hw/i386/sev: Add support to encrypt BIOS when SEV-SNP is enabled

TODO: - As with other instances noted by Paolo, move
        sev/snp_launch_update_data() into an sev_common class method
        that gets overloaded based on guest type rather than checking
        for sev_snp_enabled().

As with SEV, an SNP guest requires that the BIOS be part of the initial
encrypted/measured guest payload. Extend sev_encrypt_flash() to handle
the SNP case and plumb through the GPA of the BIOS location since this
is needed for SNP.

Signed-off-by: Brijesh Singh <brijesh.singh@amd.com>
Signed-off-by: Michael Roth <michael.roth@amd.com>

hw/i386/pc_sysfw.c

@@ -149,6 +149,8 @@ static void pc_system_flash_map(PCMachineState *pcms,
     assert(PC_MACHINE_GET_CLASS(pcms)->pci_enabled);
 
     for (i = 0; i < ARRAY_SIZE(pcms->flash); i++) {
+        hwaddr gpa;
+
         system_flash = pcms->flash[i];
         blk = pflash_cfi01_get_blk(system_flash);
         if (!blk) {
@@ -178,11 +180,11 @@ static void pc_system_flash_map(PCMachineState *pcms,
         }
 
         total_size += size;
+        gpa = 0x100000000ULL - total_size; /* where the flash is mapped */
         qdev_prop_set_uint32(DEVICE(system_flash), "num-blocks",
                              size / FLASH_SECTOR_SIZE);
         sysbus_realize_and_unref(SYS_BUS_DEVICE(system_flash), &error_fatal);
-        sysbus_mmio_map(SYS_BUS_DEVICE(system_flash), 0,
-                        0x100000000ULL - total_size);
+        sysbus_mmio_map(SYS_BUS_DEVICE(system_flash), 0, gpa);
 
         if (i == 0) {
             flash_mem = pflash_cfi01_get_memory(system_flash);
@@ -192,7 +194,7 @@ static void pc_system_flash_map(PCMachineState *pcms,
             if (sev_enabled()) {
                 flash_ptr = memory_region_get_ram_ptr(flash_mem);
                 flash_size = memory_region_size(flash_mem);
-                x86_firmware_configure(flash_ptr, flash_size);
+                x86_firmware_configure(gpa, flash_ptr, flash_size);
             }
         }
     }
@@ -245,7 +247,7 @@ void pc_system_firmware_init(PCMachineState *pcms,
     pc_system_flash_cleanup_unused(pcms);
 }
 
-void x86_firmware_configure(void *ptr, int size)
+void x86_firmware_configure(hwaddr gpa, void *ptr, int size)
 {
     int ret;
 
@@ -262,6 +264,6 @@ void x86_firmware_configure(void *ptr, int size)
             exit(1);
         }
 
-        sev_encrypt_flash(ptr, size, &error_fatal);
+        sev_encrypt_flash(gpa, ptr, size, &error_fatal);
     }
 }

hw/i386/x86.c

@@ -1161,7 +1161,7 @@ void x86_bios_rom_init(MachineState *ms, const char *default_firmware,
          */
         void *ptr = memory_region_get_ram_ptr(bios);
         load_image_size(filename, ptr, bios_size);
-        x86_firmware_configure(ptr, bios_size);
+        x86_firmware_configure(0x100000000ULL - bios_size, ptr, bios_size);
     } else {
         if (!isapc_ram_fw) {
             memory_region_set_readonly(bios, true);

include/hw/i386/x86.h

@@ -143,6 +143,6 @@ void ioapic_init_gsi(GSIState *gsi_state, Object *parent);
 DeviceState *ioapic_init_secondary(GSIState *gsi_state);
 
 /* pc_sysfw.c */
-void x86_firmware_configure(void *ptr, int size);
+void x86_firmware_configure(hwaddr gpa, void *ptr, int size);
 
 #endif

target/i386/sev-sysemu-stub.c

@@ -42,7 +42,7 @@ void qmp_sev_inject_launch_secret(const char *packet_header, const char *secret,
     error_setg(errp, "SEV is not available in this QEMU");
 }
 
-int sev_encrypt_flash(uint8_t *ptr, uint64_t len, Error **errp)
+int sev_encrypt_flash(hwaddr gpa, uint8_t *ptr, uint64_t len, Error **errp)
 {
     g_assert_not_reached();
 }

target/i386/sev.c

@@ -1449,7 +1449,7 @@ static int sev_kvm_init(ConfidentialGuestSupport *cgs, Error **errp)
 }
 
 int
-sev_encrypt_flash(uint8_t *ptr, uint64_t len, Error **errp)
+sev_encrypt_flash(hwaddr gpa, uint8_t *ptr, uint64_t len, Error **errp)
 {
     SevCommonState *sev_common = SEV_COMMON(MACHINE(qdev_get_machine())->cgs);
 
@@ -1459,7 +1459,14 @@ sev_encrypt_flash(uint8_t *ptr, uint64_t len, Error **errp)
 
     /* if SEV is in update state then encrypt the data else do nothing */
     if (sev_check_state(sev_common, SEV_STATE_LAUNCH_UPDATE)) {
-        int ret = sev_launch_update_data(SEV_GUEST(sev_common), ptr, len);
+        int ret;
+
+        if (sev_snp_enabled()) {
+            ret = snp_launch_update_data(gpa, ptr, len,
+                                         KVM_SEV_SNP_PAGE_TYPE_NORMAL);
+        } else {
+            ret = sev_launch_update_data(SEV_GUEST(sev_common), ptr, len);
+        }
         if (ret < 0) {
             error_setg(errp, "SEV: Failed to encrypt pflash rom");
             return ret;
@@ -1829,8 +1836,8 @@ bool sev_add_kernel_loader_hashes(SevKernelLoaderContext *ctx, Error **errp)
     }
 
     if (build_kernel_loader_hashes(padded_ht, ctx, errp)) {
-        if (sev_encrypt_flash((uint8_t *)padded_ht, sizeof(*padded_ht),
-                              errp) < 0) {
+        if (sev_encrypt_flash(area->base, (uint8_t *)padded_ht,
+                              sizeof(*padded_ht), errp) < 0) {
             ret = false;
         }
     } else {

target/i386/sev.h

@@ -59,7 +59,7 @@ uint32_t sev_get_cbit_position(void);
 uint32_t sev_get_reduced_phys_bits(void);
 bool sev_add_kernel_loader_hashes(SevKernelLoaderContext *ctx, Error **errp);
 
-int sev_encrypt_flash(uint8_t *ptr, uint64_t len, Error **errp);
+int sev_encrypt_flash(hwaddr gpa, uint8_t *ptr, uint64_t len, Error **errp);
 int sev_inject_launch_secret(const char *hdr, const char *secret,
                              uint64_t gpa, Error **errp);