kernel/linux.git/arch/riscv, branch v6.6.148

KVM: Introduce vcpu->wants_to_run

2026-08-03T09:15:40+00:00

[ Upstream commit a6816314af5749cd88944bfdceb270c627cdf348 ] Introduce vcpu->wants_to_run to indicate when a vCPU is in its core run loop, i.e. when the vCPU is running the KVM_RUN ioctl and immediate_exit was not set. Replace all references to vcpu->run->immediate_exit with !vcpu->wants_to_run to avoid TOCTOU races with userspace. For example, a malicious userspace could invoked KVM_RUN with immediate_exit=true and then after KVM reads it to set wants_to_run=false, flip it to false. This would result in the vCPU running in KVM_RUN with wants_to_run=false. This wouldn't cause any real bugs today but is a dangerous landmine. Signed-off-by: David Matlack Link: https://lore.kernel.org/r/20240503181734.1467938-2-dmatlack@google.com Signed-off-by: Sean Christopherson Stable-dep-of: e800decd9c0a ("KVM: x86: Only reset TSC Deadline Timer in apic_timer_expired on KVM_RUN") Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman

RISC-V: KVM: Serialize virtual interrupt pending state updates

2026-08-03T09:15:17+00:00

commit d024a0a7879e6f37c0152aacf6d8e37b214a1738 upstream. KVM RISC-V tracks guest local interrupt state with two bitmaps: - irqs_pending: interrupts that should be visible to the guest - irqs_pending_mask: interrupts whose pending state changed The current code updates those bitmaps with independent atomic bitops and assumes a multiple-producer, single-consumer protocol. That model does not actually hold. kvm_riscv_vcpu_sync_interrupts() is not a pure consumer. When the guest changes guest-visible HVIP state, sync_interrupts() writes both irqs_pending and irqs_pending_mask to reflect the new guest state back into KVM state. As a result, irqs_pending and irqs_pending_mask form a single logical state transition, but they are not updated atomically as a pair. This allows a race where a newly injected interrupt is lost. For example: CPU0 CPU1 ---- ---- kvm_riscv_vcpu_set_interrupt(VS_SOFT) set_bit(VS_SOFT, irqs_pending) kvm_riscv_vcpu_sync_interrupts() sees guest-cleared HVIP.VSSIP sets irqs_pending_mask clear_bit(IRQ_VS_SOFT, irqs_pending) set_bit(VS_SOFT, irqs_pending_mask) kvm_vcpu_kick() After that interleaving, a later flush can update HVIP without VSSIP even though a new virtual interrupt was injected. In practice, the guest can remain blocked in WFI with work pending. The same pending/mask protocol is shared by VS soft interrupts, PMU overflow delivery, and AIA high interrupt synchronization, so the race is not limited to one interrupt source. Fix this by serializing all updates to irqs_pending and irqs_pending_mask with a per-vCPU raw spinlock. This keeps the pending bit and the dirty mask as one state transition across: - set/unset interrupt - guest HVIP sync - interrupt flush to guest CSR state - vCPU reset - AIA CSR writes that clear dirty state Use non-atomic bitmap operations while holding the lock. Hold the lock across the AIA sync, flush, and pending checks as well, so both bitmap words share the same serialization domain. This intentionally replaces the existing lockless protocol instead of trying to repair it with additional barriers. The problem is not memory ordering on a single field; it is that two separate bitmaps encode one shared state machine while both producers and sync paths can modify them. A per-vCPU raw spinlock keeps the fix small, local, and suitable for backporting. Fixes: cce69aff689e ("RISC-V: KVM: Implement VCPU interrupts and requests handling") Cc: stable@vger.kernel.org Signed-off-by: Xie Bo Reviewed-by: Anup Patel Link: https://lore.kernel.org/r/20260715020359.1521354-2-xb@ultrarisc.com Signed-off-by: Anup Patel [ bo: Drop IRQ_PMU_OVF handling, which is not present in 6.6.y, and adapt the reset and CSR helpers to their older signatures. ] Signed-off-by: Sasha Levin

riscv: Prevent NULL pointer dereference in machine_kexec_prepare()

2026-07-24T14:03:44+00:00

commit 81bbcff0c053c4f5c711c31a9b72fc492bd96c3f upstream. A NULL pointer dereference issue is noticed in riscv's machine_kexec_prepare(), where image->segment[i].buf might be NULL and copied unchecked. The NULL buf comes from ima_add_kexec_buffer(), where kbuf is added by kexec_add_buffer(), but kbuf.buffer is NULL, then it is copied without a check in machine_kexec_prepare(): kexec_file_load -> kimage_file_alloc_init() -> kimage_file_prepare_segments() -> ima_add_kexec_buffer() -> kexec_add_buffer() -> machine_kexec_prepare() -> memcpy() Address this by adding a check before the data copy attempt. Fixes: b7fb4d78a6ad ("RISC-V: use memcpy for kexec_file mode") Cc: stable@vger.kernel.org Closes: https://lore.kernel.org/kexec/CAO7dBbVftLUhd2qrh7hmijTB3PEPfZAhykCGqEfrPoOcSrrj-w@mail.gmail.com/ Acked-by: Baoquan He Acked-by: Pratyush Yadav Reviewed-by: Nutty Liu Signed-off-by: Tao Liu Link: https://patch.msgid.link/20260705232706.30265-2-ltao@redhat.com Signed-off-by: Paul Walmsley Signed-off-by: Greg Kroah-Hartman

riscv: probes: save original sp in rethook trampoline

2026-07-24T14:03:44+00:00

commit bc7b086a45521a986a49045907f017e3e46c763e upstream. Reading a word from the stack in a kretprobe crashes a risc-v kernel. $ cd /sys/kernel/tracing/ $ echo 'r n_tty_write $stack0' > dynamic_events $ echo 1 > events/kprobes/enable Unable to handle kernel paging request at virtual address 0000000200000128 ... [] regs_get_kernel_stack_nth+0x26/0x38 [] process_fetch_insn+0x3ee/0x760 [] kretprobe_trace_func+0x116/0x1f0 [] kretprobe_dispatcher+0x4a/0x58 [] kretprobe_rethook_handler+0x5e/0x90 [] rethook_trampoline_handler+0x70/0x108 [] arch_rethook_trampoline_callback+0x12/0x1c [] arch_rethook_trampoline+0x48/0x94 [] tty_write+0x1a/0x30 In regs_get_kernel_stack_nth, regs->sp contains an arbitrary value. arch_rethook_trampoline saves the registers from the probed function in a struct pt_regs. sp is not saved. Instead, sp is decremented for arch_rethook_trampoline's local stack. Fix this crash and save the original sp along with the other registers. Use a0 as a temporary register, it is overwritten anyway. Cc: stable@vger.kernel.org Fixes: c22b0bcb1dd02 ("riscv: Add kprobes supported") Signed-off-by: Martin Kaiser Acked-by: Masami Hiramatsu (Google) Link: https://patch.msgid.link/20260630194010.1824039-1-martin@kaiser.cx [pjw@kernel.org: added Fixes tag; cc'ed stable] Signed-off-by: Paul Walmsley Signed-off-by: Greg Kroah-Hartman

riscv: cacheinfo: Fix node reference leak in populate_cache_leaves

2026-07-24T14:03:36+00:00

commit bf4a195f063b0a0805c1417f6aad1dd32ea48f0f upstream. Currently, the while loop drops the reference to prev in each iteration. If the loop terminates early due to a break, the final of_node_put(np) correctly drops the reference to the current node. However, if the loop terminates naturally because np == NULL, calling of_node_put(np) is a no-op. This leaves the last valid node stored in prev without its reference dropped, resulting in a node reference leak. Fix this by changing the final `of_node_put(np)` to `of_node_put(prev)`. Fixes: 94f9bf118f1e ("RISC-V: Fix of_node_* refcount") Cc: stable@vger.kernel.org Assisted-by: Gemini:gemini-3.1-pro Signed-off-by: Zishun Yi Link: https://patch.msgid.link/20260509074040.1747800-1-vulab@iscas.ac.cn Signed-off-by: Paul Walmsley Signed-off-by: Greg Kroah-Hartman

riscv: stacktrace: Remove bogus -0x4 offset in non-FP walk_stackframe

2026-07-24T14:03:07+00:00

[ Upstream commit 8ac35bac70e7e581d673b76878f7691cdadc33b8 ] In the non-frame-pointer version of walk_stackframe, each value read from the stack is treated as a potential return address and has 0x4 subtracted before being used as the program counter. This was intended to convert the return address (the instruction after a call) back to the call site, but it is incorrect: 1. RISC-V has variable-length instructions due to the RVC (compressed instruction) extension. A call instruction can be either 4 bytes (regular) or 2 bytes (compressed, e.g. c.jal). Subtracting a fixed 0x4 assumes all call instructions are 4 bytes, which is wrong for compressed instructions. 2. Stack traces conventionally report return addresses, not call sites. Other architectures (ARM64, x86, ARM) do not subtract instruction size from return addresses in their stack unwinding code. 3. The frame-pointer version of walk_stackframe already dropped the -0x4 offset. Commit b785ec129bd9 ("riscv/ftrace: Add HAVE_FUNCTION_GRAPH_RET_ADDR_PTR support") replaced "pc = frame->ra - 0x4" with ftrace_graph_ret_addr(), and the commit message explicitly noted that "the original calculation, pc = frame->ra - 4, is buggy when the instruction at the return address happened to be a compressed inst." The non-FP version was simply overlooked. Remove the bogus -0x4 offset to match the FP version and the conventions used by other architectures. Fixes: 5d8544e2d007 ("RISC-V: Generic library routines and assembly") Signed-off-by: Rui Qi Link: https://patch.msgid.link/20260603115329.791603-2-qirui.001@bytedance.com Signed-off-by: Paul Walmsley Signed-off-by: Sasha Levin

bpf: Restrict JIT predictor flush to cBPF

2026-07-24T14:02:57+00:00

commit 0bb99f2cfaae6822d734d69722de30af823efdf3 upstream. Currently predictor flush on memory reuse is done for all BPF JIT allocations, but only cBPF programs can be loaded by an unprivileged user. eBPF is privileged by default, and flushing predictors for all CPUs on every eBPF reuse penalizes the common case for no security benefit. eBPF allocations can be frequent on busy systems, only flush predictors for cBPF programs. Trampoline and dispatcher allocations also skip the flush as they are eBPF-only. [pawan: backport dropped "was_classic" hunk for arches that do not support pack allocator] Signed-off-by: Pawan Gupta Acked-by: Daniel Borkmann Signed-off-by: Daniel Borkmann Signed-off-by: Sasha Levin

riscv: kgdb: fix several debug register assignment bugs

2026-04-11T12:19:25+00:00

[ Upstream commit 834911eb8eef2501485d819b4eabebadc25c3497 ] Fix several bugs in the RISC-V kgdb implementation: - The element of dbg_reg_def[] that is supposed to pertain to the S1 register embeds instead the struct pt_regs offset of the A1 register. Fix this to use the S1 register offset in struct pt_regs. - The sleeping_thread_to_gdb_regs() function copies the value of the S10 register into the gdb_regs[] array element meant for the S9 register, and copies the value of the S11 register into the array element meant for the S10 register. It also neglects to copy the value of the S11 register. Fix all of these issues. Fixes: fe89bd2be8667 ("riscv: Add KGDB support") Cc: Vincent Chen Link: https://patch.msgid.link/fde376f8-bcfd-bfe4-e467-07d8f7608d05@kernel.org Signed-off-by: Paul Walmsley Signed-off-by: Sasha Levin

riscv: Sanitize syscall table indexing under speculation

2026-03-25T10:06:00+00:00

[ Upstream commit 25fd7ee7bf58ac3ec7be3c9f82ceff153451946c ] The syscall number is a user-controlled value used to index into the syscall table. Use array_index_nospec() to clamp this value after the bounds check to prevent speculative out-of-bounds access and subsequent data leakage via cache side channels. Signed-off-by: Lukas Gerlach Link: https://patch.msgid.link/20251218191332.35849-3-lukas.gerlach@cispa.de Signed-off-by: Paul Walmsley [ Added linux/nospec.h for array_index_nospec() to make sure compile without error ] Signed-off-by: Leon Chen Signed-off-by: Greg Kroah-Hartman

riscv: compat: fix COMPAT_UTS_MACHINE definition

2026-02-06T15:48:24+00:00

commit 0ea05c4f7527a98f5946f96c829733788934311d upstream. The COMPAT_UTS_MACHINE for riscv was incorrectly defined as "riscv". Change it to "riscv32" to reflect the correct 32-bit compat name. Fixes: 06d0e3723647 ("riscv: compat: Add basic compat data type implementation") Cc: stable@vger.kernel.org Signed-off-by: Han Gao Reviewed-by: Guo Ren (Alibaba Damo Academy) Link: https://patch.msgid.link/20260127190711.2264664-1-gaohan@iscas.ac.cn Signed-off-by: Paul Walmsley Signed-off-by: Greg Kroah-Hartman