This is a note to let you know that I've just added the patch titled
Reapply "arm64: fpsimd: Implement lazy restore for kernel mode FPSIMD"
to the 6.9-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
reapply-arm64-fpsimd-implement-lazy-restore-for-kernel-mode-fpsimd.patch
and it can be found in the queue-6.9 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From f481bb32d60e45fb3d19ea68ce79c5629f3fc3a0 Mon Sep 17 00:00:00 2001
From: Will Deacon <will@xxxxxxxxxx>
Date: Wed, 22 May 2024 11:53:05 +0100
Subject: Reapply "arm64: fpsimd: Implement lazy restore for kernel mode FPSIMD"
From: Will Deacon <will@xxxxxxxxxx>
commit f481bb32d60e45fb3d19ea68ce79c5629f3fc3a0 upstream.
This reverts commit b8995a18417088bb53f87c49d200ec72a9dd4ec1.
Ard managed to reproduce the dm-crypt corruption problem and got to the
bottom of it, so re-apply the problematic patch in preparation for
fixing things properly.
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Will Deacon <will@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
arch/arm64/include/asm/processor.h | 1 +
arch/arm64/kernel/fpsimd.c | 18 ++++++++++++++++++
2 files changed, 19 insertions(+)
--- a/arch/arm64/include/asm/processor.h
+++ b/arch/arm64/include/asm/processor.h
@@ -171,6 +171,7 @@ struct thread_struct {
struct debug_info debug; /* debugging */
struct user_fpsimd_state kernel_fpsimd_state;
+ unsigned int kernel_fpsimd_cpu;
#ifdef CONFIG_ARM64_PTR_AUTH
struct ptrauth_keys_user keys_user;
#ifdef CONFIG_ARM64_PTR_AUTH_KERNEL
--- a/arch/arm64/kernel/fpsimd.c
+++ b/arch/arm64/kernel/fpsimd.c
@@ -1509,12 +1509,30 @@ void do_fpsimd_exc(unsigned long esr, st
static void fpsimd_load_kernel_state(struct task_struct *task)
{
+ struct cpu_fp_state *last = this_cpu_ptr(&fpsimd_last_state);
+
+ /*
+ * Elide the load if this CPU holds the most recent kernel mode
+ * FPSIMD context of the current task.
+ */
+ if (last->st == &task->thread.kernel_fpsimd_state &&
+ task->thread.kernel_fpsimd_cpu == smp_processor_id())
+ return;
+
fpsimd_load_state(&task->thread.kernel_fpsimd_state);
}
static void fpsimd_save_kernel_state(struct task_struct *task)
{
+ struct cpu_fp_state cpu_fp_state = {
+ .st = &task->thread.kernel_fpsimd_state,
+ .to_save = FP_STATE_FPSIMD,
+ };
+
fpsimd_save_state(&task->thread.kernel_fpsimd_state);
+ fpsimd_bind_state_to_cpu(&cpu_fp_state);
+
+ task->thread.kernel_fpsimd_cpu = smp_processor_id();
}
/*
Patches currently in stable-queue which might be from will@xxxxxxxxxx are
queue-6.9/revert-arm64-fpsimd-implement-lazy-restore-for-kernel-mode-fpsimd.patch
queue-6.9/reapply-arm64-fpsimd-implement-lazy-restore-for-kernel-mode-fpsimd.patch
queue-6.9/arm64-fpsimd-avoid-erroneous-elide-of-user-state-reload.patch
