Update Linux to v5.10.109

Sourced from [1]

[1] https://cdn.kernel.org/pub/linux/kernel/v5.x/linux-5.10.109.tar.xz

Change-Id: I19bca9fc6762d4e63bcf3e4cba88bbe560d9c76c
Signed-off-by: Olivier Deprez <olivier.deprez@arm.com>
diff --git a/arch/x86/realmode/init.c b/arch/x86/realmode/init.c
index 262f83c..1a702c6 100644
--- a/arch/x86/realmode/init.c
+++ b/arch/x86/realmode/init.c
@@ -3,12 +3,13 @@
 #include <linux/slab.h>
 #include <linux/memblock.h>
 #include <linux/mem_encrypt.h>
+#include <linux/pgtable.h>
 
 #include <asm/set_memory.h>
-#include <asm/pgtable.h>
 #include <asm/realmode.h>
 #include <asm/tlbflush.h>
 #include <asm/crash.h>
+#include <asm/sev-es.h>
 
 struct real_mode_header *real_mode_header;
 u32 *trampoline_cr4_features;
@@ -16,6 +17,32 @@
 /* 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;
@@ -38,6 +65,25 @@
 	crash_reserve_low_1M();
 }
 
+static void sme_sev_setup_real_mode(struct trampoline_header *th)
+{
+#ifdef CONFIG_AMD_MEM_ENCRYPT
+	if (sme_active())
+		th->flags |= TH_FLAGS_SME_ACTIVE;
+
+	if (sev_es_active()) {
+		/*
+		 * Skip the call to verify_cpu() in secondary_startup_64 as it
+		 * will cause #VC exceptions when the AP can't handle them yet.
+		 */
+		th->start = (u64) secondary_startup_64_no_verify;
+
+		if (sev_es_setup_ap_jump_table(real_mode_header))
+			panic("Failed to get/update SEV-ES AP Jump Table");
+	}
+#endif
+}
+
 static void __init setup_real_mode(void)
 {
 	u16 real_mode_seg;
@@ -50,6 +96,7 @@
 #ifdef CONFIG_X86_64
 	u64 *trampoline_pgd;
 	u64 efer;
+	int i;
 #endif
 
 	base = (unsigned char *)real_mode_header;
@@ -104,13 +151,22 @@
 	*trampoline_cr4_features = mmu_cr4_features;
 
 	trampoline_header->flags = 0;
-	if (sme_active())
-		trampoline_header->flags |= TH_FLAGS_SME_ACTIVE;
 
 	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);
 }
 
 /*