Fedora QA reported the following panic: BUG: unable to handle page fault for address: 0000000040003e54 #PF: supervisor write access in kernel mode #PF: error_code(0x0002) - not-present page Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS edk2-20251119-3.fc43 11/19/2025 RIP: 0010:vmware_hypercall4.constprop.0+0x52/0x90 .. Call Trace: vmmouse_report_events+0x13e/0x1b0 psmouse_handle_byte+0x15/0x60 ps2_interrupt+0x8a/0xd0 ... because the QEMU VMware mouse emulation is buggy, and clears the top 32 bits of %rdi that the kernel kept a pointer in. The QEMU vmmouse driver saves and restores the register state in a "uint32_t data[6];" and as a result restores the state with the high bits all cleared. RDI originally contained the value of a valid kernel stack address (0xff5eeb3240003e54). After the vmware hypercall it now contains 0x40003e54, and we get a page fault as a result when it is dereferenced. The proper fix would be in QEMU, but this works around the issue in the kernel to keep old setups working, when old kernels had not happened to keep any state in %rdi over the hypercall. In theory this same issue exists for all the hypercalls in the vmmouse driver; in practice it has only been seen with vmware_hypercall3() and vmware_hypercall4(). For now, just mark RDI/RSI as clobbered for those two calls. This should have a minimal effect on code generation overall as it should be rare for the compiler to want to make RDI/RSI live across hypercalls. Reported-by: Justin Forbes <jforbes@fedoraproject.org> Link: https://lore.kernel.org/all/99a9c69a-fc1a-43b7-8d1e-c42d6493b41f@broadcom.com/ Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org> Cc: stable@kernel.org Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Pull ARM fix from Russell King: "Just one fix for memset64() on big endian 32-bit ARM systems" * tag 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/rmk/linux: ARM: 9468/1: fix memset64() on big-endian
Pull misc fixes from Andrew Morton: "Five hotfixes. Two are cc:stable, two are for MM. All are singletons - please see the changelogs for details" * tag 'mm-hotfixes-stable-2026-02-04-15-55' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: Documentation: document liveupdate cmdline parameter mm, shmem: prevent infinite loop on truncate race mailmap: update Alexander Mikhalitsyn's emails liveupdate: luo_file: do not clear serialized_data on unfreeze x86/kfence: fix booting on 32bit non-PAE systems
Pull KVM fixes from Paolo Bonzini:
- Fix a bug where AVIC is incorrectly inhibited when running with
x2AVIC disabled via module param (or on a system without x2AVIC)
- Fix a dangling device posted IRQs bug by explicitly checking if the
irqfd is still active (on the list) when handling an eventfd signal,
instead of zeroing the irqfd's routing information when the irqfd is
deassigned.
Zeroing the irqfd's routing info causes arm64 and x86's to not
disable posting for the IRQ (kvm_arch_irq_bypass_del_producer() looks
for an MSI), incorrectly leaving the IRQ in posted mode (and leading
to use-after-free and memory leaks on AMD in particular).
This is both the most pressing and scariest, but it's been in -next
for a while.
- Disable FORTIFY_SOURCE for KVM selftests to prevent the compiler from
generating calls to the checked versions of memset() and friends,
which leads to unexpected page faults in guest code due e.g.
__memset_chk@plt not being resolved.
- Explicitly configure the supported XSS capabilities from within
{svm,vmx}_set_cpu_caps() to fix a bug where VMX will compute the
reference VMCS configuration with SHSTK and IBT enabled, but then
compute each CPUs local config with SHSTK and IBT disabled if not all
CET xfeatures are enabled, e.g. if the kernel is built with
X86_KERNEL_IBT=n.
The mismatch in features results in differing nVMX setting, and
ultimately causes kvm-intel.ko to refuse to load with nested=1.
* tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm:
KVM: x86: Explicitly configure supported XSS from {svm,vmx}_set_cpu_caps()
KVM: selftests: Add -U_FORTIFY_SOURCE to avoid some unpredictable test failures
KVM: x86: Assert that non-MSI doesn't have bypass vCPU when deleting producer
KVM: Don't clobber irqfd routing type when deassigning irqfd
KVM: SVM: Check vCPU ID against max x2AVIC ID if and only if x2AVIC is enabled
Final KVM fixes for 6.19:
- Fix a bug where AVIC is incorrectly inhibited when running with x2AVIC
disabled via module param (or on a system without x2AVIC).
- Fix a dangling device posted IRQs bug by explicitly checking if the irqfd is
still active (on the list) when handling an eventfd signal, instead of
zeroing the irqfd's routing information when the irqfd is deassigned.
Zeroing the irqfd's routing info causes arm64 and x86's to not disable
posting for the IRQ (kvm_arch_irq_bypass_del_producer() looks for an MSI),
incorrectly leaving the IRQ in posted mode (and leading to use-after-free
and memory leaks on AMD in particular).
This is both the most pressing and scariest, but it's been in -next for
a while.
- Disable FORTIFY_SOURCE for KVM selftests to prevent the compiler from
generating calls to the checked versions of memset() and friends, which
leads to unexpected page faults in guest code due e.g. __memset_chk@plt
not being resolved.
- Explicitly configure the support XSS from within {svm,vmx}_set_cpu_caps() to
fix a bug where VMX will compute the reference VMCS configuration with SHSTK
and IBT enabled, but then compute each CPUs local config with SHSTK and IBT
disabled if not all CET xfeatures are enabled, e.g. if the kernel is built
with X86_KERNEL_IBT=n. The mismatch in features results in differing nVMX
setting, and ultimately causes kvm-intel.ko to refuse to load with nested=1.
The original patch inverted the PTE unconditionally to avoid
L1TF-vulnerable PTEs, but Linux doesn't make this adjustment in 2-level
paging.
Adjust the logic to use the flip_protnone_guard() helper, which is a nop
on 2-level paging but inverts the address bits in all other paging modes.
This doesn't matter for the Xen aspect of the original change. Linux no
longer supports running 32bit PV under Xen, and Xen doesn't support
running any 32bit PV guests without using PAE paging.
Link: https://lkml.kernel.org/r/20260126211046.2096622-1-andrew.cooper3@citrix.com
Fixes: b505f1944535 ("x86/kfence: avoid writing L1TF-vulnerable PTEs")
Reported-by: Ryusuke Konishi <konishi.ryusuke@gmail.com>
Closes: https://lore.kernel.org/lkml/CAKFNMokwjw68ubYQM9WkzOuH51wLznHpEOMSqtMoV1Rn9JV_gw@mail.gmail.com/
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Tested-by: Ryusuke Konishi <konishi.ryusuke@gmail.com>
Tested-by: Borislav Petkov (AMD) <bp@alien8.de>
Cc: Alexander Potapenko <glider@google.com>
Cc: Marco Elver <elver@google.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Jann Horn <jannh@google.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
On big-endian systems the 32-bit low and high halves need to be swapped
for the underlying assembly implementation to work correctly.
Fixes: fd1d362600e2 ("ARM: implement memset32 & memset64")
Cc: stable@vger.kernel.org
Signed-off-by: Thomas Weißschuh <thomas.weissschuh@linutronix.de>
Reviewed-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
Pull RISC-V fixes from Paul Walmsley: - Correct the RISC-V compat.h COMPAT_UTS_MACHINE architecture name - Avoid printing a false warning message on kernels with the SiFive and MIPS errata compiled in - Address a few warnings generated by sparse in the signal handling code - Fix a comment typo * tag 'riscv-for-linus-6.19-rc8' of git://git.kernel.org/pub/scm/linux/kernel/git/riscv/linux: riscv: compat: fix COMPAT_UTS_MACHINE definition errata/sifive: remove unreliable warn_miss_errata riscv: fix minor typo in syscall.h comment riscv: signal: fix some warnings reported by sparse
Explicitly configure KVM's supported XSS as part of each vendor's setup
flow to fix a bug where clearing SHSTK and IBT in kvm_cpu_caps, e.g. due
to lack of CET XFEATURE support, makes kvm-intel.ko unloadable when nested
VMX is enabled, i.e. when nested=1. The late clearing results in
nested_vmx_setup_{entry,exit}_ctls() clearing VM_{ENTRY,EXIT}_LOAD_CET_STATE
when nested_vmx_setup_ctls_msrs() runs during the CPU compatibility checks,
ultimately leading to a mismatched VMCS config due to the reference config
having the CET bits set, but every CPU's "local" config having the bits
cleared.
Note, kvm_caps.supported_{xcr0,xss} are unconditionally initialized by
kvm_x86_vendor_init(), before calling into vendor code, and not referenced
between ops->hardware_setup() and their current/old location.
Fixes: 69cc3e886582 ("KVM: x86: Add XSS support for CET_KERNEL and CET_USER")
Cc: stable@vger.kernel.org
Cc: Mathias Krause <minipli@grsecurity.net>
Cc: John Allen <john.allen@amd.com>
Cc: Rick Edgecombe <rick.p.edgecombe@intel.com>
Cc: Chao Gao <chao.gao@intel.com>
Cc: Binbin Wu <binbin.wu@linux.intel.com>
Cc: Xiaoyao Li <xiaoyao.li@intel.com>
Reviewed-by: Xiaoyao Li <xiaoyao.li@intel.com>
Reviewed-by: Binbin Wu <binbin.wu@linux.intel.com>
Link: https://patch.msgid.link/20260128014310.3255561-2-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
Pull misc fixes from Andrew Morton: "16 hotfixes. 9 are cc:stable, 12 are for MM. There's a patch series from Pratyush Yadav which fixes a few things in the new-in-6.19 LUO memfd code. Plus the usual shower of singletons - please see the changelogs for details" * tag 'mm-hotfixes-stable-2026-01-29-09-41' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: vmcoreinfo: make hwerr_data visible for debugging mm/zone_device: reinitialize large zone device private folios mm/mm_init: don't cond_resched() in deferred_init_memmap_chunk() if called from deferred_grow_zone() mm/kfence: randomize the freelist on initialization kho: kho_preserve_vmalloc(): don't return 0 when ENOMEM kho: init alloc tags when restoring pages from reserved memory mm: memfd_luo: restore and free memfd_luo_ser on failure mm: memfd_luo: use memfd_alloc_file() instead of shmem_file_setup() memfd: export alloc_file() flex_proportions: make fprop_new_period() hardirq safe mailmap: add entry for Viacheslav Bocharov mm/memory-failure: teach kill_accessing_process to accept hugetlb tail page pfn mm/memory-failure: fix missing ->mf_stats count in hugetlb poison mm, swap: restore swap_space attr aviod kernel panic mm/kasan: fix KASAN poisoning in vrealloc() mm/shmem, swap: fix race of truncate and swap entry split