[PATCH v11 20/20] x86/efi: EFI stub DRTM launch support for Secure Launch

[Ross Philipson]

This support allows the DRTM launch to be initiated after an EFI stub
launch of the Linux kernel is done. This is accomplished by providing
a handler to jump to when a Secure Launch is in progress. This has to be
called after the EFI stub does Exit Boot Services.

Signed-off-by: Ross Philipson <ross.philipson@xxxxxxxxxx>
Reviewed-by: Ard Biesheuvel <ardb@xxxxxxxxxx>
---
 drivers/firmware/efi/libstub/efistub.h  |  8 ++
 drivers/firmware/efi/libstub/x86-stub.c | 99 +++++++++++++++++++++++++
 2 files changed, 107 insertions(+)

diff --git a/drivers/firmware/efi/libstub/efistub.h b/drivers/firmware/efi/libstub/efistub.h
index d33ccbc4a2c6..baf42d6d0796 100644
--- a/drivers/firmware/efi/libstub/efistub.h
+++ b/drivers/firmware/efi/libstub/efistub.h
@@ -135,6 +135,14 @@ void efi_set_u64_split(u64 data, u32 *lo, u32 *hi)
 	*hi = upper_32_bits(data);
 }
 
+static inline
+void efi_set_u64_form(u32 lo, u32 hi, u64 *data)
+{
+	u64 upper = hi;
+
+	*data = lo | upper << 32;
+}
+
 /*
  * Allocation types for calls to boottime->allocate_pages.
  */
diff --git a/drivers/firmware/efi/libstub/x86-stub.c b/drivers/firmware/efi/libstub/x86-stub.c
index f8e465da344d..2e063bce1080 100644
--- a/drivers/firmware/efi/libstub/x86-stub.c
+++ b/drivers/firmware/efi/libstub/x86-stub.c
@@ -9,6 +9,8 @@
 #include <linux/efi.h>
 #include <linux/pci.h>
 #include <linux/stddef.h>
+#include <linux/slr_table.h>
+#include <linux/slaunch.h>
 
 #include <asm/efi.h>
 #include <asm/e820/types.h>
@@ -923,6 +925,98 @@ static efi_status_t efi_decompress_kernel(unsigned long *kernel_entry)
 	return efi_adjust_memory_range_protection(addr, kernel_text_size);
 }
 
+#if (IS_ENABLED(CONFIG_SECURE_LAUNCH))
+static bool efi_secure_launch_update_boot_params(struct slr_table *slrt,
+						 struct boot_params *boot_params)
+{
+	struct slr_entry_intel_info *txt_info;
+	struct slr_entry_policy *policy;
+	struct txt_os_mle_data *os_mle;
+	bool updated = false;
+	int i;
+
+	txt_info = slr_next_entry_by_tag(slrt, NULL, SLR_ENTRY_INTEL_INFO);
+	if (!txt_info)
+		return false;
+
+	os_mle = txt_os_mle_data_start((void *)txt_info->txt_heap);
+	if (!os_mle)
+		return false;
+
+	os_mle->boot_params_addr = (u64)boot_params;
+
+	policy = slr_next_entry_by_tag(slrt, NULL, SLR_ENTRY_ENTRY_POLICY);
+	if (!policy)
+		return false;
+
+	for (i = 0; i < policy->nr_entries; i++) {
+		if (policy->policy_entries[i].entity_type == SLR_ET_BOOT_PARAMS) {
+			policy->policy_entries[i].entity = (u64)boot_params;
+			updated = true;
+			break;
+		}
+	}
+
+	/*
+	 * If this is a PE entry into EFI stub the mocked up boot params will
+	 * be missing some of the setup header data needed for the second stage
+	 * of the Secure Launch boot.
+	 */
+	if (image) {
+		struct setup_header *hdr = (struct setup_header *)((u8 *)image->image_base +
+					    offsetof(struct boot_params, hdr));
+		u64 cmdline_ptr;
+
+		boot_params->hdr.setup_sects = hdr->setup_sects;
+		boot_params->hdr.syssize = hdr->syssize;
+		boot_params->hdr.version = hdr->version;
+		boot_params->hdr.loadflags = hdr->loadflags;
+		boot_params->hdr.kernel_alignment = hdr->kernel_alignment;
+		boot_params->hdr.min_alignment = hdr->min_alignment;
+		boot_params->hdr.xloadflags = hdr->xloadflags;
+		boot_params->hdr.init_size = hdr->init_size;
+		boot_params->hdr.kernel_info_offset = hdr->kernel_info_offset;
+		efi_set_u64_form(boot_params->hdr.cmd_line_ptr, boot_params->ext_cmd_line_ptr,
+				 &cmdline_ptr);
+		boot_params->hdr.cmdline_size = strlen((const char *)cmdline_ptr);
+	}
+
+	return updated;
+}
+
+static void efi_secure_launch(struct boot_params *boot_params)
+{
+	struct slr_entry_dl_info *dlinfo;
+	efi_guid_t guid = SLR_TABLE_GUID;
+	dl_handler_func handler_callback;
+	struct slr_table *slrt;
+
+	/*
+	 * The presence of this table indicated a Secure Launch
+	 * is being requested.
+	 */
+	slrt = (struct slr_table *)get_efi_config_table(guid);
+	if (!slrt || slrt->magic != SLR_TABLE_MAGIC)
+		return;
+
+	/*
+	 * Since the EFI stub library creates its own boot_params on entry, the
+	 * SLRT and TXT heap have to be updated with this version.
+	 */
+	if (!efi_secure_launch_update_boot_params(slrt, boot_params))
+		return;
+
+	/* Jump through DL stub to initiate Secure Launch */
+	dlinfo = slr_next_entry_by_tag(slrt, NULL, SLR_ENTRY_DL_INFO);
+
+	handler_callback = (dl_handler_func)dlinfo->dl_handler;
+
+	handler_callback(&dlinfo->bl_context);
+
+	unreachable();
+}
+#endif
+
 static void __noreturn enter_kernel(unsigned long kernel_addr,
 				    struct boot_params *boot_params)
 {
@@ -1050,6 +1144,11 @@ void __noreturn efi_stub_entry(efi_handle_t handle,
 		goto fail;
 	}
 
+#if (IS_ENABLED(CONFIG_SECURE_LAUNCH))
+	/* If a Secure Launch is in progress, this never returns */
+	efi_secure_launch(boot_params);
+#endif
+
 	/*
 	 * Call the SEV init code while still running with the firmware's
 	 * GDT/IDT, so #VC exceptions will be handled by EFI.
-- 
2.39.3