x86/compressed/acpi: Move EFI system table lookup to helper

Future patches for SEV-SNP-validated CPUID will also require early
parsing of the EFI configuration. Incrementally move the related
code into a set of helpers that can be re-used for that purpose.

Signed-off-by: Michael Roth <michael.roth@amd.com>
Signed-off-by: Brijesh Singh <brijesh.singh@amd.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lore.kernel.org/r/20220307213356.2797205-26-brijesh.singh@amd.com

diff --git a/arch/x86/boot/compressed/acpi.c b/arch/x86/boot/compressed/acpi.c
index db6c561..58a3d3f 100644 (file)
--- a/arch/x86/boot/compressed/acpi.c
+++ b/arch/x86/boot/compressed/acpi.c
@@ -105,7 +105,7 @@ static acpi_physical_address kexec_get_rsdp_addr(void)
        }
 
        /* Get systab from boot params. */
-       systab = (efi_system_table_64_t *) (ei->efi_systab | ((__u64)ei->efi_systab_hi << 32));
+       systab = (efi_system_table_64_t *)efi_get_system_table(boot_params);
        if (!systab)
                error("EFI system table not found in kexec boot_params.");
 
@@ -118,9 +118,8 @@ static acpi_physical_address kexec_get_rsdp_addr(void) { return 0; }
 static acpi_physical_address efi_get_rsdp_addr(void)
 {
 #ifdef CONFIG_EFI
-       unsigned long systab, config_tables;
+       unsigned long systab_pa, config_tables;
        unsigned int nr_tables;
-       struct efi_info *ei;
        enum efi_type et;
        bool efi_64;
 
@@ -132,24 +131,18 @@ static acpi_physical_address efi_get_rsdp_addr(void)
        else
                return 0;
 
-       /* Get systab from boot params. */
-       ei = &boot_params->efi_info;
-#ifdef CONFIG_X86_64
-       systab = ei->efi_systab | ((__u64)ei->efi_systab_hi << 32);
-#else
-       systab = ei->efi_systab;
-#endif
-       if (!systab)
-               error("EFI system table not found.");
+       systab_pa = efi_get_system_table(boot_params);
+       if (!systab_pa)
+               error("EFI support advertised, but unable to locate system table.");
 
        /* Handle EFI bitness properly */
        if (efi_64) {
-               efi_system_table_64_t *stbl = (efi_system_table_64_t *)systab;
+               efi_system_table_64_t *stbl = (efi_system_table_64_t *)systab_pa;
 
                config_tables   = stbl->tables;
                nr_tables       = stbl->nr_tables;
        } else {
-               efi_system_table_32_t *stbl = (efi_system_table_32_t *)systab;
+               efi_system_table_32_t *stbl = (efi_system_table_32_t *)systab_pa;
 
                config_tables   = stbl->tables;
                nr_tables       = stbl->nr_tables;

diff --git a/arch/x86/boot/compressed/efi.c b/arch/x86/boot/compressed/efi.c
index bad0ce3..72a81ba 100644 (file)
--- a/arch/x86/boot/compressed/efi.c
+++ b/arch/x86/boot/compressed/efi.c
@@ -48,3 +48,32 @@ enum efi_type efi_get_type(struct boot_params *bp)
 
        return et;
 }
+
+/**
+ * efi_get_system_table - Given a pointer to boot_params, retrieve the physical address
+ *                        of the EFI system table.
+ *
+ * @bp:         pointer to boot_params
+ *
+ * Return: EFI system table address on success. On error, return 0.
+ */
+unsigned long efi_get_system_table(struct boot_params *bp)
+{
+       unsigned long sys_tbl_pa;
+       struct efi_info *ei;
+       enum efi_type et;
+
+       /* Get systab from boot params. */
+       ei = &bp->efi_info;
+#ifdef CONFIG_X86_64
+       sys_tbl_pa = ei->efi_systab | ((__u64)ei->efi_systab_hi << 32);
+#else
+       sys_tbl_pa = ei->efi_systab;
+#endif
+       if (!sys_tbl_pa) {
+               debug_putstr("EFI system table not found.");
+               return 0;
+       }
+
+       return sys_tbl_pa;
+}

diff --git a/arch/x86/boot/compressed/misc.h b/arch/x86/boot/compressed/misc.h
index fede1af..b2acd3a 100644 (file)
--- a/arch/x86/boot/compressed/misc.h
+++ b/arch/x86/boot/compressed/misc.h
@@ -185,11 +185,17 @@ enum efi_type {
 #ifdef CONFIG_EFI
 /* helpers for early EFI config table access */
 enum efi_type efi_get_type(struct boot_params *bp);
+unsigned long efi_get_system_table(struct boot_params *bp);
 #else
 static inline enum efi_type efi_get_type(struct boot_params *bp)
 {
        return EFI_TYPE_NONE;
 }
+
+static inline unsigned long efi_get_system_table(struct boot_params *bp)
+{
+       return 0;
+}
 #endif /* CONFIG_EFI */
 
 #endif /* BOOT_COMPRESSED_MISC_H */