Commit Graph

1485 Commits

Author SHA1 Message Date
Dheeraj Kumar Srivastava
5a257f3553 x86/apic: Fix kernel panic when booting with intremap=off and x2apic_phys
[ Upstream commit 85d38d5810e285d5aec7fb5283107d1da70c12a9 ]

When booting with "intremap=off" and "x2apic_phys" on the kernel command
line, the physical x2APIC driver ends up being used even when x2APIC
mode is disabled ("intremap=off" disables x2APIC mode). This happens
because the first compound condition check in x2apic_phys_probe() is
false due to x2apic_mode == 0 and so the following one returns true
after default_acpi_madt_oem_check() having already selected the physical
x2APIC driver.

This results in the following panic:

   kernel BUG at arch/x86/kernel/apic/io_apic.c:2409!
   invalid opcode: 0000 [#1] PREEMPT SMP NOPTI
   CPU: 0 PID: 0 Comm: swapper/0 Not tainted 6.4.0-rc2-ver4.1rc2 #2
   Hardware name: Dell Inc. PowerEdge R6515/07PXPY, BIOS 2.3.6 07/06/2021
   RIP: 0010:setup_IO_APIC+0x9c/0xaf0
   Call Trace:
    <TASK>
    ? native_read_msr
    apic_intr_mode_init
    x86_late_time_init
    start_kernel
    x86_64_start_reservations
    x86_64_start_kernel
    secondary_startup_64_no_verify
    </TASK>

which is:

setup_IO_APIC:
  apic_printk(APIC_VERBOSE, "ENABLING IO-APIC IRQs\n");
  for_each_ioapic(ioapic)
  	BUG_ON(mp_irqdomain_create(ioapic));

Return 0 to denote that x2APIC has not been enabled when probing the
physical x2APIC driver.

  [ bp: Massage commit message heavily. ]

Fixes: 9ebd680bd0 ("x86, apic: Use probe routines to simplify apic selection")
Signed-off-by: Dheeraj Kumar Srivastava <dheerajkumar.srivastava@amd.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: Kishon Vijay Abraham I <kvijayab@amd.com>
Reviewed-by: Vasant Hegde <vasant.hegde@amd.com>
Reviewed-by: Cyrill Gorcunov <gorcunov@gmail.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20230616212236.1389-1-dheerajkumar.srivastava@amd.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
2023-06-28 10:28:16 +02:00
Saurabh Sengar
55fc2246c4 x86/ioapic: Don't return 0 from arch_dynirq_lower_bound()
[ Upstream commit 5af507bef93c09a94fb8f058213b489178f4cbe5 ]

arch_dynirq_lower_bound() is invoked by the core interrupt code to
retrieve the lowest possible Linux interrupt number for dynamically
allocated interrupts like MSI.

The x86 implementation uses this to exclude the IO/APIC GSI space.
This works correctly as long as there is an IO/APIC registered, but
returns 0 if not. This has been observed in VMs where the BIOS does
not advertise an IO/APIC.

0 is an invalid interrupt number except for the legacy timer interrupt
on x86. The return value is unchecked in the core code, so it ends up
to allocate interrupt number 0 which is subsequently considered to be
invalid by the caller, e.g. the MSI allocation code.

The function has already a check for 0 in the case that an IO/APIC is
registered, as ioapic_dynirq_base is 0 in case of device tree setups.

Consolidate this and zero check for both ioapic_dynirq_base and gsi_top,
which is used in the case that no IO/APIC is registered.

Fixes: 3e5bedc2c2 ("x86/apic: Fix arch_dynirq_lower_bound() bug for DT enabled machines")
Signed-off-by: Saurabh Sengar <ssengar@linux.microsoft.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/1679988604-20308-1-git-send-email-ssengar@linux.microsoft.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
2023-05-17 11:47:45 +02:00
Uros Bizjak
4883f0f7ee x86/apic: Fix atomic update of offset in reserve_eilvt_offset()
[ Upstream commit f96fb2df3eb31ede1b34b0521560967310267750 ]

The detection of atomic update failure in reserve_eilvt_offset() is
not correct. The value returned by atomic_cmpxchg() should be compared
to the old value from the location to be updated.

If these two are the same, then atomic update succeeded and
"eilvt_offsets[offset]" location is updated to "new" in an atomic way.

Otherwise, the atomic update failed and it should be retried with the
value from "eilvt_offsets[offset]" - exactly what atomic_try_cmpxchg()
does in a correct and more optimal way.

Fixes: a68c439b19 ("apic, x86: Check if EILVT APIC registers are available (AMD only)")
Signed-off-by: Uros Bizjak <ubizjak@gmail.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Link: https://lore.kernel.org/r/20230227160917.107820-1-ubizjak@gmail.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
2023-05-17 11:47:43 +02:00
Randy Dunlap
35abf2081f x86: Fix return value of __setup handlers
[ Upstream commit 12441ccdf5e2f5a01a46e344976cbbd3d46845c9 ]

__setup() handlers should return 1 to obsolete_checksetup() in
init/main.c to indicate that the boot option has been handled. A return
of 0 causes the boot option/value to be listed as an Unknown kernel
parameter and added to init's (limited) argument (no '=') or environment
(with '=') strings. So return 1 from these x86 __setup handlers.

Examples:

  Unknown kernel command line parameters "apicpmtimer
    BOOT_IMAGE=/boot/bzImage-517rc8 vdso=1 ring3mwait=disable", will be
    passed to user space.

  Run /sbin/init as init process
   with arguments:
     /sbin/init
     apicpmtimer
   with environment:
     HOME=/
     TERM=linux
     BOOT_IMAGE=/boot/bzImage-517rc8
     vdso=1
     ring3mwait=disable

Fixes: 2aae950b21 ("x86_64: Add vDSO for x86-64 with gettimeofday/clock_gettime/getcpu")
Fixes: 77b52b4c5c ("x86: add "debugpat" boot option")
Fixes: e16fd002af ("x86/cpufeature: Enable RING3MWAIT for Knights Landing")
Fixes: b8ce335906 ("x86_64: convert to clock events")
Reported-by: Igor Zhbanov <i.zhbanov@omprussia.ru>
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lore.kernel.org/r/64644a2f-4a20-bab3-1e15-3b2cdd0defe3@omprussia.ru
Link: https://lore.kernel.org/r/20220314012725.26661-1-rdunlap@infradead.org
Signed-off-by: Sasha Levin <sashal@kernel.org>
2022-06-09 10:21:05 +02:00
Mike Travis
29cb802966 x86/platform/uv: Update TSC sync state for UV5
[ Upstream commit bb3ab81bdbd53f88f26ffabc9fb15bd8466486ec ]

The UV5 platform synchronizes the TSCs among all chassis, and will not
proceed to OS boot without achieving synchronization.  Previous UV
platforms provided a register indicating successful synchronization.
This is no longer available on UV5.  On this platform TSC_ADJUST
should not be reset by the kernel.

Signed-off-by: Mike Travis <mike.travis@hpe.com>
Signed-off-by: Steve Wahl <steve.wahl@hpe.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Dimitri Sivanich <dimitri.sivanich@hpe.com>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20220406195149.228164-3-steve.wahl@hpe.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
2022-06-09 10:20:50 +02:00
Thomas Gleixner
25216ed97d x86/ioapic: Force affinity setup before startup
commit 0c0e37dc11671384e53ba6ede53a4d91162a2cc5 upstream.

The IO/APIC cannot handle interrupt affinity changes safely after startup
other than from an interrupt handler. The startup sequence in the generic
interrupt code violates that assumption.

Mark the irq chip with the new IRQCHIP_AFFINITY_PRE_STARTUP flag so that
the default interrupt setting happens before the interrupt is started up
for the first time.

Fixes: 1840475676 ("genirq: Expose default irq affinity mask (take 3)")
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Marc Zyngier <maz@kernel.org>
Reviewed-by: Marc Zyngier <maz@kernel.org>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20210729222542.832143400@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-08-18 08:59:15 +02:00
Thomas Gleixner
19fb5dabed x86/msi: Force affinity setup before startup
commit ff363f480e5997051dd1de949121ffda3b753741 upstream.

The X86 MSI mechanism cannot handle interrupt affinity changes safely after
startup other than from an interrupt handler, unless interrupt remapping is
enabled. The startup sequence in the generic interrupt code violates that
assumption.

Mark the irq chips with the new IRQCHIP_AFFINITY_PRE_STARTUP flag so that
the default interrupt setting happens before the interrupt is started up
for the first time.

While the interrupt remapping MSI chip does not require this, there is no
point in treating it differently as this might spare an interrupt to a CPU
which is not in the default affinity mask.

For the non-remapping case go to the direct write path when the interrupt
is not yet started similar to the not yet activated case.

Fixes: 1840475676 ("genirq: Expose default irq affinity mask (take 3)")
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Marc Zyngier <maz@kernel.org>
Reviewed-by: Marc Zyngier <maz@kernel.org>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20210729222542.886722080@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-08-18 08:59:15 +02:00
Thomas Gleixner
42f75a4381 x86/apic: Mark _all_ legacy interrupts when IO/APIC is missing
commit 7d65f9e80646c595e8c853640a9d0768a33e204c upstream.

PIC interrupts do not support affinity setting and they can end up on
any online CPU. Therefore, it's required to mark the associated vectors
as system-wide reserved. Otherwise, the corresponding irq descriptors
are copied to the secondary CPUs but the vectors are not marked as
assigned or reserved. This works correctly for the IO/APIC case.

When the IO/APIC is disabled via config, kernel command line or lack of
enumeration then all legacy interrupts are routed through the PIC, but
nothing marks them as system-wide reserved vectors.

As a consequence, a subsequent allocation on a secondary CPU can result in
allocating one of these vectors, which triggers the BUG() in
apic_update_vector() because the interrupt descriptor slot is not empty.

Imran tried to work around that by marking those interrupts as allocated
when a CPU comes online. But that's wrong in case that the IO/APIC is
available and one of the legacy interrupts, e.g. IRQ0, has been switched to
PIC mode because then marking them as allocated will fail as they are
already marked as system vectors.

Stay consistent and update the legacy vectors after attempting IO/APIC
initialization and mark them as system vectors in case that no IO/APIC is
available.

Fixes: 69cde0004a ("x86/vector: Use matrix allocator for vector assignment")
Reported-by: Imran Khan <imran.f.khan@oracle.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Borislav Petkov <bp@suse.de>
Cc: stable@vger.kernel.org
Link: https://lkml.kernel.org/r/20210519233928.2157496-1-imran.f.khan@oracle.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-06-10 13:39:27 +02:00
Mike Travis
7c5e96e89c x86/platform/uv: Set section block size for hubless architectures
[ Upstream commit 6840a150b9daf35e4d21ab9780d0a03b4ed74a5b ]

Commit

  bbbd2b51a2 ("x86/platform/UV: Use new set memory block size function")

added a call to set the block size value that is needed by the kernel
to set the boundaries in the section list. This was done for UV Hubbed
systems but missed in the UV Hubless setup. Fix that mistake by adding
that same set call for hubless systems, which support the same NVRAMs
and Intel BIOS, thus the same problem occurs.

 [ bp: Massage commit message. ]

Fixes: bbbd2b51a2 ("x86/platform/UV: Use new set memory block size function")
Signed-off-by: Mike Travis <mike.travis@hpe.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Steve Wahl <steve.wahl@hpe.com>
Reviewed-by: Russ Anderson <rja@hpe.com>
Link: https://lkml.kernel.org/r/20210305162853.299892-1-mike.travis@hpe.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
2021-05-14 09:50:07 +02:00
Johan Hovold
21536d7b7e x86/apic/of: Fix CPU devicetree-node lookups
commit dd926880da8dbbe409e709c1d3c1620729a94732 upstream.

Architectures that describe the CPU topology in devicetree and do not have
an identity mapping between physical and logical CPU ids must override the
default implementation of arch_match_cpu_phys_id().

Failing to do so breaks CPU devicetree-node lookups using of_get_cpu_node()
and of_cpu_device_node_get() which several drivers rely on. It also causes
the CPU struct devices exported through sysfs to point to the wrong
devicetree nodes.

On x86, CPUs are described in devicetree using their APIC ids and those
do not generally coincide with the logical ids, even if CPU0 typically
uses APIC id 0.

Add the missing implementation of arch_match_cpu_phys_id() so that CPU-node
lookups work also with SMP.

Apart from fixing the broken sysfs devicetree-node links this likely does
not affect current users of mainline kernels on x86.

Fixes: 4e07db9c8d ("x86/devicetree: Use CPU description from Device Tree")
Signed-off-by: Johan Hovold <johan@kernel.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20210312092033.26317-1-johan@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-03-25 09:04:18 +01:00
Thomas Gleixner
0e245256e3 x86/ioapic: Ignore IRQ2 again
commit a501b048a95b79e1e34f03cac3c87ff1e9f229ad upstream.

Vitaly ran into an issue with hotplugging CPU0 on an Amazon instance where
the matrix allocator claimed to be out of vectors. He analyzed it down to
the point that IRQ2, the PIC cascade interrupt, which is supposed to be not
ever routed to the IO/APIC ended up having an interrupt vector assigned
which got moved during unplug of CPU0.

The underlying issue is that IRQ2 for various reasons (see commit
af174783b9 ("x86: I/O APIC: Never configure IRQ2" for details) is treated
as a reserved system vector by the vector core code and is not accounted as
a regular vector. The Amazon BIOS has an routing entry of pin2 to IRQ2
which causes the IO/APIC setup to claim that interrupt which is granted by
the vector domain because there is no sanity check. As a consequence the
allocation counter of CPU0 underflows which causes a subsequent unplug to
fail with:

  [ ... ] CPU 0 has 4294967295 vectors, 589 available. Cannot disable CPU

There is another sanity check missing in the matrix allocator, but the
underlying root cause is that the IO/APIC code lost the IRQ2 ignore logic
during the conversion to irqdomains.

For almost 6 years nobody complained about this wreckage, which might
indicate that this requirement could be lifted, but for any system which
actually has a PIC IRQ2 is unusable by design so any routing entry has no
effect and the interrupt cannot be connected to a device anyway.

Due to that and due to history biased paranoia reasons restore the IRQ2
ignore logic and treat it as non existent despite a routing entry claiming
otherwise.

Fixes: d32932d02e ("x86/irq: Convert IOAPIC to use hierarchical irqdomain interfaces")
Reported-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20210318192819.636943062@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-03-25 09:04:16 +01:00
Dave Hansen
2ce5be67d1 x86/apic: Add extra serialization for non-serializing MSRs
commit 25a068b8e9a4eb193d755d58efcb3c98928636e0 upstream.

Jan Kiszka reported that the x2apic_wrmsr_fence() function uses a plain
MFENCE while the Intel SDM (10.12.3 MSR Access in x2APIC Mode) calls for
MFENCE; LFENCE.

Short summary: we have special MSRs that have weaker ordering than all
the rest. Add fencing consistent with current SDM recommendations.

This is not known to cause any issues in practice, only in theory.

Longer story below:

The reason the kernel uses a different semantic is that the SDM changed
(roughly in late 2017). The SDM changed because folks at Intel were
auditing all of the recommended fences in the SDM and realized that the
x2apic fences were insufficient.

Why was the pain MFENCE judged insufficient?

WRMSR itself is normally a serializing instruction. No fences are needed
because the instruction itself serializes everything.

But, there are explicit exceptions for this serializing behavior written
into the WRMSR instruction documentation for two classes of MSRs:
IA32_TSC_DEADLINE and the X2APIC MSRs.

Back to x2apic: WRMSR is *not* serializing in this specific case.
But why is MFENCE insufficient? MFENCE makes writes visible, but
only affects load/store instructions. WRMSR is unfortunately not a
load/store instruction and is unaffected by MFENCE. This means that a
non-serializing WRMSR could be reordered by the CPU to execute before
the writes made visible by the MFENCE have even occurred in the first
place.

This means that an x2apic IPI could theoretically be triggered before
there is any (visible) data to process.

Does this affect anything in practice? I honestly don't know. It seems
quite possible that by the time an interrupt gets to consume the (not
yet) MFENCE'd data, it has become visible, mostly by accident.

To be safe, add the SDM-recommended fences for all x2apic WRMSRs.

This also leaves open the question of the _other_ weakly-ordered WRMSR:
MSR_IA32_TSC_DEADLINE. While it has the same ordering architecture as
the x2APIC MSRs, it seems substantially less likely to be a problem in
practice. While writes to the in-memory Local Vector Table (LVT) might
theoretically be reordered with respect to a weakly-ordered WRMSR like
TSC_DEADLINE, the SDM has this to say:

  In x2APIC mode, the WRMSR instruction is used to write to the LVT
  entry. The processor ensures the ordering of this write and any
  subsequent WRMSR to the deadline; no fencing is required.

But, that might still leave xAPIC exposed. The safest thing to do for
now is to add the extra, recommended LFENCE.

 [ bp: Massage commit message, fix typos, drop accidentally added
   newline to tools/arch/x86/include/asm/barrier.h. ]

Reported-by: Jan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Cc: <stable@vger.kernel.org>
Link: https://lkml.kernel.org/r/20200305174708.F77040DD@viggo.jf.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-02-10 09:29:22 +01:00
David Woodhouse
b8ab21e017 x86/apic: Fix x2apic enablement without interrupt remapping
[ Upstream commit 26573a97746c7a99f394f9d398ce91a8853b3b89 ]

Currently, Linux as a hypervisor guest will enable x2apic only if there are
no CPUs present at boot time with an APIC ID above 255.

Hotplugging a CPU later with a higher APIC ID would result in a CPU which
cannot be targeted by external interrupts.

Add a filter in x2apic_apic_id_valid() which can be used to prevent such
CPUs from coming online, and allow x2apic to be enabled even if they are
present at boot time.

Fixes: ce69a78450 ("x86/apic: Enable x2APIC without interrupt remapping under KVM")
Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20201024213535.443185-2-dwmw2@infradead.org
Signed-off-by: Sasha Levin <sashal@kernel.org>
2020-12-30 11:52:59 +01:00
Thomas Gleixner
190113b4c6 x86/apic/vector: Fix ordering in vector assignment
Prarit reported that depending on the affinity setting the

 ' irq $N: Affinity broken due to vector space exhaustion.'

message is showing up in dmesg, but the vector space on the CPUs in the
affinity mask is definitely not exhausted.

Shung-Hsi provided traces and analysis which pinpoints the problem:

The ordering of trying to assign an interrupt vector in
assign_irq_vector_any_locked() is simply wrong if the interrupt data has a
valid node assigned. It does:

 1) Try the intersection of affinity mask and node mask
 2) Try the node mask
 3) Try the full affinity mask
 4) Try the full online mask

Obviously #2 and #3 are in the wrong order as the requested affinity
mask has to take precedence.

In the observed cases #1 failed because the affinity mask did not contain
CPUs from node 0. That made it allocate a vector from node 0, thereby
breaking affinity and emitting the misleading message.

Revert the order of #2 and #3 so the full affinity mask without the node
intersection is tried before actually affinity is broken.

If no node is assigned then only the full affinity mask and if that fails
the full online mask is tried.

Fixes: d6ffc6ac83 ("x86/vector: Respect affinity mask in irq descriptor")
Reported-by: Prarit Bhargava <prarit@redhat.com>
Reported-by: Shung-Hsi Yu <shung-hsi.yu@suse.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Shung-Hsi Yu <shung-hsi.yu@suse.com>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/87ft4djtyp.fsf@nanos.tec.linutronix.de
2020-12-10 23:00:54 +01:00
Mike Travis
8dcc0e19df x86/platform/uv: Fix UV4 hub revision adjustment
Currently, UV4 is incorrectly identified as UV4A and UV4A as UV5. Hub
chip starts with revision 1, fix it.

 [ bp: Massage commit message. ]

Fixes: 647128f153 ("x86/platform/uv: Update UV MMRs for UV5")
Signed-off-by: Mike Travis <mike.travis@hpe.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Steve Wahl <steve.wahl@hpe.com>
Acked-by: Dimitri Sivanich <dimitri.sivanich@hpe.com>
Link: https://lkml.kernel.org/r/20201203152252.371199-1-mike.travis@hpe.com
2020-12-03 18:09:18 +01:00
Mike Travis
77c7e1bc06 x86/platform/uv: Fix copied UV5 output archtype
A test shows that the output contains a space:
    # cat /proc/sgi_uv/archtype
    NSGI4 U/UVX

Remove that embedded space by copying the "trimmed" buffer instead of the
untrimmed input character list.  Use sizeof to remove size dependency on
copy out length.  Increase output buffer size by one character just in case
BIOS sends an 8 character string for archtype.

Fixes: 1e61f5a95f ("Add and decode Arch Type in UVsystab")
Signed-off-by: Mike Travis <mike.travis@hpe.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Steve Wahl <steve.wahl@hpe.com>
Link: https://lore.kernel.org/r/20201111010418.82133-1-mike.travis@hpe.com
2020-11-13 00:00:31 +01:00
Mike Travis
801284f973 x86/platform/uv: Recognize UV5 hubless system identifier
Testing shows a problem in that UV5 hubless systems were not being
recognized.  Add them to the list of OEM IDs checked.

Fixes: 6c7794423a ("Add UV5 direct references")
Signed-off-by: Mike Travis <mike.travis@hpe.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20201105222741.157029-4-mike.travis@hpe.com
2020-11-07 11:17:39 +01:00
Mike Travis
1aee505e01 x86/platform/uv: Remove spaces from OEM IDs
Testing shows that trailing spaces caused problems with the OEM_ID and
the OEM_TABLE_ID.  One being that the OEM_ID would not string compare
correctly.  Another the OEM_ID and OEM_TABLE_ID would be concatenated
in the printout.  Remove any trailing spaces.

Fixes: 1e61f5a95f ("Add and decode Arch Type in UVsystab")
Signed-off-by: Mike Travis <mike.travis@hpe.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20201105222741.157029-3-mike.travis@hpe.com
2020-11-07 11:17:39 +01:00
Mike Travis
1aec69ae56 x86/platform/uv: Fix missing OEM_TABLE_ID
Testing shows a problem in that the OEM_TABLE_ID was missing for
hubless systems.  This is used to determine the APIC type (legacy or
extended).  Add the OEM_TABLE_ID to the early hubless processing.

Fixes: 1e61f5a95f ("Add and decode Arch Type in UVsystab")
Signed-off-by: Mike Travis <mike.travis@hpe.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20201105222741.157029-2-mike.travis@hpe.com
2020-11-07 11:17:39 +01:00
Linus Torvalds
cc7343724e Merge tag 'x86-irq-2020-10-12' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull x86 irq updates from Thomas Gleixner:
 "Surgery of the MSI interrupt handling to prepare the support of
  upcoming devices which require non-PCI based MSI handling:

   - Cleanup historical leftovers all over the place

   - Rework the code to utilize more core functionality

   - Wrap XEN PCI/MSI interrupts into an irqdomain to make irqdomain
     assignment to PCI devices possible.

   - Assign irqdomains to PCI devices at initialization time which
     allows to utilize the full functionality of hierarchical
     irqdomains.

   - Remove arch_.*_msi_irq() functions from X86 and utilize the
     irqdomain which is assigned to the device for interrupt management.

   - Make the arch_.*_msi_irq() support conditional on a config switch
     and let the last few users select it"

* tag 'x86-irq-2020-10-12' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (40 commits)
  PCI: MSI: Fix Kconfig dependencies for PCI_MSI_ARCH_FALLBACKS
  x86/apic/msi: Unbreak DMAR and HPET MSI
  iommu/amd: Remove domain search for PCI/MSI
  iommu/vt-d: Remove domain search for PCI/MSI[X]
  x86/irq: Make most MSI ops XEN private
  x86/irq: Cleanup the arch_*_msi_irqs() leftovers
  PCI/MSI: Make arch_.*_msi_irq[s] fallbacks selectable
  x86/pci: Set default irq domain in pcibios_add_device()
  iommm/amd: Store irq domain in struct device
  iommm/vt-d: Store irq domain in struct device
  x86/xen: Wrap XEN MSI management into irqdomain
  irqdomain/msi: Allow to override msi_domain_alloc/free_irqs()
  x86/xen: Consolidate XEN-MSI init
  x86/xen: Rework MSI teardown
  x86/xen: Make xen_msi_init() static and rename it to xen_hvm_msi_init()
  PCI/MSI: Provide pci_dev_has_special_msi_domain() helper
  PCI_vmd_Mark_VMD_irqdomain_with_DOMAIN_BUS_VMD_MSI
  irqdomain/msi: Provide DOMAIN_BUS_VMD_MSI
  x86/irq: Initialize PCI/MSI domain at PCI init time
  x86/pci: Reducde #ifdeffery in PCI init code
  ...
2020-10-12 11:40:41 -07:00
Mike Travis
7a6d94f0ed x86/platform/uv: Update Copyrights to conform to HPE standards
Add Copyrights to those files that have been updated for UV5 changes.

Signed-off-by: Mike Travis <mike.travis@hpe.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/20201005203929.148656-14-mike.travis@hpe.com
2020-10-07 09:10:07 +02:00
Mike Travis
6a7cf55e9f x86/platform/uv: Update UV5 TSC checking
Update check of BIOS TSC sync status to include both possible "invalid"
states provided by newer UV5 BIOS.

Signed-off-by: Mike Travis <mike.travis@hpe.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Steve Wahl <steve.wahl@hpe.com>
Link: https://lkml.kernel.org/r/20201005203929.148656-12-mike.travis@hpe.com
2020-10-07 09:09:04 +02:00
Mike Travis
d6922effe4 x86/platform/uv: Update node present counting
The changes in the UV5 arch shrunk the NODE PRESENT table to just 2x64
entries (128 total) so are in to 64 bit MMRs instead of a depth of 64
bits in an array.  Adjust references when counting up the nodes present.

Signed-off-by: Mike Travis <mike.travis@hpe.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Dimitri Sivanich <dimitri.sivanich@hpe.com>
Reviewed-by: Steve Wahl <steve.wahl@hpe.com>
Link: https://lkml.kernel.org/r/20201005203929.148656-11-mike.travis@hpe.com
2020-10-07 09:08:35 +02:00
Mike Travis
a74a7e992c x86/platform/uv: Update UV5 MMR references in UV GRU
Make modifications to the GRU mappings to accommodate changes for UV5.

Signed-off-by: Mike Travis <mike.travis@hpe.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Dimitri Sivanich <dimitri.sivanich@hpe.com>
Reviewed-by: Steve Wahl <steve.wahl@hpe.com>
Link: https://lkml.kernel.org/r/20201005203929.148656-10-mike.travis@hpe.com
2020-10-07 09:08:00 +02:00
Mike Travis
8540b2cf0d x86/platform/uv: Adjust GAM MMR references affected by UV5 updates
Make modifications to the GAM MMR mappings to accommodate changes for UV5.

Signed-off-by: Mike Travis <mike.travis@hpe.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Dimitri Sivanich <dimitri.sivanich@hpe.com>
Reviewed-by: Steve Wahl <steve.wahl@hpe.com>
Link: https://lkml.kernel.org/r/20201005203929.148656-9-mike.travis@hpe.com
2020-10-07 09:07:44 +02:00
Mike Travis
ffe2febca4 x86/platform/uv: Update MMIOH references based on new UV5 MMRs
Make modifications to the MMIOH mappings to accommodate changes for UV5.

[ Fix W=1 build warnings. ]
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Mike Travis <mike.travis@hpe.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Steve Wahl <steve.wahl@hpe.com>
Link: https://lkml.kernel.org/r/20201005203929.148656-8-mike.travis@hpe.com
2020-10-07 09:07:27 +02:00
Mike Travis
1e61f5a95f x86/platform/uv: Add and decode Arch Type in UVsystab
When the UV BIOS starts the kernel it passes the UVsystab info struct to
the kernel which contains information elements more specific than ACPI,
and generally pertinent only to the MMRs. These are read only fields
so information is passed one way only. A new field starting with UV5 is
the UV architecture type so the ACPI OEM_ID field can be used for other
purposes going forward. The UV Arch Type selects the entirety of the
MMRs available, with their addresses and fields defined in uv_mmrs.h.

Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Mike Travis <mike.travis@hpe.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Dimitri Sivanich <dimitri.sivanich@hpe.com>
Reviewed-by: Steve Wahl <steve.wahl@hpe.com>
Link: https://lkml.kernel.org/r/20201005203929.148656-7-mike.travis@hpe.com
2020-10-07 09:06:10 +02:00
Mike Travis
6c7794423a x86/platform/uv: Add UV5 direct references
Add new references to UV5 (and UVY class) system MMR addresses and
fields primarily caused by the expansion from 46 to 52 bits of physical
memory address.

Signed-off-by: Mike Travis <mike.travis@hpe.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Dimitri Sivanich <dimitri.sivanich@hpe.com>
Reviewed-by: Steve Wahl <steve.wahl@hpe.com>
Link: https://lkml.kernel.org/r/20201005203929.148656-6-mike.travis@hpe.com
2020-10-07 09:01:46 +02:00
Mike Travis
647128f153 x86/platform/uv: Update UV MMRs for UV5
Update UV MMRs in uv_mmrs.h for UV5 based on Verilog output from the
UV Hub hardware design files.  This is the next UV architecture with
a new class (UVY) being defined for 52 bit physical address masks.
Uses a bitmask for UV arch identification so a single test can cover
multiple versions.  Includes other adjustments to match the uv_mmrs.h
file to keep from encountering compile errors.  New UV5 functionality
is added in the patches that follow.

[ Fix W=1 build warnings. ]
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Mike Travis <mike.travis@hpe.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Steve Wahl <steve.wahl@hpe.com>
Link: https://lkml.kernel.org/r/20201005203929.148656-5-mike.travis@hpe.com
2020-10-07 09:00:57 +02:00
Mike Travis
c4d9807744 x86/platform/uv: Remove SCIR MMR references for UV systems
UV class systems no longer use System Controller for monitoring of CPU
activity provided by this driver. Other methods have been developed for
BIOS and the management controller (BMC). Remove that supporting code.

Signed-off-by: Mike Travis <mike.travis@hpe.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Dimitri Sivanich <dimitri.sivanich@hpe.com>
Link: https://lkml.kernel.org/r/20201005203929.148656-3-mike.travis@hpe.com
2020-10-07 08:53:51 +02:00
Thomas Gleixner
d27e623ace x86/apic/msi: Unbreak DMAR and HPET MSI
Switching the DMAR and HPET MSI code to use the generic MSI domain ops
missed to add the flag which tells the core code to update the domain
operations with the defaults. As a consequence the core code crashes
when an interrupt in one of those domains is allocated.

Add the missing flags.

Fixes: 9006c133a4 ("x86/msi: Use generic MSI domain ops")
Reported-by: Qian Cai <cai@redhat.com>
Reported-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/87wo0fli8b.fsf@nanos.tec.linutronix.de
2020-09-27 21:53:41 +02:00
Thomas Gleixner
86a82ae0b5 x86/ioapic: Unbreak check_timer()
Several people reported in the kernel bugzilla that between v4.12 and v4.13
the magic which works around broken hardware and BIOSes to find the proper
timer interrupt delivery mode stopped working for some older affected
platforms which need to fall back to ExtINT delivery mode.

The reason is that the core code changed to keep track of the masked and
disabled state of an interrupt line more accurately to avoid the expensive
hardware operations.

That broke an assumption in i8259_make_irq() which invokes

     disable_irq_nosync();
     irq_set_chip_and_handler();
     enable_irq();

Up to v4.12 this worked because enable_irq() unconditionally unmasked the
interrupt line, but after the state tracking improvements this is not
longer the case because the IO/APIC uses lazy disabling. So the line state
is unmasked which means that enable_irq() does not call into the new irq
chip to unmask it.

In principle this is a shortcoming of the core code, but it's more than
unclear whether the core code should try to reset state. At least this
cannot be done unconditionally as that would break other existing use cases
where the chip type is changed, e.g. when changing the trigger type, but
the callers expect the state to be preserved.

As the way how check_timer() is switching the delivery modes is truly
unique, the obvious fix is to simply unmask the i8259 manually after
changing the mode to ExtINT delivery and switching the irq chip to the
legacy PIC.

Note, that the fixes tag is not really precise, but identifies the commit
which broke the assumptions in the IO/APIC and i8259 code and that's the
kernel version to which this needs to be backported.

Fixes: bf22ff45be ("genirq: Avoid unnecessary low level irq function calls")
Reported-by: p_c_chan@hotmail.com
Reported-by: ecm4@mail.com
Reported-by: perdigao1@yahoo.com
Reported-by: matzes@users.sourceforge.net
Reported-by: rvelascog@gmail.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: p_c_chan@hotmail.com
Tested-by: matzes@users.sourceforge.net
Cc: stable@vger.kernel.org
Link: https://bugzilla.kernel.org/show_bug.cgi?id=197769
2020-09-23 22:44:56 +02:00
Thomas Gleixner
7ca435cf85 x86/irq: Cleanup the arch_*_msi_irqs() leftovers
Get rid of all the gunk and remove the 'select PCI_MSI_ARCH_FALLBACK' from
the x86 Kconfig so the weak functions in the PCI core are replaced by stubs
which emit a warning, which ensures that any fail to set the irq domain
pointer results in a warning when the device is used.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20200826112334.086003720@linutronix.de
2020-09-16 16:52:38 +02:00
Thomas Gleixner
2c681e6b37 x86/pci: Set default irq domain in pcibios_add_device()
Now that interrupt remapping sets the irqdomain pointer when a PCI device
is added it's possible to store the default irq domain in the device struct
in pcibios_add_device().

If the bus to which a device is connected has an irq domain associated then
this domain is used otherwise the default domain (PCI/MSI native or XEN
PCI/MSI) is used. Using the bus domain ensures that special MSI bus domains
like VMD work.

This makes XEN and the non-remapped native case work solely based on the
irq domain pointer in struct device for PCI/MSI and allows to remove the
arch fallback and make most of the x86_msi ops private to XEN in the next
steps.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20200826112333.900423047@linutronix.de
2020-09-16 16:52:37 +02:00
Thomas Gleixner
6b15ffa07d x86/irq: Initialize PCI/MSI domain at PCI init time
No point in initializing the default PCI/MSI interrupt domain early and no
point to create it when XEN PV/HVM/DOM0 are active.

Move the initialization to pci_arch_init() and convert it to init ops so
that XEN can override it as XEN has it's own PCI/MSI management. The XEN
override comes in a later step.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20200826112332.859209894@linutronix.de
2020-09-16 16:52:35 +02:00
Thomas Gleixner
bb733e4336 x86/irq: Move apic_post_init() invocation to one place
No point to call it from both 32bit and 64bit implementations of
default_setup_apic_routing(). Move it to the caller.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20200826112332.658496557@linutronix.de
2020-09-16 16:52:35 +02:00
Thomas Gleixner
9006c133a4 x86/msi: Use generic MSI domain ops
pci_msi_get_hwirq() and pci_msi_set_desc are not longer special. Enable the
generic MSI domain ops in the core and PCI MSI code unconditionally and get
rid of the x86 specific implementations in the X86 MSI code and in the
hyperv PCI driver.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20200826112332.564274859@linutronix.de
2020-09-16 16:52:35 +02:00
Thomas Gleixner
3b9c1d377d x86/msi: Consolidate MSI allocation
Convert the interrupt remap drivers to retrieve the pci device from the msi
descriptor and use info::hwirq.

This is the first step to prepare x86 for using the generic MSI domain ops.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Wei Liu <wei.liu@kernel.org>
Acked-by: Joerg Roedel <jroedel@suse.de>
Link: https://lore.kernel.org/r/20200826112332.466405395@linutronix.de
2020-09-16 16:52:35 +02:00
Thomas Gleixner
dfb9eb7cf6 PCI/MSI: Rework pci_msi_domain_calc_hwirq()
Retrieve the PCI device from the msi descriptor instead of doing so at the
call sites.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Bjorn Helgaas <bhelgaas@google.com>
Acked-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20200826112332.352583299@linutronix.de
2020-09-16 16:52:34 +02:00
Thomas Gleixner
55e0391572 x86/irq: Consolidate DMAR irq allocation
None of the DMAR specific fields are required.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20200826112332.163462706@linutronix.de
2020-09-16 16:52:33 +02:00
Thomas Gleixner
33a65ba470 x86_ioapic_Consolidate_IOAPIC_allocation
Move the IOAPIC specific fields into their own struct and reuse the common
devid. Get rid of the #ifdeffery as it does not matter at all whether the
alloc info is a couple of bytes longer or not.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Wei Liu <wei.liu@kernel.org>
Acked-by: Joerg Roedel <jroedel@suse.de>
Link: https://lore.kernel.org/r/20200826112332.054367732@linutronix.de
2020-09-16 16:52:32 +02:00
Thomas Gleixner
2bf1e7bced x86/msi: Consolidate HPET allocation
None of the magic HPET fields are required in any way.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Joerg Roedel <jroedel@suse.de>
Link: https://lore.kernel.org/r/20200826112331.943993771@linutronix.de
2020-09-16 16:52:31 +02:00
Thomas Gleixner
6b6256e616 iommu/irq_remapping: Consolidate irq domain lookup
Now that the iommu implementations handle the X86_*_GET_PARENT_DOMAIN
types, consolidate the two getter functions.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Joerg Roedel <jroedel@suse.de>
Link: https://lore.kernel.org/r/20200826112331.741909337@linutronix.de
2020-09-16 16:52:30 +02:00
Thomas Gleixner
b4c364da32 x86/irq: Add allocation type for parent domain retrieval
irq_remapping_ir_irq_domain() is used to retrieve the remapping parent
domain for an allocation type. irq_remapping_irq_domain() is for retrieving
the actual device domain for allocating interrupts for a device.

The two functions are similar and can be unified by using explicit modes
for parent irq domain retrieval.

Add X86_IRQ_ALLOC_TYPE_IOAPIC/HPET_GET_PARENT and use it in the iommu
implementations. Drop the parent domain retrieval for PCI_MSI/X as that is
unused.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Joerg Roedel <jroedel@suse.de>
Link: https://lore.kernel.org/r/20200826112331.436350257@linutronix.de
2020-09-16 16:52:29 +02:00
Thomas Gleixner
801b5e4c4e x86_irq_Rename_X86_IRQ_ALLOC_TYPE_MSI_to_reflect_PCI_dependency
No functional change.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Joerg Roedel <jroedel@suse.de>
Link: https://lore.kernel.org/r/20200826112331.343103175@linutronix.de
2020-09-16 16:52:29 +02:00
Thomas Gleixner
9d55f02ad4 x86/msi: Remove pointless vcpu_affinity callback
Setting the irq_set_vcpu_affinity() callback to
irq_chip_set_vcpu_affinity_parent() is a pointless exercise because the
function which utilizes it searchs the domain hierarchy to find a parent
domain which has such a callback.

Remove the useless indirection.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20200826112331.250130127@linutronix.de
2020-09-16 16:52:29 +02:00
Thomas Gleixner
b0a19555ef x86/msi: Move compose message callback where it belongs
Composing the MSI message at the MSI chip level is wrong because the
underlying parent domain is the one which knows how the message should be
composed for the direct vector delivery or the interrupt remapping table
entry.

The interrupt remapping aware PCI/MSI chip does that already. Make the
direct delivery chip do the same and move the composition of the direct
delivery MSI message to the vector domain irq chip.

This prepares for the upcoming device MSI support to avoid having
architecture specific knowledge in the device MSI domain irq chips.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20200826112331.157603198@linutronix.de
2020-09-16 16:52:28 +02:00
Thomas Gleixner
13b90cadfc genirq/chip: Use the first chip in irq_chip_compose_msi_msg()
The documentation of irq_chip_compose_msi_msg() claims that with
hierarchical irq domains the first chip in the hierarchy which has an
irq_compose_msi_msg() callback is chosen. But the code just keeps
iterating after it finds a chip with a compose callback.

The x86 HPET MSI implementation relies on that behaviour, but that does not
make it more correct.

The message should always be composed at the domain which manages the
underlying resource (e.g. APIC or remap table) because that domain knows
about the required layout of the message.

On X86 the following hierarchies exist:

1)   vector -------- PCI/MSI
2)   vector -- IR -- PCI/MSI

The vector domain has a different message format than the IR (remapping)
domain. So obviously the PCI/MSI domain can't compose the message without
having knowledge about the parent domain, which is exactly the opposite of
what hierarchical domains want to achieve.

X86 actually has two different PCI/MSI chips where #1 has a compose
callback and #2 does not. #2 delegates the composition to the remap domain
where it belongs, but #1 does it at the PCI/MSI level.

For the upcoming device MSI support it's necessary to change this and just
let the first domain which can compose the message take care of it. That
way the top level chip does not have to worry about it and the device MSI
code does not need special knowledge about topologies. It just sets the
compose callback to NULL and lets the hierarchy pick the first chip which
has one.

Due to that the attempt to move the compose callback from the direct
delivery PCI/MSI domain to the vector domain made the system fail to boot
with interrupt remapping enabled because in the remapping case
irq_chip_compose_msi_msg() keeps iterating and choses the compose callback
of the vector domain which obviously creates the wrong format for the remap
table.

Break out of the loop when the first irq chip with a compose callback is
found and fixup the HPET code temporarily. That workaround will be removed
once the direct delivery compose callback is moved to the place where it
belongs in the vector domain.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Marc Zyngier <maz@kernel.org>                                                                                                                                                                                                                                     Link: https://lore.kernel.org/r/20200826112331.047917603@linutronix.de
2020-09-16 16:52:28 +02:00
Linus Torvalds
dcc5c6f013 Merge tag 'x86-urgent-2020-08-30' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull x86 fixes from Thomas Gleixner:
 "Three interrupt related fixes for X86:

   - Move disabling of the local APIC after invoking fixup_irqs() to
     ensure that interrupts which are incoming are noted in the IRR and
     not ignored.

   - Unbreak affinity setting.

     The rework of the entry code reused the regular exception entry
     code for device interrupts. The vector number is pushed into the
     errorcode slot on the stack which is then lifted into an argument
     and set to -1 because that's regs->orig_ax which is used in quite
     some places to check whether the entry came from a syscall.

     But it was overlooked that orig_ax is used in the affinity cleanup
     code to validate whether the interrupt has arrived on the new
     target. It turned out that this vector check is pointless because
     interrupts are never moved from one vector to another on the same
     CPU. That check is a historical leftover from the time where x86
     supported multi-CPU affinities, but not longer needed with the now
     strict single CPU affinity. Famous last words ...

   - Add a missing check for an empty cpumask into the matrix allocator.

     The affinity change added a warning to catch the case where an
     interrupt is moved on the same CPU to a different vector. This
     triggers because a condition with an empty cpumask returns an
     assignment from the allocator as the allocator uses for_each_cpu()
     without checking the cpumask for being empty. The historical
     inconsistent for_each_cpu() behaviour of ignoring the cpumask and
     unconditionally claiming that CPU0 is in the mask struck again.
     Sigh.

  plus a new entry into the MAINTAINER file for the HPE/UV platform"

* tag 'x86-urgent-2020-08-30' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  genirq/matrix: Deal with the sillyness of for_each_cpu() on UP
  x86/irq: Unbreak interrupt affinity setting
  x86/hotplug: Silence APIC only after all interrupts are migrated
  MAINTAINERS: Add entry for HPE Superdome Flex (UV) maintainers
2020-08-30 12:01:23 -07:00
Thomas Gleixner
e027fffff7 x86/irq: Unbreak interrupt affinity setting
Several people reported that 5.8 broke the interrupt affinity setting
mechanism.

The consolidation of the entry code reused the regular exception entry code
for device interrupts and changed the way how the vector number is conveyed
from ptregs->orig_ax to a function argument.

The low level entry uses the hardware error code slot to push the vector
number onto the stack which is retrieved from there into a function
argument and the slot on stack is set to -1.

The reason for setting it to -1 is that the error code slot is at the
position where pt_regs::orig_ax is. A positive value in pt_regs::orig_ax
indicates that the entry came via a syscall. If it's not set to a negative
value then a signal delivery on return to userspace would try to restart a
syscall. But there are other places which rely on pt_regs::orig_ax being a
valid indicator for syscall entry.

But setting pt_regs::orig_ax to -1 has a nasty side effect vs. the
interrupt affinity setting mechanism, which was overlooked when this change
was made.

Moving interrupts on x86 happens in several steps. A new vector on a
different CPU is allocated and the relevant interrupt source is
reprogrammed to that. But that's racy and there might be an interrupt
already in flight to the old vector. So the old vector is preserved until
the first interrupt arrives on the new vector and the new target CPU. Once
that happens the old vector is cleaned up, but this cleanup still depends
on the vector number being stored in pt_regs::orig_ax, which is now -1.

That -1 makes the check for cleanup: pt_regs::orig_ax == new_vector
always false. As a consequence the interrupt is moved once, but then it
cannot be moved anymore because the cleanup of the old vector never
happens.

There would be several ways to convey the vector information to that place
in the guts of the interrupt handling, but on deeper inspection it turned
out that this check is pointless and a leftover from the old affinity model
of X86 which supported multi-CPU affinities. Under this model it was
possible that an interrupt had an old and a new vector on the same CPU, so
the vector match was required.

Under the new model the effective affinity of an interrupt is always a
single CPU from the requested affinity mask. If the affinity mask changes
then either the interrupt stays on the CPU and on the same vector when that
CPU is still in the new affinity mask or it is moved to a different CPU, but
it is never moved to a different vector on the same CPU.

Ergo the cleanup check for the matching vector number is not required and
can be removed which makes the dependency on pt_regs:orig_ax go away.

The remaining check for new_cpu == smp_processsor_id() is completely
sufficient. If it matches then the interrupt was successfully migrated and
the cleanup can proceed.

For paranoia sake add a warning into the vector assignment code to
validate that the assumption of never moving to a different vector on
the same CPU holds.

Fixes: 633260fa14 ("x86/irq: Convey vector as argument and not in ptregs")
Reported-by: Alex bykov <alex.bykov@scylladb.com>
Reported-by: Avi Kivity <avi@scylladb.com>
Reported-by: Alexander Graf <graf@amazon.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Alexander Graf <graf@amazon.com>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/87wo1ltaxz.fsf@nanos.tec.linutronix.de
2020-08-27 09:29:23 +02:00