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-rw-r--r--arch/x86/mm/tlb.c44
1 files changed, 44 insertions, 0 deletions
diff --git a/arch/x86/mm/tlb.c b/arch/x86/mm/tlb.c
index ce104b962a17..dbbcfd59726a 100644
--- a/arch/x86/mm/tlb.c
+++ b/arch/x86/mm/tlb.c
@@ -214,6 +214,50 @@ void switch_mm_irqs_off(struct mm_struct *prev, struct mm_struct *next,
}
/*
+ * Call this when reinitializing a CPU. It fixes the following potential
+ * problems:
+ *
+ * - The ASID changed from what cpu_tlbstate thinks it is (most likely
+ * because the CPU was taken down and came back up with CR3's PCID
+ * bits clear. CPU hotplug can do this.
+ *
+ * - The TLB contains junk in slots corresponding to inactive ASIDs.
+ *
+ * - The CPU went so far out to lunch that it may have missed a TLB
+ * flush.
+ */
+void initialize_tlbstate_and_flush(void)
+{
+ int i;
+ struct mm_struct *mm = this_cpu_read(cpu_tlbstate.loaded_mm);
+ u64 tlb_gen = atomic64_read(&init_mm.context.tlb_gen);
+ unsigned long cr3 = __read_cr3();
+
+ /* Assert that CR3 already references the right mm. */
+ WARN_ON((cr3 & CR3_ADDR_MASK) != __pa(mm->pgd));
+
+ /*
+ * Assert that CR4.PCIDE is set if needed. (CR4.PCIDE initialization
+ * doesn't work like other CR4 bits because it can only be set from
+ * long mode.)
+ */
+ WARN_ON(boot_cpu_has(X86_CR4_PCIDE) &&
+ !(cr4_read_shadow() & X86_CR4_PCIDE));
+
+ /* Force ASID 0 and force a TLB flush. */
+ write_cr3(cr3 & ~CR3_PCID_MASK);
+
+ /* Reinitialize tlbstate. */
+ this_cpu_write(cpu_tlbstate.loaded_mm_asid, 0);
+ this_cpu_write(cpu_tlbstate.next_asid, 1);
+ this_cpu_write(cpu_tlbstate.ctxs[0].ctx_id, mm->context.ctx_id);
+ this_cpu_write(cpu_tlbstate.ctxs[0].tlb_gen, tlb_gen);
+
+ for (i = 1; i < TLB_NR_DYN_ASIDS; i++)
+ this_cpu_write(cpu_tlbstate.ctxs[i].ctx_id, 0);
+}
+
+/*
* flush_tlb_func_common()'s memory ordering requirement is that any
* TLB fills that happen after we flush the TLB are ordered after we
* read active_mm's tlb_gen. We don't need any explicit barriers