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1,031,458 commits

Author SHA1 Message Date
Darrick J. Wong
b102a46ce1 xfs: detect misaligned rtinherit directory extent size hints
If we encounter a directory that has been configured to pass on an
extent size hint to a new realtime file and the hint isn't an integer
multiple of the rt extent size, we should flag the hint for
administrative review because that is a misconfiguration (that other
parts of the kernel will fix automatically).

Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
2021-07-15 09:58:42 -07:00
Darrick J. Wong
0925fecc55 xfs: fix an integer overflow error in xfs_growfs_rt
During a realtime grow operation, we run a single transaction for each
rt bitmap block added to the filesystem.  This means that each step has
to be careful to increase sb_rblocks appropriately.

Fix the integer overflow error in this calculation that can happen when
the extent size is very large.  Found by running growfs to add a rt
volume to a filesystem formatted with a 1g rt extent size.

Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
2021-07-15 09:58:42 -07:00
Darrick J. Wong
0e2af9296f xfs: improve FSGROWFSRT precondition checking
Improve the checking at the start of a realtime grow operation so that
we avoid accidentally set a new extent size that is too large and avoid
adding an rt volume to a filesystem with rmap or reflink because we
don't support rt rmap or reflink yet.

While we're at it, separate the checks so that we're only testing one
aspect at a time.

Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
2021-07-15 09:58:42 -07:00
Darrick J. Wong
5aa5b27823 xfs: don't expose misaligned extszinherit hints to userspace
Commit 603f000b15 changed xfs_ioctl_setattr_check_extsize to reject an
attempt to set an EXTSZINHERIT extent size hint on a directory with
RTINHERIT set if the hint isn't a multiple of the realtime extent size.
However, I have recently discovered that it is possible to change the
realtime extent size when adding a rt device to a filesystem, which
means that the existence of directories with misaligned inherited hints
is not an accident.

As a result, it's possible that someone could have set a valid hint and
added an rt volume with a different rt extent size, which invalidates
the ondisk hints.  After such a sequence, FSGETXATTR will report a
misaligned hint, which FSSETXATTR will trip over, causing confusion if
the user was doing the usual GET/SET sequence to change some other
attribute.  Change xfs_fill_fsxattr to omit the hint if it isn't aligned
properly.

Fixes: 603f000b15 ("xfs: validate extsz hints against rt extent size when rtinherit is set")
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
2021-07-15 09:58:42 -07:00
Darrick J. Wong
83193e5ebb xfs: correct the narrative around misaligned rtinherit/extszinherit dirs
While auditing the realtime growfs code, I realized that the GROWFSRT
ioctl (and by extension xfs_growfs) has always allowed sysadmins to
change the realtime extent size when adding a realtime section to the
filesystem.  Since we also have always allowed sysadmins to set
RTINHERIT and EXTSZINHERIT on directories even if there is no realtime
device, this invalidates the premise laid out in the comments added in
commit 603f000b15.

In other words, this is not a case of inadequate metadata validation.
This is a case of nearly forgotten (and apparently untested) but
supported functionality.  Update the comments to reflect what we've
learned, and remove the log message about correcting the misalignment.

Fixes: 603f000b15 ("xfs: validate extsz hints against rt extent size when rtinherit is set")
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Carlos Maiolino <cmaiolino@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
2021-07-15 09:58:42 -07:00
Darrick J. Wong
5838d0356b xfs: reset child dir '..' entry when unlinking child
While running xfs/168, I noticed a second source of post-shrink
corruption errors causing shutdowns.

Let's say that directory B has a low inode number and is a child of
directory A, which has a high number.  If B is empty but open, and
unlinked from A, B's dotdot link continues to point to A.  If A is then
unlinked and the filesystem shrunk so that A is no longer a valid inode,
a subsequent AIL push of B will trip the inode verifiers because the
dotdot entry points outside of the filesystem.

To avoid this problem, reset B's dotdot entry to the root directory when
unlinking directories, since the root directory cannot be removed.

Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Gao Xiang <hsiangkao@linux.alibaba.com>
2021-07-15 09:58:42 -07:00
Darrick J. Wong
da062d16a8 xfs: check for sparse inode clusters that cross new EOAG when shrinking
While running xfs/168, I noticed occasional write verifier shutdowns
involving inodes at the very end of the filesystem.  Existing inode
btree validation code checks that all inode clusters are fully contained
within the filesystem.

However, due to inadequate checking in the fs shrink code, it's possible
that there could be a sparse inode cluster at the end of the filesystem
where the upper inodes of the cluster are marked as holes and the
corresponding blocks are free.  In this case, the last blocks in the AG
are listed in the bnobt.  This enables the shrink to proceed but results
in a filesystem that trips the inode verifiers.  Fix this by disallowing
the shrink.

Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Gao Xiang <hsiangkao@linux.alibaba.com>
2021-07-15 09:58:41 -07:00
Andreas Gruenbacher
229adf3c64 iomap: Don't create iomap_page objects in iomap_page_mkwrite_actor
Now that we create those objects in iomap_writepage_map when needed,
there's no need to pre-create them in iomap_page_mkwrite_actor anymore.

Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
2021-07-15 09:58:06 -07:00
Andreas Gruenbacher
637d337595 iomap: Don't create iomap_page objects for inline files
In iomap_readpage_actor, don't create iop objects for inline inodes.
Otherwise, iomap_read_inline_data will set PageUptodate without setting
iop->uptodate, and iomap_page_release will eventually complain.

To prevent this kind of bug from occurring in the future, make sure the
page doesn't have private data attached in iomap_read_inline_data.

Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
2021-07-15 09:58:05 -07:00
Andreas Gruenbacher
8e1bcef8e1 iomap: Permit pages without an iop to enter writeback
Create an iop in the writeback path if one doesn't exist.  This allows us
to avoid creating the iop in some cases.  We'll initially do that for pages
with inline data, but it can be extended to pages which are entirely within
an extent.  It also allows for an iop to be removed from pages in the
future (eg page split).

Co-developed-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
2021-07-15 09:58:05 -07:00
Christoph Hellwig
49694d14ff iomap: remove the length variable in iomap_seek_hole
The length variable is rather pointless given that it can be trivially
deduced from offset and size.  Also the initial calculation can lead
to KASAN warnings.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reported-by: Leizhen (ThunderTown) <thunder.leizhen@huawei.com>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Matthew Wilcox (Oracle) <willy@infradead.org>
2021-07-15 09:58:04 -07:00
Christoph Hellwig
3ac1d42651 iomap: remove the length variable in iomap_seek_data
The length variable is rather pointless given that it can be trivially
deduced from offset and size.  Also the initial calculation can lead
to KASAN warnings.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reported-by: Leizhen (ThunderTown) <thunder.leizhen@huawei.com>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Matthew Wilcox (Oracle) <willy@infradead.org>
2021-07-15 09:58:04 -07:00
Mark Rutland
e6f85cbeb2 arm64: entry: fix KCOV suppression
We suppress KCOV for entry.o rather than entry-common.o. As entry.o is
built from entry.S, this is pointless, and permits instrumentation of
entry-common.o, which is built from entry-common.c.

Fix the Makefile to suppress KCOV for entry-common.o, as we had intended
to begin with. I've verified with objdump that this is working as
expected.

Fixes: bf6fa2c0dd ("arm64: entry: don't instrument entry code with KCOV")
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: James Morse <james.morse@arm.com>
Cc: Marc Zyngier <maz@kernel.org>
Cc: Will Deacon <will@kernel.org>
Link: https://lore.kernel.org/r/20210715123049.9990-1-mark.rutland@arm.com
Signed-off-by: Will Deacon <will@kernel.org>
2021-07-15 17:37:55 +01:00
Mark Rutland
31a7f0f6c8 arm64: entry: add missing noinstr
We intend that all the early exception handling code is marked as
`noinstr`, but we forgot this for __el0_error_handler_common(), which is
called before we have completed entry from user mode. If it were
instrumented, we could run into problems with RCU, lockdep, etc.

Mark it as `noinstr` to prevent this.

The few other functions in entry-common.c which do not have `noinstr` are
called once we've completed entry, and are safe to instrument.

Fixes: bb8e93a287 ("arm64: entry: convert SError handlers to C")
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Marc Zyngier <maz@kernel.org>
Cc: Joey Gouly <joey.gouly@arm.com>
Cc: James Morse <james.morse@arm.com>
Cc: Will Deacon <will@kernel.org>
Link: https://lore.kernel.org/r/20210714172801.16475-1-mark.rutland@arm.com
Signed-off-by: Will Deacon <will@kernel.org>
2021-07-15 17:36:51 +01:00
Mark Rutland
59f44069e0 arm64: mte: fix restoration of GCR_EL1 from suspend
Since commit:

  bad1e1c663 ("arm64: mte: switch GCR_EL1 in kernel entry and exit")

we saved/restored the user GCR_EL1 value at exception boundaries, and
update_gcr_el1_excl() is no longer used for this. However it is used to
restore the kernel's GCR_EL1 value when returning from a suspend state.
Thus, the comment is misleading (and an ISB is necessary).

When restoring the kernel's GCR value, we need an ISB to ensure this is
used by subsequent instructions. We don't necessarily get an ISB by
other means (e.g. if the kernel is built without support for pointer
authentication). As __cpu_setup() initialised GCR_EL1.Exclude to 0xffff,
until a context synchronization event, allocation tag 0 may be used
rather than the desired set of tags.

This patch drops the misleading comment, adds the missing ISB, and for
clarity folds update_gcr_el1_excl() into its only user.

Fixes: bad1e1c663 ("arm64: mte: switch GCR_EL1 in kernel entry and exit")
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Cc: Andrey Konovalov <andreyknvl@gmail.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Vincenzo Frascino <vincenzo.frascino@arm.com>
Cc: Will Deacon <will@kernel.org>
Link: https://lore.kernel.org/r/20210714143843.56537-2-mark.rutland@arm.com
Signed-off-by: Will Deacon <will@kernel.org>
2021-07-15 17:34:46 +01:00
Robin Murphy
295cf15623 arm64: Avoid premature usercopy failure
Al reminds us that the usercopy API must only return complete failure
if absolutely nothing could be copied. Currently, if userspace does
something silly like giving us an unaligned pointer to Device memory,
or a size which overruns MTE tag bounds, we may fail to honour that
requirement when faulting on a multi-byte access even though a smaller
access could have succeeded.

Add a mitigation to the fixup routines to fall back to a single-byte
copy if we faulted on a larger access before anything has been written
to the destination, to guarantee making *some* forward progress. We
needn't be too concerned about the overall performance since this should
only occur when callers are doing something a bit dodgy in the first
place. Particularly broken userspace might still be able to trick
generic_perform_write() into an infinite loop by targeting write() at
an mmap() of some read-only device register where the fault-in load
succeeds but any store synchronously aborts such that copy_to_user() is
genuinely unable to make progress, but, well, don't do that...

CC: stable@vger.kernel.org
Reported-by: Chen Huang <chenhuang5@huawei.com>
Suggested-by: Al Viro <viro@zeniv.linux.org.uk>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Robin Murphy <robin.murphy@arm.com>
Link: https://lore.kernel.org/r/dc03d5c675731a1f24a62417dba5429ad744234e.1626098433.git.robin.murphy@arm.com
Signed-off-by: Will Deacon <will@kernel.org>
2021-07-15 17:29:14 +01:00
Christoph Hellwig
05d69d950d xen-blkfront: sanitize the removal state machine
xen-blkfront has a weird protocol where close message from the remote
side can be delayed, and where hot removals are treated somewhat
differently from regular removals, all leading to potential NULL
pointer removals, and a del_gendisk from the block device release
method, which will deadlock. Fix this by just performing normal hot
removals even when the device is opened like all other Linux block
drivers.

Fixes: c76f48eb5c ("block: take bd_mutex around delete_partitions in del_gendisk")
Reported-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Tested-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Link: https://lore.kernel.org/r/20210715141711.1257293-1-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-07-15 09:32:34 -06:00
Jens Axboe
a347c153b1 nvme fixes for Linux 5.14
- fix various races in nvme-pci when shutting down just after probing
    (Casey Chen)
  - fix a net_device leak in nvme-tcp (Prabhakar Kushwaha)
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Merge tag 'nvme-5.14-2021-07-15' of git://git.infradead.org/nvme into block-5.14

Pull NVMe fixes from Christoph:

"nvme fixes for Linux 5.14

 - fix various races in nvme-pci when shutting down just after probing
   (Casey Chen)
 - fix a net_device leak in nvme-tcp (Prabhakar Kushwaha)"

* tag 'nvme-5.14-2021-07-15' of git://git.infradead.org/nvme:
  nvme-pci: do not call nvme_dev_remove_admin from nvme_remove
  nvme-pci: fix multiple races in nvme_setup_io_queues
  nvme-tcp: use __dev_get_by_name instead dev_get_by_name for OPT_HOST_IFACE
2021-07-15 09:31:36 -06:00
Wang Qing
16ad3db3b2 nbd: fix order of cleaning up the queue and freeing the tagset
We must release the queue before freeing the tagset.

Fixes: 4af5f2e030 ("nbd: use blk_mq_alloc_disk and blk_cleanup_disk")
Reported-and-tested-by: syzbot+9ca43ff47167c0ee3466@syzkaller.appspotmail.com
Signed-off-by: Wang Qing <wangqing@vivo.com>
Signed-off-by: Guoqing Jiang <jiangguoqing@kylinos.cn>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20210706040016.1360412-1-guoqing.jiang@linux.dev
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-07-15 09:30:15 -06:00
Guoqing Jiang
58b63e0f55 pd: fix order of cleaning up the queue and freeing the tagset
We must release the queue before freeing the tagset.

Fixes: 262d431f90 ("pd: use blk_mq_alloc_disk and blk_cleanup_disk")
Signed-off-by: Guoqing Jiang <jiangguoqing@kylinos.cn>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20210706010734.1356066-1-guoqing.jiang@linux.dev
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-07-15 09:29:22 -06:00
Rob Herring
f88321a3bf dt-bindings: Move fixed string 'patternProperties' to 'properties'
There's no need for fixed strings to be under 'patternProperties', so move
them under 'properties' instead.

Cc: Jean Delvare <jdelvare@suse.com>
Cc: Guenter Roeck <linux@roeck-us.net>
Cc: Kishon Vijay Abraham I <kishon@ti.com>
Cc: Vinod Koul <vkoul@kernel.org>
Cc: Saravanan Sekar <sravanhome@gmail.com>
Cc: Mark Brown <broonie@kernel.org>
Cc: Jagan Teki <jagan@amarulasolutions.com>
Cc: Troy Kisky <troy.kisky@boundarydevices.com>
Cc: linux-hwmon@vger.kernel.org
Cc: linux-phy@lists.infradead.org
Cc: linux-spi@vger.kernel.org
Signed-off-by: Rob Herring <robh@kernel.org>
Acked-by: Mark Brown <broonie@kernel.org>
Acked-by: Guenter Roeck <linux@roeck-us.net>
Link: https://lore.kernel.org/r/20210713193514.690894-1-robh@kernel.org
2021-07-15 08:45:33 -06:00
Rob Herring
e8917266ae dt-bindings: More dropping redundant minItems/maxItems
Another round of removing redundant minItems/maxItems from new schema in
the recent merge window.

If a property has an 'items' list, then a 'minItems' or 'maxItems' with the
same size as the list is redundant and can be dropped. Note that is DT
schema specific behavior and not standard json-schema behavior. The tooling
will fixup the final schema adding any unspecified minItems/maxItems.

This condition is partially checked with the meta-schema already, but
only if both 'minItems' and 'maxItems' are equal to the 'items' length.
An improved meta-schema is pending.

Cc: Stephen Boyd <sboyd@kernel.org>
Cc: Joerg Roedel <joro@8bytes.org>
Cc: Will Deacon <will@kernel.org>
Cc: Krzysztof Kozlowski <krzysztof.kozlowski@canonical.com>
Cc: Miquel Raynal <miquel.raynal@bootlin.com>
Cc: Richard Weinberger <richard@nod.at>
Cc: Vignesh Raghavendra <vigneshr@ti.com>
Cc: Alessandro Zummo <a.zummo@towertech.it>
Cc: Alexandre Belloni <alexandre.belloni@bootlin.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Sureshkumar Relli <naga.sureshkumar.relli@xilinx.com>
Cc: Brian Norris <computersforpeace@gmail.com>
Cc: Kamal Dasu <kdasu.kdev@gmail.com>
Cc: Linus Walleij <linus.walleij@linaro.org>
Cc: Sebastian Siewior <bigeasy@linutronix.de>
Cc: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Cc: linux-clk@vger.kernel.org
Cc: iommu@lists.linux-foundation.org
Cc: linux-mtd@lists.infradead.org
Cc: linux-rtc@vger.kernel.org
Cc: linux-usb@vger.kernel.org
Signed-off-by: Rob Herring <robh@kernel.org>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Acked-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Link: https://lore.kernel.org/r/20210713193453.690290-1-robh@kernel.org
2021-07-15 08:45:27 -06:00
Vitaly Kuznetsov
d951b2210c KVM: selftests: smm_test: Test SMM enter from L2
Two additional tests are added:
- SMM triggered from L2 does not currupt L1 host state.
- Save/restore during SMM triggered from L2 does not corrupt guest/host
  state.

Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Message-Id: <20210628104425.391276-7-vkuznets@redhat.com>
Reviewed-by: Maxim Levitsky <mlevitsk@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2021-07-15 10:19:44 -04:00
Vitaly Kuznetsov
bb00bd9c08 KVM: nSVM: Restore nested control upon leaving SMM
If the VM was migrated while in SMM, no nested state was saved/restored,
and therefore svm_leave_smm has to load both save and control area
of the vmcb12. Save area is already loaded from HSAVE area,
so now load the control area as well from the vmcb12.

Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Message-Id: <20210628104425.391276-6-vkuznets@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2021-07-15 10:19:44 -04:00
Vitaly Kuznetsov
37be407b2c KVM: nSVM: Fix L1 state corruption upon return from SMM
VMCB split commit 4995a3685f ("KVM: SVM: Use a separate vmcb for the
nested L2 guest") broke return from SMM when we entered there from guest
(L2) mode. Gen2 WS2016/Hyper-V is known to do this on boot. The problem
manifests itself like this:

  kvm_exit:             reason EXIT_RSM rip 0x7ffbb280 info 0 0
  kvm_emulate_insn:     0:7ffbb280: 0f aa
  kvm_smm_transition:   vcpu 0: leaving SMM, smbase 0x7ffb3000
  kvm_nested_vmrun:     rip: 0x000000007ffbb280 vmcb: 0x0000000008224000
    nrip: 0xffffffffffbbe119 int_ctl: 0x01020000 event_inj: 0x00000000
    npt: on
  kvm_nested_intercepts: cr_read: 0000 cr_write: 0010 excp: 40060002
    intercepts: fd44bfeb 0000217f 00000000
  kvm_entry:            vcpu 0, rip 0xffffffffffbbe119
  kvm_exit:             reason EXIT_NPF rip 0xffffffffffbbe119 info
    200000006 1ab000
  kvm_nested_vmexit:    vcpu 0 reason npf rip 0xffffffffffbbe119 info1
    0x0000000200000006 info2 0x00000000001ab000 intr_info 0x00000000
    error_code 0x00000000
  kvm_page_fault:       address 1ab000 error_code 6
  kvm_nested_vmexit_inject: reason EXIT_NPF info1 200000006 info2 1ab000
    int_info 0 int_info_err 0
  kvm_entry:            vcpu 0, rip 0x7ffbb280
  kvm_exit:             reason EXIT_EXCP_GP rip 0x7ffbb280 info 0 0
  kvm_emulate_insn:     0:7ffbb280: 0f aa
  kvm_inj_exception:    #GP (0x0)

Note: return to L2 succeeded but upon first exit to L1 its RIP points to
'RSM' instruction but we're not in SMM.

The problem appears to be that VMCB01 gets irreversibly destroyed during
SMM execution. Previously, we used to have 'hsave' VMCB where regular
(pre-SMM) L1's state was saved upon nested_svm_vmexit() but now we just
switch to VMCB01 from VMCB02.

Pre-split (working) flow looked like:
- SMM is triggered during L2's execution
- L2's state is pushed to SMRAM
- nested_svm_vmexit() restores L1's state from 'hsave'
- SMM -> RSM
- enter_svm_guest_mode() switches to L2 but keeps 'hsave' intact so we have
  pre-SMM (and pre L2 VMRUN) L1's state there
- L2's state is restored from SMRAM
- upon first exit L1's state is restored from L1.

This was always broken with regards to svm_get_nested_state()/
svm_set_nested_state(): 'hsave' was never a part of what's being
save and restored so migration happening during SMM triggered from L2 would
never restore L1's state correctly.

Post-split flow (broken) looks like:
- SMM is triggered during L2's execution
- L2's state is pushed to SMRAM
- nested_svm_vmexit() switches to VMCB01 from VMCB02
- SMM -> RSM
- enter_svm_guest_mode() switches from VMCB01 to VMCB02 but pre-SMM VMCB01
  is already lost.
- L2's state is restored from SMRAM
- upon first exit L1's state is restored from VMCB01 but it is corrupted
 (reflects the state during 'RSM' execution).

VMX doesn't have this problem because unlike VMCB, VMCS keeps both guest
and host state so when we switch back to VMCS02 L1's state is intact there.

To resolve the issue we need to save L1's state somewhere. We could've
created a third VMCB for SMM but that would require us to modify saved
state format. L1's architectural HSAVE area (pointed by MSR_VM_HSAVE_PA)
seems appropriate: L0 is free to save any (or none) of L1's state there.
Currently, KVM does 'none'.

Note, for nested state migration to succeed, both source and destination
hypervisors must have the fix. We, however, don't need to create a new
flag indicating the fact that HSAVE area is now populated as migration
during SMM triggered from L2 was always broken.

Fixes: 4995a3685f ("KVM: SVM: Use a separate vmcb for the nested L2 guest")
Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2021-07-15 10:19:44 -04:00
Vitaly Kuznetsov
0a75829076 KVM: nSVM: Introduce svm_copy_vmrun_state()
Separate the code setting non-VMLOAD-VMSAVE state from
svm_set_nested_state() into its own function. This is going to be
re-used from svm_enter_smm()/svm_leave_smm().

Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Message-Id: <20210628104425.391276-4-vkuznets@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2021-07-15 10:19:43 -04:00
Vitaly Kuznetsov
fb79f566e4 KVM: nSVM: Check that VM_HSAVE_PA MSR was set before VMRUN
APM states that "The address written to the VM_HSAVE_PA MSR, which holds
the address of the page used to save the host state on a VMRUN, must point
to a hypervisor-owned page. If this check fails, the WRMSR will fail with
a #GP(0) exception. Note that a value of 0 is not considered valid for the
VM_HSAVE_PA MSR and a VMRUN that is attempted while the HSAVE_PA is 0 will
fail with a #GP(0) exception."

svm_set_msr() already checks that the supplied address is valid, so only
check for '0' is missing. Add it to nested_svm_vmrun().

Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Message-Id: <20210628104425.391276-3-vkuznets@redhat.com>
Reviewed-by: Maxim Levitsky <mlevitsk@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2021-07-15 10:19:43 -04:00
Vitaly Kuznetsov
fce7e152ff KVM: nSVM: Check the value written to MSR_VM_HSAVE_PA
APM states that #GP is raised upon write to MSR_VM_HSAVE_PA when
the supplied address is not page-aligned or is outside of "maximum
supported physical address for this implementation".
page_address_valid() check seems suitable. Also, forcefully page-align
the address when it's written from VMM.

Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Message-Id: <20210628104425.391276-2-vkuznets@redhat.com>
Cc: stable@vger.kernel.org
Reviewed-by: Maxim Levitsky <mlevitsk@redhat.com>
[Add comment about behavior for host-provided values. - Paolo]
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2021-07-15 10:19:43 -04:00
Sean Christopherson
c7a1b2b678 KVM: SVM: Fix sev_pin_memory() error checks in SEV migration utilities
Use IS_ERR() instead of checking for a NULL pointer when querying for
sev_pin_memory() failures.  sev_pin_memory() always returns an error code
cast to a pointer, or a valid pointer; it never returns NULL.

Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Cc: Steve Rutherford <srutherford@google.com>
Cc: Brijesh Singh <brijesh.singh@amd.com>
Cc: Ashish Kalra <ashish.kalra@amd.com>
Fixes: d3d1af85e2 ("KVM: SVM: Add KVM_SEND_UPDATE_DATA command")
Fixes: 15fb7de1a7 ("KVM: SVM: Add KVM_SEV_RECEIVE_UPDATE_DATA command")
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20210506175826.2166383-3-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2021-07-15 10:19:43 -04:00
Sean Christopherson
b4a693924a KVM: SVM: Return -EFAULT if copy_to_user() for SEV mig packet header fails
Return -EFAULT if copy_to_user() fails; if accessing user memory faults,
copy_to_user() returns the number of bytes remaining, not an error code.

Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Cc: Steve Rutherford <srutherford@google.com>
Cc: Brijesh Singh <brijesh.singh@amd.com>
Cc: Ashish Kalra <ashish.kalra@amd.com>
Fixes: d3d1af85e2 ("KVM: SVM: Add KVM_SEND_UPDATE_DATA command")
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20210506175826.2166383-2-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2021-07-15 10:19:42 -04:00
Maxim Levitsky
4b639a9f82 KVM: SVM: add module param to control the #SMI interception
In theory there are no side effects of not intercepting #SMI,
because then #SMI becomes transparent to the OS and the KVM.

Plus an observation on recent Zen2 CPUs reveals that these
CPUs ignore #SMI interception and never deliver #SMI VMexits.

This is also useful to test nested KVM to see that L1
handles #SMIs correctly in case when L1 doesn't intercept #SMI.

Finally the default remains the same, the SMI are intercepted
by default thus this patch doesn't have any effect unless
non default module param value is used.

Signed-off-by: Maxim Levitsky <mlevitsk@redhat.com>
Message-Id: <20210707125100.677203-4-mlevitsk@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2021-07-15 10:19:42 -04:00
Maxim Levitsky
896707c212 KVM: SVM: remove INIT intercept handler
Kernel never sends real INIT even to CPUs, other than on boot.

Thus INIT interception is an error which should be caught
by a check for an unknown VMexit reason.

On top of that, the current INIT VM exit handler skips
the current instruction which is wrong.
That was added in commit 5ff3a351f6 ("KVM: x86: Move trivial
instruction-based exit handlers to common code").

Fixes: 5ff3a351f6 ("KVM: x86: Move trivial instruction-based exit handlers to common code")
Signed-off-by: Maxim Levitsky <mlevitsk@redhat.com>
Message-Id: <20210707125100.677203-3-mlevitsk@redhat.com>
Cc: stable@vger.kernel.org
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2021-07-15 10:19:42 -04:00
Maxim Levitsky
991afbbee8 KVM: SVM: #SMI interception must not skip the instruction
Commit 5ff3a351f6 ("KVM: x86: Move trivial instruction-based
exit handlers to common code"), unfortunately made a mistake of
treating nop_on_interception and nop_interception in the same way.

Former does truly nothing while the latter skips the instruction.

SMI VM exit handler should do nothing.
(SMI itself is handled by the host when we do STGI)

Fixes: 5ff3a351f6 ("KVM: x86: Move trivial instruction-based exit handlers to common code")
Signed-off-by: Maxim Levitsky <mlevitsk@redhat.com>
Message-Id: <20210707125100.677203-2-mlevitsk@redhat.com>
Cc: stable@vger.kernel.org
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2021-07-15 10:19:42 -04:00
Yu Zhang
c0e1303ed4 KVM: VMX: Remove vmx_msr_index from vmx.h
vmx_msr_index was used to record the list of MSRs which can be lazily
restored when kvm returns to userspace. It is now reimplemented as
kvm_uret_msrs_list, a common x86 list which is only used inside x86.c.
So just remove the obsolete declaration in vmx.h.

Signed-off-by: Yu Zhang <yu.c.zhang@linux.intel.com>
Message-Id: <20210707235702.31595-1-yu.c.zhang@linux.intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2021-07-15 10:19:41 -04:00
Lai Jiangshan
f85d401606 KVM: X86: Disable hardware breakpoints unconditionally before kvm_x86->run()
When the host is using debug registers but the guest is not using them
nor is the guest in guest-debug state, the kvm code does not reset
the host debug registers before kvm_x86->run().  Rather, it relies on
the hardware vmentry instruction to automatically reset the dr7 registers
which ensures that the host breakpoints do not affect the guest.

This however violates the non-instrumentable nature around VM entry
and exit; for example, when a host breakpoint is set on vcpu->arch.cr2,

Another issue is consistency.  When the guest debug registers are active,
the host breakpoints are reset before kvm_x86->run(). But when the
guest debug registers are inactive, the host breakpoints are delayed to
be disabled.  The host tracing tools may see different results depending
on what the guest is doing.

To fix the problems, we clear %db7 unconditionally before kvm_x86->run()
if the host has set any breakpoints, no matter if the guest is using
them or not.

Signed-off-by: Lai Jiangshan <laijs@linux.alibaba.com>
Message-Id: <20210628172632.81029-1-jiangshanlai@gmail.com>
Cc: stable@vger.kernel.org
[Only clear %db7 instead of reloading all debug registers. - Paolo]
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2021-07-15 10:19:41 -04:00
Ricardo Koller
6f2f86ec28 KVM: selftests: Address extra memslot parameters in vm_vaddr_alloc
Commit a75a895e64 ("KVM: selftests: Unconditionally use memslot 0 for
vaddr allocations") removed the memslot parameters from vm_vaddr_alloc.
It addressed all callers except one under lib/aarch64/, due to a race
with commit e3db7579ef ("KVM: selftests: Add exception handling
support for aarch64")

Fix the vm_vaddr_alloc call in lib/aarch64/processor.c.

Reported-by: Zenghui Yu <yuzenghui@huawei.com>
Signed-off-by: Ricardo Koller <ricarkol@google.com>
Message-Id: <20210702201042.4036162-1-ricarkol@google.com>
Reviewed-by: Eric Auger <eric.auger@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2021-07-15 10:19:41 -04:00
Pavel Skripkin
004d62eb4e kvm: debugfs: fix memory leak in kvm_create_vm_debugfs
In commit bc9e9e672d ("KVM: debugfs: Reuse binary stats descriptors")
loop for filling debugfs_stat_data was copy-pasted 2 times, but
in the second loop pointers are saved over pointers allocated
in the first loop.  All this causes is a memory leak, fix it.

Fixes: bc9e9e672d ("KVM: debugfs: Reuse binary stats descriptors")
Signed-off-by: Pavel Skripkin <paskripkin@gmail.com>
Reviewed-by: Jing Zhang <jingzhangos@google.com>
Message-Id: <20210701195500.27097-1-paskripkin@gmail.com>
Reviewed-by: Jing Zhang <jingzhangos@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2021-07-15 10:19:40 -04:00
Thierry Reding
d549c66766 dt-bindings: net: dsa: sja1105: Fix indentation warnings
Some of the lines aren't properly indented, causing yamllint to warn
about them:

    .../nxp,sja1105.yaml:70:17: [warning] wrong indentation: expected 18 but found 16 (indentation)

Use the proper indentation to fix those warnings.

Signed-off-by: Thierry Reding <treding@nvidia.com>
Fixes: 070f5b701d ("dt-bindings: net: dsa: sja1105: add SJA1110 bindings")
Tested-by: Geert Uytterhoeven <geert+renesas@glider.be>
Link: https://lore.kernel.org/r/20210622113327.3613595-1-thierry.reding@gmail.com
Signed-off-by: Rob Herring <robh@kernel.org>
2021-07-15 07:35:15 -06:00
Hu Haowen
530c4374e2 docs/zh_CN: add a missing space character
"LinusTorvalds" is not pretty. Replace it with "Linus Torvalds".

Signed-off-by: Hu Haowen <src.res@email.cn>
Link: https://lore.kernel.org/r/20210620010444.24813-1-src.res@email.cn
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
2021-07-15 06:33:44 -06:00
Ingo Molnar
d3fb38266a Documentation/features: Add THREAD_INFO_IN_TASK feature matrix
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/YN2nhV5F0hBVNPuX@gmail.com
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
2021-07-15 06:33:44 -06:00
Ingo Molnar
842f697776 Documentation/features: Update the ARCH_HAS_TICK_BROADCAST entry
Risc-V gained support recently.

Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/YN2nqOVHgGDt4Iid@gmail.com
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
2021-07-15 06:33:44 -06:00
Nishanth Menon
21de80b53b LICENSES/dual/CC-BY-4.0: Git rid of "smart quotes"
A couple of exotic quote characters came in with this license text; they
can confuse software that is not expecting non-ASCII text.  Switch to
normal quotes here, with no changes to the actual license text.

Reported-by: Rahul T R <r-ravikumar@ti.com>
Signed-off-by: Nishanth Menon <nm@ti.com>
CC: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Thorsten Leemhuis <linux@leemhuis.info>
Acked-by: Randy Dunlap <rdunlap@infradead.org>
Link: https://lore.kernel.org/r/20210703012931.30604-1-nm@ti.com
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
2021-07-15 06:31:24 -06:00
Nicholas Piggin
e44fbdb680 KVM: PPC: Book3S HV P9: Fix guest TM support
The conversion to C introduced several bugs in TM handling that can
cause host crashes with TM bad thing interrupts. Mostly just simple
typos or missed logic in the conversion that got through due to my
not testing TM in the guest sufficiently.

- Early TM emulation for the softpatch interrupt should be done if fake
  suspend mode is _not_ active.

- Early TM emulation wants to return immediately to the guest so as to
  not doom transactions unnecessarily.

- And if exiting from the guest, the host MSR should include the TM[S]
  bit if the guest was T/S, before it is treclaimed.

After this fix, all the TM selftests pass when running on a P9 processor
that implements TM with softpatch interrupt.

Fixes: 89d35b2391 ("KVM: PPC: Book3S HV P9: Implement the rest of the P9 path in C")
Reported-by: Alexey Kardashevskiy <aik@ozlabs.ru>
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20210712013650.376325-1-npiggin@gmail.com
2021-07-15 21:53:37 +10:00
Lucas Stach
ac34de14ac Revert "soc: imx8m: change to use platform driver"
With the SoC matching changed to a platform driver the match data
is available only after other drivers, which may rely on it are
already probed. This breaks at least the CAAM driver on i.MX8M.
Revert the change until all those drivers have been audited and
changed to be able to eal with match data being available later
in the boot process.

Fixes: 7d981405d0 ("soc: imx8m: change to use platform driver")
Signed-off-by: Lucas Stach <l.stach@pengutronix.de>
Tested-by: Frieder Schrempf <frieder.schrempf@kontron.de>
Acked-by: Peng Fan <peng.fan@nxp.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>
2021-07-15 19:02:44 +08:00
Vasily Gorbik
f8c2602733 s390/ftrace: fix ftrace_update_ftrace_func implementation
s390 enforces DYNAMIC_FTRACE if FUNCTION_TRACER is selected.
At the same time implementation of ftrace_caller is not compliant with
HAVE_DYNAMIC_FTRACE since it doesn't provide implementation of
ftrace_update_ftrace_func() and calls ftrace_trace_function() directly.

The subtle difference is that during ftrace code patching ftrace
replaces function tracer via ftrace_update_ftrace_func() and activates
it back afterwards. Unexpected direct calls to ftrace_trace_function()
during ftrace code patching leads to nullptr-dereferences when tracing
is activated for one of functions which are used during code patching.
Those function currently are:
copy_from_kernel_nofault()
copy_from_kernel_nofault_allowed()
preempt_count_sub() [with debug_defconfig]
preempt_count_add() [with debug_defconfig]

Corresponding KASAN report:
 BUG: KASAN: nullptr-dereference in function_trace_call+0x316/0x3b0
 Read of size 4 at addr 0000000000001e08 by task migration/0/15

 CPU: 0 PID: 15 Comm: migration/0 Tainted: G B 5.13.0-41423-g08316af3644d
 Hardware name: IBM 3906 M04 704 (LPAR)
 Stopper: multi_cpu_stop+0x0/0x3e0 <- stop_machine_cpuslocked+0x1e4/0x218
 Call Trace:
  [<0000000001f77caa>] show_stack+0x16a/0x1d0
  [<0000000001f8de42>] dump_stack+0x15a/0x1b0
  [<0000000001f81d56>] print_address_description.constprop.0+0x66/0x2e0
  [<000000000082b0ca>] kasan_report+0x152/0x1c0
  [<00000000004cfd8e>] function_trace_call+0x316/0x3b0
  [<0000000001fb7082>] ftrace_caller+0x7a/0x7e
  [<00000000006bb3e6>] copy_from_kernel_nofault_allowed+0x6/0x10
  [<00000000006bb42e>] copy_from_kernel_nofault+0x3e/0xd0
  [<000000000014605c>] ftrace_make_call+0xb4/0x1f8
  [<000000000047a1b4>] ftrace_replace_code+0x134/0x1d8
  [<000000000047a6e0>] ftrace_modify_all_code+0x120/0x1d0
  [<000000000047a7ec>] __ftrace_modify_code+0x5c/0x78
  [<000000000042395c>] multi_cpu_stop+0x224/0x3e0
  [<0000000000423212>] cpu_stopper_thread+0x33a/0x5a0
  [<0000000000243ff2>] smpboot_thread_fn+0x302/0x708
  [<00000000002329ea>] kthread+0x342/0x408
  [<00000000001066b2>] __ret_from_fork+0x92/0xf0
  [<0000000001fb57fa>] ret_from_fork+0xa/0x30

 The buggy address belongs to the page:
 page:(____ptrval____) refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x1
 flags: 0x1ffff00000001000(reserved|node=0|zone=0|lastcpupid=0x1ffff)
 raw: 1ffff00000001000 0000040000000048 0000040000000048 0000000000000000
 raw: 0000000000000000 0000000000000000 ffffffff00000001 0000000000000000
 page dumped because: kasan: bad access detected

 Memory state around the buggy address:
  0000000000001d00: f7 f7 f7 f7 f7 f7 f7 f7 f7 f7 f7 f7 f7 f7 f7 f7
  0000000000001d80: f7 f7 f7 f7 f7 f7 f7 f7 f7 f7 f7 f7 f7 f7 f7 f7
 >0000000000001e00: f7 f7 f7 f7 f7 f7 f7 f7 f7 f7 f7 f7 f7 f7 f7 f7
                       ^
  0000000000001e80: f7 f7 f7 f7 f7 f7 f7 f7 f7 f7 f7 f7 f7 f7 f7 f7
  0000000000001f00: f7 f7 f7 f7 f7 f7 f7 f7 f7 f7 f7 f7 f7 f7 f7 f7
 ==================================================================

To fix that introduce ftrace_func callback to be called from
ftrace_caller and update it in ftrace_update_ftrace_func().

Fixes: 4cc9bed034 ("[S390] cleanup ftrace backend functions")
Cc: stable@vger.kernel.org
Reviewed-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
2021-07-15 12:54:58 +02:00
Maxime Ripard
32a19de21a
drm/vc4: hdmi: Drop devm interrupt handler for CEC interrupts
The CEC interrupt handlers are registered through the
devm_request_threaded_irq function. However, while free_irq is indeed
called properly when the device is unbound or bind fails, it's called
after unbind or bind is done.

In our particular case, it means that on failure it creates a window
where our interrupt handler can be called, but we're freeing every
resource (CEC adapter, DRM objects, etc.) it might need.

In order to address this, let's switch to the non-devm variant to
control better when the handler will be unregistered and allow us to
make it safe.

Fixes: 15b4511a4a ("drm/vc4: add HDMI CEC support")
Signed-off-by: Maxime Ripard <maxime@cerno.tech>
Reviewed-by: Dave Stevenson <dave.stevenson@raspberrypi.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20210707095112.1469670-2-maxime@cerno.tech
2021-07-15 10:43:20 +02:00
Yang Yingliang
95edbbf78c platform/x86: amd-pmc: Fix missing unlock on error in amd_pmc_send_cmd()
Add the missing unlock before return from function amd_pmc_send_cmd()
in the error handling case.

Fixes: 95e1b60f8d ("platform/x86: amd-pmc: Fix command completion code")
Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>
Link: https://lore.kernel.org/r/20210715074327.1966083-1-yangyingliang@huawei.com
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
2021-07-15 10:27:20 +02:00
Suravee Suthikulpanit
4a5c155a5a MAINTAINERS: Add Suravee Suthikulpanit as Reviewer for AMD IOMMU (AMD-Vi)
To help review changes related to AMD IOMMU.

Signed-off-by: Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>
Link: https://lore.kernel.org/r/1626296542-30454-1-git-send-email-suravee.suthikulpanit@amd.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>
2021-07-15 09:00:16 +02:00
Nicolas Saenz Julienne
aebacb7f6c timers: Fix get_next_timer_interrupt() with no timers pending
31cd0e119d ("timers: Recalculate next timer interrupt only when
necessary") subtly altered get_next_timer_interrupt()'s behaviour. The
function no longer consistently returns KTIME_MAX with no timers
pending.

In order to decide if there are any timers pending we check whether the
next expiry will happen NEXT_TIMER_MAX_DELTA jiffies from now.
Unfortunately, the next expiry time and the timer base clock are no
longer updated in unison. The former changes upon certain timer
operations (enqueue, expire, detach), whereas the latter keeps track of
jiffies as they move forward. Ultimately breaking the logic above.

A simplified example:

- Upon entering get_next_timer_interrupt() with:

	jiffies = 1
	base->clk = 0;
	base->next_expiry = NEXT_TIMER_MAX_DELTA;

  'base->next_expiry == base->clk + NEXT_TIMER_MAX_DELTA', the function
  returns KTIME_MAX.

- 'base->clk' is updated to the jiffies value.

- The next time we enter get_next_timer_interrupt(), taking into account
  no timer operations happened:

	base->clk = 1;
	base->next_expiry = NEXT_TIMER_MAX_DELTA;

  'base->next_expiry != base->clk + NEXT_TIMER_MAX_DELTA', the function
  returns a valid expire time, which is incorrect.

This ultimately might unnecessarily rearm sched's timer on nohz_full
setups, and add latency to the system[1].

So, introduce 'base->timers_pending'[2], update it every time
'base->next_expiry' changes, and use it in get_next_timer_interrupt().

[1] See tick_nohz_stop_tick().
[2] A quick pahole check on x86_64 and arm64 shows it doesn't make
    'struct timer_base' any bigger.

Fixes: 31cd0e119d ("timers: Recalculate next timer interrupt only when necessary")
Signed-off-by: Nicolas Saenz Julienne <nsaenzju@redhat.com>
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
2021-07-15 01:23:54 +02:00
Frederic Weisbecker
1a3402d93c posix-cpu-timers: Fix rearm racing against process tick
Since the process wide cputime counter is started locklessly from
posix_cpu_timer_rearm(), it can be concurrently stopped by operations
on other timers from the same thread group, such as in the following
unlucky scenario:

         CPU 0                                CPU 1
         -----                                -----
                                           timer_settime(TIMER B)
   posix_cpu_timer_rearm(TIMER A)
       cpu_clock_sample_group()
           (pct->timers_active already true)

                                           handle_posix_cpu_timers()
                                               check_process_timers()
                                                   stop_process_timers()
                                                       pct->timers_active = false
       arm_timer(TIMER A)

   tick -> run_posix_cpu_timers()
       // sees !pct->timers_active, ignore
       // our TIMER A

Fix this with simply locking process wide cputime counting start and
timer arm in the same block.

Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Fixes: 60f2ceaa81 ("posix-cpu-timers: Remove unnecessary locking around cpu_clock_sample_group")
Cc: stable@vger.kernel.org
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Eric W. Biederman <ebiederm@xmission.com>
2021-07-15 01:20:10 +02:00