tjh.dev
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.
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
1442907
3
927
Clone this repository
https://tangled.org/tjh.dev/kernel
https://tangled.org/did:plc:65gha4t3avpfpzmvpbwovss7/kernel
git@gordian.tjh.dev:tjh.dev/kernel
git@gordian.tjh.dev:did:plc:65gha4t3avpfpzmvpbwovss7/kernel
For self-hosted knots, clone URLs may differ based on your setup.
Download tar.gz
Pull kvm fixes from Paolo Bonzini:
"x86:
- Fixes for Xen emulation. While nobody should be enabling it in the
kernel (the only public users of the feature are the selftests),
the bug effectively allows userspace to read arbitrary memory.
- Correctness fixes for nested hypervisors that do not intercept INIT
or SHUTDOWN on AMD; the subsequent CPU reset can cause a
use-after-free when it disables virtualization extensions. While
downgrading the panic to a WARN is quite easy, the full fix is a
bit more laborious; there are also tests. This is the bulk of the
pull request.
- Fix race condition due to incorrect mmu_lock use around
make_mmu_pages_available().
Generic:
- Obey changes to the kvm.halt_poll_ns module parameter in VMs not
using KVM_CAP_HALT_POLL, restoring behavior from before the
introduction of the capability"
* tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm:
KVM: Update gfn_to_pfn_cache khva when it moves within the same page
KVM: x86/xen: Only do in-kernel acceleration of hypercalls for guest CPL0
KVM: x86/xen: Validate port number in SCHEDOP_poll
KVM: x86/mmu: Fix race condition in direct_page_fault
KVM: x86: remove exit_int_info warning in svm_handle_exit
KVM: selftests: add svm part to triple_fault_test
KVM: x86: allow L1 to not intercept triple fault
kvm: selftests: add svm nested shutdown test
KVM: selftests: move idt_entry to header
KVM: x86: forcibly leave nested mode on vCPU reset
KVM: x86: add kvm_leave_nested
KVM: x86: nSVM: harden svm_free_nested against freeing vmcb02 while still in use
KVM: x86: nSVM: leave nested mode on vCPU free
KVM: Obey kvm.halt_poll_ns in VMs not using KVM_CAP_HALT_POLL
KVM: Avoid re-reading kvm->max_halt_poll_ns during halt-polling
KVM: Cap vcpu->halt_poll_ns before halting rather than after
Pull cifs fixes from Steve French:
"Two small cifs/smb3 client fixes:
- an unlock missing in an error path in copychunk_range found by
xfstest 476
- a fix for a use after free in a debug code path"
* tag '6.1-rc6-smb3-fixes' of git://git.samba.org/sfrench/cifs-2.6:
cifs: fix missing unlock in cifs_file_copychunk_range()
cifs: Use after free in debug code
This brings in a few important fixes for Xen emulation.
While nobody should be enabling it, the bug effectively
allows userspace to read arbitrary memory.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Pull Kbuild fixes from Masahiro Yamada:
- Fix CC_HAS_ASM_GOTO_TIED_OUTPUT test in Kconfig
- Fix noisy "No such file or directory" message when
KBUILD_BUILD_VERSION is passed
- Include rust/ in source tarballs
- Fix missing FORCE for ARCH=nios2 builds
* tag 'kbuild-fixes-v6.1-4' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild:
nios2: add FORCE for vmlinuz.gz
scripts: add rust in scripts/Makefile.package
kbuild: fix "cat: .version: No such file or directory"
init/Kconfig: fix CC_HAS_ASM_GOTO_TIED_OUTPUT test with dash
xfstests generic/013 and generic/476 reported WARNING as follows:
WARNING: lock held when returning to user space!
6.1.0-rc5+ #4 Not tainted
------------------------------------------------
fsstress/504233 is leaving the kernel with locks still held!
2 locks held by fsstress/504233:
#0: ffff888054c38850 (&sb->s_type->i_mutex_key#21){+.+.}-{3:3}, at:
lock_two_nondirectories+0xcf/0xf0
#1: ffff8880b8fec750 (&sb->s_type->i_mutex_key#21/4){+.+.}-{3:3}, at:
lock_two_nondirectories+0xb7/0xf0
This will lead to deadlock and hungtask.
Fix this by releasing locks when failed to write out on a file range in
cifs_file_copychunk_range().
Fixes: 3e3761f1ec7d ("smb3: use filemap_write_and_wait_range instead of filemap_write_and_wait")
Cc: stable@vger.kernel.org # 6.0
Reviewed-by: Paulo Alcantara (SUSE) <pc@cjr.nz>
Signed-off-by: ChenXiaoSong <chenxiaosong2@huawei.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
make_mmu_pages_available() must be called with mmu_lock held for write.
However, if the TDP MMU is used, it will be called with mmu_lock held for
read.
This function does nothing unless shadow pages are used, so there is no
race unless nested TDP is used.
Since nested TDP uses shadow pages, old shadow pages may be zapped by this
function even when the TDP MMU is enabled.
Since shadow pages are never allocated by kvm_tdp_mmu_map(), a race
condition can be avoided by not calling make_mmu_pages_available() if the
TDP MMU is currently in use.
I encountered this when repeatedly starting and stopping nested VM.
It can be artificially caused by allocating a large number of nested TDP
SPTEs.
For example, the following BUG and general protection fault are caused in
the host kernel.
pte_list_remove: 00000000cd54fc10 many->many
------------[ cut here ]------------
kernel BUG at arch/x86/kvm/mmu/mmu.c:963!
invalid opcode: 0000 [#1] PREEMPT SMP NOPTI
RIP: 0010:pte_list_remove.cold+0x16/0x48 [kvm]
Call Trace:
<TASK>
drop_spte+0xe0/0x180 [kvm]
mmu_page_zap_pte+0x4f/0x140 [kvm]
__kvm_mmu_prepare_zap_page+0x62/0x3e0 [kvm]
kvm_mmu_zap_oldest_mmu_pages+0x7d/0xf0 [kvm]
direct_page_fault+0x3cb/0x9b0 [kvm]
kvm_tdp_page_fault+0x2c/0xa0 [kvm]
kvm_mmu_page_fault+0x207/0x930 [kvm]
npf_interception+0x47/0xb0 [kvm_amd]
svm_invoke_exit_handler+0x13c/0x1a0 [kvm_amd]
svm_handle_exit+0xfc/0x2c0 [kvm_amd]
kvm_arch_vcpu_ioctl_run+0xa79/0x1780 [kvm]
kvm_vcpu_ioctl+0x29b/0x6f0 [kvm]
__x64_sys_ioctl+0x95/0xd0
do_syscall_64+0x5c/0x90
general protection fault, probably for non-canonical address
0xdead000000000122: 0000 [#1] PREEMPT SMP NOPTI
RIP: 0010:kvm_mmu_commit_zap_page.part.0+0x4b/0xe0 [kvm]
Call Trace:
<TASK>
kvm_mmu_zap_oldest_mmu_pages+0xae/0xf0 [kvm]
direct_page_fault+0x3cb/0x9b0 [kvm]
kvm_tdp_page_fault+0x2c/0xa0 [kvm]
kvm_mmu_page_fault+0x207/0x930 [kvm]
npf_interception+0x47/0xb0 [kvm_amd]
CVE: CVE-2022-45869
Fixes: a2855afc7ee8 ("KVM: x86/mmu: Allow parallel page faults for the TDP MMU")
Signed-off-by: Kazuki Takiguchi <takiguchi.kazuki171@gmail.com>
Cc: stable@vger.kernel.org
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
In the case where a GPC is refreshed to a different location within the
same page, we didn't bother to update it. Mostly we don't need to, but
since the ->khva field also includes the offset within the page, that
does have to be updated.
Fixes: 3ba2c95ea180 ("KVM: Do not incorporate page offset into gfn=>pfn cache user address")
Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
Reviewed-by: Paul Durrant <paul@xen.org>
Reviewed-by: Sean Christopherson <seanjc@google.com>
Cc: stable@kernel.org
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Pull nfsd fix from Chuck Lever:
- Fix rare data corruption on READ operations
* tag 'nfsd-6.1-6' of git://git.kernel.org/pub/scm/linux/kernel/git/cel/linux:
NFSD: Fix reads with a non-zero offset that don't end on a page boundary
Add FORCE to placate a warning from make:
arch/nios2/boot/Makefile:24: FORCE prerequisite is missing
Fixes: 2fc8483fdcde ("nios2: Build infrastructure")
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Reviewed-by: Masahiro Yamada <masahiroy@kernel.org>
This debug code dereferences "old_iface" after it was already freed by
the call to release_iface(). Re-order the debugging to avoid this
issue.
Fixes: b54034a73baf ("cifs: during reconnect, update interface if necessary")
Cc: stable@vger.kernel.org # 5.19+
Reviewed-by: Paulo Alcantara (SUSE) <pc@cjr.nz>
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
This fixes three issues in nested SVM:
1) in the shutdown_interception() vmexit handler we call kvm_vcpu_reset().
However, if running nested and L1 doesn't intercept shutdown, the function
resets vcpu->arch.hflags without properly leaving the nested state.
This leaves the vCPU in inconsistent state and later triggers a kernel
panic in SVM code. The same bug can likely be triggered by sending INIT
via local apic to a vCPU which runs a nested guest.
On VMX we are lucky that the issue can't happen because VMX always
intercepts triple faults, thus triple fault in L2 will always be
redirected to L1. Plus, handle_triple_fault() doesn't reset the vCPU.
INIT IPI can't happen on VMX either because INIT events are masked while
in VMX mode.
Secondarily, KVM doesn't honour SHUTDOWN intercept bit of L1 on SVM.
A normal hypervisor should always intercept SHUTDOWN, a unit test on
the other hand might want to not do so.
Finally, the guest can trigger a kernel non rate limited printk on SVM
from the guest, which is fixed as well.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
There are almost no hypercalls which are valid from CPL > 0, and definitely
none which are handled by the kernel.
Fixes: 2fd6df2f2b47 ("KVM: x86/xen: intercept EVTCHNOP_send from guests")
Reported-by: Michal Luczaj <mhal@rbox.co>
Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
Reviewed-by: Sean Christopherson <seanjc@google.com>
Cc: stable@kernel.org
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Pull power supply fixes from Sebastian Reichel:
- rk817: Two error handling fixes
- ip5xxx: fix inter overflow in current calculation
- ab8500: fix thermal zone probing
* tag 'for-v6.1-rc' of git://git.kernel.org/pub/scm/linux/kernel/git/sre/linux-power-supply:
power: supply: ab8500: Defer thermal zone probe
power: supply: ip5xxx: Fix integer overflow in current_now calculation
power: supply: rk817: Change rk817_chg_cur_to_reg to int
power: supply: rk817: check correct variable
This was found when virtual machines with nfs-mounted qcow2 disks
failed to boot properly.
Reported-by: Anders Blomdell <anders.blomdell@control.lth.se>
Suggested-by: Al Viro <viro@zeniv.linux.org.uk>
Link: https://bugzilla.redhat.com/show_bug.cgi?id=2142132
Fixes: bfbfb6182ad1 ("nfsd_splice_actor(): handle compound pages")
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Add rust argument at TAR_CONTENT in
scripts/Makefile.package script with alphabetical order.
Signed-off-by: Paran Lee <p4ranlee@gmail.com>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
README