David and a few others reported that on certain newer systems some legacy
interrupts fail to work correctly.

Debugging revealed that the BIOS of these systems leaves the legacy PIC in
uninitialized state which makes the PIC detection fail and the kernel
switches to a dummy implementation.

Unfortunately this fallback causes quite some code to fail as it depends on
checks for the number of legacy PIC interrupts or the availability of the
real PIC.

In theory there is no reason to use the PIC on any modern system when
IO/APIC is available, but the dependencies on the related checks cannot be
resolved trivially and on short notice. This needs lots of analysis and
rework.

The PIC detection has been added to avoid quirky checks and force selection
of the dummy implementation all over the place, especially in VM guest
scenarios. So it's not an option to revert the relevant commit as that
would break a lot of other scenarios.

One solution would be to try to initialize the PIC on detection fail and
retry the detection, but that puts the burden on everything which does not
have a PIC.

Fortunately the ACPI/MADT table header has a flag field, which advertises
in bit 0 that the system is PCAT compatible, which means it has a legacy
8259 PIC.

Evaluate that bit and if set avoid the detection routine and keep the real
PIC installed, which then gets initialized (for nothing) and makes the rest
of the code with all the dependencies work again.

Fixes: e179f6914152 ("x86, irq, pic: Probe for legacy PIC and set legacy_pic appropriately")
Reported-by: David Lazar <dlazar@gmail.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: David Lazar <dlazar@gmail.com>
Reviewed-by: Hans de Goede <hdegoede@redhat.com>
Reviewed-by: Mario Limonciello <mario.limonciello@amd.com>
Cc: stable@vger.kernel.org
Closes: https://bugzilla.kernel.org/show_bug.cgi?id=218003
Link: https://lore.kernel.org/r/875y2u5s8g.ffs@tglx

For "reasons" Intel has code-named this CPU with a "_H" suffix.

[ dhansen: As usual, apply this and send it upstream quickly to
	   make it easier for anyone who is doing work that
	   consumes this. ]

Signed-off-by: Tony Luck <tony.luck@intel.com>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Link: https://lore.kernel.org/all/20231025202513.12358-1-tony.luck%40intel.com

Pull kvm fixes from Paolo Bonzini:
 "ARM:

   - Fix the handling of the phycal timer offset when FEAT_ECV and
     CNTPOFF_EL2 are implemented

   - Restore the functionnality of Permission Indirection that was
     broken by the Fine Grained Trapping rework

   - Cleanup some PMU event sharing code

  MIPS:

   - Fix W=1 build

  s390:

   - One small fix for gisa to avoid stalls

  x86:

   - Truncate writes to PMU counters to the counter's width to avoid
     spurious overflows when emulating counter events in software

   - Set the LVTPC entry mask bit when handling a PMI (to match
     Intel-defined architectural behavior)

   - Treat KVM_REQ_PMI as a wake event instead of queueing host IRQ work
     to kick the guest out of emulated halt

   - Fix for loading XSAVE state from an old kernel into a new one

   - Fixes for AMD AVIC

  selftests:

   - Play nice with %llx when formatting guest printf and assert
     statements

   - Clean up stale test metadata

   - Zero-initialize structures in memslot perf test to workaround a
     suspected 'may be used uninitialized' false positives from GCC"

* tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm: (21 commits)
  KVM: arm64: timers: Correctly handle TGE flip with CNTPOFF_EL2
  KVM: arm64: POR{E0}_EL1 do not need trap handlers
  KVM: arm64: Add nPIR{E0}_EL1 to HFG traps
  KVM: MIPS: fix -Wunused-but-set-variable warning
  KVM: arm64: pmu: Drop redundant check for non-NULL kvm_pmu_events
  KVM: SVM: Fix build error when using -Werror=unused-but-set-variable
  x86: KVM: SVM: refresh AVIC inhibition in svm_leave_nested()
  x86: KVM: SVM: add support for Invalid IPI Vector interception
  x86: KVM: SVM: always update the x2avic msr interception
  KVM: selftests: Force load all supported XSAVE state in state test
  KVM: selftests: Load XSAVE state into untouched vCPU during state test
  KVM: selftests: Touch relevant XSAVE state in guest for state test
  KVM: x86: Constrain guest-supported xfeatures only at KVM_GET_XSAVE{2}
  x86/fpu: Allow caller to constrain xfeatures when copying to uabi buffer
  KVM: selftests: Zero-initialize entire test_result in memslot perf test
  KVM: selftests: Remove obsolete and incorrect test case metadata
  KVM: selftests: Treat %llx like %lx when formatting guest printf
  KVM: x86/pmu: Synthesize at most one PMI per VM-exit
  KVM: x86: Mask LVTPC when handling a PMI
  KVM: x86/pmu: Truncate counter value to allowed width on write
  ...

This reverts commit 45e34c8af58f23db4474e2bfe79183efec09a18b, and the
two subsequent fixes to it:

  3f874c9b2aae ("x86/smp: Don't send INIT to non-present and non-booted CPUs")
  b1472a60a584 ("x86/smp: Don't send INIT to boot CPU")

because it seems to result in hung machines at shutdown.  Particularly
some Dell machines, but Thomas says

 "The rest seems to be Lenovo and Sony with Alderlake/Raptorlake CPUs -
  at least that's what I could figure out from the various bug reports.

  I don't know which CPUs the DELL machines have, so I can't say it's a
  pattern.

  I agree with the revert for now"

Ashok Raj chimes in:

 "There was a report (probably this same one), and it turns out it was a
  bug in the BIOS SMI handler.

  The client BIOS's were waiting for the lowest APICID to be the SMI
  rendevous master. If this is MeteorLake, the BSP wasn't the one with
  the lowest APIC and it triped here.

  The BIOS change is also being pushed to others for assimilation :)

  Server BIOS's had this correctly for a while now"

and it does look likely to be some bad interaction between SMI and the
non-BSP cores having put into INIT (and thus unresponsive until reset).

Link: https://bbs.archlinux.org/viewtopic.php?pid=2124429
Link: https://www.reddit.com/r/openSUSE/comments/16qq99b/tumbleweed_shutdown_did_not_finish_completely/
Link: https://forum.artixlinux.org/index.php/topic,5997.0.html
Link: https://bugzilla.redhat.com/show_bug.cgi?id=2241279
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Ashok Raj <ashok.raj@intel.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Pull CPU hotplug fix from Ingo Molnar:
 "Fix a Longsoon build warning by harmonizing the
  arch_[un]register_cpu() prototypes between architectures"

* tag 'smp-urgent-2023-10-15' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  cpu-hotplug: Provide prototypes for arch CPU registration

KVM x86/pmu fixes for 6.6:

 - Truncate writes to PMU counters to the counter's width to avoid spurious
   overflows when emulating counter events in software.

 - Set the LVTPC entry mask bit when handling a PMI (to match Intel-defined
   architectural behavior).

 - Treat KVM_REQ_PMI as a wake event instead of queueing host IRQ work to
   kick the guest out of emulated halt.

Pull x86 fixes from Ingo Molnar:
 "Fix a false-positive KASAN warning, fix an AMD erratum on Zen4 CPUs,
  and fix kernel-doc build warnings"

* tag 'x86-urgent-2023-10-15' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/alternatives: Disable KASAN in apply_alternatives()
  x86/cpu: Fix AMD erratum #1485 on Zen4-based CPUs
  x86/resctrl: Fix kernel-doc warnings

In later revisions of AMD's APM, there is a new 'incomplete IPI' exit code:

"Invalid IPI Vector - The vector for the specified IPI was set to an
illegal value (VEC < 16)"

Note that tests on Zen2 machine show that this VM exit doesn't happen and
instead AVIC just does nothing.

Add support for this exit code by doing nothing, instead of filling
the kernel log with errors.

Also replace an unthrottled 'pr_err()' if another unknown incomplete
IPI exit happens with vcpu_unimpl()

(e.g in case AMD adds yet another 'Invalid IPI' exit reason)

Cc: <stable@vger.kernel.org>
Signed-off-by: Maxim Levitsky <mlevitsk@redhat.com>
Reviewed-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20230928173354.217464-3-mlevitsk@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

Plumb an xfeatures mask into __copy_xstate_to_uabi_buf() so that KVM can
constrain which xfeatures are saved into the userspace buffer without
having to modify the user_xfeatures field in KVM's guest_fpu state.

KVM's ABI for KVM_GET_XSAVE{2} is that features that are not exposed to
guest must not show up in the effective xstate_bv field of the buffer.
Saving only the guest-supported xfeatures allows userspace to load the
saved state on a different host with a fewer xfeatures, so long as the
target host supports the xfeatures that are exposed to the guest.

KVM currently sets user_xfeatures directly to restrict KVM_GET_XSAVE{2} to
the set of guest-supported xfeatures, but doing so broke KVM's historical
ABI for KVM_SET_XSAVE, which allows userspace to load any xfeatures that
are supported by the *host*.

Cc: stable@vger.kernel.org
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20230928001956.924301-2-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

Provide common prototypes for arch_register_cpu() and
arch_unregister_cpu(). These are called by acpi_processor.c, with weak
versions, so the prototype for this is already set. It is generally not
necessary for function prototypes to be conditional on preprocessor macros.

Some architectures (e.g. Loongarch) are missing the prototype for this, and
rather than add it to Loongarch's asm/cpu.h, do the job once for everyone.

Since this covers everyone, remove the now unnecessary prototypes in
asm/cpu.h, and therefore remove the 'static' from one of ia64's
arch_register_cpu() definitions.

[ tglx: Bring back the ia64 part and remove the ACPI prototypes ]

Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/E1qkoRr-0088Q8-Da@rmk-PC.armlinux.org.uk