kernel/linux.git/arch/x86, branch v7.2-rc5

Merge tag 'x86-urgent-2026-07-26' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

2026-07-26T15:52:38+00:00

Pull x86 fix from Ingo Molnar: - Disable jump/lookup tables in the x86 boot decompressor code a bit more widely, because newer versions of LLVM started optimizing it a bit better and introduced run-time relocations in PIE code (Nathan Chancellor) * tag 'x86-urgent-2026-07-26' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: x86/boot/compressed: Disable jump tables

x86/boot/compressed: Disable jump tables

2026-07-23T08:06:58+00:00

After a recent upstream LLVM change to start generating jump and lookup tables in switch statements in more instances [1], linking the compressed x86 boot image when CONFIG_KERNEL_ZSTD is enabled fails with: ld.lld: error: Unexpected run-time relocations (.rela) detected! Dumping the relocations in misc.o, which is the only file influenced by CONFIG_KERNEL_ZSTD in the decompressor, shows dynamic relocations to some string constants, which correspond to the string literals in the switch statement in handle_zstd_error(): Relocation section '.rela.data.rel.ro' at offset 0x277b0 contains 31 entries: Offset Info Type Symbol's Value Symbol's Name + Addend 0000000000000000 0000006600000001 R_X86_64_64 0000000000000000 .rodata.str1.1 + 73a 0000000000000008 0000006600000001 R_X86_64_64 0000000000000000 .rodata.str1.1 + 78e 0000000000000010 0000006600000001 R_X86_64_64 0000000000000000 .rodata.str1.1 + 78e 0000000000000018 0000006600000001 R_X86_64_64 0000000000000000 .rodata.str1.1 + 78e ... This optimization is problematic for the decompressor environment, as it is built as -fPIE without any explicit absolute references (as described at the top of misc.c) while not applying any dynamic relocations, hence the linker assertion. To opt out of this optimization, which is of little value in this special early boot code, and to mirror the other x86 startup code in arch/x86/boot/startup, disable jump tables in the decompressor. Signed-off-by: Nathan Chancellor Signed-off-by: Ingo Molnar Acked-by: Ard Biesheuvel Cc: Bill Wendling Cc: Justin Stitt Cc: Nick Desaulniers Cc: "H. Peter Anvin" Cc: Peter Zijlstra Cc: stable@vger.kernel.org Link: https://github.com/llvm/llvm-project/commit/fa02a6ed66b1700c996b49c96c6bc0eb014c9518 [1] Link: https://patch.msgid.link/20260722-x86-boot-compressed-disable-jt-clang-v2-1-7373d38482fb@kernel.org Closes: https://github.com/ClangBuiltLinux/linux/issues/2165

Merge tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm

2026-07-21T15:26:21+00:00

Pull kvm fixes from Paolo Bonzini: "RISC-V: - Avoid redundant allocations when allocating IMSIC page tables - Apply SBI FWFT LOCK flag only on successful set - Bound SBI PMU counter mask scan to BITS_PER_LONG, since on RV32 the PMU SBI start/stop helper can only access 32 PMU counters. - Skip TLB flush when G-stage PTE becomes valid if the Svvptc extension is available. - Always show Zicbo[m|z|p] block sizes in ONE_REG - Inject instruction access fault on unmapped guest fetch - Use raw spinlock for irqs_pending and irqs_pending_mask - Fix Spectre-v1 in vector register access via ONE_REG x86: - Fixes to SEV selftests - Once free_nested() did a VMCLEAR of shadow VMCS, there's no need to VMCLEAR it again if the kernel is preempted and thread migration happens - Preserve nested TDP shadow page tables if they are used as roots, instead of clearing them unnecessarily - Fix use of stale data if out-of-memory happens after vendor module reload - Check for invalid/obsolete root *after* making MMU pages available, because the latter can make a page invalid - Only reset TSC Deadline Timer in apic_timer_expired on KVM_RUN" * tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm: KVM: x86: Only reset TSC Deadline Timer in apic_timer_expired on KVM_RUN KVM: selftests: sev_init2_tests: Derive SEV availability from KVM KVM: selftests: sev_smoke_test: Only run VM types the host offers KVM: x86/mmu: Fix use-after-free on vendor module reload KVM: x86/mmu: Preserve nested TDP shadow page tables if they are used as roots KVM: x86: Check for invalid/obsolete root *after* making MMU pages available KVM: nVMX: Hide shadow VMCS right after VMCLEAR KVM: riscv: Fix Spectre-v1 in vector register access RISC-V: KVM: Serialize virtual interrupt pending state updates RISC-V: KVM: Inject instruction access fault on unmapped guest fetch RISC-V: KVM: Zicbo[m|z|p] block sizes should be always present in ONE_REG riscv: kvm: Skip TLB flush when G-stage PTE becomes valid with Svvptc KVM: riscv: PMU: Bound counter mask scan to BITS_PER_LONG KVM: riscv: SBI FWFT: Apply LOCK flag only on successful set RISC-V: KVM: Avoid redundant page-table allocations in ioremap topup

KVM: x86: Only reset TSC Deadline Timer in apic_timer_expired on KVM_RUN

2026-07-21T10:25:28+00:00

On Intel platforms with a VMX preemption timer and APICv, if a VMM calls KVM_GET_LAPIC before KVM_GET_MSRS to save the vCPU state, it is possible to lose a pending timer interrupt. If the thread running these ioctls is migrated to another core after calling KVM_GET_LAPIC but before KVM_GET_MSRS and the guest is using their LAPIC timer in TSC-deadline mode, not only does the save LAPIC state not carry the pending interrupt, the TSCDEADLINE MSR will be zeroed. After migration across CPUs, KVM_GET_MSRS calls vcpu_load, posting the interrupt and clearing the MSR: vcpu_load() -> kvm_arch_vcpu_load() -> kvm_lapic_restart_hv_timer() -> start_hv_timer() -> apic_timer_expired() -> kvm_apic_inject_pending_timer_irqs() . post interrupt into the LAPIC state . clear IA32_TSCDEADLINE The saved LAPIC state will be missing the pending interrupt and the saved MSR will be zero. Oops. Fix by only posting an interrupt when we're attempting to enter the guest (vcpu->wants_to_run == true), not for vcpu_load from other paths. Assisted-by: gemini:gemini-3.1-pro-preview Debugged-by: David Matlack Debugged-by: Sean Christopherson Debugged-by: Jim Mattson Debugged-by: James Houghton Signed-off-by: Venkatesh Srinivas Message-ID: <20260715234234.15382-2-venkateshs@chromium.org> Reviewed-by: James Houghton Reviewed-by: Chao Gao Cc: stable@vger.kernel.org Fixes: ae95f566b3d2 ("KVM: X86: TSCDEADLINE MSR emulation fastpath", 2020-05-15) Signed-off-by: Paolo Bonzini

KVM: x86/mmu: Fix use-after-free on vendor module reload

2026-07-21T10:25:20+00:00

mmu_destroy_caches() destroys pte_list_desc_cache and mmu_page_header_cache, but leaves both pointers unchanged. The pointers live in kvm.ko, and therefore survive when a vendor module is unloaded while kvm.ko remains loaded. If creation of pte_list_desc_cache fails during a subsequent vendor module load, its assignment sets pte_list_desc_cache to NULL and the error path calls mmu_destroy_caches(). mmu_page_header_cache still points to the cache destroyed during the preceding vendor module unload. Passing that stale pointer to kmem_cache_destroy() causes a slab use-after-free. Reproduce the issue on a v7.1.3 kernel with CONFIG_KASAN=y, CONFIG_KASAN_GENERIC=y, CONFIG_KVM=m, and CONFIG_KVM_INTEL=m. A one-shot test hook forces pte_list_desc_cache to NULL on the second invocation of kvm_mmu_vendor_module_init(): 1. Load kvm.ko and kvm-intel.ko, creating both caches. 2. Unload only kvm_intel, leaving kvm.ko loaded. 3. Reload kvm_intel and force initialization through the -ENOMEM path. KASAN reports: BUG: KASAN: slab-use-after-free in kvm_mmu_vendor_module_init+0x5b/0x170 [kvm] ... kmem_cache_destroy+0x21/0x1d0 kvm_mmu_vendor_module_init+0x5b/0x170 [kvm] ... Allocated by task 16817: __kmem_cache_create_args+0x12c/0x3b0 __kmem_cache_create.constprop.0+0xb6/0xf0 [kvm] kvm_mmu_vendor_module_init+0x13b/0x170 [kvm] ... Freed by task 16820: kmem_cache_destroy+0x117/0x1d0 kvm_mmu_vendor_module_exit+0x21/0x30 [kvm] Clear both pointers immediately after destroying their caches so that the stored state reflects the caches' lifetime and repeated cleanup is safe. With the fix applied, the same injected vendor module reload fails with -ENOMEM as expected and produces no KASAN report. Fixes: cb498ea2ce1d ("KVM: Portability: Combine kvm_init and kvm_init_x86") Cc: stable@vger.kernel.org Signed-off-by: Phil Rosenthal Message-ID: <20260718-kvm-mmu-cache-uaf-v3-1-e103b93c74e1@phil.gs> Signed-off-by: Paolo Bonzini

KVM: x86/mmu: Preserve nested TDP shadow page tables if they are used as roots

2026-07-21T10:25:18+00:00

kvm_mmu_zap_oldest_mmu_pages() excludes a shadow page whose root_count is non-zero from top-level reclaim, because such a page cannot be freed. The path in mmu_page_zap_pte() that recursively zaps a parentless nested TDP child has no such check. As a result, a shadow page can be zapped even if the page itself can't be freed; as the comment in kvm_mmu_zap_oldest_mmu_pages() notes, zapping it will just force vCPUs to rebuild the page. As in top-level reclaim, do not recursively prepare zapping of a nested TDP child whose root_count is non-zero. Fixes: 2de4085cccea ("KVM: x86/MMU: Recursively zap nested TDP SPs when zapping last/only parent") Signed-off-by: Hyunwoo Kim Signed-off-by: Paolo Bonzini

KVM: x86: Check for invalid/obsolete root after making MMU pages available

2026-07-21T10:25:10+00:00

Check for a "stale" page fault, i.e. for an invalid and/or obsolete root, after making MMU pages available for the shadow MMU. If reclaiming shadow pages zaps an in-use root, i.e. marks it invalid, then KVM will attempt to map memory into an invalid root. On its own, populating an invalid root is "fine", but because child shadow pages inherit their parent's role, any children created during the map/fetch will be created as invalid pages, thus violating KVM's invariant that invalid pages are never on the list of active MMU pages. Note, the underlying flaw has existed since KVM first started tracking invalid roots in 2008 (commit 2e53d63acba7, "KVM: MMU: ignore zapped root pagetables"), but the true badness only came along in 2020 (Linux 5.9) with the invariant that invalid shadow pages can't be on the list of active pages. Note #2, inheriting role.invalid when creating child shadow pages is also far from ideal; that flaw will be addressed separately. Reported-by: Hyunwoo Kim Fixes: f95eec9bed76 ("KVM: x86/mmu: Don't put invalid SPs back on the list of active pages") Cc: stable@vger.kernel.org Signed-off-by: Sean Christopherson Signed-off-by: Paolo Bonzini

KVM: nVMX: Hide shadow VMCS right after VMCLEAR

2026-07-21T10:24:49+00:00

free_nested() frees the shadow VMCS while vmcs01 still points to it. But because it is asynchronous with respect to loaded_vmcs_clear(), the vCPU might migrate before the pointer is cleared and __loaded_vmcs_clear() may then execute VMCLEAR. The VMCS needs to stay attached until its explicit VMCLEAR completes, but then it can be hidden and the page safely freed. Fixes: 355f4fb1405e ("kvm: nVMX: VMCLEAR an active shadow VMCS after last use") Cc: stable@vger.kernel.org Signed-off-by: Hyunwoo Kim Signed-off-by: Paolo Bonzini

Merge tag 'x86-urgent-2026-07-19' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

2026-07-19T15:55:38+00:00

Pull x86 fixes from Ingo Molnar: - Reject too long acpi_rsdp= boot parameter values (Thorsten Blum) - Validate console=uart8250 baud rate to fix early boot hang (Thorsten Blum) - Remove dead Makefile rule (Ethan Nelson-Moore) * tag 'x86-urgent-2026-07-19' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: x86/boot: Validate console=uart8250 baud rate to fix early boot hang x86/boot: Reject too long acpi_rsdp= values x86/cpu: Remove Makefile rule for removed UMC CPU support

KVM: SVM: Bump asid_generation on CPU online to avoid ASID collision after hotplug

2026-07-16T06:55:03+00:00

If a vCPU stays scheduled out (or blocked) while the last pCPU it ran on goes through a hotplug cycle (online->offline->online), and the vCPU then resumes execution on the same pCPU, then it is possible for it to run with an ASID that has now been assigned to a different vCPU, resulting in stale TLB translations being used. svm_enable_virtualization_cpu() resets asid_generation to 1 and sets next_asid to max_asid + 1 on every CPU online event, including hotplug cycles. Because next_asid starts beyond the pool boundary, the first call to new_asid() after an online event always wraps the pool, incrementing asid_generation to 2 and assigning ASIDs starting from min_asid. Consider two vCPUs from different VMs, vCPU-A pinned to CPU-X holding asid_generation=2 and ASID=N from before the hotplug event: 1. CPU-X goes offline and back online: asid_generation resets to 1, next_asid = max_asid + 1. 2. One or more vCPUs migrate to CPU-X and call new_asid(), wrapping the pool and consuming ASIDs starting from min_asid. Eventually vCPU-B from a different VM is assigned asid_generation=2, ASID=N — the same ASID that vCPU-A held before the hotplug. 3. vCPU-A enters pre_svm_run() on CPU-X: current_vmcb->cpu is unchanged so the migration branch is skipped. Its saved asid_generation=2 matches sd->asid_generation=2, so the generation check silently passes and vCPU-A continues running with ASID=N — the same ASID just freshly assigned to vCPU-B. Both vCPUs from different VMs now run on CPU-X with the same ASID, causing them to share NPT TLB entries and producing stale translations. The collision manifests as a KVM internal error (Suberror: 1, emulation failure). The NPT page fault reports a faulting GPA far outside the VM's physical memory range — a sign of stale TLB translations being used. KVM falls back to instruction emulation, which fails on FPU/XSave instructions (XRSTOR, STMXCSR) that the emulator does not implement. Fix this by incrementing asid_generation instead of resetting it to 1 in svm_enable_virtualization_cpu(). On module load, asid_generation starts at 0 (memset) and the increment produces 1, identical to the old behaviour. On subsequent hotplug cycles the generation advances beyond any value a vCPU previously observed on this CPU, so the generation check in pre_svm_run() reliably forces new_asid() on every vCPU after every hotplug cycle. Fixes: 774c47f1d78e ("[PATCH] KVM: cpu hotplug support") Reported-by: Chandrakanth Silveru Tested-by: Srikanth Aithal Reviewed-by: K Prateek Nayak Reviewed-by: Tom Lendacky Signed-off-by: Nikunj A Dadhania Message-ID: <20260715063506.672432-1-nikunj@amd.com> Signed-off-by: Paolo Bonzini