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Subject[tip:efi/urgent] efi/arm: Defer persistent reservations until after paging_init()
Commit-ID:  eff896288872d687d9662000ec9ae11b6d61766f
Gitweb: https://git.kernel.org/tip/eff896288872d687d9662000ec9ae11b6d61766f
Author: Ard Biesheuvel <ard.biesheuvel@linaro.org>
AuthorDate: Wed, 14 Nov 2018 09:55:43 -0800
Committer: Ingo Molnar <mingo@kernel.org>
CommitDate: Thu, 15 Nov 2018 10:04:46 +0100

efi/arm: Defer persistent reservations until after paging_init()

The new memory EFI reservation feature we introduced to allow memory
reservations to persist across kexec may trigger an unbounded number
of calls to memblock_reserve(). The memblock subsystem can deal with
this fine, but not before memblock resizing is enabled, which we can
only do after paging_init(), when the memory we reallocate the array
into is actually mapped.

So break out the memreserve table processing into a separate routine
and call it after paging_init() on arm64. On ARM, because of limited
reviewing bandwidth of the maintainer, we cannot currently fix this,
so instead, disable the EFI persistent memreserve entirely on ARM so
we can fix it later.

Tested-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-efi@vger.kernel.org
Link: http://lkml.kernel.org/r/20181114175544.12860-5-ard.biesheuvel@linaro.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
arch/arm64/kernel/setup.c | 1 +
drivers/firmware/efi/efi.c | 4 ++++
drivers/firmware/efi/libstub/arm-stub.c | 3 +++
include/linux/efi.h | 7 +++++++
4 files changed, 15 insertions(+)

diff --git a/arch/arm64/kernel/setup.c b/arch/arm64/kernel/setup.c
index 953e316521fc..f4fc1e0544b7 100644
--- a/arch/arm64/kernel/setup.c
+++ b/arch/arm64/kernel/setup.c
@@ -313,6 +313,7 @@ void __init setup_arch(char **cmdline_p)
arm64_memblock_init();

paging_init();
+ efi_apply_persistent_mem_reservations();

acpi_table_upgrade();

diff --git a/drivers/firmware/efi/efi.c b/drivers/firmware/efi/efi.c
index 249eb70691b0..72a4da76d274 100644
--- a/drivers/firmware/efi/efi.c
+++ b/drivers/firmware/efi/efi.c
@@ -592,7 +592,11 @@ int __init efi_config_parse_tables(void *config_tables, int count, int sz,

early_memunmap(tbl, sizeof(*tbl));
}
+ return 0;
+}

+int __init efi_apply_persistent_mem_reservations(void)
+{
if (efi.mem_reserve != EFI_INVALID_TABLE_ADDR) {
unsigned long prsv = efi.mem_reserve;

diff --git a/drivers/firmware/efi/libstub/arm-stub.c b/drivers/firmware/efi/libstub/arm-stub.c
index 30ac0c975f8a..3d36142cf812 100644
--- a/drivers/firmware/efi/libstub/arm-stub.c
+++ b/drivers/firmware/efi/libstub/arm-stub.c
@@ -75,6 +75,9 @@ void install_memreserve_table(efi_system_table_t *sys_table_arg)
efi_guid_t memreserve_table_guid = LINUX_EFI_MEMRESERVE_TABLE_GUID;
efi_status_t status;

+ if (IS_ENABLED(CONFIG_ARM))
+ return;
+
status = efi_call_early(allocate_pool, EFI_LOADER_DATA, sizeof(*rsv),
(void **)&rsv);
if (status != EFI_SUCCESS) {
diff --git a/include/linux/efi.h b/include/linux/efi.h
index 845174e113ce..100ce4a4aff6 100644
--- a/include/linux/efi.h
+++ b/include/linux/efi.h
@@ -1167,6 +1167,8 @@ static inline bool efi_enabled(int feature)
extern void efi_reboot(enum reboot_mode reboot_mode, const char *__unused);

extern bool efi_is_table_address(unsigned long phys_addr);
+
+extern int efi_apply_persistent_mem_reservations(void);
#else
static inline bool efi_enabled(int feature)
{
@@ -1185,6 +1187,11 @@ static inline bool efi_is_table_address(unsigned long phys_addr)
{
return false;
}
+
+static inline int efi_apply_persistent_mem_reservations(void)
+{
+ return 0;
+}
#endif

extern int efi_status_to_err(efi_status_t status);
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