x86/realmode: Setup AP jump table

As part of the GHCB specification, the booting of APs under SEV-ES
requires an AP jump table when transitioning from one layer of code to
another (e.g. when going from UEFI to the OS). As a result, each layer
that parks an AP must provide the physical address of an AP jump table
to the next layer via the hypervisor.

Upon booting of the kernel, read the AP jump table address from the
hypervisor. Under SEV-ES, APs are started using the INIT-SIPI-SIPI
sequence. Before issuing the first SIPI request for an AP, the start
CS and IP is programmed into the AP jump table. Upon issuing the SIPI
request, the AP will awaken and jump to that start CS:IP address.

Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com>
[ jroedel@suse.de: - Adapted to different code base
                   - Moved AP table setup from SIPI sending path to
		     real-mode setup code
		   - Fix sparse warnings ]
Co-developed-by: Joerg Roedel <jroedel@suse.de>
Signed-off-by: Joerg Roedel <jroedel@suse.de>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/20200907131613.12703-67-joro@8bytes.org

1 files changed, 16 insertions, 2 deletions

diff --git a/arch/x86/realmode/init.c b/arch/x86/realmode/init.c
index 1ed1208931e0..3fb9b60be07a 100644
--- a/arch/x86/realmode/init.c
+++ b/arch/x86/realmode/init.c
@@ -9,6 +9,7 @@
 #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;
@@ -38,6 +39,19 @@ void __init reserve_real_mode(void)
 	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()) {
+		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;
@@ -104,13 +118,13 @@ static void __init setup_real_mode(void)
 	*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);
 	trampoline_pgd[0] = trampoline_pgd_entry.pgd;
 	trampoline_pgd[511] = init_top_pgt[511].pgd;
 #endif
+
+	sme_sev_setup_real_mode(trampoline_header);
 }
 
 /*