Pull arm64 cBPF BHB mitigation from James Morse:
 "This adds the BHB mitigation into the code JITted for cBPF programs as
  these can be loaded by unprivileged users via features like seccomp.

  The existing mechanisms to disable the BHB mitigation will also
  prevent the mitigation being JITted. In addition, cBPF programs loaded
  by processes with the SYS_ADMIN capability are not mitigated as these
  could equally load an eBPF program that does the same thing.

  For good measure, the list of 'k' values for CPU's local mitigations
  is updated from the version on arm's website"

* tag 'arm64_cbpf_mitigation_2025_05_08' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux:
  arm64: proton-pack: Add new CPUs 'k' values for branch mitigation
  arm64: bpf: Only mitigate cBPF programs loaded by unprivileged users
  arm64: bpf: Add BHB mitigation to the epilogue for cBPF programs
  arm64: proton-pack: Expose whether the branchy loop k value
  arm64: proton-pack: Expose whether the platform is mitigated by firmware
  arm64: insn: Add support for encoding DSB

Pull KVM fixes from Paolo Bonzini:
 "ARM:

   - Avoid use of uninitialized memcache pointer in user_mem_abort()

   - Always set HCR_EL2.xMO bits when running in VHE, allowing
     interrupts to be taken while TGE=0 and fixing an ugly bug on
     AmpereOne that occurs when taking an interrupt while clearing the
     xMO bits (AC03_CPU_36)

   - Prevent VMMs from hiding support for AArch64 at any EL virtualized
     by KVM

   - Save/restore the host value for HCRX_EL2 instead of restoring an
     incorrect fixed value

   - Make host_stage2_set_owner_locked() check that the entire requested
     range is memory rather than just the first page

  RISC-V:

   - Add missing reset of smstateen CSRs

  x86:

   - Forcibly leave SMM on SHUTDOWN interception on AMD CPUs to avoid
     causing problems due to KVM stuffing INIT on SHUTDOWN (KVM needs to
     sanitize the VMCB as its state is undefined after SHUTDOWN,
     emulating INIT is the least awful choice).

   - Track the valid sync/dirty fields in kvm_run as a u64 to ensure KVM
     KVM doesn't goof a sanity check in the future.

   - Free obsolete roots when (re)loading the MMU to fix a bug where
     pre-faulting memory can get stuck due to always encountering a
     stale root.

   - When dumping GHCB state, use KVM's snapshot instead of the raw GHCB
     page to print state, so that KVM doesn't print stale/wrong
     information.

   - When changing memory attributes (e.g. shared <=> private), add
     potential hugepage ranges to the mmu_invalidate_range_{start,end}
     set so that KVM doesn't create a shared/private hugepage when the
     the corresponding attributes will become mixed (the attributes are
     commited *after* KVM finishes the invalidation).

   - Rework the SRSO mitigation to enable BP_SPEC_REDUCE only when KVM
     has at least one active VM. Effectively BP_SPEC_REDUCE when KVM is
     loaded led to very measurable performance regressions for non-KVM
     workloads"

* tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm:
  KVM: SVM: Set/clear SRSO's BP_SPEC_REDUCE on 0 <=> 1 VM count transitions
  KVM: arm64: Fix memory check in host_stage2_set_owner_locked()
  KVM: arm64: Kill HCRX_HOST_FLAGS
  KVM: arm64: Properly save/restore HCRX_EL2
  KVM: arm64: selftest: Don't try to disable AArch64 support
  KVM: arm64: Prevent userspace from disabling AArch64 support at any virtualisable EL
  KVM: arm64: Force HCR_EL2.xMO to 1 at all times in VHE mode
  KVM: arm64: Fix uninitialized memcache pointer in user_mem_abort()
  KVM: x86/mmu: Prevent installing hugepages when mem attributes are changing
  KVM: SVM: Update dump_ghcb() to use the GHCB snapshot fields
  KVM: RISC-V: reset smstateen CSRs
  KVM: x86/mmu: Check and free obsolete roots in kvm_mmu_reload()
  KVM: x86: Check that the high 32bits are clear in kvm_arch_vcpu_ioctl_run()
  KVM: SVM: Forcibly leave SMM mode on SHUTDOWN interception

Update the list of 'k' values for the branch mitigation from arm's
website.

Add the values for Cortex-X1C. The MIDR_EL1 value can be found here:
https://developer.arm.com/documentation/101968/0002/Register-descriptions/AArch>

Link: https://developer.arm.com/documentation/110280/2-0/?lang=en
Signed-off-by: James Morse <james.morse@arm.com>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>

A malicious BPF program may manipulate the branch history to influence
what the hardware speculates will happen next.

On exit from a BPF program, emit the BHB mititgation sequence.

This is only applied for 'classic' cBPF programs that are loaded by
seccomp.

Signed-off-by: James Morse <james.morse@arm.com>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>

Add a helper to expose the k value of the branchy loop. This is needed
by the BPF JIT to generate the mitigation sequence in BPF programs.

Signed-off-by: James Morse <james.morse@arm.com>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>

is_spectre_bhb_fw_affected() allows the caller to determine if the CPU
is known to need a firmware mitigation. CPUs are either on the list
of CPUs we know about, or firmware has been queried and reported that
the platform is affected - and mitigated by firmware.

This helper is not useful to determine if the platform is mitigated
by firmware. A CPU could be on the know list, but the firmware may
not be implemented. Its affected but not mitigated.

spectre_bhb_enable_mitigation() handles this distinction by checking
the firmware state before enabling the mitigation.

Add a helper to expose this state. This will be used by the BPF JIT
to determine if calling firmware for a mitigation is necessary and
supported.

Signed-off-by: James Morse <james.morse@arm.com>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>

To generate code in the eBPF epilogue that uses the DSB instruction,
insn.c needs a heler to encode the type and domain.

Re-use the crm encoding logic from the DMB instruction.

Signed-off-by: James Morse <james.morse@arm.com>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>

HCRX_HOST_FLAGS, like most of these hardcoded setups, are not
a good match for options that can be selectively enabled or
disabled.

Nothing but the early setup is relying on it now, so kill the
macro and move the bag of bits where they belong.

Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20250430105916.3815157-3-maz@kernel.org
Signed-off-by: Oliver Upton <oliver.upton@linux.dev>

We keep setting and clearing these bits depending on the role of
the host kernel, mimicking what we do for nVHE. But that's actually
pretty pointless, as we always want physical interrupts to make it
to the host, at EL2.

This has also two problems:

- it prevents IRQs from being taken when these bits are cleared
  if the implementation has chosen to implement these bits as
  masks when HCR_EL2.{TGE,xMO}=={0,0}

- it triggers a bad erratum on the AmpereOne HW, which catches
  fire on clearing these bits while an interrupt is being taken
  (AC03_CPU_36).

Let's kill these two birds with a single stone, and permanently
set the xMO bits when running VHE. This involves a bit of surgery
on code paths that rely on flipping these bits on and off for
other purposes.

Note that the earliest setting of hcr_el2 (in the init_hcr_el2
macro) is left untouched as is runs extremely early, with interrupts
disabled, and soon enough overwritten with the final value containing
the xMO bits.

Reported-by: D Scott Phillips <scott@os.amperecomputing.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20250429114326.3618875-1-maz@kernel.org
Signed-off-by: Oliver Upton <oliver.upton@linux.dev>

All vDSO code needs to be completely position independent.  Symbol
references are marked as hidden so the compiler emits PC-relative
relocations.

However GCC emits absolute relocations for symbol-relative references with
an offset >= 64KiB. After recent refactorings in the vDSO code this is the
case in __arch_get_vdso_u_timens_data() with a page size of 64KiB.

Work around the issue by preventing the optimizer from seeing the offsets.

Fixes: 83a2a6b8cfc5 ("vdso/gettimeofday: Prepare do_hres_timens() for introduction of struct vdso_clock")
Reported-by: Jan Stancek <jstancek@redhat.com>
Signed-off-by: Thomas Weißschuh <thomas.weissschuh@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Link: https://lore.kernel.org/all/20250430-vdso-absolute-reloc-v2-1-5efcc3bc4b26@linutronix.de
Link: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=120002
Closes: https://lore.kernel.org/lkml/aApGPAoctq_eoE2g@t14ultra/