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[GIT PULL 00/14] EFI changes for v4.6

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  [GIT PULL 00/14] EFI changes for v4.6 Matt Fleming <matt@codeblueprint.co.uk> - 2016-02-01 23:20 +0100
    [PATCH 02/14] efi: Remove redundant efi_set_variable_nonblocking prototype Matt Fleming <matt@codeblueprint.co.uk> - 2016-02-01 23:20 +0100
      [tip:efi/core] efi: Remove redundant efi_set_variable_nonblocking  () prototype tip-bot for Ard Biesheuvel <tipbot@zytor.com> - 2016-02-03 12:40 +0100
    [PATCH 05/14] efi: runtime-wrappers: Remove out of date comment regarding in_nmi() Matt Fleming <matt@codeblueprint.co.uk> - 2016-02-01 23:20 +0100
      [tip:efi/core] efi/runtime-wrappers:   Remove out of date comment regarding in_nmi() tip-bot for Ard Biesheuvel <tipbot@zytor.com> - 2016-02-03 12:40 +0100
    [PATCH 04/14] efi: Add nonblocking option to efi_query_variable_store() Matt Fleming <matt@codeblueprint.co.uk> - 2016-02-01 23:20 +0100
      [tip:efi/core] efi:   Add nonblocking option to efi_query_variable_store() tip-bot for Ard Biesheuvel <tipbot@zytor.com> - 2016-02-03 12:40 +0100

#1323569 — [GIT PULL 00/14] EFI changes for v4.6

Folks, please pull the following changes for v4.6. This mostly
consists of cleanups but the patches to execute EFI runtime services
with interrupts enabled would benefit from a thorough baking in
linux-next.

I'm sending this pull nice and early so that we can shake out any bugs
before the next merge window.

The following changes since commit 753b11ef8e92a1c1bbe97f2a5ec14bdd1ef2e6fe:

  x86/efi: Setup separate EFI page tables in kexec paths (2016-01-21 21:01:34 +0100)

are available in the git repository at:

  git://git.kernel.org/pub/scm/linux/kernel/git/mfleming/efi.git tags/efi-next

for you to fetch changes up to 921c2e93a5d7f14a803663389b9541f14744d048:

  x86/efi: Print size in binary units in efi_print_memmap (2016-02-01 20:52:49 +0000)

----------------------------------------------------------------
 * Run EFI runtime services with interrupts enabled for the benefit of
   uniprocessor machines with slow variable stores and because there's
   no good reason to disable them since we don't invoke runtime services
   from IRQ code paths - Ard Biesheuvel

 * Use the existing to_efivar_entry() accessor function in the efivars
   code instead of open-coding it - Geliang Tang

 * Align the ACPI BGRT driver more closely with how Windows interprets
   the 'status' field so we can use the BGRT image - Môshe van der Sterre

 * checkpatch.pl cleanup of the GUIDs in efi.h which has the added
   benefit of making them more closely resemble how they're presented
   in the UEFI specification - Peter Jones

 * Refactor the x86 EFI memory map printing code and add improved
   support for printing Persistent Memory entries - Robert Elliott,
   Andy Shevchenko

----------------------------------------------------------------
Ard Biesheuvel (7):
      efi: Expose non-blocking set_variable() wrapper to efivars
      efi: Remove redundant efi_set_variable_nonblocking prototype
      efi: runtime-wrappers: Add a nonblocking version of QueryVariableInfo
      efi: Add nonblocking option to efi_query_variable_store()
      efi: runtime-wrappers: Remove out of date comment regarding in_nmi()
      efi: runtime-wrapper: Get rid of the rtc_lock spinlock
      efi: runtime-wrappers: Run UEFI Runtime Services with interrupts enabled

Geliang Tang (1):
      efivars: Use to_efivar_entry

Môshe van der Sterre (1):
      x86/efi-bgrt: Don't ignore the BGRT if the 'valid' bit is 0

Peter Jones (1):
      efi: Make checkpatch complain less about efi.h GUID additions

Robert Elliott (4):
      x86/efi: Show actual ending addresses in efi_print_memmap
      efi: Add NV memory attribute
      efi: Add Persistent Memory type name
      x86/efi: Print size in binary units in efi_print_memmap

 arch/x86/platform/efi/efi-bgrt.c        |  10 +--
 arch/x86/platform/efi/efi.c             |  25 +++++--
 arch/x86/platform/efi/quirks.c          |  33 ++++++++-
 drivers/firmware/efi/efi.c              |   9 ++-
 drivers/firmware/efi/efivars.c          |   2 +-
 drivers/firmware/efi/runtime-wrappers.c | 115 ++++++++++++--------------------
 drivers/firmware/efi/vars.c             |  16 ++++-
 include/linux/efi.h                     |  85 ++++++++++++++---------
 8 files changed, 173 insertions(+), 122 deletions(-)

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#1323570 — [PATCH 02/14] efi: Remove redundant efi_set_variable_nonblocking prototype

From: Ard Biesheuvel <ard.biesheuvel@linaro.org>

There is no need for a separate nonblocking prototype definition
for the SetVariable() UEFI Runtime Service, since it is identical
to the blocking version.

Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Matt Fleming <matt@codeblueprint.co.uk>
---
 include/linux/efi.h | 8 ++------
 1 file changed, 2 insertions(+), 6 deletions(-)

diff --git a/include/linux/efi.h b/include/linux/efi.h
index 569b5a866bb1..8706e0aabedc 100644
--- a/include/linux/efi.h
+++ b/include/linux/efi.h
@@ -507,10 +507,6 @@ typedef efi_status_t efi_get_next_variable_t (unsigned long *name_size, efi_char
 typedef efi_status_t efi_set_variable_t (efi_char16_t *name, efi_guid_t *vendor, 
 					 u32 attr, unsigned long data_size,
 					 void *data);
-typedef efi_status_t
-efi_set_variable_nonblocking_t(efi_char16_t *name, efi_guid_t *vendor,
-			       u32 attr, unsigned long data_size, void *data);
-
 typedef efi_status_t efi_get_next_high_mono_count_t (u32 *count);
 typedef void efi_reset_system_t (int reset_type, efi_status_t status,
 				 unsigned long data_size, efi_char16_t *data);
@@ -851,7 +847,7 @@ extern struct efi {
 	efi_get_variable_t *get_variable;
 	efi_get_next_variable_t *get_next_variable;
 	efi_set_variable_t *set_variable;
-	efi_set_variable_nonblocking_t *set_variable_nonblocking;
+	efi_set_variable_t *set_variable_nonblocking;
 	efi_query_variable_info_t *query_variable_info;
 	efi_update_capsule_t *update_capsule;
 	efi_query_capsule_caps_t *query_capsule_caps;
@@ -1091,7 +1087,7 @@ struct efivar_operations {
 	efi_get_variable_t *get_variable;
 	efi_get_next_variable_t *get_next_variable;
 	efi_set_variable_t *set_variable;
-	efi_set_variable_nonblocking_t *set_variable_nonblocking;
+	efi_set_variable_t *set_variable_nonblocking;
 	efi_query_variable_store_t *query_variable_store;
 };
 
-- 
2.6.2

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#1325242 — [tip:efi/core] efi: Remove redundant efi_set_variable_nonblocking () prototype

Commit-ID:  70d2a3cf2f4ae2e93b7a661842d84c2b5132cee7
Gitweb:     http://git.kernel.org/tip/70d2a3cf2f4ae2e93b7a661842d84c2b5132cee7
Author:     Ard Biesheuvel <ard.biesheuvel@linaro.org>
AuthorDate: Mon, 1 Feb 2016 22:06:56 +0000
Committer:  Ingo Molnar <mingo@kernel.org>
CommitDate: Wed, 3 Feb 2016 11:31:02 +0100

efi: Remove redundant efi_set_variable_nonblocking() prototype

There is no need for a separate nonblocking prototype definition
for the SetVariable() UEFI Runtime Service, since it is
identical to the blocking version.

Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Matt Fleming <matt@codeblueprint.co.uk>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
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/1454364428-494-3-git-send-email-matt@codeblueprint.co.uk
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
 include/linux/efi.h | 8 ++------
 1 file changed, 2 insertions(+), 6 deletions(-)

diff --git a/include/linux/efi.h b/include/linux/efi.h
index 569b5a8..8706e0a 100644
--- a/include/linux/efi.h
+++ b/include/linux/efi.h
@@ -507,10 +507,6 @@ typedef efi_status_t efi_get_next_variable_t (unsigned long *name_size, efi_char
 typedef efi_status_t efi_set_variable_t (efi_char16_t *name, efi_guid_t *vendor, 
 					 u32 attr, unsigned long data_size,
 					 void *data);
-typedef efi_status_t
-efi_set_variable_nonblocking_t(efi_char16_t *name, efi_guid_t *vendor,
-			       u32 attr, unsigned long data_size, void *data);
-
 typedef efi_status_t efi_get_next_high_mono_count_t (u32 *count);
 typedef void efi_reset_system_t (int reset_type, efi_status_t status,
 				 unsigned long data_size, efi_char16_t *data);
@@ -851,7 +847,7 @@ extern struct efi {
 	efi_get_variable_t *get_variable;
 	efi_get_next_variable_t *get_next_variable;
 	efi_set_variable_t *set_variable;
-	efi_set_variable_nonblocking_t *set_variable_nonblocking;
+	efi_set_variable_t *set_variable_nonblocking;
 	efi_query_variable_info_t *query_variable_info;
 	efi_update_capsule_t *update_capsule;
 	efi_query_capsule_caps_t *query_capsule_caps;
@@ -1091,7 +1087,7 @@ struct efivar_operations {
 	efi_get_variable_t *get_variable;
 	efi_get_next_variable_t *get_next_variable;
 	efi_set_variable_t *set_variable;
-	efi_set_variable_nonblocking_t *set_variable_nonblocking;
+	efi_set_variable_t *set_variable_nonblocking;
 	efi_query_variable_store_t *query_variable_store;
 };
 

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#1323572 — [PATCH 05/14] efi: runtime-wrappers: Remove out of date comment regarding in_nmi()

From: Ard Biesheuvel <ard.biesheuvel@linaro.org>

This code is long gone, so remove the comment as well.

Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Matt Fleming <matt@codeblueprint.co.uk>
---
 drivers/firmware/efi/runtime-wrappers.c | 26 --------------------------
 1 file changed, 26 deletions(-)

diff --git a/drivers/firmware/efi/runtime-wrappers.c b/drivers/firmware/efi/runtime-wrappers.c
index e9f2867f0d91..311f415bff51 100644
--- a/drivers/firmware/efi/runtime-wrappers.c
+++ b/drivers/firmware/efi/runtime-wrappers.c
@@ -62,32 +62,6 @@
 static DEFINE_SPINLOCK(efi_runtime_lock);
 
 /*
- * Some runtime services calls can be reentrant under NMI, even if the table
- * above says they are not. (source: UEFI Specification v2.4A)
- *
- * Table 32. Functions that may be called after Machine Check, INIT and NMI
- * +----------------------------+------------------------------------------+
- * | Function			| Called after Machine Check, INIT and NMI |
- * +----------------------------+------------------------------------------+
- * | GetTime()			| Yes, even if previously busy.		   |
- * | GetVariable()		| Yes, even if previously busy		   |
- * | GetNextVariableName()	| Yes, even if previously busy		   |
- * | QueryVariableInfo()	| Yes, even if previously busy		   |
- * | SetVariable()		| Yes, even if previously busy		   |
- * | UpdateCapsule()		| Yes, even if previously busy		   |
- * | QueryCapsuleCapabilities()	| Yes, even if previously busy		   |
- * | ResetSystem()		| Yes, even if previously busy		   |
- * +----------------------------+------------------------------------------+
- *
- * In order to prevent deadlocks under NMI, the wrappers for these functions
- * may only grab the efi_runtime_lock or rtc_lock spinlocks if !efi_in_nmi().
- * However, not all of the services listed are reachable through NMI code paths,
- * so the the special handling as suggested by the UEFI spec is only implemented
- * for QueryVariableInfo() and SetVariable(), as these can be reached in NMI
- * context through efi_pstore_write().
- */
-
-/*
  * As per commit ef68c8f87ed1 ("x86: Serialize EFI time accesses on rtc_lock"),
  * the EFI specification requires that callers of the time related runtime
  * functions serialize with other CMOS accesses in the kernel, as the EFI time
-- 
2.6.2

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#1325241 — [tip:efi/core] efi/runtime-wrappers: Remove out of date comment regarding in_nmi()

Commit-ID:  774846defceb16dcab2f0215cfc467f7c93f1c26
Gitweb:     http://git.kernel.org/tip/774846defceb16dcab2f0215cfc467f7c93f1c26
Author:     Ard Biesheuvel <ard.biesheuvel@linaro.org>
AuthorDate: Mon, 1 Feb 2016 22:06:59 +0000
Committer:  Ingo Molnar <mingo@kernel.org>
CommitDate: Wed, 3 Feb 2016 11:31:04 +0100

efi/runtime-wrappers: Remove out of date comment regarding in_nmi()

This code is long gone, so remove the comment as well.

Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Matt Fleming <matt@codeblueprint.co.uk>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
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/1454364428-494-6-git-send-email-matt@codeblueprint.co.uk
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
 drivers/firmware/efi/runtime-wrappers.c | 26 --------------------------
 1 file changed, 26 deletions(-)

diff --git a/drivers/firmware/efi/runtime-wrappers.c b/drivers/firmware/efi/runtime-wrappers.c
index e9f2867..311f415 100644
--- a/drivers/firmware/efi/runtime-wrappers.c
+++ b/drivers/firmware/efi/runtime-wrappers.c
@@ -62,32 +62,6 @@
 static DEFINE_SPINLOCK(efi_runtime_lock);
 
 /*
- * Some runtime services calls can be reentrant under NMI, even if the table
- * above says they are not. (source: UEFI Specification v2.4A)
- *
- * Table 32. Functions that may be called after Machine Check, INIT and NMI
- * +----------------------------+------------------------------------------+
- * | Function			| Called after Machine Check, INIT and NMI |
- * +----------------------------+------------------------------------------+
- * | GetTime()			| Yes, even if previously busy.		   |
- * | GetVariable()		| Yes, even if previously busy		   |
- * | GetNextVariableName()	| Yes, even if previously busy		   |
- * | QueryVariableInfo()	| Yes, even if previously busy		   |
- * | SetVariable()		| Yes, even if previously busy		   |
- * | UpdateCapsule()		| Yes, even if previously busy		   |
- * | QueryCapsuleCapabilities()	| Yes, even if previously busy		   |
- * | ResetSystem()		| Yes, even if previously busy		   |
- * +----------------------------+------------------------------------------+
- *
- * In order to prevent deadlocks under NMI, the wrappers for these functions
- * may only grab the efi_runtime_lock or rtc_lock spinlocks if !efi_in_nmi().
- * However, not all of the services listed are reachable through NMI code paths,
- * so the the special handling as suggested by the UEFI spec is only implemented
- * for QueryVariableInfo() and SetVariable(), as these can be reached in NMI
- * context through efi_pstore_write().
- */
-
-/*
  * As per commit ef68c8f87ed1 ("x86: Serialize EFI time accesses on rtc_lock"),
  * the EFI specification requires that callers of the time related runtime
  * functions serialize with other CMOS accesses in the kernel, as the EFI time

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#1323573 — [PATCH 04/14] efi: Add nonblocking option to efi_query_variable_store()

From: Ard Biesheuvel <ard.biesheuvel@linaro.org>

The function efi_query_variable_store() may be invoked by
efivar_entry_set_nonblocking(), which itself takes care to only call
a non-blocking version of the SetVariable() runtime wrapper. However,
efi_query_variable_store() may call the SetVariable() wrapper directly,
as well as the wrapper for QueryVariableInfo(), both of which could
deadlock in the same way we are trying to prevent by calling
efivar_entry_set_nonblocking() in the first place.

So instead, modify efi_query_variable_store() to use the non-blocking
variants of QueryVariableInfo() (and give up rather than free up space
if the available space is below EFI_MIN_RESERVE) if invoked with the
'nonblocking' argument set to true.

Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Matt Fleming <matt@codeblueprint.co.uk>
---
 arch/x86/platform/efi/quirks.c | 33 ++++++++++++++++++++++++++++++++-
 drivers/firmware/efi/vars.c    | 16 ++++++++++++++--
 include/linux/efi.h            | 12 +++++++++---
 3 files changed, 55 insertions(+), 6 deletions(-)

diff --git a/arch/x86/platform/efi/quirks.c b/arch/x86/platform/efi/quirks.c
index 6452070f3025..dc4f7b51abf9 100644
--- a/arch/x86/platform/efi/quirks.c
+++ b/arch/x86/platform/efi/quirks.c
@@ -56,13 +56,41 @@ void efi_delete_dummy_variable(void)
 }
 
 /*
+ * In the nonblocking case we do not attempt to perform garbage
+ * collection if we do not have enough free space. Rather, we do the
+ * bare minimum check and give up immediately if the available space
+ * is below EFI_MIN_RESERVE.
+ *
+ * This function is intended to be small and simple because it is
+ * invoked from crash handler paths.
+ */
+static efi_status_t query_variable_store_nonblocking(u32 attributes,
+						     unsigned long size)
+{
+	efi_status_t status;
+	u64 storage_size, remaining_size, max_size;
+
+	status = efi.query_variable_info_nonblocking(attributes, &storage_size,
+						     &remaining_size,
+						     &max_size);
+	if (status != EFI_SUCCESS)
+		return status;
+
+	if (remaining_size - size < EFI_MIN_RESERVE)
+		return EFI_OUT_OF_RESOURCES;
+
+	return EFI_SUCCESS;
+}
+
+/*
  * Some firmware implementations refuse to boot if there's insufficient space
  * in the variable store. Ensure that we never use more than a safe limit.
  *
  * Return EFI_SUCCESS if it is safe to write 'size' bytes to the variable
  * store.
  */
-efi_status_t efi_query_variable_store(u32 attributes, unsigned long size)
+efi_status_t efi_query_variable_store(u32 attributes, unsigned long size,
+				      bool nonblocking)
 {
 	efi_status_t status;
 	u64 storage_size, remaining_size, max_size;
@@ -70,6 +98,9 @@ efi_status_t efi_query_variable_store(u32 attributes, unsigned long size)
 	if (!(attributes & EFI_VARIABLE_NON_VOLATILE))
 		return 0;
 
+	if (nonblocking)
+		return query_variable_store_nonblocking(attributes, size);
+
 	status = efi.query_variable_info(attributes, &storage_size,
 					 &remaining_size, &max_size);
 	if (status != EFI_SUCCESS)
diff --git a/drivers/firmware/efi/vars.c b/drivers/firmware/efi/vars.c
index 70a0fb10517f..d2a49626a335 100644
--- a/drivers/firmware/efi/vars.c
+++ b/drivers/firmware/efi/vars.c
@@ -234,7 +234,18 @@ check_var_size(u32 attributes, unsigned long size)
 	if (!fops->query_variable_store)
 		return EFI_UNSUPPORTED;
 
-	return fops->query_variable_store(attributes, size);
+	return fops->query_variable_store(attributes, size, false);
+}
+
+static efi_status_t
+check_var_size_nonblocking(u32 attributes, unsigned long size)
+{
+	const struct efivar_operations *fops = __efivars->ops;
+
+	if (!fops->query_variable_store)
+		return EFI_UNSUPPORTED;
+
+	return fops->query_variable_store(attributes, size, true);
 }
 
 static int efi_status_to_err(efi_status_t status)
@@ -615,7 +626,8 @@ efivar_entry_set_nonblocking(efi_char16_t *name, efi_guid_t vendor,
 	if (!spin_trylock_irqsave(&__efivars->lock, flags))
 		return -EBUSY;
 
-	status = check_var_size(attributes, size + ucs2_strsize(name, 1024));
+	status = check_var_size_nonblocking(attributes,
+					    size + ucs2_strsize(name, 1024));
 	if (status != EFI_SUCCESS) {
 		spin_unlock_irqrestore(&__efivars->lock, flags);
 		return -ENOSPC;
diff --git a/include/linux/efi.h b/include/linux/efi.h
index ad1e177ba48e..09f1559e7525 100644
--- a/include/linux/efi.h
+++ b/include/linux/efi.h
@@ -525,7 +525,9 @@ typedef efi_status_t efi_query_capsule_caps_t(efi_capsule_header_t **capsules,
 					      unsigned long count,
 					      u64 *max_size,
 					      int *reset_type);
-typedef efi_status_t efi_query_variable_store_t(u32 attributes, unsigned long size);
+typedef efi_status_t efi_query_variable_store_t(u32 attributes,
+						unsigned long size,
+						bool nonblocking);
 
 void efi_native_runtime_setup(void);
 
@@ -881,13 +883,17 @@ extern void efi_enter_virtual_mode (void);	/* switch EFI to virtual mode, if pos
 #ifdef CONFIG_X86
 extern void efi_late_init(void);
 extern void efi_free_boot_services(void);
-extern efi_status_t efi_query_variable_store(u32 attributes, unsigned long size);
+extern efi_status_t efi_query_variable_store(u32 attributes,
+					     unsigned long size,
+					     bool nonblocking);
 extern void efi_find_mirror(void);
 #else
 static inline void efi_late_init(void) {}
 static inline void efi_free_boot_services(void) {}
 
-static inline efi_status_t efi_query_variable_store(u32 attributes, unsigned long size)
+static inline efi_status_t efi_query_variable_store(u32 attributes,
+						    unsigned long size,
+						    bool nonblocking)
 {
 	return EFI_SUCCESS;
 }
-- 
2.6.2

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#1325271 — [tip:efi/core] efi: Add nonblocking option to efi_query_variable_store()

Commit-ID:  ca0e30dcaa53a3fcb2dfdf74252d30bc40603eea
Gitweb:     http://git.kernel.org/tip/ca0e30dcaa53a3fcb2dfdf74252d30bc40603eea
Author:     Ard Biesheuvel <ard.biesheuvel@linaro.org>
AuthorDate: Mon, 1 Feb 2016 22:06:58 +0000
Committer:  Ingo Molnar <mingo@kernel.org>
CommitDate: Wed, 3 Feb 2016 11:31:04 +0100

efi: Add nonblocking option to efi_query_variable_store()

The function efi_query_variable_store() may be invoked by
efivar_entry_set_nonblocking(), which itself takes care to only
call a non-blocking version of the SetVariable() runtime
wrapper. However, efi_query_variable_store() may call the
SetVariable() wrapper directly, as well as the wrapper for
QueryVariableInfo(), both of which could deadlock in the same
way we are trying to prevent by calling
efivar_entry_set_nonblocking() in the first place.

So instead, modify efi_query_variable_store() to use the
non-blocking variants of QueryVariableInfo() (and give up rather
than free up space if the available space is below
EFI_MIN_RESERVE) if invoked with the 'nonblocking' argument set
to true.

Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Matt Fleming <matt@codeblueprint.co.uk>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
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/1454364428-494-5-git-send-email-matt@codeblueprint.co.uk
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
 arch/x86/platform/efi/quirks.c | 33 ++++++++++++++++++++++++++++++++-
 drivers/firmware/efi/vars.c    | 16 ++++++++++++++--
 include/linux/efi.h            | 12 +++++++++---
 3 files changed, 55 insertions(+), 6 deletions(-)

diff --git a/arch/x86/platform/efi/quirks.c b/arch/x86/platform/efi/quirks.c
index 4535046..2326bf5 100644
--- a/arch/x86/platform/efi/quirks.c
+++ b/arch/x86/platform/efi/quirks.c
@@ -57,13 +57,41 @@ void efi_delete_dummy_variable(void)
 }
 
 /*
+ * In the nonblocking case we do not attempt to perform garbage
+ * collection if we do not have enough free space. Rather, we do the
+ * bare minimum check and give up immediately if the available space
+ * is below EFI_MIN_RESERVE.
+ *
+ * This function is intended to be small and simple because it is
+ * invoked from crash handler paths.
+ */
+static efi_status_t
+query_variable_store_nonblocking(u32 attributes, unsigned long size)
+{
+	efi_status_t status;
+	u64 storage_size, remaining_size, max_size;
+
+	status = efi.query_variable_info_nonblocking(attributes, &storage_size,
+						     &remaining_size,
+						     &max_size);
+	if (status != EFI_SUCCESS)
+		return status;
+
+	if (remaining_size - size < EFI_MIN_RESERVE)
+		return EFI_OUT_OF_RESOURCES;
+
+	return EFI_SUCCESS;
+}
+
+/*
  * Some firmware implementations refuse to boot if there's insufficient space
  * in the variable store. Ensure that we never use more than a safe limit.
  *
  * Return EFI_SUCCESS if it is safe to write 'size' bytes to the variable
  * store.
  */
-efi_status_t efi_query_variable_store(u32 attributes, unsigned long size)
+efi_status_t efi_query_variable_store(u32 attributes, unsigned long size,
+				      bool nonblocking)
 {
 	efi_status_t status;
 	u64 storage_size, remaining_size, max_size;
@@ -71,6 +99,9 @@ efi_status_t efi_query_variable_store(u32 attributes, unsigned long size)
 	if (!(attributes & EFI_VARIABLE_NON_VOLATILE))
 		return 0;
 
+	if (nonblocking)
+		return query_variable_store_nonblocking(attributes, size);
+
 	status = efi.query_variable_info(attributes, &storage_size,
 					 &remaining_size, &max_size);
 	if (status != EFI_SUCCESS)
diff --git a/drivers/firmware/efi/vars.c b/drivers/firmware/efi/vars.c
index 70a0fb1..d2a4962 100644
--- a/drivers/firmware/efi/vars.c
+++ b/drivers/firmware/efi/vars.c
@@ -234,7 +234,18 @@ check_var_size(u32 attributes, unsigned long size)
 	if (!fops->query_variable_store)
 		return EFI_UNSUPPORTED;
 
-	return fops->query_variable_store(attributes, size);
+	return fops->query_variable_store(attributes, size, false);
+}
+
+static efi_status_t
+check_var_size_nonblocking(u32 attributes, unsigned long size)
+{
+	const struct efivar_operations *fops = __efivars->ops;
+
+	if (!fops->query_variable_store)
+		return EFI_UNSUPPORTED;
+
+	return fops->query_variable_store(attributes, size, true);
 }
 
 static int efi_status_to_err(efi_status_t status)
@@ -615,7 +626,8 @@ efivar_entry_set_nonblocking(efi_char16_t *name, efi_guid_t vendor,
 	if (!spin_trylock_irqsave(&__efivars->lock, flags))
 		return -EBUSY;
 
-	status = check_var_size(attributes, size + ucs2_strsize(name, 1024));
+	status = check_var_size_nonblocking(attributes,
+					    size + ucs2_strsize(name, 1024));
 	if (status != EFI_SUCCESS) {
 		spin_unlock_irqrestore(&__efivars->lock, flags);
 		return -ENOSPC;
diff --git a/include/linux/efi.h b/include/linux/efi.h
index ad1e177..09f1559 100644
--- a/include/linux/efi.h
+++ b/include/linux/efi.h
@@ -525,7 +525,9 @@ typedef efi_status_t efi_query_capsule_caps_t(efi_capsule_header_t **capsules,
 					      unsigned long count,
 					      u64 *max_size,
 					      int *reset_type);
-typedef efi_status_t efi_query_variable_store_t(u32 attributes, unsigned long size);
+typedef efi_status_t efi_query_variable_store_t(u32 attributes,
+						unsigned long size,
+						bool nonblocking);
 
 void efi_native_runtime_setup(void);
 
@@ -881,13 +883,17 @@ extern void efi_enter_virtual_mode (void);	/* switch EFI to virtual mode, if pos
 #ifdef CONFIG_X86
 extern void efi_late_init(void);
 extern void efi_free_boot_services(void);
-extern efi_status_t efi_query_variable_store(u32 attributes, unsigned long size);
+extern efi_status_t efi_query_variable_store(u32 attributes,
+					     unsigned long size,
+					     bool nonblocking);
 extern void efi_find_mirror(void);
 #else
 static inline void efi_late_init(void) {}
 static inline void efi_free_boot_services(void) {}
 
-static inline efi_status_t efi_query_variable_store(u32 attributes, unsigned long size)
+static inline efi_status_t efi_query_variable_store(u32 attributes,
+						    unsigned long size,
+						    bool nonblocking)
 {
 	return EFI_SUCCESS;
 }

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