On March 28, 2025 4:08:14 PM PDT, Ross Philipson <[email protected]> wrote: >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 <[email protected]> >Reviewed-by: Ard Biesheuvel <[email protected]> >--- > drivers/firmware/efi/libstub/efistub.h | 8 +++ > drivers/firmware/efi/libstub/x86-stub.c | 94 +++++++++++++++++++++++++ > 2 files changed, 102 insertions(+) > >diff --git a/drivers/firmware/efi/libstub/efistub.h >b/drivers/firmware/efi/libstub/efistub.h >index d96d4494070d..bbbc4b327ce1 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 863910e9eefc..033133e7d953 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> >@@ -798,6 +800,93 @@ 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; >+ bool updated = false; >+ int i; >+ >+ txt_info = slr_next_entry_by_tag(slrt, NULL, SLR_ENTRY_INTEL_INFO); >+ if (!txt_info) >+ return false; >+ >+ txt_info->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) > { >@@ -925,6 +1014,11 @@ 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.
efi_set_u64_form()? What the heck is that? If it actually involves two u32 packed into a 64 field, why not simply do two stores?
