[PATCH 2/2] efi: Capsule update support

Matt Fleming
2014-10-07T14:42:31Z

From: Matt Fleming <matt.fleming-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>

The EFI capsule mechanism allows data blobs to be passed to the EFI
firmware. This patch just introduces the main infrastruture for
interacting with the firmware.

Once a capsule has been passed to the firmware, the next reboot will
always be performed using the ResetSystem() EFI runtime service, which
may involve overriding the reboot type specified by reboot=. This
ensures the reset value returned by QueryCapsuleCapabilities() is used
to reset the system, which is required for the capsule to be processed.

Cc: Leif Lindholm <leif.lindholm-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org>
Cc: "Kweh, Hock Leong" <hock.leong.kweh-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>
Signed-off-by: Matt Fleming <matt.fleming-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>
---
arch/x86/kernel/reboot.c | 7 ++
drivers/firmware/efi/Makefile | 2 +-
drivers/firmware/efi/capsule.c | 239 +++++++++++++++++++++++++++++++++++++++++
drivers/firmware/efi/reboot.c | 12 ++-
include/linux/efi.h | 20 ++++
5 files changed, 278 insertions(+), 2 deletions(-)
create mode 100644 drivers/firmware/efi/capsule.c

diff --git a/arch/x86/kernel/reboot.c b/arch/x86/kernel/reboot.c
index 17962e667a91..59fe1c03c71a 100644
--- a/arch/x86/kernel/reboot.c
+++ b/arch/x86/kernel/reboot.c
@@ -516,6 +516,13 @@ static void native_machine_emergency_restart(void)
mode = reboot_mode == REBOOT_WARM ? 0x1234 : 0;
*((unsigned short *)__va(0x472)) = mode;

+ /*
+ * If an EFI capsule has been registered with the firmware then
+ * override the reboot= parameter.
+ */
+ if (efi_capsule_pending(NULL))
+ reboot_type = BOOT_EFI;
+
for (;;) {
/* Could also try the reset bit in the Hammer NB */
switch (reboot_type) {
diff --git a/drivers/firmware/efi/Makefile b/drivers/firmware/efi/Makefile
index d8be608a9f3b..698846e67b09 100644
--- a/drivers/firmware/efi/Makefile
+++ b/drivers/firmware/efi/Makefile
@@ -1,7 +1,7 @@
#
# Makefile for linux kernel
#
-obj-$(CONFIG_EFI) += efi.o vars.o reboot.o
+obj-$(CONFIG_EFI) += efi.o vars.o reboot.o capsule.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/capsule.c b/drivers/firmware/efi/capsule.c
new file mode 100644
index 000000000000..475643d66258
--- /dev/null
+++ b/drivers/firmware/efi/capsule.c
@@ -0,0 +1,239 @@
+/*
+ * EFI capsule support.
+ *
+ * Copyright 2013 Intel Corporation <matt.fleming-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>
+ *
+ * This file is part of the Linux kernel, and is made available under
+ * the terms of the GNU General Public License version 2.
+ */
+
+#define pr_fmt(fmt) "efi-capsule: " fmt
+
+#include <linux/slab.h>
+#include <linux/mutex.h>
+#include <linux/highmem.h>
+#include <linux/efi.h>
+#include <linux/vmalloc.h>
+#include <asm/io.h>
+
+typedef struct {
+ u64 length;
+ u64 data;
+} efi_capsule_block_desc_t;
+
+static bool capsule_pending;
+static int efi_reset_type = -1;
+
+/*
+ * capsule_mutex serialises access to both 'capsule_pending' and
+ * 'efi_reset_type'.
+ *
+ * This mutex must be held across calls to efi_capsule_supported() and
+ * efi_update_capsule() so that the operation is atomic. This ensures
+ * that efi_update_capsule() isn't called with a capsule that requires a
+ * different reset type to the registered 'efi_reset_type'.
+ */
+static DEFINE_MUTEX(capsule_mutex);
+
+static int efi_update_capsule(efi_capsule_header_t *capsule,
+ struct page **pages, size_t size, int reset);
+
+/**
+ * efi_capsule_pending - has a capsule been passed to the firmware?
+ * @reset_type: store the type of EFI reset if capsule is pending
+ *
+ * To ensure that the registered capsule is processed correctly by the
+ * firmware we need to perform a specific type of reset. If a capsule is
+ * pending return the reset type in @reset_type.
+ */
+bool efi_capsule_pending(int *reset_type)
+{
+ bool rv = false;
+
+ mutex_lock(&capsule_mutex);
+ if (!capsule_pending)
+ goto out;
+
+ if (reset_type)
+ *reset_type = efi_reset_type;
+ rv = true;
+
+out:
+ mutex_unlock(&capsule_mutex);
+ return rv;
+}
+
+/**
+ * efi_capsule_supported - does the firmware support the capsule?
+ * @guid: vendor guid of capsule
+ * @flags: capsule flags
+ * @size: size of capsule data
+ * @reset: the reset type required for this capsule
+ *
+ * Check whether a capsule with @flags is supported and that @size
+ * doesn't exceed the maximum size for a capsule.
+ */
+int efi_capsule_supported(efi_guid_t guid, u32 flags, size_t size, int *reset)
+{
+ efi_capsule_header_t *capsule;
+ efi_status_t status;
+ u64 max_size;
+ int rv = 0;
+
+ lockdep_assert_held(&capsule_mutex);
+
+ capsule = kmalloc(sizeof(*capsule), GFP_KERNEL);
+ if (!capsule)
+ return -ENOMEM;
+
+ capsule->headersize = capsule->imagesize = sizeof(*capsule);
+ memcpy(&capsule->guid, &guid, sizeof(efi_guid_t));
+ capsule->flags = flags;
+
+ status = efi.query_capsule_caps(&capsule, 1, &max_size, reset);
+ if (status != EFI_SUCCESS) {
+ rv = efi_status_to_err(status);
+ goto out;
+ }
+
+ if (size > max_size)
+ rv = -ENOSPC;
+out:
+ kfree(capsule);
+ return rv;
+}
+
+/**
+ * efi_capsule_update - send a capsule to the firmware
+ * @capsule: capsule to send to firmware
+ * @pages: an array of capsule data
+ *
+ * Check that @capsule is supported by the firmware and that it doesn't
+ * conflict with any previously registered capsule.
+ */
+int efi_capsule_update(efi_capsule_header_t *capsule, struct page **pages)
+{
+ efi_guid_t guid = capsule->guid;
+ size_t size = capsule->imagesize;
+ u32 flags = capsule->flags;
+ int rv, reset_type;
+
+ mutex_lock(&capsule_mutex);
+ rv = efi_capsule_supported(guid, flags, size, &reset_type);
+ if (rv)
+ goto out;
+
+ if (efi_reset_type >= 0 && efi_reset_type != reset_type) {
+ pr_err("Incompatible capsule reset type %d\n", reset_type);
+ rv = -EINVAL;
+ goto out;
+ }
+
+ rv = efi_update_capsule(capsule, pages, size, reset_type);
+out:
+ mutex_unlock(&capsule_mutex);
+ return rv;
+}
+EXPORT_SYMBOL_GPL(efi_capsule_update);
+
+#define BLOCKS_PER_PAGE (PAGE_SIZE / sizeof(efi_capsule_block_desc_t))
+
+/*
+ * How many pages of block descriptors do we need to map 'nr_pages'?
+ *
+ * Every list of block descriptors in a page must end with a
+ * continuation pointer. The last continuation pointer of the lage page
+ * must be zero to mark the end of the chain.
+ */
+static inline unsigned int num_block_pages(unsigned int nr_pages)
+{
+ return DIV_ROUND_UP(nr_pages, BLOCKS_PER_PAGE - 1);
+}
+
+/**
+ * efi_update_capsule - pass a single capsule to the firmware.
+ * @capsule: capsule to send to the firmware.
+ * @pages: an array of capsule data.
+ * @size: total size of capsule data + headers in @capsule.
+ * @reset: the reset type required for @capsule
+ *
+ * Map @capsule with EFI capsule block descriptors in PAGE_SIZE chunks.
+ * @size needn't necessarily be a multiple of PAGE_SIZE - we can handle
+ * a trailing chunk that is smaller than PAGE_SIZE.
+ *
+ * @capsule MUST be virtually contiguous.
+ *
+ * Return 0 on success.
+ */
+static int efi_update_capsule(efi_capsule_header_t *capsule,
+ struct page **pages, size_t size, int reset)
+{
+ efi_capsule_block_desc_t *block = NULL;
+ struct page **block_pgs;
+ efi_status_t status;
+ unsigned int nr_data_pgs, nr_block_pgs;
+ int i, j, err = -ENOMEM;
+
+ lockdep_assert_held(&capsule_mutex);
+
+ nr_data_pgs = DIV_ROUND_UP(size, PAGE_SIZE);
+ nr_block_pgs = num_block_pages(nr_data_pgs);
+
+ block_pgs = kzalloc(nr_block_pgs * sizeof(*block_pgs), GFP_KERNEL);
+ if (!block_pgs)
+ return -ENOMEM;
+
+ for (i = 0; i < nr_block_pgs; i++) {
+ block_pgs[i] = alloc_page(GFP_KERNEL);
+ if (!block_pgs[i])
+ goto fail;
+ }
+
+ for (i = 0; i < nr_block_pgs; i++) {
+ block = kmap(block_pgs[i]);
+ if (!block)
+ goto fail;
+
+ for (j = 0; j < BLOCKS_PER_PAGE - 1 && nr_data_pgs > 0; j++) {
+ u64 sz = min_t(u64, size, PAGE_SIZE);
+
+ block[j].length = sz;
+ block[j].data = page_to_phys(*pages++);
+
+ size -= sz;
+ nr_data_pgs--;
+ }
+
+ /* Continuation pointer */
+ block[j].length = 0;
+
+ if (i + 1 == nr_block_pgs)
+ block[j].data = 0;
+ else
+ block[j].data = page_to_phys(block_pgs[i + 1]);
+
+ kunmap(block_pgs[i]);
+ }
+
+ status = efi.update_capsule(&capsule, 1, page_to_phys(block_pgs[0]));
+ if (status != EFI_SUCCESS) {
+ pr_err("update_capsule fail: 0x%lx\n", status);
+ err = efi_status_to_err(status);
+ goto fail;
+ }
+
+ capsule_pending = true;
+ efi_reset_type = reset;
+
+ kfree(block_pgs);
+ return 0;
+
+fail:
+ for (i = 0; i < nr_block_pgs; i++) {
+ if (block_pgs[i])
+ __free_page(block_pgs[i]);
+ }
+
+ kfree(block_pgs);
+ return err;
+}
diff --git a/drivers/firmware/efi/reboot.c b/drivers/firmware/efi/reboot.c
index 9c59d1c795d1..1afb3e932cd1 100644
--- a/drivers/firmware/efi/reboot.c
+++ b/drivers/firmware/efi/reboot.c
@@ -9,7 +9,8 @@ int efi_reboot_quirk_mode = -1;

void efi_reboot(enum reboot_mode reboot_mode, const char *__unused)
{
- int efi_mode;
+ const char *str[] = { "cold", "warm", "shutdown", "platform" };
+ int efi_mode, cap_reset_mode;

if (!efi_enabled(EFI_RUNTIME_SERVICES))
return;
@@ -30,6 +31,15 @@ void efi_reboot(enum reboot_mode reboot_mode, const char *__unused)
if (efi_reboot_quirk_mode != -1)
efi_mode = efi_reboot_quirk_mode;

+ if (efi_capsule_pending(&cap_reset_mode)) {
+ if (efi_mode != cap_reset_mode)
+ printk("efi: %s reset requested but pending capsule "
+ "update requires %s reset... Performing "
+ "%s reset\n", str[efi_mode], str[cap_reset_mode],
+ str[cap_reset_mode]);
+ efi_mode = cap_reset_mode;
+ }
+
efi.reset_system(efi_mode, EFI_SUCCESS, 0, NULL);
}

diff --git a/include/linux/efi.h b/include/linux/efi.h
index 48d936cf17d3..3730cb071e4e 100644
--- a/include/linux/efi.h
+++ b/include/linux/efi.h
@@ -119,6 +119,13 @@ typedef struct {
} efi_capsule_header_t;

/*
+ * EFI capsule flags
+ */
+#define EFI_CAPSULE_PERSIST_ACROSS_RESET 0x00010000
+#define EFI_CAPSULE_POPULATE_SYSTEM_TABLE 0x00020000
+#define EFI_CAPSULE_INITIATE_RESET 0x00040000
+
+/*
* Allocation types for calls to boottime->allocate_pages.
*/
#define EFI_ALLOCATE_ANY_PAGES 0
@@ -953,6 +960,12 @@ static inline bool efi_enabled(int feature)
}
static inline void
efi_reboot(enum reboot_mode reboot_mode, const char *__unused) {}
+
+static inline bool
+efi_capsule_pending(int *reset_type)
+{
+ return false;
+}
#endif

/*
@@ -1199,6 +1212,10 @@ int efivars_sysfs_init(void);
#define EFIVARS_DATA_SIZE_MAX 1024

#endif /* CONFIG_EFI_VARS */
+extern bool efi_capsule_pending(int *reset_type);
+
+extern int efi_capsule_supported(efi_guid_t guid, u32 flags,
+ size_t size, int *reset);

#ifdef CONFIG_EFI_RUNTIME_MAP
int efi_runtime_map_init(struct kobject *);
@@ -1277,4 +1294,7 @@ efi_status_t handle_cmdline_files(efi_system_table_t *sys_table_arg,
efi_status_t efi_parse_options(char *cmdline);

bool efi_runtime_disabled(void);
+
+extern int efi_capsule_update(efi_capsule_header_t *capsule,
+ struct page **pages);
#endif /* _LINUX_EFI_H */
--
1.9.3