From: Michael Roth <michael.roth@amd.com>
Date: Thu, 24 Feb 2022 10:56:06 -0600
Subject: x86/compressed/acpi: Move EFI config table lookup to helper
Git-commit: 61c14ceda8405f37545a0983d6b9bc45c6236793
Patch-mainline: v5.19-rc1
References: jsc#SLE-19924, jsc#SLE-24814

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.

  [ bp: Remove superfluous zeroing of a stack variable. ]

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/20220307213356.2797205-27-brijesh.singh@amd.com

Acked-by: Joerg Roedel <jroedel@suse.de>
---
 arch/x86/boot/compressed/acpi.c |   25 +++++++----------------
 arch/x86/boot/compressed/efi.c  |   43 ++++++++++++++++++++++++++++++++++++++++
 arch/x86/boot/compressed/misc.h |    9 ++++++++
 3 files changed, 60 insertions(+), 17 deletions(-)

--- a/arch/x86/boot/compressed/acpi.c
+++ b/arch/x86/boot/compressed/acpi.c
@@ -118,10 +118,13 @@ static acpi_physical_address kexec_get_r
 static acpi_physical_address efi_get_rsdp_addr(void)
 {
 #ifdef CONFIG_EFI
-	unsigned long systab_pa, config_tables;
+	unsigned long cfg_tbl_pa = 0;
+	unsigned int cfg_tbl_len;
+	unsigned long systab_pa;
 	unsigned int nr_tables;
 	enum efi_type et;
 	bool efi_64;
+	int ret;
 
 	et = efi_get_type(boot_params);
 	if (et == EFI_TYPE_64)
@@ -135,23 +138,11 @@ static acpi_physical_address efi_get_rsd
 	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_pa;
+	ret = efi_get_conf_table(boot_params, &cfg_tbl_pa, &cfg_tbl_len);
+	if (ret || !cfg_tbl_pa)
+		error("EFI config table not found.");
 
-		config_tables	= stbl->tables;
-		nr_tables	= stbl->nr_tables;
-	} else {
-		efi_system_table_32_t *stbl = (efi_system_table_32_t *)systab_pa;
-
-		config_tables	= stbl->tables;
-		nr_tables	= stbl->nr_tables;
-	}
-
-	if (!config_tables)
-		error("EFI config tables not found.");
-
-	return __efi_get_rsdp_addr(config_tables, nr_tables, efi_64);
+	return __efi_get_rsdp_addr(cfg_tbl_pa, cfg_tbl_len, efi_64);
 #else
 	return 0;
 #endif
--- a/arch/x86/boot/compressed/efi.c
+++ b/arch/x86/boot/compressed/efi.c
@@ -77,3 +77,46 @@ unsigned long efi_get_system_table(struc
 
 	return sys_tbl_pa;
 }
+
+/**
+ * efi_get_conf_table - Given a pointer to boot_params, locate and return the physical
+ *                      address of EFI configuration table.
+ *
+ * @bp:                 pointer to boot_params
+ * @cfg_tbl_pa:         location to store physical address of config table
+ * @cfg_tbl_len:        location to store number of config table entries
+ *
+ * Return: 0 on success. On error, return params are left unchanged.
+ */
+int efi_get_conf_table(struct boot_params *bp, unsigned long *cfg_tbl_pa,
+		       unsigned int *cfg_tbl_len)
+{
+	unsigned long sys_tbl_pa;
+	enum efi_type et;
+	int ret;
+
+	if (!cfg_tbl_pa || !cfg_tbl_len)
+		return -EINVAL;
+
+	sys_tbl_pa = efi_get_system_table(bp);
+	if (!sys_tbl_pa)
+		return -EINVAL;
+
+	/* Handle EFI bitness properly */
+	et = efi_get_type(bp);
+	if (et == EFI_TYPE_64) {
+		efi_system_table_64_t *stbl = (efi_system_table_64_t *)sys_tbl_pa;
+
+		*cfg_tbl_pa = stbl->tables;
+		*cfg_tbl_len = stbl->nr_tables;
+	} else if (et == EFI_TYPE_32) {
+		efi_system_table_32_t *stbl = (efi_system_table_32_t *)sys_tbl_pa;
+
+		*cfg_tbl_pa = stbl->tables;
+		*cfg_tbl_len = stbl->nr_tables;
+	} else {
+		return -EINVAL;
+	}
+
+	return 0;
+}
--- a/arch/x86/boot/compressed/misc.h
+++ b/arch/x86/boot/compressed/misc.h
@@ -182,6 +182,8 @@ enum efi_type {
 /* 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);
+int efi_get_conf_table(struct boot_params *bp, unsigned long *cfg_tbl_pa,
+		       unsigned int *cfg_tbl_len);
 #else
 static inline enum efi_type efi_get_type(struct boot_params *bp)
 {
@@ -192,6 +194,13 @@ static inline unsigned long efi_get_syst
 {
 	return 0;
 }
+
+static inline int efi_get_conf_table(struct boot_params *bp,
+				     unsigned long *cfg_tbl_pa,
+				     unsigned int *cfg_tbl_len)
+{
+	return -ENOENT;
+}
 #endif /* CONFIG_EFI */
 
 #endif /* BOOT_COMPRESSED_MISC_H */