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Linux kernel
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Pull x86 fix from Thomas Gleixner:
"A single fix for x86.
Revert the recent change to the MTRR code which aimed to support
SEV-SNP guests on Hyper-V. It caused a regression on XEN Dom0 kernels.
The underlying issue of MTTR (mis)handling in the x86 code needs some
deeper investigation and is definitely not 6.2 material"
* tag 'x86-urgent-2023-02-19' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
x86/mtrr: Revert 90b926e68f50 ("x86/pat: Fix pat_x_mtrr_type() for MTRR disabled case")
Pull timer fix from Thomas Gleixner:
"A fix for a long standing issue in the alarmtimer code.
Posix-timers armed with a short interval with an ignored signal result
in an unpriviledged DoS. Due to the ignored signal the timer switches
into self rearm mode. This issue had been "fixed" before but a rework
of the alarmtimer code 5 years ago lost that workaround.
There is no real good solution for this issue, which is also worked
around in the core posix-timer code in the same way, but it certainly
moved way up on the ever growing todo list"
* tag 'timers-urgent-2023-02-19' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
alarmtimer: Prevent starvation by small intervals and SIG_IGN
Commit
90b926e68f50 ("x86/pat: Fix pat_x_mtrr_type() for MTRR disabled case")
broke the use case of running Xen dom0 kernels on machines with an
external disk enclosure attached via USB, see Link tag.
What this commit was originally fixing - SEV-SNP guests on Hyper-V - is
a more specialized situation which has other issues at the moment anyway
so reverting this now and addressing the issue properly later is the
prudent thing to do.
So revert it in time for the 6.2 proper release.
[ bp: Rewrite commit message. ]
Reported-by: Christian Kujau <lists@nerdbynature.de>
Tested-by: Christian Kujau <lists@nerdbynature.de>
Signed-off-by: Juergen Gross <jgross@suse.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Link: https://lore.kernel.org/r/4fe9541e-4d4c-2b2a-f8c8-2d34a7284930@nerdbynature.de
Pull irq fix from Thomas Gleixner:
"A single build fix for the PCI/MSI infrastructure.
The addition of the new alloc/free interfaces in this cycle forgot to
add stub functions for pci_msix_alloc_irq_at() and pci_msix_free_irq()
for the CONFIG_PCI_MSI=n case"
* tag 'irq-urgent-2023-02-19' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
PCI/MSI: Provide missing stubs for CONFIG_PCI_MSI=n
syzbot reported a RCU stall which is caused by setting up an alarmtimer
with a very small interval and ignoring the signal. The reproducer arms the
alarm timer with a relative expiry of 8ns and an interval of 9ns. Not a
problem per se, but that's an issue when the signal is ignored because then
the timer is immediately rearmed because there is no way to delay that
rearming to the signal delivery path. See posix_timer_fn() and commit
58229a189942 ("posix-timers: Prevent softirq starvation by small intervals
and SIG_IGN") for details.
The reproducer does not set SIG_IGN explicitely, but it sets up the timers
signal with SIGCONT. That has the same effect as explicitely setting
SIG_IGN for a signal as SIGCONT is ignored if there is no handler set and
the task is not ptraced.
The log clearly shows that:
[pid 5102] --- SIGCONT {si_signo=SIGCONT, si_code=SI_TIMER, si_timerid=0, si_overrun=316014, si_int=0, si_ptr=NULL} ---
It works because the tasks are traced and therefore the signal is queued so
the tracer can see it, which delays the restart of the timer to the signal
delivery path. But then the tracer is killed:
[pid 5087] kill(-5102, SIGKILL <unfinished ...>
...
./strace-static-x86_64: Process 5107 detached
and after it's gone the stall can be observed:
syzkaller login: [ 79.439102][ C0] hrtimer: interrupt took 68471 ns
[ 184.460538][ C1] rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
...
[ 184.658237][ C1] rcu: Stack dump where RCU GP kthread last ran:
[ 184.664574][ C1] Sending NMI from CPU 1 to CPUs 0:
[ 184.669821][ C0] NMI backtrace for cpu 0
[ 184.669831][ C0] CPU: 0 PID: 5108 Comm: syz-executor192 Not tainted 6.2.0-rc6-next-20230203-syzkaller #0
...
[ 184.670036][ C0] Call Trace:
[ 184.670041][ C0] <IRQ>
[ 184.670045][ C0] alarmtimer_fired+0x327/0x670
posix_timer_fn() prevents that by checking whether the interval for
timers which have the signal ignored is smaller than a jiffie and
artifically delay it by shifting the next expiry out by a jiffie. That's
accurate vs. the overrun accounting, but slightly inaccurate
vs. timer_gettimer(2).
The comment in that function says what needs to be done and there was a fix
available for the regular userspace induced SIG_IGN mechanism, but that did
not work due to the implicit ignore for SIGCONT and similar signals. This
needs to be worked on, but for now the only available workaround is to do
exactly what posix_timer_fn() does:
Increase the interval of self-rearming timers, which have their signal
ignored, to at least a jiffie.
Interestingly this has been fixed before via commit ff86bf0c65f1
("alarmtimer: Rate limit periodic intervals") already, but that fix got
lost in a later rework.
Reported-by: syzbot+b9564ba6e8e00694511b@syzkaller.appspotmail.com
Fixes: f2c45807d399 ("alarmtimer: Switch over to generic set/get/rearm routine")
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: John Stultz <jstultz@google.com>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/87k00q1no2.ffs@tglx
Pull kvm/x86 fixes from Paolo Bonzini:
- zero all padding for KVM_GET_DEBUGREGS
- fix rST warning
- disable vPMU support on hybrid CPUs
* tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm:
kvm: initialize all of the kvm_debugregs structure before sending it to userspace
perf/x86: Refuse to export capabilities for hybrid PMUs
KVM: x86/pmu: Disable vPMU support on hybrid CPUs (host PMUs)
Documentation/hw-vuln: Fix rST warning
pci_msix_alloc_irq_at() and pci_msix_free_irq() are not declared when
CONFIG_PCI_MSI is disabled.
Users of these two calls do not yet exist but when users do appear (shown
below is an attempt to use the new API in vfio-pci) the following errors
will be encountered when compiling with CONFIG_PCI_MSI disabled:
drivers/vfio/pci/vfio_pci_intrs.c:461:4: error: implicit declaration of\
function 'pci_msix_free_irq' is invalid in C99\
[-Werror,-Wimplicit-function-declaration]
pci_msix_free_irq(pdev, msix_map);
^
drivers/vfio/pci/vfio_pci_intrs.c:511:15: error: implicit declaration of\
function 'pci_msix_alloc_irq_at' is invalid in C99\
[-Werror,-Wimplicit-function-declaration]
msix_map = pci_msix_alloc_irq_at(pdev, vector, NULL);
Provide definitions for pci_msix_alloc_irq_at() and pci_msix_free_irq() in
preparation for users that need to compile when CONFIG_PCI_MSI is
disabled.
Reported-by: kernel test robot <lkp@intel.com>
Fixes: 34026364df8e ("PCI/MSI: Provide post-enable dynamic allocation interfaces for MSI-X")
Signed-off-by: Reinette Chatre <reinette.chatre@intel.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/158e40e1cfcfc58ae30ecb2bbfaf86e5bba7a1ef.1675978686.git.reinette.chatre@intel.com
Both Rich Felker and Yoshinori Sato haven't done any work on arch/sh
for a while. As I have been maintaining Debian's sh4 port since 2014,
I am interested to keep the architecture alive.
Signed-off-by: John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de>
Acked-by: Yoshinori Sato <ysato@users.sourceforge.jp>
Acked-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Pull arm64 regression fix from Will Deacon:
"Apologies for the _extremely_ late pull request here, but we had a
'perf' (i.e. CPU PMU) regression on the Apple M1 reported on Wednesday
[1] which was introduced by bd2756811766 ("perf: Rewrite core context
handling") during the merge window.
Mark and I looked into this and noticed an additional problem caused
by the same patch, where the 'CHAIN' event (used to combine two
adjacent 32-bit counters into a single 64-bit counter) was not being
filtered correctly. Mark posted a series on Thursday [2] which
addresses both of these regressions and I queued it the same day.
The changes are small, self-contained and have been confirmed to fix
the original regression.
Summary:
- Fix 'perf' regression for non-standard CPU PMU hardware (i.e. Apple
M1)"
* tag 'arm64-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux:
arm64: perf: reject CHAIN events at creation time
arm_pmu: fix event CPU filtering
When calling the KVM_GET_DEBUGREGS ioctl, on some configurations, there
might be some unitialized portions of the kvm_debugregs structure that
could be copied to userspace. Prevent this as is done in the other kvm
ioctls, by setting the whole structure to 0 before copying anything into
it.
Bonus is that this reduces the lines of code as the explicit flag
setting and reserved space zeroing out can be removed.
Cc: Sean Christopherson <seanjc@google.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: <x86@kernel.org>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: stable <stable@kernel.org>
Reported-by: Xingyuan Mo <hdthky0@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Message-Id: <20230214103304.3689213-1-gregkh@linuxfoundation.org>
Tested-by: Xingyuan Mo <hdthky0@gmail.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Pull tracing fix from Steven Rostedt:
"Fix showing of TASK_COMM_LEN instead of its value
The TASK_COMM_LEN was converted from a macro into an enum so that BTF
would have access to it. But this unfortunately caused TASK_COMM_LEN
to display in the format fields of trace events, as they are created
by the TRACE_EVENT() macro and such, macros convert to their values,
where as enums do not.
To handle this, instead of using the field itself to be display, save
the value of the array size as another field in the trace_event_fields
structure, and use that instead.
Not only does this fix the issue, but also converts the other trace
events that have this same problem (but were not breaking tooling).
With this change, the original work around b3bc8547d3be6 ("tracing:
Have TRACE_DEFINE_ENUM affect trace event types as well") could be
reverted (but that should be done in the merge window)"
* tag 'trace-v6.2-rc7' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace:
tracing: Fix TASK_COMM_LEN in trace event format file
Pull block fix from Jens Axboe:
"I guess this is what can happen when you prep things early for going
away, something else comes in last minute. This one fixes another
regression in 6.2 for NVMe, from this release, and hence we should
probably get it submitted for 6.2.
Still waiting for the original reporter (see bugzilla linked in the
commit) to test this, but Keith managed to setup and recreate the
issue and tested the patch that way"
* tag 'block-6.2-2023-02-17' of git://git.kernel.dk/linux:
nvme-pci: refresh visible attrs for cmb attributes
Currently it's possible for a user to open CHAIN events arbitrarily,
which we previously tried to rule out in commit:
ca2b497253ad01c8 ("arm64: perf: Reject stand-alone CHAIN events for PMUv3")
Which allowed the events to be opened, but prevented them from being
scheduled by by using an arm_pmu::filter_match hook to reject the
relevant events.
The CHAIN event filtering in the arm_pmu::filter_match hook was silently
removed in commit:
bd27568117664b8b ("perf: Rewrite core context handling")
As a result, it's now possible for users to open CHAIN events, and for
these to be installed arbitrarily.
Fix this by rejecting CHAIN events at creation time. This avoids the
creation of events which will never count, and doesn't require using the
dynamic filtering.
Attempting to open a CHAIN event (0x1e) will now be rejected:
| # ./perf stat -e armv8_pmuv3/config=0x1e/ ls
| perf
|
| Performance counter stats for 'ls':
|
| <not supported> armv8_pmuv3/config=0x1e/
|
| 0.002197470 seconds time elapsed
|
| 0.000000000 seconds user
| 0.002294000 seconds sys
Other events (e.g. CPU_CYCLES / 0x11) will open as usual:
| # ./perf stat -e armv8_pmuv3/config=0x11/ ls
| perf
|
| Performance counter stats for 'ls':
|
| 2538761 armv8_pmuv3/config=0x11/
|
| 0.002227330 seconds time elapsed
|
| 0.002369000 seconds user
| 0.000000000 seconds sys
Fixes: bd2756811766 ("perf: Rewrite core context handling")
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ravi Bangoria <ravi.bangoria@amd.com>
Cc: Will Deacon <will@kernel.org>
Link: https://lore.kernel.org/r/20230216141240.3833272-3-mark.rutland@arm.com
Signed-off-by: Will Deacon <will@kernel.org>
Now that KVM disables vPMU support on hybrid CPUs, WARN and return zeros
if perf_get_x86_pmu_capability() is invoked on a hybrid CPU. The helper
doesn't provide an accurate accounting of the PMU capabilities for hybrid
CPUs and needs to be enhanced if KVM, or anything else outside of perf,
wants to act on the PMU capabilities.
Cc: stable@vger.kernel.org
Cc: Andrew Cooper <Andrew.Cooper3@citrix.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Kan Liang <kan.liang@linux.intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
Link: https://lore.kernel.org/all/20220818181530.2355034-1-kan.liang@linux.intel.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20230208204230.1360502-3-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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