From 2bc6b218717b9d08f466f88209251d54bc09b207 Mon Sep 17 00:00:00 2001 From: Fuad Tabba Date: Tue, 22 Sep 2026 19:14:30 +0100 Subject: arm64/boot: Disable trapping of PMZR_EL0 writes to EL2 __init_el2_fgt2() writes one mask to both HDFGRTR2_EL2 and HDFGWTR2_EL2. PMZR_EL0 is write-only, so its trap bit, nPMZR_EL0, exists only in HDFGWTR2_EL2 and is therefore never set: a PMZR_EL0 write from the host traps to EL2, where the nVHE hypervisor has no handler and BUG()s. The kernel never writes PMZR_EL0, but kernel.perf_user_access=1 has the PMU driver set PMUSERENR_EL0.UEN for a task with a user-read event, so a write from EL0 reaches the trap and takes the host down without a panic message. Accumulate the HDFGWTR2_EL2 bits separately, as __init_el2_fgt() already does for HDFGWTR_EL2, and set nPMZR_EL0 with the other FEAT_PMUv3p9 bits. Fixes: 858c7bfcb35e1 ("arm64/boot: Enable EL2 requirements for FEAT_PMUv3p9") Cc: stable@vger.kernel.org Signed-off-by: Fuad Tabba Reviewed-by: Anshuman Khandual Reviewed-by: Oliver Upton Signed-off-by: Will Deacon --- include/drm/task_barrier.h | 107 +++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 107 insertions(+) create mode 100644 include/drm/task_barrier.h (limited to 'include/drm/task_barrier.h') diff --git a/include/drm/task_barrier.h b/include/drm/task_barrier.h new file mode 100644 index 000000000..f6e6ed529 --- /dev/null +++ b/include/drm/task_barrier.h @@ -0,0 +1,107 @@ +/* + * Copyright 2019 Advanced Micro Devices, Inc. + * + * Permission is hereby granted, free of charge, to any person obtaining a + * copy of this software and associated documentation files (the "Software"), + * to deal in the Software without restriction, including without limitation + * the rights to use, copy, modify, merge, publish, distribute, sublicense, + * and/or sell copies of the Software, and to permit persons to whom the + * Software is furnished to do so, subject to the following conditions: + * + * The above copyright notice and this permission notice shall be included in + * all copies or substantial portions of the Software. + * + * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR + * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, + * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL + * THE COPYRIGHT HOLDER(S) OR AUTHOR(S) BE LIABLE FOR ANY CLAIM, DAMAGES OR + * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, + * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR + * OTHER DEALINGS IN THE SOFTWARE. + * + */ +#include +#include + +/* + * Reusable 2 PHASE task barrier (rendez-vous point) implementation for N tasks. + * Based on the Little book of semaphores - https://greenteapress.com/wp/semaphores/ + */ + + + +#ifndef DRM_TASK_BARRIER_H_ +#define DRM_TASK_BARRIER_H_ + +/* + * Represents an instance of a task barrier. + */ +struct task_barrier { + unsigned int n; + atomic_t count; + struct semaphore enter_turnstile; + struct semaphore exit_turnstile; +}; + +static inline void task_barrier_signal_turnstile(struct semaphore *turnstile, + unsigned int n) +{ + int i; + + for (i = 0 ; i < n; i++) + up(turnstile); +} + +static inline void task_barrier_init(struct task_barrier *tb) +{ + tb->n = 0; + atomic_set(&tb->count, 0); + sema_init(&tb->enter_turnstile, 0); + sema_init(&tb->exit_turnstile, 0); +} + +static inline void task_barrier_add_task(struct task_barrier *tb) +{ + tb->n++; +} + +static inline void task_barrier_rem_task(struct task_barrier *tb) +{ + tb->n--; +} + +/* + * Lines up all the threads BEFORE the critical point. + * + * When all thread passed this code the entry barrier is back to locked state. + */ +static inline void task_barrier_enter(struct task_barrier *tb) +{ + if (atomic_inc_return(&tb->count) == tb->n) + task_barrier_signal_turnstile(&tb->enter_turnstile, tb->n); + + down(&tb->enter_turnstile); +} + +/* + * Lines up all the threads AFTER the critical point. + * + * This function is used to avoid any one thread running ahead if the barrier is + * used repeatedly . + */ +static inline void task_barrier_exit(struct task_barrier *tb) +{ + if (atomic_dec_return(&tb->count) == 0) + task_barrier_signal_turnstile(&tb->exit_turnstile, tb->n); + + down(&tb->exit_turnstile); +} + +/* Convinieince function when nothing to be done in between entry and exit */ +static inline void task_barrier_full(struct task_barrier *tb) +{ + task_barrier_enter(tb); + task_barrier_exit(tb); +} + +#endif -- cgit v1.3.1