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 6.6-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-kern.patch
and it can be found in the queue-6.6 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 87a7238bf9d1b72ed2f9a136b04d22d6e5db2781
Author: Will Deacon <will@xxxxxxxxxx>
Date: Wed May 22 11:53:05 2024 +0100
Reapply "arm64: fpsimd: Implement lazy restore for kernel mode FPSIMD"
[ Upstream commit f481bb32d60e45fb3d19ea68ce79c5629f3fc3a0 ]
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: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/arch/arm64/include/asm/processor.h b/arch/arm64/include/asm/processor.h
index ce6eebd6c08bd..5b0a04810b236 100644
--- a/arch/arm64/include/asm/processor.h
+++ b/arch/arm64/include/asm/processor.h
@@ -169,6 +169,7 @@ 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
diff --git a/arch/arm64/kernel/fpsimd.c b/arch/arm64/kernel/fpsimd.c
index 55963fa64dec8..4c7bc3c01afc2 100644
--- a/arch/arm64/kernel/fpsimd.c
+++ b/arch/arm64/kernel/fpsimd.c
@@ -1552,12 +1552,30 @@ void do_fpsimd_exc(unsigned long esr, struct pt_regs *regs)
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();
}
/*
