linux-stable.git/arch/x86/kernel/apic/vector.c, branch linux-5.2.y

x86/apic/vector: Warn when vector space exhaustion breaks affinity

2019-10-05T11:13:50+00:00

[ Upstream commit 743dac494d61d991967ebcfab92e4f80dc7583b3 ]

On x86, CPUs are limited in the number of interrupts they can have affined
to them as they only support 256 interrupt vectors per CPU. 32 vectors are
reserved for the CPU and the kernel reserves another 22 for internal
purposes. That leaves 202 vectors for assignement to devices.

When an interrupt is set up or the affinity is changed by the kernel or the
administrator, the vector assignment code attempts to honor the requested
affinity mask. If the vector space on the CPUs in that affinity mask is
exhausted the code falls back to a wider set of CPUs and assigns a vector
on a CPU outside of the requested affinity mask silently.

While the effective affinity is reflected in the corresponding
/proc/irq/$N/effective_affinity* files the silent breakage of the requested
affinity can lead to unexpected behaviour for administrators.

Add a pr_warn() when this happens so that adminstrators get at least
informed about it in the syslog.

[ tglx: Massaged changelog and made the pr_warn() more informative ]

Reported-by: djuran@redhat.com
Signed-off-by: Neil Horman 
Signed-off-by: Thomas Gleixner 
Tested-by: djuran@redhat.com
Link: https://lkml.kernel.org/r/20190822143421.9535-1-nhorman@tuxdriver.com
Signed-off-by: Sasha Levin

x86/irq: Handle spurious interrupt after shutdown gracefully

2019-07-21T07:00:40+00:00

commit b7107a67f0d125459fe41f86e8079afd1a5e0b15 upstream.

Since the rework of the vector management, warnings about spurious
interrupts have been reported. Robert provided some more information and
did an initial analysis. The following situation leads to these warnings:

   CPU 0                  CPU 1               IO_APIC

                                              interrupt is raised
                                              sent to CPU1
			  Unable to handle
			  immediately
			  (interrupts off,
			   deep idle delay)
   mask()
   ...
   free()
     shutdown()
     synchronize_irq()
     clear_vector()
                          do_IRQ()
                            -> vector is clear

Before the rework the vector entries of legacy interrupts were statically
assigned and occupied precious vector space while most of them were
unused. Due to that the above situation was handled silently because the
vector was handled and the core handler of the assigned interrupt
descriptor noticed that it is shut down and returned.

While this has been usually observed with legacy interrupts, this situation
is not limited to them. Any other interrupt source, e.g. MSI, can cause the
same issue.

After adding proper synchronization for level triggered interrupts, this
can only happen for edge triggered interrupts where the IO-APIC obviously
cannot provide information about interrupts in flight.

While the spurious warning is actually harmless in this case it worries
users and driver developers.

Handle it gracefully by marking the vector entry as VECTOR_SHUTDOWN instead
of VECTOR_UNUSED when the vector is freed up.

If that above late handling happens the spurious detector will not complain
and switch the entry to VECTOR_UNUSED. Any subsequent spurious interrupt on
that line will trigger the spurious warning as before.

Fixes: 464d12309e1b ("x86/vector: Switch IOAPIC to global reservation mode")
Reported-by: Robert Hodaszi 
Signed-off-by: Thomas Gleixner -
Tested-by: Robert Hodaszi 
Cc: Marc Zyngier 
Link: https://lkml.kernel.org/r/20190628111440.459647741@linutronix.de
Signed-off-by: Greg Kroah-Hartman

treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 500

2019-06-19T15:09:55+00:00

Based on 2 normalized pattern(s):

  this program is free software you can redistribute it and or modify
  it under the terms of the gnu general public license version 2 as
  published by the free software foundation

  this program is free software you can redistribute it and or modify
  it under the terms of the gnu general public license version 2 as
  published by the free software foundation #

extracted by the scancode license scanner the SPDX license identifier

  GPL-2.0-only

has been chosen to replace the boilerplate/reference in 4122 file(s).

Signed-off-by: Thomas Gleixner 
Reviewed-by: Enrico Weigelt 
Reviewed-by: Kate Stewart 
Reviewed-by: Allison Randal 
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190604081206.933168790@linutronix.de
Signed-off-by: Greg Kroah-Hartman

x86/kernel: Fix more -Wmissing-prototypes warnings

2018-12-08T11:24:35+00:00

... with the goal of eventually enabling -Wmissing-prototypes by
default. At least on x86.

Make functions static where possible, otherwise add prototypes or make
them visible through includes.

asm/trace/ changes courtesy of Steven Rostedt .

Signed-off-by: Borislav Petkov 
Reviewed-by: Masami Hiramatsu 
Reviewed-by: Ingo Molnar 
Acked-by: Rafael J. Wysocki  # ACPI + cpufreq bits
Cc: Andrew Banman 
Cc: Dimitri Sivanich 
Cc: "H. Peter Anvin" 
Cc: Ingo Molnar 
Cc: Masami Hiramatsu 
Cc: Mike Travis 
Cc: "Steven Rostedt (VMware)" 
Cc: Thomas Gleixner 
Cc: Yi Wang 
Cc: linux-acpi@vger.kernel.org

irq/matrix: Spread managed interrupts on allocation

2018-09-18T16:27:24+00:00

Linux spreads out the non managed interrupt across the possible target CPUs
to avoid vector space exhaustion.

Managed interrupts are treated differently, as for them the vectors are
reserved (with guarantee) when the interrupt descriptors are initialized.

When the interrupt is requested a real vector is assigned. The assignment
logic uses the first CPU in the affinity mask for assignment. If the
interrupt has more than one CPU in the affinity mask, which happens when a
multi queue device has less queues than CPUs, then doing the same search as
for non managed interrupts makes sense as it puts the interrupt on the
least interrupt plagued CPU. For single CPU affine vectors that's obviously
a NOOP.

Restructre the matrix allocation code so it does the 'best CPU' search, add
the sanity check for an empty affinity mask and adapt the call site in the
x86 vector management code.

[ tglx: Added the empty mask check to the core and improved change log ]

Signed-off-by: Dou Liyang 
Signed-off-by: Thomas Gleixner 
Cc: hpa@zytor.com
Link: https://lkml.kernel.org/r/20180908175838.14450-2-dou_liyang@163.com

x86/apic/vector: Make error return value negative

2018-09-08T10:12:40+00:00

activate_managed() returns EINVAL instead of -EINVAL in case of
error. While this is unlikely to happen, the positive return value would
cause further malfunction at the call site.

Fixes: 2db1f959d9dc ("x86/vector: Handle managed interrupts proper")
Signed-off-by: Thomas Gleixner 
Cc: stable@vger.kernel.org

Merge branch 'l1tf-final' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

2018-08-14T16:46:06+00:00

Merge L1 Terminal Fault fixes from Thomas Gleixner:
 "L1TF, aka L1 Terminal Fault, is yet another speculative hardware
  engineering trainwreck. It's a hardware vulnerability which allows
  unprivileged speculative access to data which is available in the
  Level 1 Data Cache when the page table entry controlling the virtual
  address, which is used for the access, has the Present bit cleared or
  other reserved bits set.

  If an instruction accesses a virtual address for which the relevant
  page table entry (PTE) has the Present bit cleared or other reserved
  bits set, then speculative execution ignores the invalid PTE and loads
  the referenced data if it is present in the Level 1 Data Cache, as if
  the page referenced by the address bits in the PTE was still present
  and accessible.

  While this is a purely speculative mechanism and the instruction will
  raise a page fault when it is retired eventually, the pure act of
  loading the data and making it available to other speculative
  instructions opens up the opportunity for side channel attacks to
  unprivileged malicious code, similar to the Meltdown attack.

  While Meltdown breaks the user space to kernel space protection, L1TF
  allows to attack any physical memory address in the system and the
  attack works across all protection domains. It allows an attack of SGX
  and also works from inside virtual machines because the speculation
  bypasses the extended page table (EPT) protection mechanism.

  The assoicated CVEs are: CVE-2018-3615, CVE-2018-3620, CVE-2018-3646

  The mitigations provided by this pull request include:

   - Host side protection by inverting the upper address bits of a non
     present page table entry so the entry points to uncacheable memory.

   - Hypervisor protection by flushing L1 Data Cache on VMENTER.

   - SMT (HyperThreading) control knobs, which allow to 'turn off' SMT
     by offlining the sibling CPU threads. The knobs are available on
     the kernel command line and at runtime via sysfs

   - Control knobs for the hypervisor mitigation, related to L1D flush
     and SMT control. The knobs are available on the kernel command line
     and at runtime via sysfs

   - Extensive documentation about L1TF including various degrees of
     mitigations.

  Thanks to all people who have contributed to this in various ways -
  patches, review, testing, backporting - and the fruitful, sometimes
  heated, but at the end constructive discussions.

  There is work in progress to provide other forms of mitigations, which
  might be less horrible performance wise for a particular kind of
  workloads, but this is not yet ready for consumption due to their
  complexity and limitations"

* 'l1tf-final' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (75 commits)
  x86/microcode: Allow late microcode loading with SMT disabled
  tools headers: Synchronise x86 cpufeatures.h for L1TF additions
  x86/mm/kmmio: Make the tracer robust against L1TF
  x86/mm/pat: Make set_memory_np() L1TF safe
  x86/speculation/l1tf: Make pmd/pud_mknotpresent() invert
  x86/speculation/l1tf: Invert all not present mappings
  cpu/hotplug: Fix SMT supported evaluation
  KVM: VMX: Tell the nested hypervisor to skip L1D flush on vmentry
  x86/speculation: Use ARCH_CAPABILITIES to skip L1D flush on vmentry
  x86/speculation: Simplify sysfs report of VMX L1TF vulnerability
  Documentation/l1tf: Remove Yonah processors from not vulnerable list
  x86/KVM/VMX: Don't set l1tf_flush_l1d from vmx_handle_external_intr()
  x86/irq: Let interrupt handlers set kvm_cpu_l1tf_flush_l1d
  x86: Don't include linux/irq.h from asm/hardirq.h
  x86/KVM/VMX: Introduce per-host-cpu analogue of l1tf_flush_l1d
  x86/irq: Demote irq_cpustat_t::__softirq_pending to u16
  x86/KVM/VMX: Move the l1tf_flush_l1d test to vmx_l1d_flush()
  x86/KVM/VMX: Replace 'vmx_l1d_flush_always' with 'vmx_l1d_flush_cond'
  x86/KVM/VMX: Don't set l1tf_flush_l1d to true from vmx_l1d_flush()
  cpu/hotplug: detect SMT disabled by BIOS
  ...

Merge branch 'x86-apic-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

2018-08-13T20:31:08+00:00

Pull x86 apic update from Thomas Gleixner:
 "Trivial cleanups of the APIC related code"

* 'x86-apic-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/apic: Trivial coding style fixes
  x86/vector: Merge allocate_vector() into assign_vector_locked()

x86: Don't include linux/irq.h from asm/hardirq.h

2018-08-05T07:53:13+00:00

The next patch in this series will have to make the definition of
irq_cpustat_t available to entering_irq().

Inclusion of asm/hardirq.h into asm/apic.h would cause circular header
dependencies like

  asm/smp.h
    asm/apic.h
      asm/hardirq.h
        linux/irq.h
          linux/topology.h
            linux/smp.h
              asm/smp.h

or

  linux/gfp.h
    linux/mmzone.h
      asm/mmzone.h
        asm/mmzone_64.h
          asm/smp.h
            asm/apic.h
              asm/hardirq.h
                linux/irq.h
                  linux/irqdesc.h
                    linux/kobject.h
                      linux/sysfs.h
                        linux/kernfs.h
                          linux/idr.h
                            linux/gfp.h

and others.

This causes compilation errors because of the header guards becoming
effective in the second inclusion: symbols/macros that had been defined
before wouldn't be available to intermediate headers in the #include chain
anymore.

A possible workaround would be to move the definition of irq_cpustat_t
into its own header and include that from both, asm/hardirq.h and
asm/apic.h.

However, this wouldn't solve the real problem, namely asm/harirq.h
unnecessarily pulling in all the linux/irq.h cruft: nothing in
asm/hardirq.h itself requires it. Also, note that there are some other
archs, like e.g. arm64, which don't have that #include in their
asm/hardirq.h.

Remove the linux/irq.h #include from x86' asm/hardirq.h.

Fix resulting compilation errors by adding appropriate #includes to *.c
files as needed.

Note that some of these *.c files could be cleaned up a bit wrt. to their
set of #includes, but that should better be done from separate patches, if
at all.

Signed-off-by: Nicolai Stange 
Signed-off-by: Thomas Gleixner

x86/apic: Trivial coding style fixes

2018-07-30T17:56:30+00:00

There is inconsistent indenting in calibrate_APIC_clock() and
activate_managed(). Remove the surplus TAB.

Signed-off-by: Yi Wang 
Signed-off-by: Thomas Gleixner 
Reviewed-by: Jiang Biao 
Acked-by: Steven Rostedt (VMware) 
Cc: hpa@zytor.com
Cc: douly.fnst@cn.fujitsu.com
Cc: jgross@suse.com
Cc: ville.syrjala@linux.intel.com
Cc: len.brown@intel.com
Cc: gregkh@linuxfoundation.org
Cc: zhong.weidong@zte.com.cn
Link: https://lkml.kernel.org/r/1532672103-32250-1-git-send-email-wang.yi59@zte.com.cn