument change 2021-05-19 10:12:57 +02:00
scripts kbuild: generate Module.symvers only when vmlinux exists 2021-05-19 10:12:59 +02:00
security KEYS: trusted: Fix memory leak on object td 2021-05-19 10:12:50 +02:00
sound ASoC: rt286: Make RT286_SET_GPIO_* readable and writable 2021-05-19 10:13:00 +02:00
tools perf tools: Fix dynamic libbpf link 2021-05-19 10:13:13 +02:00
usr Merge branch 'work.fdpic' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2020-08-07 13:29:39 -07:00
virt kvm: exit halt polling on need_resched() as well 2021-05-19 10:13:12 +02:00
.clang-format RDMA 5.10 pull request 2020-10-17 11:18:18 -07:00
.cocciconfig
.get_maintainer.ignore Opt out of scripts/get_maintainer.pl 2019-05-16 10:53:40 -07:00
.gitattributes .gitattributes: use 'dts' diff driver for dts files 2019-12-04 19:44:11 -08:00
.gitignore kbuild: generate Module.symvers only when vmlinux exists 2021-05-19 10:12:59 +02:00
.mailmap mailmap: add two more addresses of Uwe Kleine-König 2020-12-06 10:19:07 -08:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS MAINTAINERS: Move Jason Cooper to CREDITS 2020-11-30 10:20:34 +01:00
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 f2fs: move ioctl interface definitions to separated file 2021-05-19 10:13:00 +02:00
Makefile kbuild: generate Module.symvers only when vmlinux exists 2021-05-19 10:12:59 +02:00
README Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -06:00

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.