[PATCH 0/3] EFI reboot/poweroff support

[PATCH 0/3] EFI reboot/poweroff support

[Matt Fleming]

From: Matt Fleming <matt.fleming@intel.com>

Both x86 and ARM need a way to reboot/poweroff machines using the EFI
runtime services.

For x86, we want to really, really restrict this support to those
platforms that absolultely have no other method because EfiResetSystem()
doesn't generally work very well in the wild. The ARM folks probably
need to be less picky.

This series is against the EFI 'next' branch.

Matt Fleming (3):
  efi/reboot: Add generic wrapper around EfiResetSystem()
  efi/reboot: Allow powering off machines using EFI
  x86/reboot: Add EFI reboot quirk for ACPI Hardware Reduced flag

 arch/ia64/kernel/process.c     |  2 +-
 arch/x86/include/asm/efi.h     |  6 +++++
 arch/x86/kernel/reboot.c       | 24 ++++++++++++------
 arch/x86/platform/efi/quirks.c | 23 ++++++++++++++++++
 drivers/firmware/efi/Makefile  |  2 +-
 drivers/firmware/efi/reboot.c  | 55 ++++++++++++++++++++++++++++++++++++++++++
 include/linux/efi.h            |  7 ++++++
 7 files changed, 110 insertions(+), 9 deletions(-)
 create mode 100644 drivers/firmware/efi/reboot.c

-- 
1.9.0

[PATCH 1/3] efi/reboot: Add generic wrapper around EfiResetSystem()

[Matt Fleming]

From: Matt Fleming <matt.fleming@intel.com>

Implement efi_reboot(), which is really just a wrapper around the
EfiResetSystem() EFI runtime service, but it does at least allow us to
funnel all callers through a single location.

It also simplifies the callsites since users no longer need to check to
see whether EFI_RUNTIME_SERVICES are enabled.

Cc: Tony Luck <tony.luck@intel.com>
Cc: Mark Salter <msalter@redhat.com>
Signed-off-by: Matt Fleming <matt.fleming@intel.com>
---

Mark, I reworked my efi_reboot() to more closely match your versino.
Since we essentially wrote the same code I'd be happy to include your
chosen Copyright notice, I just didn't want to be presumptuous and do it
on your behalf without asking.

 arch/ia64/kernel/process.c    |  2 +-
 arch/x86/kernel/reboot.c      |  6 +-----
 drivers/firmware/efi/Makefile |  2 +-
 drivers/firmware/efi/reboot.c | 25 +++++++++++++++++++++++++
 include/linux/efi.h           |  4 ++++
 5 files changed, 32 insertions(+), 7 deletions(-)
 create mode 100644 drivers/firmware/efi/reboot.c

diff --git a/arch/ia64/kernel/process.c b/arch/ia64/kernel/process.c
index 55d4ba47a907..deed6fa96bb0 100644
--- a/arch/ia64/kernel/process.c
+++ b/arch/ia64/kernel/process.c
@@ -662,7 +662,7 @@ void
 machine_restart (char *restart_cmd)
 {
 	(void) notify_die(DIE_MACHINE_RESTART, restart_cmd, NULL, 0, 0, 0);
-	(*efi.reset_system)(EFI_RESET_WARM, 0, 0, NULL);
+	efi_reboot(REBOOT_WARM, NULL);
 }
 
 void
diff --git a/arch/x86/kernel/reboot.c b/arch/x86/kernel/reboot.c
index 52b1157c53eb..09e709fd1830 100644
--- a/arch/x86/kernel/reboot.c
+++ b/arch/x86/kernel/reboot.c
@@ -528,11 +528,7 @@ static void native_machine_emergency_restart(void)
 			break;
 
 		case BOOT_EFI:
-			if (efi_enabled(EFI_RUNTIME_SERVICES))
-				efi.reset_system(reboot_mode == REBOOT_WARM ?
-						 EFI_RESET_WARM :
-						 EFI_RESET_COLD,
-						 EFI_SUCCESS, 0, NULL);
+			efi_reboot(reboot_mode, NULL);
 			reboot_type = BOOT_BIOS;
 			break;
 
diff --git a/drivers/firmware/efi/Makefile b/drivers/firmware/efi/Makefile
index 9553496b0f43..c135154ead89 100644
--- a/drivers/firmware/efi/Makefile
+++ b/drivers/firmware/efi/Makefile
@@ -1,7 +1,7 @@
 #
 # Makefile for linux kernel
 #
-obj-$(CONFIG_EFI)			+= efi.o vars.o
+obj-$(CONFIG_EFI)			+= efi.o vars.o reboot.o
 obj-$(CONFIG_EFI_VARS)			+= efivars.o
 obj-$(CONFIG_EFI_VARS_PSTORE)		+= efi-pstore.o
 obj-$(CONFIG_UEFI_CPER)			+= cper.o
diff --git a/drivers/firmware/efi/reboot.c b/drivers/firmware/efi/reboot.c
new file mode 100644
index 000000000000..d10acc0a0370
--- /dev/null
+++ b/drivers/firmware/efi/reboot.c
@@ -0,0 +1,25 @@
+/*
+ * Copyright (C) 2014 Intel Corporation; author Matt Fleming
+ */
+#include <linux/efi.h>
+#include <linux/reboot.h>
+
+void efi_reboot(enum reboot_mode reboot_mode, const char *__unused)
+{
+	int efi_mode;
+
+	if (!efi_enabled(EFI_RUNTIME_SERVICES))
+		return;
+
+	switch (reboot_mode) {
+	case REBOOT_WARM:
+	case REBOOT_SOFT:
+		efi_mode = EFI_RESET_WARM;
+		break;
+	default:
+		efi_mode = EFI_RESET_COLD;
+		break;
+	}
+
+	efi.reset_system(efi_mode, EFI_SUCCESS, 0, NULL);
+}
diff --git a/include/linux/efi.h b/include/linux/efi.h
index 41bbf8ba4ba8..0958d4bb399f 100644
--- a/include/linux/efi.h
+++ b/include/linux/efi.h
@@ -20,6 +20,7 @@
 #include <linux/ioport.h>
 #include <linux/pfn.h>
 #include <linux/pstore.h>
+#include <linux/reboot.h>
 
 #include <asm/page.h>
 
@@ -926,11 +927,14 @@ static inline bool efi_enabled(int feature)
 {
 	return test_bit(feature, &efi.flags) != 0;
 }
+extern void efi_reboot(enum reboot_mode reboot_mode, const char *__unused);
 #else
 static inline bool efi_enabled(int feature)
 {
 	return false;
 }
+static inline void
+efi_reboot(enum reboot_mode reboot_mode, const char *__unused) {}
 #endif
 
 /*
-- 
1.9.0

[PATCH 2/3] efi/reboot: Allow powering off machines using EFI

[Matt Fleming]

From: Matt Fleming <matt.fleming@intel.com>

Not only can EfiResetSystem() be used to reboot, it can also be used to
power down machines.

By and large, this functionality doesn't work very well across the range
of EFI machines in the wild, so it should definitely only be used as a
last resort. In an ideal world, this wouldn't be needed at all.

Unfortunately, we're starting to see machines where EFI is the *only*
reliable way to power down, and nothing else, not PCI, not ACPI, works.

efi_poweroff_required() should be implemented on a per-architecture
basis, since exactly when we should be using EFI runtime services is a
platform-specific decision. There's no analogue for reboot because each
architecture handles reboot very differently - the x86 code in
particular is pretty complex.

Patches to enable this for specific classes of hardware will be
submitted separately.

Cc: Mark Salter <msalter@redhat.com>
Signed-off-by: Matt Fleming <matt.fleming@intel.com>
---
 drivers/firmware/efi/reboot.c | 22 ++++++++++++++++++++++
 include/linux/efi.h           |  2 ++
 2 files changed, 24 insertions(+)

diff --git a/drivers/firmware/efi/reboot.c b/drivers/firmware/efi/reboot.c
index d10acc0a0370..794a276dbe92 100644
--- a/drivers/firmware/efi/reboot.c
+++ b/drivers/firmware/efi/reboot.c
@@ -23,3 +23,25 @@ void efi_reboot(enum reboot_mode reboot_mode, const char *__unused)
 
 	efi.reset_system(efi_mode, EFI_SUCCESS, 0, NULL);
 }
+
+bool __weak efi_poweroff_required(void)
+{
+	return false;
+}
+
+static void efi_power_off(void)
+{
+	efi.reset_system(EFI_RESET_SHUTDOWN, EFI_SUCCESS, 0, NULL);
+}
+
+static int __init efi_shutdown_init(void)
+{
+	if (!efi_enabled(EFI_RUNTIME_SERVICES))
+		return -ENODEV;
+
+	if (efi_poweroff_required())
+		pm_power_off = efi_power_off;
+
+	return 0;
+}
+late_initcall(efi_shutdown_init);
diff --git a/include/linux/efi.h b/include/linux/efi.h
index 0958d4bb399f..2539aff31808 100644
--- a/include/linux/efi.h
+++ b/include/linux/efi.h
@@ -876,6 +876,8 @@ extern void efi_reserve_boot_services(void);
 extern int efi_get_fdt_params(struct efi_fdt_params *params, int verbose);
 extern struct efi_memory_map memmap;
 
+extern bool efi_poweroff_required(void);
+
 /* Iterate through an efi_memory_map */
 #define for_each_efi_memory_desc(m, md)					   \
 	for ((md) = (m)->map;						   \
-- 
1.9.0

[PATCH 3/3] x86/reboot: Add EFI reboot quirk for ACPI Hardware Reduced flag

[Matt Fleming]

From: Matt Fleming <matt.fleming@intel.com>

It appears that the BayTrail-T class of hardware requires EFI in order
to powerdown and reboot and no other reliable method exists.

This quirk is generally applicable to all hardware that has the ACPI
Hardware Reduced bit set, since usually ACPI would be the preferred
method.

Cc: Len Brown <len.brown@intel.com>
Cc: Mark Salter <msalter@redhat.com>
Cc: "Rafael J. Wysocki" <rafael.j.wysocki@intel.com>
Signed-off-by: Matt Fleming <matt.fleming@intel.com>
---
 arch/x86/include/asm/efi.h     |  6 ++++++
 arch/x86/kernel/reboot.c       | 18 ++++++++++++++++--
 arch/x86/platform/efi/quirks.c | 23 +++++++++++++++++++++++
 drivers/firmware/efi/reboot.c  |  8 ++++++++
 include/linux/efi.h            |  1 +
 5 files changed, 54 insertions(+), 2 deletions(-)

diff --git a/arch/x86/include/asm/efi.h b/arch/x86/include/asm/efi.h
index 3dbf56eb540d..5d71d0eb50b3 100644
--- a/arch/x86/include/asm/efi.h
+++ b/arch/x86/include/asm/efi.h
@@ -158,6 +158,8 @@ static inline efi_status_t efi_thunk_set_virtual_address_map(
 	return EFI_SUCCESS;
 }
 #endif /* CONFIG_EFI_MIXED */
+
+extern bool efi_reboot_required(void);
 #else
 /*
  * IF EFI is not configured, have the EFI calls return -ENOSYS.
@@ -170,6 +172,10 @@ static inline efi_status_t efi_thunk_set_virtual_address_map(
 #define efi_call5(_f, _a1, _a2, _a3, _a4, _a5)		(-ENOSYS)
 #define efi_call6(_f, _a1, _a2, _a3, _a4, _a5, _a6)	(-ENOSYS)
 static inline void parse_efi_setup(u64 phys_addr, u32 data_len) {}
+static inline bool efi_reboot_required(void)
+{
+	return false;
+}
 #endif /* CONFIG_EFI */
 
 #endif /* _ASM_X86_EFI_H */
diff --git a/arch/x86/kernel/reboot.c b/arch/x86/kernel/reboot.c
index 09e709fd1830..17962e667a91 100644
--- a/arch/x86/kernel/reboot.c
+++ b/arch/x86/kernel/reboot.c
@@ -28,6 +28,7 @@
 #include <linux/mc146818rtc.h>
 #include <asm/realmode.h>
 #include <asm/x86_init.h>
+#include <asm/efi.h>
 
 /*
  * Power off function, if any
@@ -401,12 +402,25 @@ static struct dmi_system_id __initdata reboot_dmi_table[] = {
 
 static int __init reboot_init(void)
 {
+	int rv;
+
 	/*
 	 * Only do the DMI check if reboot_type hasn't been overridden
 	 * on the command line
 	 */
-	if (reboot_default)
-		dmi_check_system(reboot_dmi_table);
+	if (!reboot_default)
+		return 0;
+
+	/*
+	 * The DMI quirks table takes precedence. If no quirks entry
+	 * matches and the ACPI Hardware Reduced bit is set, force EFI
+	 * reboot.
+	 */
+	rv = dmi_check_system(reboot_dmi_table);
+
+	if (!rv && efi_reboot_required())
+		reboot_type = BOOT_EFI;
+
 	return 0;
 }
 core_initcall(reboot_init);
diff --git a/arch/x86/platform/efi/quirks.c b/arch/x86/platform/efi/quirks.c
index b4cb9182f155..1c7380da65ff 100644
--- a/arch/x86/platform/efi/quirks.c
+++ b/arch/x86/platform/efi/quirks.c
@@ -7,6 +7,7 @@
 #include <linux/slab.h>
 #include <linux/memblock.h>
 #include <linux/bootmem.h>
+#include <linux/acpi.h>
 #include <asm/efi.h>
 #include <asm/uv/uv.h>
 
@@ -265,3 +266,25 @@ void __init efi_apply_memmap_quirks(void)
 	if (is_uv_system())
 		set_bit(EFI_OLD_MEMMAP, &efi.flags);
 }
+
+/*
+ * For most modern platforms the preferred method of powering off is via
+ * ACPI. However, there are some that are known to require the use of
+ * EFI runtime services and for which ACPI does not work at all.
+ *
+ * Using EFI is a last resort, to be used only if no other option
+ * exists.
+ */
+bool efi_reboot_required(void)
+{
+	if (!acpi_gbl_reduced_hardware)
+		return false;
+
+	efi_reboot_quirk_mode = EFI_RESET_WARM;
+	return true;
+}
+
+bool efi_poweroff_required(void)
+{
+	return !!acpi_gbl_reduced_hardware;
+}
diff --git a/drivers/firmware/efi/reboot.c b/drivers/firmware/efi/reboot.c
index 794a276dbe92..f94fb95db3b7 100644
--- a/drivers/firmware/efi/reboot.c
+++ b/drivers/firmware/efi/reboot.c
@@ -4,6 +4,8 @@
 #include <linux/efi.h>
 #include <linux/reboot.h>
 
+int efi_reboot_quirk_mode = -1;
+
 void efi_reboot(enum reboot_mode reboot_mode, const char *__unused)
 {
 	int efi_mode;
@@ -21,6 +23,12 @@ void efi_reboot(enum reboot_mode reboot_mode, const char *__unused)
 		break;
 	}
 
+	/*
+	 * If a quirk forced an EFI reset mode, always use that.
+	 */
+	if (efi_reboot_quirk_mode != -1)
+		efi_mode = efi_reboot_quirk_mode;
+
 	efi.reset_system(efi_mode, EFI_SUCCESS, 0, NULL);
 }
 
diff --git a/include/linux/efi.h b/include/linux/efi.h
index 2539aff31808..b3fac7c1656c 100644
--- a/include/linux/efi.h
+++ b/include/linux/efi.h
@@ -876,6 +876,7 @@ extern void efi_reserve_boot_services(void);
 extern int efi_get_fdt_params(struct efi_fdt_params *params, int verbose);
 extern struct efi_memory_map memmap;
 
+extern int efi_reboot_quirk_mode;
 extern bool efi_poweroff_required(void);
 
 /* Iterate through an efi_memory_map */
-- 
1.9.0

Re: [PATCH 1/3] efi/reboot: Add generic wrapper around EfiResetSystem()

[Mark Salter]

On Thu, 2014-06-19 at 14:40 +0100, Matt Fleming wrote:
> From: Matt Fleming <matt.fleming@intel.com>
> 
> Implement efi_reboot(), which is really just a wrapper around the
> EfiResetSystem() EFI runtime service, but it does at least allow us to
> funnel all callers through a single location.
> 
> It also simplifies the callsites since users no longer need to check to
> see whether EFI_RUNTIME_SERVICES are enabled.
> 
> Cc: Tony Luck <tony.luck@intel.com>
> Cc: Mark Salter <msalter@redhat.com>
> Signed-off-by: Matt Fleming <matt.fleming@intel.com>
> ---

Tested-by: Mark Salter <msalter@redhat.com>

> 
> Mark, I reworked my efi_reboot() to more closely match your versino.
> Since we essentially wrote the same code I'd be happy to include your
> chosen Copyright notice, I just didn't want to be presumptuous and do it
> on your behalf without asking.
> 

Copyright (c) 2014 Red Hat, Inc., Mark Salter <msalter@redhat.com>

Thanks.

Re: [PATCH 2/3] efi/reboot: Allow powering off machines using EFI

[Mark Salter]

On Thu, 2014-06-19 at 14:40 +0100, Matt Fleming wrote:
> From: Matt Fleming <matt.fleming@intel.com>
> 
> Not only can EfiResetSystem() be used to reboot, it can also be used to
> power down machines.
> 
> By and large, this functionality doesn't work very well across the range
> of EFI machines in the wild, so it should definitely only be used as a
> last resort. In an ideal world, this wouldn't be needed at all.
> 
> Unfortunately, we're starting to see machines where EFI is the *only*
> reliable way to power down, and nothing else, not PCI, not ACPI, works.
> 
> efi_poweroff_required() should be implemented on a per-architecture
> basis, since exactly when we should be using EFI runtime services is a
> platform-specific decision. There's no analogue for reboot because each
> architecture handles reboot very differently - the x86 code in
> particular is pretty complex.
> 
> Patches to enable this for specific classes of hardware will be
> submitted separately.
> 
> Cc: Mark Salter <msalter@redhat.com>
> Signed-off-by: Matt Fleming <matt.fleming@intel.com>
> ---

Tested-by: Mark Salter <msalter@redhat.com>