x86/mm: Flush global TLB when switching to trampoline page-table

[mirror_ubuntu-jammy-kernel.git] / arch / x86 / realmode / init.c

diff --git a/arch/x86/realmode/init.c b/arch/x86/realmode/init.c
index d3eee1ebcf1d565fecfad980bfa3d3982b477fa9..1d20ed4b28729cef36e3203fdec7d9864dfd30bb 100644 (file)
--- a/arch/x86/realmode/init.c
+++ b/arch/x86/realmode/init.c
@@ -17,6 +17,32 @@ u32 *trampoline_cr4_features;
 /* Hold the pgd entry used on booting additional CPUs */
 pgd_t trampoline_pgd_entry;
 
+void load_trampoline_pgtable(void)
+{
+#ifdef CONFIG_X86_32
+       load_cr3(initial_page_table);
+#else
+       /*
+        * This function is called before exiting to real-mode and that will
+        * fail with CR4.PCIDE still set.
+        */
+       if (boot_cpu_has(X86_FEATURE_PCID))
+               cr4_clear_bits(X86_CR4_PCIDE);
+
+       write_cr3(real_mode_header->trampoline_pgd);
+#endif
+
+       /*
+        * The CR3 write above will not flush global TLB entries.
+        * Stale, global entries from previous page tables may still be
+        * present.  Flush those stale entries.
+        *
+        * This ensures that memory accessed while running with
+        * trampoline_pgd is *actually* mapped into trampoline_pgd.
+        */
+       __flush_tlb_all();
+}
+
 void __init reserve_real_mode(void)
 {
        phys_addr_t mem;