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Diffstat (limited to 'arch/x86/realmode/init.c')
-rw-r--r--arch/x86/realmode/init.c38
1 files changed, 37 insertions, 1 deletions
diff --git a/arch/x86/realmode/init.c b/arch/x86/realmode/init.c
index 4a3da7592b99..c5e29db02a46 100644
--- 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;
@@ -72,6 +98,7 @@ static void __init setup_real_mode(void)
#ifdef CONFIG_X86_64
u64 *trampoline_pgd;
u64 efer;
+ int i;
#endif
base = (unsigned char *)real_mode_header;
@@ -128,8 +155,17 @@ static void __init setup_real_mode(void)
trampoline_header->flags = 0;
trampoline_pgd = (u64 *) __va(real_mode_header->trampoline_pgd);
+
+ /* Map the real mode stub as virtual == physical */
trampoline_pgd[0] = trampoline_pgd_entry.pgd;
- trampoline_pgd[511] = init_top_pgt[511].pgd;
+
+ /*
+ * Include the entirety of the kernel mapping into the trampoline
+ * PGD. This way, all mappings present in the normal kernel page
+ * tables are usable while running on trampoline_pgd.
+ */
+ for (i = pgd_index(__PAGE_OFFSET); i < PTRS_PER_PGD; i++)
+ trampoline_pgd[i] = init_top_pgt[i].pgd;
#endif
sme_sev_setup_real_mode(trampoline_header);