[PATCH v16 37/38] x86/efistub: EFI stub DRTM support for Secure Launch

[Ross Philipson <ross.philipson@gmail.com>]

From: Ard Biesheuvel <ardb@kernel.org>

Invoke the Secure Launch protocol exposed by the boot loader at the
appropriate time to perform a measured launch of the decompressed
kernel after ExitBootServices().

Co-developed-by: Ross Philipson <ross.philipson@gmail.com>
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: Ross Philipson <ross.philipson@gmail.com>
---
 drivers/firmware/efi/libstub/Makefile      |  1 +
 drivers/firmware/efi/libstub/efistub.h     | 24 ++++++++++++++
 drivers/firmware/efi/libstub/x86-slaunch.c | 38 ++++++++++++++++++++++
 drivers/firmware/efi/libstub/x86-stub.c    | 27 ++++++++++++---
 4 files changed, 86 insertions(+), 4 deletions(-)
 create mode 100644 drivers/firmware/efi/libstub/x86-slaunch.c

diff --git a/drivers/firmware/efi/libstub/Makefile b/drivers/firmware/efi/libstub/Makefile
index e386ffd009b7..fd5eaf3142b2 100644
--- a/drivers/firmware/efi/libstub/Makefile
+++ b/drivers/firmware/efi/libstub/Makefile
@@ -86,6 +86,7 @@ lib-$(CONFIG_ARM)		+= arm32-stub.o
 lib-$(CONFIG_ARM64)		+= kaslr.o arm64.o arm64-stub.o smbios.o
 lib-$(CONFIG_X86)		+= x86-stub.o smbios.o
 lib-$(CONFIG_X86_64)		+= x86-5lvl.o
+lib-$(CONFIG_SECURE_LAUNCH)	+= x86-slaunch.o
 lib-$(CONFIG_RISCV)		+= kaslr.o riscv.o riscv-stub.o
 lib-$(CONFIG_LOONGARCH)		+= loongarch.o loongarch-stub.o
 
diff --git a/drivers/firmware/efi/libstub/efistub.h b/drivers/firmware/efi/libstub/efistub.h
index 979a21818cc1..18301ba3ae0f 100644
--- a/drivers/firmware/efi/libstub/efistub.h
+++ b/drivers/firmware/efi/libstub/efistub.h
@@ -1267,4 +1267,28 @@ void arch_accept_memory(phys_addr_t start, phys_addr_t end);
 efi_status_t efi_zboot_decompress_init(unsigned long *alloc_size);
 efi_status_t efi_zboot_decompress(u8 *out, unsigned long outlen);
 
+#ifdef CONFIG_SECURE_LAUNCH
+efi_status_t efi_secure_launch_init(efi_handle_t image_handle);
+efi_status_t efi_secure_launch_prepare(struct boot_params *boot_params,
+				       phys_addr_t base);
+void efi_secure_launch(void);
+#else
+static inline
+efi_status_t efi_secure_launch_init(efi_handle_t image_handle)
+{
+	return EFI_UNSUPPORTED;
+}
+
+static inline
+efi_status_t efi_secure_launch_prepare(struct boot_params *boot_params,
+				       phys_addr_t base)
+{
+	return EFI_SUCCESS;
+}
+
+static inline void efi_secure_launch(void)
+{
+}
+#endif
+
 #endif
diff --git a/drivers/firmware/efi/libstub/x86-slaunch.c b/drivers/firmware/efi/libstub/x86-slaunch.c
new file mode 100644
index 000000000000..98ff15f94996
--- /dev/null
+++ b/drivers/firmware/efi/libstub/x86-slaunch.c
@@ -0,0 +1,38 @@
+// SPDX-License-Identifier: GPL-2.0-only
+
+#include <linux/efi.h>
+#include <linux/pci.h>
+#include <linux/stddef.h>
+#include <linux/slr_efi.h>
+#include <linux/slaunch.h>
+
+#include <asm/boot.h>
+#include <asm/bootparam.h>
+#include <asm/efi.h>
+
+#include "efistub.h"
+
+static struct efi_slaunch_protocol *slaunch;
+
+efi_status_t efi_secure_launch_init(efi_handle_t image_handle)
+{
+	return efi_bs_call(handle_protocol, image_handle,
+			   &EFI_SLAUNCH_PROTOCOL_GUID, (void **)&slaunch);
+}
+
+efi_status_t efi_secure_launch_prepare(struct boot_params *boot_params,
+				       phys_addr_t base)
+{
+	if (!slaunch)
+		return EFI_SUCCESS;
+
+	return slaunch->setup_dlme(slaunch, base, mle_header_offset, (u64)boot_params);
+}
+
+void efi_secure_launch(void)
+{
+	if (!slaunch)
+		return;
+
+	slaunch->launch(slaunch);
+}
diff --git a/drivers/firmware/efi/libstub/x86-stub.c b/drivers/firmware/efi/libstub/x86-stub.c
index cef32e2c82d8..339e63ae84ef 100644
--- a/drivers/firmware/efi/libstub/x86-stub.c
+++ b/drivers/firmware/efi/libstub/x86-stub.c
@@ -833,7 +833,8 @@ static efi_status_t parse_options(const char *cmdline)
 }
 
 static efi_status_t efi_decompress_kernel(unsigned long *kernel_entry,
-					  struct boot_params *boot_params)
+					  struct boot_params *boot_params,
+					  unsigned long alloc_limit)
 {
 	unsigned long virt_addr = LOAD_PHYSICAL_ADDR;
 	unsigned long addr, alloc_size, entry;
@@ -877,8 +878,7 @@ static efi_status_t efi_decompress_kernel(unsigned long *kernel_entry,
 
 	status = efi_random_alloc(alloc_size, CONFIG_PHYSICAL_ALIGN, &addr,
 				  seed[0], EFI_LOADER_CODE,
-				  LOAD_PHYSICAL_ADDR,
-				  EFI_X86_KERNEL_ALLOC_LIMIT);
+				  LOAD_PHYSICAL_ADDR, alloc_limit);
 	if (status != EFI_SUCCESS)
 		return status;
 
@@ -890,6 +890,10 @@ static efi_status_t efi_decompress_kernel(unsigned long *kernel_entry,
 
 	*kernel_entry = addr + entry;
 
+	status = efi_secure_launch_prepare(boot_params, addr);
+	if (status != EFI_SUCCESS)
+		return status;
+
 	return efi_adjust_memory_range_protection(addr, kernel_text_size) ?:
 	       efi_adjust_memory_range_protection(addr + kernel_inittext_offset,
 						  kernel_inittext_size);
@@ -914,6 +918,7 @@ void __noreturn efi_stub_entry(efi_handle_t handle,
 			       struct boot_params *boot_params)
 
 {
+	unsigned long alloc_limit = EFI_X86_KERNEL_ALLOC_LIMIT;
 	efi_guid_t guid = EFI_MEMORY_ATTRIBUTE_PROTOCOL_GUID;
 	const struct linux_efi_initrd *initrd = NULL;
 	unsigned long kernel_entry;
@@ -925,6 +930,17 @@ void __noreturn efi_stub_entry(efi_handle_t handle,
 	if (efi_system_table->hdr.signature != EFI_SYSTEM_TABLE_SIGNATURE)
 		efi_exit(handle, EFI_INVALID_PARAMETER);
 
+	status = efi_secure_launch_init(handle);
+	switch (status) {
+	case EFI_SUCCESS:
+		alloc_limit = U32_MAX;
+		break;
+	case EFI_UNSUPPORTED:
+		break;
+	default:
+		efi_exit(handle, status);
+	}
+
 	if (!IS_ENABLED(CONFIG_EFI_HANDOVER_PROTOCOL) || !boot_params) {
 		status = efi_allocate_bootparams(handle, &boot_params);
 		if (status != EFI_SUCCESS)
@@ -974,7 +990,7 @@ void __noreturn efi_stub_entry(efi_handle_t handle,
 	if (efi_mem_encrypt > 0)
 		hdr->xloadflags |= XLF_MEM_ENCRYPTION;
 
-	status = efi_decompress_kernel(&kernel_entry, boot_params);
+	status = efi_decompress_kernel(&kernel_entry, boot_params, alloc_limit);
 	if (status != EFI_SUCCESS) {
 		efi_err("Failed to decompress kernel\n");
 		goto fail;
@@ -1029,6 +1045,9 @@ void __noreturn efi_stub_entry(efi_handle_t handle,
 		goto fail;
 	}
 
+	/* If a Secure Launch is in progress, this never returns */
+	efi_secure_launch();
+
 	/*
 	 * Call the SEV init code while still running with the firmware's
 	 * GDT/IDT, so #VC exceptions will be handled by EFI.
-- 
2.47.3