[PATCH 2/3] efi: Retain the address of the LINUX_EFI_MEMRESERVE table

[Ard Biesheuvel <ardb+git@google.com>]

From: Ard Biesheuvel <ardb@kernel.org>

The physical address of the LINUX_EFI_MEMRESERVE configuration table is
only kept in __initdata, but a kexec loader that runs the incoming
kernel's EFI stub needs it in order to pass the table on, so that the
persistent memory reservations made by this kernel and its predecessors
(e.g., for the GICv3 LPI tables) are carried over.

So move it into struct efi, alongside the addresses of the other EFI
configuration tables that may be passed on in this way.

Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
---
 drivers/firmware/efi/efi.c | 12 ++++++------
 include/linux/efi.h        |  1 +
 2 files changed, 7 insertions(+), 6 deletions(-)

diff --git a/drivers/firmware/efi/efi.c b/drivers/firmware/efi/efi.c
index b4504542cb2c..14b9c7ebb5df 100644
--- a/drivers/firmware/efi/efi.c
+++ b/drivers/firmware/efi/efi.c
@@ -46,6 +46,7 @@ struct efi __read_mostly efi = {
 	.tpm_log		= EFI_INVALID_TABLE_ADDR,
 	.tpm_final_log		= EFI_INVALID_TABLE_ADDR,
 	.ovmf_debug_log         = EFI_INVALID_TABLE_ADDR,
+	.mem_reserve		= EFI_INVALID_TABLE_ADDR,
 #ifdef CONFIG_LOAD_UEFI_KEYS
 	.mokvar_table		= EFI_INVALID_TABLE_ADDR,
 #endif
@@ -59,7 +60,6 @@ struct efi __read_mostly efi = {
 EXPORT_SYMBOL(efi);
 
 unsigned long __ro_after_init efi_rng_seed = EFI_INVALID_TABLE_ADDR;
-static unsigned long __initdata mem_reserve = EFI_INVALID_TABLE_ADDR;
 static unsigned long __initdata rt_prop = EFI_INVALID_TABLE_ADDR;
 static unsigned long __initdata initrd = EFI_INVALID_TABLE_ADDR;
 
@@ -663,7 +663,7 @@ static const efi_config_table_type_t common_tables[] __initconst = {
 	{LINUX_EFI_TPM_EVENT_LOG_GUID,		&efi.tpm_log,		"TPMEventLog"	},
 	{EFI_TCG2_FINAL_EVENTS_TABLE_GUID,	&efi.tpm_final_log,	"TPMFinalLog"	},
 	{EFI_CC_FINAL_EVENTS_TABLE_GUID,	&efi.tpm_final_log,	"CCFinalLog"	},
-	{LINUX_EFI_MEMRESERVE_TABLE_GUID,	&mem_reserve,		"MEMRESERVE"	},
+	{LINUX_EFI_MEMRESERVE_TABLE_GUID,	&efi.mem_reserve,	"MEMRESERVE"	},
 	{LINUX_EFI_INITRD_MEDIA_GUID,		&initrd,		"INITRD"	},
 	{EFI_RT_PROPERTIES_TABLE_GUID,		&rt_prop,		"RTPROP"	},
 #ifdef CONFIG_OVMF_DEBUG_LOG
@@ -806,8 +806,8 @@ int __init efi_config_parse_tables(const efi_config_table_t *config_tables,
 
 	efi_tpm_eventlog_init();
 
-	if (mem_reserve != EFI_INVALID_TABLE_ADDR) {
-		unsigned long prsv = mem_reserve;
+	if (efi.mem_reserve != EFI_INVALID_TABLE_ADDR) {
+		unsigned long prsv = efi.mem_reserve;
 
 		while (prsv) {
 			struct linux_efi_memreserve *rsv;
@@ -1094,10 +1094,10 @@ static struct linux_efi_memreserve *efi_memreserve_root __ro_after_init;
 
 static int __init efi_memreserve_map_root(void)
 {
-	if (mem_reserve == EFI_INVALID_TABLE_ADDR)
+	if (efi.mem_reserve == EFI_INVALID_TABLE_ADDR)
 		return -ENODEV;
 
-	efi_memreserve_root = memremap(mem_reserve,
+	efi_memreserve_root = memremap(efi.mem_reserve,
 				       sizeof(*efi_memreserve_root),
 				       MEMREMAP_WB);
 	if (WARN_ON_ONCE(!efi_memreserve_root))
diff --git a/include/linux/efi.h b/include/linux/efi.h
index fda81d7c4850..cd8728702e93 100644
--- a/include/linux/efi.h
+++ b/include/linux/efi.h
@@ -650,6 +650,7 @@ extern struct efi {
 	unsigned long			mokvar_table;		/* MOK variable config table */
 	unsigned long			coco_secret;		/* Confidential computing secret table */
 	unsigned long			unaccepted;		/* Unaccepted memory table */
+	unsigned long			mem_reserve;		/* Persistent memory reservations */
 
 	efi_get_time_t			*get_time;
 	efi_set_time_t			*set_time;
-- 
2.56.0.385.gd3acb90ef8-goog