kernel/linux.git/Documentation, branch v6.12.80

ovl: make fsync after metadata copy-up opt-in mount option

2026-04-02T11:09:50+00:00

commit 1f6ee9be92f8df85a8c9a5a78c20fd39c0c21a95 upstream. Commit 7d6899fb69d25 ("ovl: fsync after metadata copy-up") was done to fix durability of overlayfs copy up on an upper filesystem which does not enforce ordering on storing of metadata changes (e.g. ubifs). In an earlier revision of the regressing commit by Lei Lv, the metadata fsync behavior was opt-in via a new "fsync=strict" mount option. We were hoping that the opt-in mount option could be avoided, so the change was only made to depend on metacopy=off, in the hope of not hurting performance of metadata heavy workloads, which are more likely to be using metacopy=on. This hope was proven wrong by a performance regression report from Google COS workload after upgrade to kernel 6.12. This is an adaptation of Lei's original "fsync=strict" mount option to the existing upstream code. The new mount option is mutually exclusive with the "volatile" mount option, so the latter is now an alias to the "fsync=volatile" mount option. Reported-by: Chenglong Tang Closes: https://lore.kernel.org/linux-unionfs/CAOdxtTadAFH01Vui1FvWfcmQ8jH1O45owTzUcpYbNvBxnLeM7Q@mail.gmail.com/ Link: https://lore.kernel.org/linux-unionfs/CAOQ4uxgKC1SgjMWre=fUb00v8rxtd6sQi-S+dxR8oDzAuiGu8g@mail.gmail.com/ Fixes: 7d6899fb69d25 ("ovl: fsync after metadata copy-up") Depends: 50e638beb67e0 ("ovl: Use str_on_off() helper in ovl_show_options()") Cc: stable@vger.kernel.org # v6.12+ Signed-off-by: Fei Lv Signed-off-by: Amir Goldstein Signed-off-by: Greg Kroah-Hartman

hwmon: (peci/cputemp) Fix crit_hyst returning delta instead of absolute temperature

2026-04-02T11:09:43+00:00

commit 0adc752b4f7d82af7bd14f7cad3091b3b5d702ba upstream. The hwmon sysfs ABI expects tempN_crit_hyst to report the temperature at which the critical condition clears, not the hysteresis delta from the critical limit. The peci cputemp driver currently returns tjmax - tcontrol for crit_hyst_type, which is the hysteresis margin rather than the corresponding absolute temperature. Return tcontrol directly, and update the documentation accordingly. Fixes: bf3608f338e9 ("hwmon: peci: Add cputemp driver") Cc: stable@vger.kernel.org Signed-off-by: Sanman Pradhan Link: https://lore.kernel.org/r/20260323002352.93417-2-sanman.pradhan@hpe.com Signed-off-by: Guenter Roeck Signed-off-by: Greg Kroah-Hartman

hwmon: (adm1177) fix sysfs ABI violation and current unit conversion

2026-04-02T11:09:40+00:00

[ Upstream commit bf08749a6abb6d1959bfdc0edc32c640df407558 ] The adm1177 driver exposes the current alert threshold through hwmon_curr_max_alarm. This violates the hwmon sysfs ABI, where *_alarm attributes are read-only status flags and writable thresholds must use currN_max. The driver also stores the threshold internally in microamps, while currN_max is defined in milliamps. Convert the threshold accordingly on both the read and write paths. Widen the cached threshold and related calculations to 64 bits so that small shunt resistor values do not cause truncation or overflow. Also use 64-bit arithmetic for the mA/uA conversions, clamp writes to the range the hardware can represent, and propagate failures from adm1177_write_alert_thr() instead of silently ignoring them. Update the hwmon documentation to reflect the attribute rename and the correct units returned by the driver. Fixes: 09b08ac9e8d5 ("hwmon: (adm1177) Add ADM1177 Hot Swap Controller and Digital Power Monitor driver") Signed-off-by: Sanman Pradhan Acked-by: Nuno Sá Link: https://lore.kernel.org/r/20260325051246.28262-1-sanman.pradhan@hpe.com Signed-off-by: Guenter Roeck Signed-off-by: Sasha Levin

usb: core: new quirk to handle devices with zero configurations

2026-04-02T11:09:30+00:00

[ Upstream commit 9f6a983cfa22ac662c86e60816d3a357d4b551e9 ] Some USB devices incorrectly report bNumConfigurations as 0 in their device descriptor, which causes the USB core to reject them during enumeration. logs: usb 1-2: device descriptor read/64, error -71 usb 1-2: no configurations usb 1-2: can't read configurations, error -22 However, these devices actually work correctly when treated as having a single configuration. Add a new quirk USB_QUIRK_FORCE_ONE_CONFIG to handle such devices. When this quirk is set, assume the device has 1 configuration instead of failing with -EINVAL. This quirk is applied to the device with VID:PID 5131:2007 which exhibits this behavior. Signed-off-by: Jie Deng Link: https://patch.msgid.link/20260227084931.1527461-1-dengjie03@kylinos.cn Signed-off-by: Greg Kroah-Hartman Signed-off-by: Sasha Levin

KVM: x86: Introduce KVM_X86_QUIRK_VMCS12_ALLOW_FREEZE_IN_SMM

2026-03-25T10:08:43+00:00

[ Upstream commit e2ffe85b6d2bb7780174b87aa4468a39be17eb81 ] Add KVM_X86_QUIRK_VMCS12_ALLOW_FREEZE_IN_SMM to allow L1 to set FREEZE_IN_SMM in vmcs12's GUEST_IA32_DEBUGCTL field, as permitted prior to commit 6b1dd26544d0 ("KVM: VMX: Preserve host's DEBUGCTLMSR_FREEZE_IN_SMM while running the guest"). Enable the quirk by default for backwards compatibility (like all quirks); userspace can disable it via KVM_CAP_DISABLE_QUIRKS2 for consistency with the constraints on WRMSR(IA32_DEBUGCTL). Note that the quirk only bypasses the consistency check. The vmcs02 bit is still owned by the host, and PMCs are not frozen during virtualized SMM. In particular, if a host administrator decides that PMCs should not be frozen during physical SMM, then L1 has no say in the matter. Fixes: 095686e6fcb4 ("KVM: nVMX: Check vmcs12->guest_ia32_debugctl on nested VM-Enter") Cc: stable@vger.kernel.org Signed-off-by: Jim Mattson Link: https://patch.msgid.link/20260205231537.1278753-1-jmattson@google.com [sean: tag for stable@, clean-up and fix goofs in the comment and docs] Signed-off-by: Sean Christopherson [Rename quirk. - Paolo] Signed-off-by: Paolo Bonzini Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman

KVM: x86: Introduce Intel specific quirk KVM_X86_QUIRK_IGNORE_GUEST_PAT

2026-03-25T10:08:43+00:00

[ Upstream commit c9c1e20b4c7d60fa084b3257525d21a49fe651a1 ] Introduce an Intel specific quirk KVM_X86_QUIRK_IGNORE_GUEST_PAT to have KVM ignore guest PAT when this quirk is enabled. On AMD platforms, KVM always honors guest PAT. On Intel however there are two issues. First, KVM *cannot* honor guest PAT if CPU feature self-snoop is not supported. Second, UC access on certain Intel platforms can be very slow[1] and honoring guest PAT on those platforms may break some old guests that accidentally specify video RAM as UC. Those old guests may never expect the slowness since KVM always forces WB previously. See [2]. So, introduce a quirk that KVM can enable by default on all Intel platforms to avoid breaking old unmodifiable guests. Newer userspace can disable this quirk if it wishes KVM to honor guest PAT; disabling the quirk will fail if self-snoop is not supported, i.e. if KVM cannot obey the wish. The quirk is a no-op on AMD and also if any assigned devices have non-coherent DMA. This is not an issue, as KVM_X86_QUIRK_CD_NW_CLEARED is another example of a quirk that is sometimes automatically disabled. Suggested-by: Paolo Bonzini Suggested-by: Sean Christopherson Cc: Kevin Tian Signed-off-by: Yan Zhao Link: https://lore.kernel.org/all/Ztl9NWCOupNfVaCA@yzhao56-desk.sh.intel.com # [1] Link: https://lore.kernel.org/all/87jzfutmfc.fsf@redhat.com # [2] Message-ID: <20250224070946.31482-1-yan.y.zhao@intel.com> [Use supported_quirks/inapplicable_quirks to support both AMD and no-self-snoop cases, as well as to remove the shadow_memtype_mask check from kvm_mmu_may_ignore_guest_pat(). - Paolo] Signed-off-by: Paolo Bonzini Stable-dep-of: e2ffe85b6d2b ("KVM: x86: Introduce KVM_X86_QUIRK_VMCS12_ALLOW_FREEZE_IN_SMM") Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman

KVM: x86: Quirk initialization of feature MSRs to KVM's max configuration

2026-03-25T10:08:43+00:00

[ Upstream commit dcb988cdac85bad177de86fbf409524eda4f9467 ] Add a quirk to control KVM's misguided initialization of select feature MSRs to KVM's max configuration, as enabling features by default violates KVM's approach of letting userspace own the vCPU model, and is actively problematic for MSRs that are conditionally supported, as the vCPU will end up with an MSR value that userspace can't restore. E.g. if the vCPU is configured with PDCM=0, userspace will save and attempt to restore a non-zero PERF_CAPABILITIES, thanks to KVM's meddling. Link: https://lore.kernel.org/r/20240802185511.305849-4-seanjc@google.com Signed-off-by: Sean Christopherson Stable-dep-of: e2ffe85b6d2b ("KVM: x86: Introduce KVM_X86_QUIRK_VMCS12_ALLOW_FREEZE_IN_SMM") Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman

hwmon: (aht10) Add support for dht20

2026-03-13T16:20:37+00:00

[ Upstream commit 3eaf1b631506e8de2cb37c278d5bc042521e82c1 ] Add support for dht20 temperature and humidity sensor from Aosong. Modify aht10 driver to handle different init command for dht20 sensor by adding init_cmd entry in the driver data. dht20 sensor is compatible with aht10 hwmon driver with this change. Tested on TI am62x SK board with dht20 sensor connected at i2c-2 port. Signed-off-by: Akhilesh Patil Link: https://lore.kernel.org/r/2025112-94320-906858@bhairav-test.ee.iitb.ac.in Signed-off-by: Guenter Roeck Stable-dep-of: b7497b5a99f5 ("hwmon: (aht10) Fix initialization commands for AHT20") Signed-off-by: Sasha Levin

ASoC: dt-bindings: asahi-kasei,ak5558: Fix the supply names

2026-03-04T12:20:48+00:00

commit 80ca113671a005430207d351cb403c1637106212 upstream. In the original txt format binding document ak4458.txt, the supply names are 'AVDD-supply', 'DVDD-supply', and they are also used in driver. But in the commit converting to yaml format, they are changed to 'avdd-supply', 'dvdd-supply'. After search all the dts file, these names 'AVDD-supply', 'DVDD-supply', 'avdd-supply', 'dvdd-supply' are not used in any dts file. So it is safe to fix the yaml binding document. Fixes: 829d78e3ea32 ("ASoC: dt-bindings: ak5558: Convert to dtschema") Cc: stable@vger.kernel.org Signed-off-by: Shengjiu Wang Reviewed-by: Krzysztof Kozlowski Link: https://patch.msgid.link/20260212021829.3244736-4-shengjiu.wang@nxp.com Signed-off-by: Mark Brown Signed-off-by: Greg Kroah-Hartman

ASoC: dt-bindings: asahi-kasei,ak4458: Fix the supply names

2026-03-04T12:20:48+00:00

commit e570a5ca307f6d7a6acd080fc219db2ce3c0737b upstream. In the original txt format binding document ak4458.txt, the supply names are 'AVDD-supply', 'DVDD-supply', and they are also used in driver. But in the commit converting to yaml format, they are changed to 'avdd-supply', 'dvdd-supply'. After search all the dts file, these names 'AVDD-supply', 'DVDD-supply', 'avdd-supply', 'dvdd-supply' are not used in any dts file. So it is safe to fix this yaml binding document. Fixes: 009e83b591dd ("ASoC: dt-bindings: ak4458: Convert to dtschema") Cc: stable@vger.kernel.org Signed-off-by: Shengjiu Wang Reviewed-by: Krzysztof Kozlowski Link: https://patch.msgid.link/20260212021829.3244736-3-shengjiu.wang@nxp.com Signed-off-by: Mark Brown Signed-off-by: Greg Kroah-Hartman