Framebuffer overrides by tonynguien · Pull Request #54 · delphix/linux-kernel-generic

tonynguien · 2025-09-25T20:26:28Z

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BugLink: https://bugs.launchpad.net/bugs/2115252 commit 211dcf7 upstream. Starting with Rust 1.88.0 (expected 2025-06-26) [1], `rustc` may move back the `uninlined_format_args` to `style` from `pedantic` (it was there waiting for rust-analyzer suppotr), and thus we will start to see lints like: warning: variables can be used directly in the `format!` string --> rust/macros/kunit.rs:105:37 | 105 | let kunit_wrapper_fn_name = format!("kunit_rust_wrapper_{}", test); | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ | = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#uninlined_format_args help: change this to | 105 - let kunit_wrapper_fn_name = format!("kunit_rust_wrapper_{}", test); 105 + let kunit_wrapper_fn_name = format!("kunit_rust_wrapper_{test}"); There is even a case that is a pure removal: warning: variables can be used directly in the `format!` string --> rust/macros/module.rs:51:13 | 51 | format!("{field}={content}\0", field = field, content = content) | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ | = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#uninlined_format_args help: change this to | 51 - format!("{field}={content}\0", field = field, content = content) 51 + format!("{field}={content}\0") The lints all seem like nice cleanups, thus just apply them. We may want to disable `allow-mixed-uninlined-format-args` in the future. Cc: stable@vger.kernel.org # Needed in 6.12.y and later (Rust is pinned in older LTSs). Link: rust-lang/rust-clippy#14160 [1] Acked-by: Benno Lossin <lossin@kernel.org> Reviewed-by: Tamir Duberstein <tamird@gmail.com> Reviewed-by: Alice Ryhl <aliceryhl@google.com> Link: https://lore.kernel.org/r/20250502140237.1659624-6-ojeda@kernel.org Signed-off-by: Miguel Ojeda <ojeda@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Manuel Diewald <manuel.diewald@canonical.com> Signed-off-by: Stefan Bader <stefan.bader@canonical.com>

BugLink: https://bugs.launchpad.net/bugs/2115252 Commit b53e523 upstream. There are a few spots where linked timeouts are armed, and not all of them adhere to the pre-arm, attempt issue, post-arm pattern. This can be problematic if the linked request returns that it will trigger a callback later, and does so before the linked timeout is fully armed. Consolidate all the linked timeout handling into __io_issue_sqe(), rather than have it spread throughout the various issue entry points. Cc: stable@vger.kernel.org Link: axboe/liburing#1390 Reported-by: Chase Hiltz <chase@path.net> Signed-off-by: Jens Axboe <axboe@kernel.dk> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Manuel Diewald <manuel.diewald@canonical.com> Signed-off-by: Stefan Bader <stefan.bader@canonical.com>

BugLink: https://bugs.launchpad.net/bugs/2115252 commit 33634e2 upstream. Remove the resetting step before downloading the fw, as it may cause other usb devices to fail to initialise when connected during boot on kernels 6.11 and newer. Signed-off-by: Hao Qin <hao.qin@mediatek.com> Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com> Cc: "Geoffrey D. Bennett" <g@b4.vu> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Manuel Diewald <manuel.diewald@canonical.com> Signed-off-by: Stefan Bader <stefan.bader@canonical.com>

@steal

BugLink: https://bugs.launchpad.net/bugs/2115252 commit c2f6ea3 upstream. The fallback code searches for the biggest buddy first in an attempt to steal the whole block and encourage type grouping down the line. The approach used to be this: - Non-movable requests will split the largest buddy and steal the remainder. This splits up contiguity, but it allows subsequent requests of this type to fall back into adjacent space. - Movable requests go and look for the smallest buddy instead. The thinking is that movable requests can be compacted, so grouping is less important than retaining contiguity. c0cd6f5 ("mm: page_alloc: fix freelist movement during block conversion") enforces freelist type hygiene, which restricts stealing to either claiming the whole block or just taking the requested chunk; no additional pages or buddy remainders can be stolen any more. The patch mishandled when to switch to finding the smallest buddy in that new reality. As a result, it may steal the exact request size, but from the biggest buddy. This causes fracturing for no good reason. Fix this by committing to the new behavior: either steal the whole block, or fall back to the smallest buddy. Remove single-page stealing from steal_suitable_fallback(). Rename it to try_to_steal_block() to make the intentions clear. If this fails, always fall back to the smallest buddy. The following is from 4 runs of mmtest's thpchallenge. "Pollute" is single page fallback, "steal" is conversion of a partially used block. The numbers for free block conversions (omitted) are comparable. vanilla patched @pollute[unmovable from reclaimable]: 27 106 @pollute[unmovable from movable]: 82 46 @pollute[reclaimable from unmovable]: 256 83 @pollute[reclaimable from movable]: 46 8 @pollute[movable from unmovable]: 4841 868 @pollute[movable from reclaimable]: 5278 12568 @steal[unmovable from reclaimable]: 11 12 @steal[unmovable from movable]: 113 49 @steal[reclaimable from unmovable]: 19 34 @steal[reclaimable from movable]: 47 21 @steal[movable from unmovable]: 250 183 @steal[movable from reclaimable]: 81 93 The allocator appears to do a better job at keeping stealing and polluting to the first fallback preference. As a result, the numbers for "from movable" - the least preferred fallback option, and most detrimental to compactability - are down across the board. Link: https://lkml.kernel.org/r/20250225001023.1494422-2-hannes@cmpxchg.org Fixes: c0cd6f5 ("mm: page_alloc: fix freelist movement during block conversion") Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Suggested-by: Vlastimil Babka <vbabka@suse.cz> Reviewed-by: Brendan Jackman <jackmanb@google.com> Reviewed-by: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Manuel Diewald <manuel.diewald@canonical.com> Signed-off-by: Stefan Bader <stefan.bader@canonical.com>

BugLink: https://bugs.launchpad.net/bugs/2115252 commit 90abee6 upstream. The test robot identified c2f6ea3 ("mm: page_alloc: don't steal single pages from biggest buddy") as the root cause of a 56.4% regression in vm-scalability::lru-file-mmap-read. Carlos reports an earlier patch, c0cd6f5 ("mm: page_alloc: fix freelist movement during block conversion"), as the root cause for a regression in worst-case zone->lock+irqoff hold times. Both of these patches modify the page allocator's fallback path to be less greedy in an effort to stave off fragmentation. The flip side of this is that fallbacks are also less productive each time around, which means the fallback search can run much more frequently. Carlos' traces point to rmqueue_bulk() specifically, which tries to refill the percpu cache by allocating a large batch of pages in a loop. It highlights how once the native freelists are exhausted, the fallback code first scans orders top-down for whole blocks to claim, then falls back to a bottom-up search for the smallest buddy to steal. For the next batch page, it goes through the same thing again. This can be made more efficient. Since rmqueue_bulk() holds the zone->lock over the entire batch, the freelists are not subject to outside changes; when the search for a block to claim has already failed, there is no point in trying again for the next page. Modify __rmqueue() to remember the last successful fallback mode, and restart directly from there on the next rmqueue_bulk() iteration. Oliver confirms that this improves beyond the regression that the test robot reported against c2f6ea3: commit: f3b9217 ("tools/selftests: add guard region test for /proc/$pid/pagemap") c2f6ea3 ("mm: page_alloc: don't steal single pages from biggest buddy") acc4d5f ("Merge tag 'net-6.15-rc0' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net") 2c847f27c3 ("mm: page_alloc: speed up fallbacks in rmqueue_bulk()") <--- your patch f3b9217 c2f6ea3 acc4d5f 2c847f27c37da65a93d23c237c5 ---------------- --------------------------- --------------------------- --------------------------- %stddev %change %stddev %change %stddev %change %stddev \ | \ | \ | \ 25525364 ± 3% -56.4% 11135467 -57.8% 10779336 +31.6% 33581409 vm-scalability.throughput Carlos confirms that worst-case times are almost fully recovered compared to before the earlier culprit patch: 2dd482b (before freelist hygiene): 1ms c0cd6f5 (after freelist hygiene): 90ms next-20250319 (steal smallest buddy): 280ms this patch : 8ms [jackmanb@google.com: comment updates] Link: https://lkml.kernel.org/r/D92AC0P9594X.3BML64MUKTF8Z@google.com [hannes@cmpxchg.org: reset rmqueue_mode in rmqueue_buddy() error loop, per Yunsheng Lin] Link: https://lkml.kernel.org/r/20250409140023.GA2313@cmpxchg.org Link: https://lkml.kernel.org/r/20250407180154.63348-1-hannes@cmpxchg.org Fixes: c0cd6f5 ("mm: page_alloc: fix freelist movement during block conversion") Fixes: c2f6ea3 ("mm: page_alloc: don't steal single pages from biggest buddy") Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Signed-off-by: Brendan Jackman <jackmanb@google.com> Reported-by: kernel test robot <oliver.sang@intel.com> Reported-by: Carlos Song <carlos.song@nxp.com> Tested-by: Carlos Song <carlos.song@nxp.com> Tested-by: kernel test robot <oliver.sang@intel.com> Closes: https://lore.kernel.org/oe-lkp/202503271547.fc08b188-lkp@intel.com Reviewed-by: Brendan Jackman <jackmanb@google.com> Tested-by: Shivank Garg <shivankg@amd.com> Acked-by: Zi Yan <ziy@nvidia.com> Reviewed-by: Vlastimil Babka <vbabka@suse.cz> Cc: <stable@vger.kernel.org> [6.10+] Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Manuel Diewald <manuel.diewald@canonical.com> Signed-off-by: Stefan Bader <stefan.bader@canonical.com>

BugLink: https://bugs.launchpad.net/bugs/2115252 commit 63de8ab upstream. 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> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Manuel Diewald <manuel.diewald@canonical.com> Signed-off-by: Stefan Bader <stefan.bader@canonical.com>

BugLink: https://bugs.launchpad.net/bugs/2115252 commit e7956c9 upstream. 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> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Manuel Diewald <manuel.diewald@canonical.com> Signed-off-by: Stefan Bader <stefan.bader@canonical.com>

BugLink: https://bugs.launchpad.net/bugs/2115252 commit a1152be upstream. 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> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Manuel Diewald <manuel.diewald@canonical.com> Signed-off-by: Stefan Bader <stefan.bader@canonical.com>

BugLink: https://bugs.launchpad.net/bugs/2115252 commit 0dfefc2 upstream. 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> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> CVE-2025-37948 Signed-off-by: Manuel Diewald <manuel.diewald@canonical.com> Signed-off-by: Stefan Bader <stefan.bader@canonical.com>

BugLink: https://bugs.launchpad.net/bugs/2115252 commit f300769 upstream. Support for eBPF programs loaded by unprivileged users is typically disabled. This means only cBPF programs need to be mitigated for BHB. In addition, only mitigate cBPF programs that were loaded by an unprivileged user. Privileged users can also load the same program via eBPF, making the mitigation pointless. Signed-off-by: James Morse <james.morse@arm.com> Reviewed-by: Catalin Marinas <catalin.marinas@arm.com> Acked-by: Daniel Borkmann <daniel@iogearbox.net> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> CVE-2025-37963 Signed-off-by: Manuel Diewald <manuel.diewald@canonical.com> Signed-off-by: Stefan Bader <stefan.bader@canonical.com>

BugLink: https://bugs.launchpad.net/bugs/2115252 commit efe676a upstream. 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> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Manuel Diewald <manuel.diewald@canonical.com> Signed-off-by: Stefan Bader <stefan.bader@canonical.com>

BugLink: https://bugs.launchpad.net/bugs/2115252 commit d4e89d2 upstream. Classic BPF programs have been identified as potential vectors for intra-mode Branch Target Injection (BTI) attacks. Classic BPF programs can be run by unprivileged users. They allow unprivileged code to execute inside the kernel. Attackers can use unprivileged cBPF to craft branch history in kernel mode that can influence the target of indirect branches. Introduce a branch history buffer (BHB) clearing sequence during the JIT compilation of classic BPF programs. The clearing sequence is the same as is used in previous mitigations to protect syscalls. Since eBPF programs already have their own mitigations in place, only insert the call on classic programs that aren't run by privileged users. Signed-off-by: Daniel Sneddon <daniel.sneddon@linux.intel.com> Signed-off-by: Pawan Gupta <pawan.kumar.gupta@linux.intel.com> Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com> Acked-by: Daniel Borkmann <daniel@iogearbox.net> Reviewed-by: Alexandre Chartre <alexandre.chartre@oracle.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Manuel Diewald <manuel.diewald@canonical.com> Signed-off-by: Stefan Bader <stefan.bader@canonical.com>

BugLink: https://bugs.launchpad.net/bugs/2115252 commit 9f725ee upstream. Classic BPF programs can be run by unprivileged users, allowing unprivileged code to execute inside the kernel. Attackers can use this to craft branch history in kernel mode that can influence the target of indirect branches. BHI_DIS_S provides user-kernel isolation of branch history, but cBPF can be used to bypass this protection by crafting branch history in kernel mode. To stop intra-mode attacks via cBPF programs, Intel created a new instruction Indirect Branch History Fence (IBHF). IBHF prevents the predicted targets of subsequent indirect branches from being influenced by branch history prior to the IBHF. IBHF is only effective while BHI_DIS_S is enabled. Add the IBHF instruction to cBPF jitted code's exit path. Add the new fence when the hardware mitigation is enabled (i.e., X86_FEATURE_CLEAR_BHB_HW is set) or after the software sequence (X86_FEATURE_CLEAR_BHB_LOOP) is being used in a virtual machine. Note that X86_FEATURE_CLEAR_BHB_HW and X86_FEATURE_CLEAR_BHB_LOOP are mutually exclusive, so the JIT compiler will only emit the new fence, not the SW sequence, when X86_FEATURE_CLEAR_BHB_HW is set. Hardware that enumerates BHI_NO basically has BHI_DIS_S protections always enabled, regardless of the value of BHI_DIS_S. Since BHI_DIS_S doesn't protect against intra-mode attacks, enumerate BHI bug on BHI_NO hardware as well. Signed-off-by: Daniel Sneddon <daniel.sneddon@linux.intel.com> Signed-off-by: Pawan Gupta <pawan.kumar.gupta@linux.intel.com> Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com> Acked-by: Daniel Borkmann <daniel@iogearbox.net> Reviewed-by: Alexandre Chartre <alexandre.chartre@oracle.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Manuel Diewald <manuel.diewald@canonical.com> Signed-off-by: Stefan Bader <stefan.bader@canonical.com>

BugLink: https://bugs.launchpad.net/bugs/2115252 commit 073fdbe upstream. With the possibility of intra-mode BHI via cBPF, complete mitigation for BHI is to use IBHF (history fence) instruction with BHI_DIS_S set. Since this new instruction is only available in 64-bit mode, setting BHI_DIS_S in 32-bit mode is only a partial mitigation. Do not set BHI_DIS_S in 32-bit mode so as to avoid reporting misleading mitigated status. With this change IBHF won't be used in 32-bit mode, also remove the CONFIG_X86_64 check from emit_spectre_bhb_barrier(). Suggested-by: Josh Poimboeuf <jpoimboe@kernel.org> Signed-off-by: Pawan Gupta <pawan.kumar.gupta@linux.intel.com> Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com> Reviewed-by: Josh Poimboeuf <jpoimboe@kernel.org> Reviewed-by: Alexandre Chartre <alexandre.chartre@oracle.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Manuel Diewald <manuel.diewald@canonical.com> Signed-off-by: Stefan Bader <stefan.bader@canonical.com>

BugLink: https://bugs.launchpad.net/bugs/2115252 commit 1ac116c upstream. Add the admin-guide for Indirect Target Selection (ITS). Signed-off-by: Pawan Gupta <pawan.kumar.gupta@linux.intel.com> Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com> Reviewed-by: Josh Poimboeuf <jpoimboe@kernel.org> Reviewed-by: Alexandre Chartre <alexandre.chartre@oracle.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Manuel Diewald <manuel.diewald@canonical.com> Signed-off-by: Stefan Bader <stefan.bader@canonical.com>

BugLink: https://bugs.launchpad.net/bugs/2115252 commit 159013a upstream. ITS bug in some pre-Alderlake Intel CPUs may allow indirect branches in the first half of a cache line get predicted to a target of a branch located in the second half of the cache line. Set X86_BUG_ITS on affected CPUs. Mitigation to follow in later commits. Signed-off-by: Pawan Gupta <pawan.kumar.gupta@linux.intel.com> Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com> Reviewed-by: Josh Poimboeuf <jpoimboe@kernel.org> Reviewed-by: Alexandre Chartre <alexandre.chartre@oracle.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Manuel Diewald <manuel.diewald@canonical.com> Signed-off-by: Stefan Bader <stefan.bader@canonical.com>

BugLink: https://bugs.launchpad.net/bugs/2115252 commit 8754e67 upstream. Due to ITS, indirect branches in the lower half of a cacheline may be vulnerable to branch target injection attack. Introduce ITS-safe thunks to patch indirect branches in the lower half of cacheline with the thunk. Also thunk any eBPF generated indirect branches in emit_indirect_jump(). Below category of indirect branches are not mitigated: - Indirect branches in the .init section are not mitigated because they are discarded after boot. - Indirect branches that are explicitly marked retpoline-safe. Note that retpoline also mitigates the indirect branches against ITS. This is because the retpoline sequence fills an RSB entry before RET, and it does not suffer from RSB-underflow part of the ITS. Signed-off-by: Pawan Gupta <pawan.kumar.gupta@linux.intel.com> Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com> Reviewed-by: Josh Poimboeuf <jpoimboe@kernel.org> Reviewed-by: Alexandre Chartre <alexandre.chartre@oracle.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Manuel Diewald <manuel.diewald@canonical.com> Signed-off-by: Stefan Bader <stefan.bader@canonical.com>

BugLink: https://bugs.launchpad.net/bugs/2115252 commit a75bf27 upstream. RETs in the lower half of cacheline may be affected by ITS bug, specifically when the RSB-underflows. Use ITS-safe return thunk for such RETs. RETs that are not patched: - RET in retpoline sequence does not need to be patched, because the sequence itself fills an RSB before RET. - RET in Call Depth Tracking (CDT) thunks __x86_indirect_{call|jump}_thunk and call_depth_return_thunk are not patched because CDT by design prevents RSB-underflow. - RETs in .init section are not reachable after init. - RETs that are explicitly marked safe with ANNOTATE_UNRET_SAFE. Signed-off-by: Pawan Gupta <pawan.kumar.gupta@linux.intel.com> Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com> Reviewed-by: Josh Poimboeuf <jpoimboe@kernel.org> Reviewed-by: Alexandre Chartre <alexandre.chartre@oracle.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Manuel Diewald <manuel.diewald@canonical.com> Signed-off-by: Stefan Bader <stefan.bader@canonical.com>

BugLink: https://bugs.launchpad.net/bugs/2115252 commit f481888 upstream. Indirect Target Selection (ITS) is a bug in some pre-ADL Intel CPUs with eIBRS. It affects prediction of indirect branch and RETs in the lower half of cacheline. Due to ITS such branches may get wrongly predicted to a target of (direct or indirect) branch that is located in the upper half of the cacheline. Scope of impact =============== Guest/host isolation -------------------- When eIBRS is used for guest/host isolation, the indirect branches in the VMM may still be predicted with targets corresponding to branches in the guest. Intra-mode ---------- cBPF or other native gadgets can be used for intra-mode training and disclosure using ITS. User/kernel isolation --------------------- When eIBRS is enabled user/kernel isolation is not impacted. Indirect Branch Prediction Barrier (IBPB) ----------------------------------------- After an IBPB, indirect branches may be predicted with targets corresponding to direct branches which were executed prior to IBPB. This is mitigated by a microcode update. Add cmdline parameter indirect_target_selection=off|on|force to control the mitigation to relocate the affected branches to an ITS-safe thunk i.e. located in the upper half of cacheline. Also add the sysfs reporting. When retpoline mitigation is deployed, ITS safe-thunks are not needed, because retpoline sequence is already ITS-safe. Similarly, when call depth tracking (CDT) mitigation is deployed (retbleed=stuff), ITS safe return thunk is not used, as CDT prevents RSB-underflow. To not overcomplicate things, ITS mitigation is not supported with spectre-v2 lfence;jmp mitigation. Moreover, it is less practical to deploy lfence;jmp mitigation on ITS affected parts anyways. Signed-off-by: Pawan Gupta <pawan.kumar.gupta@linux.intel.com> Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com> Reviewed-by: Josh Poimboeuf <jpoimboe@kernel.org> Reviewed-by: Alexandre Chartre <alexandre.chartre@oracle.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Manuel Diewald <manuel.diewald@canonical.com> Signed-off-by: Stefan Bader <stefan.bader@canonical.com>

BugLink: https://bugs.launchpad.net/bugs/2115252 Signed-off-by: Manuel Diewald <manuel.diewald@canonical.com> Signed-off-by: Stefan Bader <stefan.bader@canonical.com>

BugLink: https://bugs.launchpad.net/bugs/2115252 commit 2665281 upstream. Ice Lake generation CPUs are not affected by guest/host isolation part of ITS. If a user is only concerned about KVM guests, they can now choose a new cmdline option "vmexit" that will not deploy the ITS mitigation when CPU is not affected by guest/host isolation. This saves the performance overhead of ITS mitigation on Ice Lake gen CPUs. When "vmexit" option selected, if the CPU is affected by ITS guest/host isolation, the default ITS mitigation is deployed. Signed-off-by: Pawan Gupta <pawan.kumar.gupta@linux.intel.com> Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com> Reviewed-by: Josh Poimboeuf <jpoimboe@kernel.org> Reviewed-by: Alexandre Chartre <alexandre.chartre@oracle.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Manuel Diewald <manuel.diewald@canonical.com> Signed-off-by: Stefan Bader <stefan.bader@canonical.com>

BugLink: https://bugs.launchpad.net/bugs/2115252 commit facd226 upstream. When retpoline mitigation is enabled for spectre-v2, enabling call-depth-tracking and RSB stuffing also mitigates ITS. Add cmdline option indirect_target_selection=stuff to allow enabling RSB stuffing mitigation. When retpoline mitigation is not enabled, =stuff option is ignored, and default mitigation for ITS is deployed. Signed-off-by: Pawan Gupta <pawan.kumar.gupta@linux.intel.com> Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com> Reviewed-by: Josh Poimboeuf <jpoimboe@kernel.org> Reviewed-by: Alexandre Chartre <alexandre.chartre@oracle.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Manuel Diewald <manuel.diewald@canonical.com> Signed-off-by: Stefan Bader <stefan.bader@canonical.com>

BugLink: https://bugs.launchpad.net/bugs/2115252 commit f0cd709 upstream. The software mitigation for BHI is to execute BHB clear sequence at syscall entry, and possibly after a cBPF program. ITS mitigation thunks RETs in the lower half of the cacheline. This causes the RETs in the BHB clear sequence to be thunked as well, adding unnecessary branches to the BHB clear sequence. Since the sequence is in hot path, align the RET instructions in the sequence to avoid thunking. This is how disassembly clear_bhb_loop() looks like after this change: 0x44 <+4>: mov $0x5,%ecx 0x49 <+9>: call 0xffffffff81001d9b <clear_bhb_loop+91> 0x4e <+14>: jmp 0xffffffff81001de5 <clear_bhb_loop+165> 0x53 <+19>: int3 ... 0x9b <+91>: call 0xffffffff81001dce <clear_bhb_loop+142> 0xa0 <+96>: ret 0xa1 <+97>: int3 ... 0xce <+142>: mov $0x5,%eax 0xd3 <+147>: jmp 0xffffffff81001dd6 <clear_bhb_loop+150> 0xd5 <+149>: nop 0xd6 <+150>: sub $0x1,%eax 0xd9 <+153>: jne 0xffffffff81001dd3 <clear_bhb_loop+147> 0xdb <+155>: sub $0x1,%ecx 0xde <+158>: jne 0xffffffff81001d9b <clear_bhb_loop+91> 0xe0 <+160>: ret 0xe1 <+161>: int3 0xe2 <+162>: int3 0xe3 <+163>: int3 0xe4 <+164>: int3 0xe5 <+165>: lfence 0xe8 <+168>: pop %rbp 0xe9 <+169>: ret Suggested-by: Andrew Cooper <andrew.cooper3@citrix.com> Signed-off-by: Pawan Gupta <pawan.kumar.gupta@linux.intel.com> Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com> Reviewed-by: Alexandre Chartre <alexandre.chartre@oracle.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Manuel Diewald <manuel.diewald@canonical.com> Signed-off-by: Stefan Bader <stefan.bader@canonical.com>

BugLink: https://bugs.launchpad.net/bugs/2115252 commit ebebe30 upstream. cfi_rewrite_callers() updates the fineIBT hash matching at the caller side, but except for paranoid-mode it relies on apply_retpoline() and friends for any ENDBR relocation. This could temporarily cause an indirect branch to land on a poisoned ENDBR. For instance, with para-virtualization enabled, a simple wrmsrl() could have an indirect branch pointing to native_write_msr() who's ENDBR has been relocated due to fineIBT: <wrmsrl>: push %rbp mov %rsp,%rbp mov %esi,%eax mov %rsi,%rdx shr $0x20,%rdx mov %edi,%edi mov %rax,%rsi call *0x21e65d0(%rip) # <pv_ops+0xb8> ^^^^^^^^^^^^^^^^^^^^^^^ Such an indirect call during the alternative patching could #CP if the caller is not *yet* adjusted for the new target ENDBR. To prevent a false #CP, keep CET-IBT disabled until all callers are patched. Patching during the module load does not need to be guarded by IBT-disable because the module code is not executed until the patching is complete. Signed-off-by: Pawan Gupta <pawan.kumar.gupta@linux.intel.com> Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com> Reviewed-by: Alexandre Chartre <alexandre.chartre@oracle.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Manuel Diewald <manuel.diewald@canonical.com> Signed-off-by: Stefan Bader <stefan.bader@canonical.com>

BugLink: https://bugs.launchpad.net/bugs/2115252 commit 872df34 upstream. ITS mitigation moves the unsafe indirect branches to a safe thunk. This could degrade the prediction accuracy as the source address of indirect branches becomes same for different execution paths. To improve the predictions, and hence the performance, assign a separate thunk for each indirect callsite. This is also a defense-in-depth measure to avoid indirect branches aliasing with each other. As an example, 5000 dynamic thunks would utilize around 16 bits of the address space, thereby gaining entropy. For a BTB that uses 32 bits for indexing, dynamic thunks could provide better prediction accuracy over fixed thunks. Have ITS thunks be variable sized and use EXECMEM_MODULE_TEXT such that they are both more flexible (got to extend them later) and live in 2M TLBs, just like kernel code, avoiding undue TLB pressure. [ pawan: CONFIG_EXECMEM_ROX is not supported on backport kernel, made adjustments to set memory to RW and ROX ] Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Pawan Gupta <pawan.kumar.gupta@linux.intel.com> Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com> Reviewed-by: Alexandre Chartre <alexandre.chartre@oracle.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Manuel Diewald <manuel.diewald@canonical.com> Signed-off-by: Stefan Bader <stefan.bader@canonical.com>

BugLink: https://bugs.launchpad.net/bugs/2115252 commit 7a9b709 upstream. Below are the tests added for Indirect Target Selection (ITS): - its_sysfs.py - Check if sysfs reflects the correct mitigation status for the mitigation selected via the kernel cmdline. - its_permutations.py - tests mitigation selection with cmdline permutations with other bugs like spectre_v2 and retbleed. - its_indirect_alignment.py - verifies that for addresses in .retpoline_sites section that belong to lower half of cacheline are patched to ITS-safe thunk. Typical output looks like below: Site 49: function symbol: __x64_sys_restart_syscall+0x1f <0xffffffffbb1509af> # vmlinux: 0xffffffff813509af: jmp 0xffffffff81f5a8e0 # kcore: 0xffffffffbb1509af: jmpq *%rax # ITS thunk NOT expected for site 49 # PASSED: Found *%rax # Site 50: function symbol: __resched_curr+0xb0 <0xffffffffbb181910> # vmlinux: 0xffffffff81381910: jmp 0xffffffff81f5a8e0 # kcore: 0xffffffffbb181910: jmp 0xffffffffc02000fc # ITS thunk expected for site 50 # PASSED: Found 0xffffffffc02000fc -> jmpq *%rax <scattered-thunk?> - its_ret_alignment.py - verifies that for addresses in .return_sites section that belong to lower half of cacheline are patched to its_return_thunk. Typical output looks like below: Site 97: function symbol: collect_event+0x48 <0xffffffffbb007f18> # vmlinux: 0xffffffff81207f18: jmp 0xffffffff81f5b500 # kcore: 0xffffffffbb007f18: jmp 0xffffffffbbd5b560 # PASSED: Found jmp 0xffffffffbbd5b560 <its_return_thunk> # Site 98: function symbol: collect_event+0xa4 <0xffffffffbb007f74> # vmlinux: 0xffffffff81207f74: jmp 0xffffffff81f5b500 # kcore: 0xffffffffbb007f74: retq # PASSED: Found retq Some of these tests have dependency on tools like virtme-ng[1] and drgn[2]. When the dependencies are not met, the test will be skipped. [1] https://github.com/arighi/virtme-ng [2] https://github.com/osandov/drgn Co-developed-by: Tao Zhang <tao1.zhang@linux.intel.com> Signed-off-by: Tao Zhang <tao1.zhang@linux.intel.com> Signed-off-by: Pawan Gupta <pawan.kumar.gupta@linux.intel.com> Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Manuel Diewald <manuel.diewald@canonical.com> Signed-off-by: Stefan Bader <stefan.bader@canonical.com>

BugLink: https://bugs.launchpad.net/bugs/2115252 commit 9f35e33 upstream. Fix several build errors when CONFIG_MODULES=n, including the following: ../arch/x86/kernel/alternative.c:195:25: error: incomplete definition of type 'struct module' 195 | for (int i = 0; i < mod->its_num_pages; i++) { Fixes: 872df34 ("x86/its: Use dynamic thunks for indirect branches") Cc: stable@vger.kernel.org Signed-off-by: Eric Biggers <ebiggers@google.com> Acked-by: Dave Hansen <dave.hansen@intel.com> Tested-by: Steven Rostedt (Google) <rostedt@goodmis.org> Reviewed-by: Alexandre Chartre <alexandre.chartre@oracle.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Manuel Diewald <manuel.diewald@canonical.com> Signed-off-by: Stefan Bader <stefan.bader@canonical.com>

BugLink: https://bugs.launchpad.net/bugs/2115252 commit e52c1dc upstream. FineIBT-paranoid was using the retpoline bytes for the paranoid check, disabling retpolines, because all parts that have IBT also have eIBRS and thus don't need no stinking retpolines. Except... ITS needs the retpolines for indirect calls must not be in the first half of a cacheline :-/ So what was the paranoid call sequence: <fineibt_paranoid_start>: 0: 41 ba 78 56 34 12 mov $0x12345678, %r10d 6: 45 3b 53 f7 cmp -0x9(%r11), %r10d a: 4d 8d 5b <f0> lea -0x10(%r11), %r11 e: 75 fd jne d <fineibt_paranoid_start+0xd> 10: 41 ff d3 call *%r11 13: 90 nop Now becomes: <fineibt_paranoid_start>: 0: 41 ba 78 56 34 12 mov $0x12345678, %r10d 6: 45 3b 53 f7 cmp -0x9(%r11), %r10d a: 4d 8d 5b f0 lea -0x10(%r11), %r11 e: 2e e8 XX XX XX XX cs call __x86_indirect_paranoid_thunk_r11 Where the paranoid_thunk looks like: 1d: <ea> (bad) __x86_indirect_paranoid_thunk_r11: 1e: 75 fd jne 1d __x86_indirect_its_thunk_r11: 20: 41 ff eb jmp *%r11 23: cc int3 [ dhansen: remove initialization to false ] Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Pawan Gupta <pawan.kumar.gupta@linux.intel.com> Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com> Reviewed-by: Alexandre Chartre <alexandre.chartre@oracle.com> [ Just a portion of the original commit, in order to fix a build issue in stable kernels due to backports ] Tested-by: Holger Hoffstätte <holger@applied-asynchrony.com> Link: https://lore.kernel.org/r/20250514113952.GB16434@noisy.programming.kicks-ass.net Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Manuel Diewald <manuel.diewald@canonical.com> Signed-off-by: Stefan Bader <stefan.bader@canonical.com>

BugLink: https://bugs.launchpad.net/bugs/2115252 Link: https://lore.kernel.org/r/20250512172044.326436266@linuxfoundation.org Tested-by: Jon Hunter <jonathanh@nvidia.com> Tested-by: Salvatore Bonaccorso <carnil@debian.org> Tested-by: Ron Economos <re@w6rz.net> Tested-by: Mark Brown <broonie@kernel.org> Tested-by: Takeshi Ogasawara <takeshi.ogasawara@futuring-girl.com> Tested-by: Florian Fainelli <florian.fainelli@broadcom.com> Tested-by: Markus Reichelt <lkt+2023@mareichelt.com> Tested-by: Peter Schneider <pschneider1968@googlemail.com> Tested-by: Shuah Khan <skhan@linuxfoundation.org> Tested-by: Christian Heusel <christian@heusel.eu> Tested-by: Hardik Garg <hargar@linux.microsoft.com> Link: https://lore.kernel.org/r/20250514125625.496402993@linuxfoundation.org Tested-by: Jon Hunter <jonathanh@nvidia.com> Tested-by: Mark Brown <broonie@kernel.org> Tested-by: Florian Fainelli <florian.fainelli@broadcom.com> Tested-by: Takeshi Ogasawara <takeshi.ogasawara@futuring-girl.com> Tested-by: Linux Kernel Functional Testing <lkft@linaro.org> Tested-by: Peter Schneider <pschneider1968@googlemail.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Manuel Diewald <manuel.diewald@canonical.com> Signed-off-by: Stefan Bader <stefan.bader@canonical.com>

BugLink: https://bugs.launchpad.net/bugs/2115252 Ignore: yes Signed-off-by: Manuel Diewald <manuel.diewald@canonical.com> Signed-off-by: Stefan Bader <stefan.bader@canonical.com>

Signed-off-by: Stefan Bader <stefan.bader@canonical.com>

Ignore: yes Signed-off-by: Stefan Bader <stefan.bader@canonical.com>

BugLink: https://bugs.launchpad.net/bugs/2117502 Properties: no-test-build Signed-off-by: Stefan Bader <stefan.bader@canonical.com>

Signed-off-by: Stefan Bader <stefan.bader@canonical.com>

Ignore: yes Signed-off-by: Stefan Bader <stefan.bader@canonical.com>

BugLink: https://bugs.launchpad.net/bugs/2117647 Properties: no-test-build Signed-off-by: Stefan Bader <stefan.bader@canonical.com>

…el-versions (main/2025.07.14) BugLink: https://bugs.launchpad.net/bugs/1786013 Signed-off-by: Stefan Bader <stefan.bader@canonical.com>

Signed-off-by: Stefan Bader <stefan.bader@canonical.com>

Ignore: yes Signed-off-by: Stefan Bader <stefan.bader@canonical.com>

BugLink: https://bugs.launchpad.net/bugs/2119946 Properties: no-test-build Signed-off-by: Stefan Bader <stefan.bader@canonical.com>

Signed-off-by: Stefan Bader <stefan.bader@canonical.com>

This is a placeholder commit to separate the Ubuntu kernel source and our patches. Used by kernel_merge_with_upstream() in the linux-pkg repo.

…messages (#2)

…operly started (#14)

PR URL: https://www.github.com/delphix/linux-kernel-generic/pull/54

ojeda and others added 30 commits July 23, 2025 12:05

UBUNTU: [Config] enable MITIGATION_ITS

fdc98e2

BugLink: https://bugs.launchpad.net/bugs/2115252 Signed-off-by: Manuel Diewald <manuel.diewald@canonical.com> Signed-off-by: Stefan Bader <stefan.bader@canonical.com>

UBUNTU: Upstream stable to v6.14.7

6d8a1b5

BugLink: https://bugs.launchpad.net/bugs/2115252 Ignore: yes Signed-off-by: Manuel Diewald <manuel.diewald@canonical.com> Signed-off-by: Stefan Bader <stefan.bader@canonical.com>

smb49 and others added 21 commits August 14, 2025 16:58

UBUNTU: Ubuntu-hwe-6.14-6.14.0-25.25~24.04.1

8182c2c

Signed-off-by: Stefan Bader <stefan.bader@canonical.com>

UBUNTU: Start new release

deb9d23

Ignore: yes Signed-off-by: Stefan Bader <stefan.bader@canonical.com>

UBUNTU: link-to-tracker: update tracking bug

31564e0

BugLink: https://bugs.launchpad.net/bugs/2117502 Properties: no-test-build Signed-off-by: Stefan Bader <stefan.bader@canonical.com>

UBUNTU: Ubuntu-hwe-6.14-6.14.0-27.27~24.04.1

8e65d30

Signed-off-by: Stefan Bader <stefan.bader@canonical.com>

UBUNTU: Start new release

38d5537

Ignore: yes Signed-off-by: Stefan Bader <stefan.bader@canonical.com>

UBUNTU: link-to-tracker: update tracking bug

83e254b

BugLink: https://bugs.launchpad.net/bugs/2117647 Properties: no-test-build Signed-off-by: Stefan Bader <stefan.bader@canonical.com>

UBUNTU: [Packaging] debian.hwe-6.14/dkms-versions -- update from kern…

98adccd

…el-versions (main/2025.07.14) BugLink: https://bugs.launchpad.net/bugs/1786013 Signed-off-by: Stefan Bader <stefan.bader@canonical.com>

UBUNTU: Ubuntu-hwe-6.14-6.14.0-28.28~24.04.1

21de1ed

Signed-off-by: Stefan Bader <stefan.bader@canonical.com>

UBUNTU: Start new release

079d987

Ignore: yes Signed-off-by: Stefan Bader <stefan.bader@canonical.com>

UBUNTU: link-to-tracker: update tracking bug

c110b3d

BugLink: https://bugs.launchpad.net/bugs/2119946 Properties: no-test-build Signed-off-by: Stefan Bader <stefan.bader@canonical.com>

UBUNTU: Ubuntu-hwe-6.14-6.14.0-29.29~24.04.1

a9d4b16

Signed-off-by: Stefan Bader <stefan.bader@canonical.com>

@@DELPHIX_PATCHSET_START@@

e829eb3

This is a placeholder commit to separate the Ubuntu kernel source and our patches. Used by kernel_merge_with_upstream() in the linux-pkg repo.

DLPX-71852 iSCSI: journal flooded with "Unable to locate Target IQN" …

7abe357

…messages (#2)

DLPX-72065 Aborted iSCSI command never completes after LUN reset (#4)

7cd9fe7

DLPX-83697 iscsi target login should wait until tx/rx threads have pr…

838cfaf

…operly started (#14)

DLPX-83701 Make function mnt_add_count() traceable (#16)

cfa8727

Extract PKG_ABI from mutated string

5aae71a

Reintroduce fix from DLPX-87344 to build only with amd64 annotations

d30a697

DLPX-94999 linux-kernel updates to 6.14 are failing

8852344

DLPX-94999 linux-kernel updates to 6.14 are failing

bc68dfb

Framebuffer overrides

7ef1d64

PR URL: https://www.github.com/delphix/linux-kernel-generic/pull/54

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Framebuffer overrides#54
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