hw/i386/sev: Add support to encrypt BIOS when SEV-SNP is 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>
Signed-off-by: Pankaj Gupta <pankaj.gupta@amd.com>
Message-ID: <20240530111643.1091816-25-pankaj.gupta@amd.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

hw/i386/pc_sysfw.c

@@ -148,6 +148,8 @@ 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) {
@@ -177,11 +179,11 @@ 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);
@@ -196,7 +198,7 @@ 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);
             }
         }
     }
@@ -249,7 +251,7 @@ 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;
 
@@ -270,6 +272,6 @@ 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-common.c

@@ -1013,7 +1013,7 @@ void x86_bios_rom_init(X86MachineState *x86ms, const char *default_firmware,
          */
         void *ptr = memory_region_get_ram_ptr(&x86ms->bios);
         load_image_size(filename, ptr, bios_size);
-        x86_firmware_configure(ptr, bios_size);
+        x86_firmware_configure(0x100000000ULL - bios_size, ptr, bios_size);
     } else {
         memory_region_set_readonly(&x86ms->bios, !isapc_ram_fw);
         ret = rom_add_file_fixed(bios_name, (uint32_t)(-bios_size), -1);

include/hw/i386/x86.h

@@ -154,6 +154,6 @@ 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

@@ -1484,7 +1484,7 @@ static int sev_snp_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);
 
@@ -1841,7 +1841,8 @@ bool sev_add_kernel_loader_hashes(SevKernelLoaderContext *ctx, Error **errp)
     /* zero the excess data so the measurement can be reliably calculated */
     memset(padded_ht->padding, 0, sizeof(padded_ht->padding));
 
-    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;
     }
 

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);