* This file is released under the GPLv2.
*/
+#include <linux/bug.h>
#include <linux/efi.h>
-#include <linux/spinlock.h> /* spinlock_t */
+#include <linux/mutex.h>
+#include <linux/spinlock.h>
#include <asm/efi.h>
+/*
+ * According to section 7.1 of the UEFI spec, Runtime Services are not fully
+ * reentrant, and there are particular combinations of calls that need to be
+ * serialized. (source: UEFI Specification v2.4A)
+ *
+ * Table 31. Rules for Reentry Into Runtime Services
+ * +------------------------------------+-------------------------------+
+ * | If previous call is busy in | Forbidden to call |
+ * +------------------------------------+-------------------------------+
+ * | Any | SetVirtualAddressMap() |
+ * +------------------------------------+-------------------------------+
+ * | ConvertPointer() | ConvertPointer() |
+ * +------------------------------------+-------------------------------+
+ * | SetVariable() | ResetSystem() |
+ * | UpdateCapsule() | |
+ * | SetTime() | |
+ * | SetWakeupTime() | |
+ * | GetNextHighMonotonicCount() | |
+ * +------------------------------------+-------------------------------+
+ * | GetVariable() | GetVariable() |
+ * | GetNextVariableName() | GetNextVariableName() |
+ * | SetVariable() | SetVariable() |
+ * | QueryVariableInfo() | QueryVariableInfo() |
+ * | UpdateCapsule() | UpdateCapsule() |
+ * | QueryCapsuleCapabilities() | QueryCapsuleCapabilities() |
+ * | GetNextHighMonotonicCount() | GetNextHighMonotonicCount() |
+ * +------------------------------------+-------------------------------+
+ * | GetTime() | GetTime() |
+ * | SetTime() | SetTime() |
+ * | GetWakeupTime() | GetWakeupTime() |
+ * | SetWakeupTime() | SetWakeupTime() |
+ * +------------------------------------+-------------------------------+
+ *
+ * Due to the fact that the EFI pstore may write to the variable store in
+ * interrupt context, we need to use a spinlock for at least the groups that
+ * contain SetVariable() and QueryVariableInfo(). That leaves little else, as
+ * none of the remaining functions are actually ever called at runtime.
+ * So let's just use a single spinlock to serialize all Runtime Services calls.
+ */
+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().
+ */
+#ifndef efi_in_nmi
+#define efi_in_nmi() (0)
+#endif
+
/*
* As per commit ef68c8f87ed1 ("x86: Serialize EFI time accesses on rtc_lock"),
* the EFI specification requires that callers of the time related runtime
efi_status_t status;
spin_lock_irqsave(&rtc_lock, flags);
+ spin_lock(&efi_runtime_lock);
status = efi_call_virt(get_time, tm, tc);
+ spin_unlock(&efi_runtime_lock);
spin_unlock_irqrestore(&rtc_lock, flags);
return status;
}
efi_status_t status;
spin_lock_irqsave(&rtc_lock, flags);
+ spin_lock(&efi_runtime_lock);
status = efi_call_virt(set_time, tm);
+ spin_unlock(&efi_runtime_lock);
spin_unlock_irqrestore(&rtc_lock, flags);
return status;
}
efi_status_t status;
spin_lock_irqsave(&rtc_lock, flags);
+ spin_lock(&efi_runtime_lock);
status = efi_call_virt(get_wakeup_time, enabled, pending, tm);
+ spin_unlock(&efi_runtime_lock);
spin_unlock_irqrestore(&rtc_lock, flags);
return status;
}
efi_status_t status;
spin_lock_irqsave(&rtc_lock, flags);
+ spin_lock(&efi_runtime_lock);
status = efi_call_virt(set_wakeup_time, enabled, tm);
+ spin_unlock(&efi_runtime_lock);
spin_unlock_irqrestore(&rtc_lock, flags);
return status;
}
unsigned long *data_size,
void *data)
{
- return efi_call_virt(get_variable, name, vendor, attr, data_size, data);
+ unsigned long flags;
+ efi_status_t status;
+
+ spin_lock_irqsave(&efi_runtime_lock, flags);
+ status = efi_call_virt(get_variable, name, vendor, attr, data_size,
+ data);
+ spin_unlock_irqrestore(&efi_runtime_lock, flags);
+ return status;
}
static efi_status_t virt_efi_get_next_variable(unsigned long *name_size,
efi_char16_t *name,
efi_guid_t *vendor)
{
- return efi_call_virt(get_next_variable, name_size, name, vendor);
+ unsigned long flags;
+ efi_status_t status;
+
+ spin_lock_irqsave(&efi_runtime_lock, flags);
+ status = efi_call_virt(get_next_variable, name_size, name, vendor);
+ spin_unlock_irqrestore(&efi_runtime_lock, flags);
+ return status;
}
static efi_status_t virt_efi_set_variable(efi_char16_t *name,
unsigned long data_size,
void *data)
{
- return efi_call_virt(set_variable, name, vendor, attr, data_size, data);
+ unsigned long flags;
+ efi_status_t status;
+ bool __in_nmi = efi_in_nmi();
+
+ if (!__in_nmi)
+ spin_lock_irqsave(&efi_runtime_lock, flags);
+ status = efi_call_virt(set_variable, name, vendor, attr, data_size,
+ data);
+ if (!__in_nmi)
+ spin_unlock_irqrestore(&efi_runtime_lock, flags);
+ return status;
}
static efi_status_t virt_efi_query_variable_info(u32 attr,
u64 *remaining_space,
u64 *max_variable_size)
{
+ unsigned long flags;
+ efi_status_t status;
+ bool __in_nmi = efi_in_nmi();
+
if (efi.runtime_version < EFI_2_00_SYSTEM_TABLE_REVISION)
return EFI_UNSUPPORTED;
- return efi_call_virt(query_variable_info, attr, storage_space,
- remaining_space, max_variable_size);
+ if (!__in_nmi)
+ spin_lock_irqsave(&efi_runtime_lock, flags);
+ status = efi_call_virt(query_variable_info, attr, storage_space,
+ remaining_space, max_variable_size);
+ if (!__in_nmi)
+ spin_unlock_irqrestore(&efi_runtime_lock, flags);
+ return status;
}
static efi_status_t virt_efi_get_next_high_mono_count(u32 *count)
{
- return efi_call_virt(get_next_high_mono_count, count);
+ unsigned long flags;
+ efi_status_t status;
+
+ spin_lock_irqsave(&efi_runtime_lock, flags);
+ status = efi_call_virt(get_next_high_mono_count, count);
+ spin_unlock_irqrestore(&efi_runtime_lock, flags);
+ return status;
}
static void virt_efi_reset_system(int reset_type,
unsigned long data_size,
efi_char16_t *data)
{
+ unsigned long flags;
+
+ spin_lock_irqsave(&efi_runtime_lock, flags);
__efi_call_virt(reset_system, reset_type, status, data_size, data);
+ spin_unlock_irqrestore(&efi_runtime_lock, flags);
}
static efi_status_t virt_efi_update_capsule(efi_capsule_header_t **capsules,
unsigned long count,
unsigned long sg_list)
{
+ unsigned long flags;
+ efi_status_t status;
+
if (efi.runtime_version < EFI_2_00_SYSTEM_TABLE_REVISION)
return EFI_UNSUPPORTED;
- return efi_call_virt(update_capsule, capsules, count, sg_list);
+ spin_lock_irqsave(&efi_runtime_lock, flags);
+ status = efi_call_virt(update_capsule, capsules, count, sg_list);
+ spin_unlock_irqrestore(&efi_runtime_lock, flags);
+ return status;
}
static efi_status_t virt_efi_query_capsule_caps(efi_capsule_header_t **capsules,
u64 *max_size,
int *reset_type)
{
+ unsigned long flags;
+ efi_status_t status;
+
if (efi.runtime_version < EFI_2_00_SYSTEM_TABLE_REVISION)
return EFI_UNSUPPORTED;
- return efi_call_virt(query_capsule_caps, capsules, count, max_size,
- reset_type);
+ spin_lock_irqsave(&efi_runtime_lock, flags);
+ status = efi_call_virt(query_capsule_caps, capsules, count, max_size,
+ reset_type);
+ spin_unlock_irqrestore(&efi_runtime_lock, flags);
+ return status;
}
void efi_native_runtime_setup(void)
projects / cascardo / linux.git / commitdiff