Merge branch 'for-next/c1-pro-erratum-4193714' into for-next/core

* for-next/c1-pro-erratum-4193714:
  : Work around C1-Pro erratum 4193714 (CVE-2026-0995)
  arm64: errata: Work around early CME DVMSync acknowledgement
  arm64: cputype: Add C1-Pro definitions
  arm64: tlb: Pass the corresponding mm to __tlbi_sync_s1ish()
  arm64: tlb: Introduce __tlbi_sync_s1ish_{kernel,batch}() for TLB maintenance

1 files changed, 36 insertions, 0 deletions

diff --git a/arch/arm64/kernel/process.c b/arch/arm64/kernel/process.c
index c0bf1f46cdc6..033643cd4e5e 100644
--- a/arch/arm64/kernel/process.c
+++ b/arch/arm64/kernel/process.c
@@ -26,6 +26,7 @@
 #include <linux/reboot.h>
 #include <linux/interrupt.h>
 #include <linux/init.h>
+#include <linux/cpumask.h>
 #include <linux/cpu.h>
 #include <linux/elfcore.h>
 #include <linux/pm.h>
@@ -340,8 +341,41 @@ void flush_thread(void)
 	flush_gcs();
 }
 
+#ifdef CONFIG_ARM64_ERRATUM_4193714
+
+static void arch_dup_tlbbatch_mask(struct task_struct *dst)
+{
+	/*
+	 * Clear the inherited cpumask with memset() to cover both cases where
+	 * cpumask_var_t is a pointer or an array. It will be allocated lazily
+	 * in sme_dvmsync_add_pending() if CPUMASK_OFFSTACK=y.
+	 */
+	if (alternative_has_cap_unlikely(ARM64_WORKAROUND_4193714))
+		memset(&dst->tlb_ubc.arch.cpumask, 0,
+		       sizeof(dst->tlb_ubc.arch.cpumask));
+}
+
+static void arch_release_tlbbatch_mask(struct task_struct *tsk)
+{
+	if (alternative_has_cap_unlikely(ARM64_WORKAROUND_4193714))
+		free_cpumask_var(tsk->tlb_ubc.arch.cpumask);
+}
+
+#else
+
+static void arch_dup_tlbbatch_mask(struct task_struct *dst)
+{
+}
+
+static void arch_release_tlbbatch_mask(struct task_struct *tsk)
+{
+}
+
+#endif /* CONFIG_ARM64_ERRATUM_4193714 */
+
 void arch_release_task_struct(struct task_struct *tsk)
 {
+	arch_release_tlbbatch_mask(tsk);
 	fpsimd_release_task(tsk);
 }
 
@@ -357,6 +391,8 @@ int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src)
 
 	*dst = *src;
 
+	arch_dup_tlbbatch_mask(dst);
+
 	/*
 	 * Drop stale reference to src's sve_state and convert dst to
 	 * non-streaming FPSIMD mode.