sev/i386: Allow AP booting under SEV-ES

When SEV-ES is enabled, it is not possible modify the guests register
state after it has been initially created, encrypted and measured.

Normally, an INIT-SIPI-SIPI request is used to boot the AP. However, the
hypervisor cannot emulate this because it cannot update the AP register
state. For the very first boot by an AP, the reset vector CS segment
value and the EIP value must be programmed before the register has been
encrypted and measured. Search the guest firmware for the guest for a
specific GUID that tells Qemu the value of the reset vector to use.

Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: "Michael S. Tsirkin" <mst@redhat.com>
Cc: Marcel Apfelbaum <marcel.apfelbaum@gmail.com>
Cc: Richard Henderson <richard.henderson@linaro.org>
Cc: Eduardo Habkost <ehabkost@redhat.com>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com>
Message-Id: <22db2bfb4d6551aed661a9ae95b4fdbef613ca21.1611682609.git.thomas.lendacky@amd.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

1 files changed, 8 insertions, 0 deletions

diff --git a/hw/i386/pc_sysfw.c b/hw/i386/pc_sysfw.c
index 6404b5a86f..9fe72b370e 100644
--- a/hw/i386/pc_sysfw.c
+++ b/hw/i386/pc_sysfw.c
@@ -256,6 +256,7 @@ static void pc_system_flash_map(PCMachineState *pcms,
     MemoryRegion *flash_mem;
     void *flash_ptr;
     int flash_size;
+    int ret;
 
     assert(PC_MACHINE_GET_CLASS(pcms)->pci_enabled);
 
@@ -308,6 +309,13 @@ static void pc_system_flash_map(PCMachineState *pcms,
                  * search for them
                  */
                 pc_system_parse_ovmf_flash(flash_ptr, flash_size);
+
+                ret = sev_es_save_reset_vector(flash_ptr, flash_size);
+                if (ret) {
+                    error_report("failed to locate and/or save reset vector");
+                    exit(1);
+                }
+
                 sev_encrypt_flash(flash_ptr, flash_size, &error_fatal);
             }
         }