Re: [Patch v2 1/4] efi/x86: turn EFI runtime semaphore into a global lock

On Thu, Feb 07, 2019 at 17:38 Hedi Berriche wrote:

On Thu, Feb 07, 2019 at 16:05 Ard Biesheuvel wrote:

...

On Thu, 7 Feb 2019 at 05:23, Hedi Berriche hedi.berriche@hpe.com wrote:

...

Make efi_runtime_lock semaphore global so that it can be used by EFI runtime callers that may be defined outside efi/runtime-wrappers.c.

Also now that efi_runtime_lock semaphore is no longer static, rename it to efi_runtime_sem so it doesn't clash with the efi_runtime_lock spinlock defined in arch/x86/platform/efi/efi_64.c when CONFIG_EFI_MIXED is enabled.

The immediate motivation of this change is to serialise UV platform BIOS calls using the efi_runtime_sem semaphore.

No functional changes.

Cc: Russ Anderson rja@hpe.com Cc: Mike Travis mike.travis@hpe.com Cc: Dimitri Sivanich sivanich@hpe.com Cc: Steve Wahl steve.wahl@hpe.com Cc: stable@vger.kernel.org Signed-off-by: Hedi Berriche hedi.berriche@hpe.com

Hello Hedi,

Hi Ard,

...

Same feedback as on v1: please don't rename the lock.

With the efi_runtime_lock semaphore being no longer static, not renaming it will cause a compile failure as it will clash with the declaration of the efi_runtime_lock *spinlock* in arch/x86/platform/efi/efi_64.c in the CONFIG_EFI_MIXED case.

Ard,

Any comments on whether resolving the conflict between

{efi_runtime_lock, drivers/firmware/efi/runtime-wrappers.c}

and {efi_runtime_lock, arch/x86/platform/efi/efi_64.c}

provides the required justification for renaming the efi_runtime_lock semaphore?

Cheers, Hedi.

...

...

---

drivers/firmware/efi/runtime-wrappers.c | 60 ++++++++++++------------- include/linux/efi.h | 3 ++ 2 files changed, 33 insertions(+), 30 deletions(-)

diff --git a/drivers/firmware/efi/runtime-wrappers.c b/drivers/firmware/efi/runtime-wrappers.c index 8903b9ccfc2b..ec60d6227925 100644 --- a/drivers/firmware/efi/runtime-wrappers.c +++ b/drivers/firmware/efi/runtime-wrappers.c @@ -53,7 +53,7 @@ struct efi_runtime_work efi_rts_work;

• @rts_arg<1-5>: efi_runtime_service() function arguments
• Accesses to efi_runtime_services() are serialized by a binary

• • semaphore (efi_runtime_lock) and caller waits until the work is

• • semaphore (efi_runtime_sem) and caller waits until the work is

• finished, hence _only_ one work is queued at a time and the caller
• thread waits for completion.

*/ @@ -144,7 +144,7 @@ void efi_call_virt_check_flags(unsigned long flags, const char *call)

• none of the remaining functions are actually ever called at runtime.
• So let's just use a single lock to serialize all Runtime Services calls.

*/ -static DEFINE_SEMAPHORE(efi_runtime_lock); +DEFINE_SEMAPHORE(efi_runtime_sem);

/*

• Calls the appropriate efi_runtime_service() with the appropriate

@@ -233,10 +233,10 @@ static efi_status_t virt_efi_get_time(efi_time_t *tm, efi_time_cap_t *tc) { efi_status_t status;

•   if (down_interruptible(&efi_runtime_lock))
  

•   if (down_interruptible(&efi_runtime_sem))
           return EFI_ABORTED;
   status = efi_queue_work(GET_TIME, tm, tc, NULL, NULL, NULL);
  

•   up(&efi_runtime_lock);
  

•   up(&efi_runtime_sem);
   return status;
  

}

@@ -244,10 +244,10 @@ static efi_status_t virt_efi_set_time(efi_time_t *tm) { efi_status_t status;

•   if (down_interruptible(&efi_runtime_lock))
  

•   if (down_interruptible(&efi_runtime_sem))
           return EFI_ABORTED;
   status = efi_queue_work(SET_TIME, tm, NULL, NULL, NULL, NULL);
  

•   up(&efi_runtime_lock);
  

•   up(&efi_runtime_sem);
   return status;
  

}

@@ -257,11 +257,11 @@ static efi_status_t virt_efi_get_wakeup_time(efi_bool_t *enabled, { efi_status_t status;

•   if (down_interruptible(&efi_runtime_lock))
  

•   if (down_interruptible(&efi_runtime_sem))
           return EFI_ABORTED;
   status = efi_queue_work(GET_WAKEUP_TIME, enabled, pending, tm, NULL,
                           NULL);
  

•   up(&efi_runtime_lock);
  

•   up(&efi_runtime_sem);
   return status;
  

}

@@ -269,11 +269,11 @@ static efi_status_t virt_efi_set_wakeup_time(efi_bool_t enabled, efi_time_t *tm) { efi_status_t status;

•   if (down_interruptible(&efi_runtime_lock))
  

•   if (down_interruptible(&efi_runtime_sem))
           return EFI_ABORTED;
   status = efi_queue_work(SET_WAKEUP_TIME, &enabled, tm, NULL, NULL,
                           NULL);
  

•   up(&efi_runtime_lock);
  

•   up(&efi_runtime_sem);
   return status;
  

}

@@ -285,11 +285,11 @@ static efi_status_t virt_efi_get_variable(efi_char16_t *name, { efi_status_t status;

•   if (down_interruptible(&efi_runtime_lock))
  

•   if (down_interruptible(&efi_runtime_sem))
           return EFI_ABORTED;
   status = efi_queue_work(GET_VARIABLE, name, vendor, attr, data_size,
                           data);
  

•   up(&efi_runtime_lock);
  

•   up(&efi_runtime_sem);
   return status;
  

}

@@ -299,11 +299,11 @@ static efi_status_t virt_efi_get_next_variable(unsigned long *name_size, { efi_status_t status;

•   if (down_interruptible(&efi_runtime_lock))
  

•   if (down_interruptible(&efi_runtime_sem))
           return EFI_ABORTED;
   status = efi_queue_work(GET_NEXT_VARIABLE, name_size, name, vendor,
                           NULL, NULL);
  

•   up(&efi_runtime_lock);
  

•   up(&efi_runtime_sem);
   return status;
  

}

@@ -315,11 +315,11 @@ static efi_status_t virt_efi_set_variable(efi_char16_t *name, { efi_status_t status;

•   if (down_interruptible(&efi_runtime_lock))
  

•   if (down_interruptible(&efi_runtime_sem))
           return EFI_ABORTED;
   status = efi_queue_work(SET_VARIABLE, name, vendor, &attr, &data_size,
                           data);
  

•   up(&efi_runtime_lock);
  

•   up(&efi_runtime_sem);
   return status;
  

}

@@ -330,12 +330,12 @@ virt_efi_set_variable_nonblocking(efi_char16_t *name, efi_guid_t *vendor, { efi_status_t status;

•   if (down_trylock(&efi_runtime_lock))
  

•   if (down_trylock(&efi_runtime_sem))
           return EFI_NOT_READY;
  
   status = efi_call_virt(set_variable, name, vendor, attr, data_size,
                          data);
  

•   up(&efi_runtime_lock);
  

•   up(&efi_runtime_sem);
   return status;
  

}

@@ -350,11 +350,11 @@ static efi_status_t virt_efi_query_variable_info(u32 attr, if (efi.runtime_version < EFI_2_00_SYSTEM_TABLE_REVISION) return EFI_UNSUPPORTED;

•   if (down_interruptible(&efi_runtime_lock))
  

•   if (down_interruptible(&efi_runtime_sem))
           return EFI_ABORTED;
   status = efi_queue_work(QUERY_VARIABLE_INFO, &attr, storage_space,
                           remaining_space, max_variable_size, NULL);
  

•   up(&efi_runtime_lock);
  

•   up(&efi_runtime_sem);
   return status;
  

}

@@ -369,12 +369,12 @@ virt_efi_query_variable_info_nonblocking(u32 attr, if (efi.runtime_version < EFI_2_00_SYSTEM_TABLE_REVISION) return EFI_UNSUPPORTED;

•   if (down_trylock(&efi_runtime_lock))
  

•   if (down_trylock(&efi_runtime_sem))
           return EFI_NOT_READY;
  
   status = efi_call_virt(query_variable_info, attr, storage_space,
                          remaining_space, max_variable_size);
  

•   up(&efi_runtime_lock);
  

•   up(&efi_runtime_sem);
   return status;
  

}

@@ -382,11 +382,11 @@ static efi_status_t virt_efi_get_next_high_mono_count(u32 *count) { efi_status_t status;

•   if (down_interruptible(&efi_runtime_lock))
  

•   if (down_interruptible(&efi_runtime_sem))
           return EFI_ABORTED;
   status = efi_queue_work(GET_NEXT_HIGH_MONO_COUNT, count, NULL, NULL,
                           NULL, NULL);
  

•   up(&efi_runtime_lock);
  

•   up(&efi_runtime_sem);
   return status;
  

}

@@ -395,14 +395,14 @@ static void virt_efi_reset_system(int reset_type, unsigned long data_size, efi_char16_t *data) {

•   if (down_interruptible(&efi_runtime_lock)) {
  

•   if (down_interruptible(&efi_runtime_sem)) {
           pr_warn("failed to invoke the reset_system() runtime service:\n"
                   "could not get exclusive access to the firmware\n");
           return;
   }
   efi_rts_work.efi_rts_id = RESET_SYSTEM;
   __efi_call_virt(reset_system, reset_type, status, data_size, data);
  

•   up(&efi_runtime_lock);
  

•   up(&efi_runtime_sem);
  

}

static efi_status_t virt_efi_update_capsule(efi_capsule_header_t **capsules, @@ -414,11 +414,11 @@ static efi_status_t virt_efi_update_capsule(efi_capsule_header_t **capsules, if (efi.runtime_version < EFI_2_00_SYSTEM_TABLE_REVISION) return EFI_UNSUPPORTED;

•   if (down_interruptible(&efi_runtime_lock))
  

•   if (down_interruptible(&efi_runtime_sem))
           return EFI_ABORTED;
   status = efi_queue_work(UPDATE_CAPSULE, capsules, &count, &sg_list,
                           NULL, NULL);
  

•   up(&efi_runtime_lock);
  

•   up(&efi_runtime_sem);
   return status;
  

}

@@ -432,11 +432,11 @@ static efi_status_t virt_efi_query_capsule_caps(efi_capsule_header_t **capsules, if (efi.runtime_version < EFI_2_00_SYSTEM_TABLE_REVISION) return EFI_UNSUPPORTED;

•   if (down_interruptible(&efi_runtime_lock))
  

•   if (down_interruptible(&efi_runtime_sem))
           return EFI_ABORTED;
   status = efi_queue_work(QUERY_CAPSULE_CAPS, capsules, &count,
                           max_size, reset_type, NULL);
  

•   up(&efi_runtime_lock);
  

•   up(&efi_runtime_sem);
   return status;
  

}

diff --git a/include/linux/efi.h b/include/linux/efi.h index 45ff763fba76..930cd20842b8 100644 --- a/include/linux/efi.h +++ b/include/linux/efi.h @@ -1745,6 +1745,9 @@ extern struct efi_runtime_work efi_rts_work; /* Workqueue to queue EFI Runtime Services */ extern struct workqueue_struct *efi_rts_wq;

+/* EFI runtime semaphore */ +extern struct semaphore efi_runtime_sem;

struct linux_efi_memreserve { int size; // allocated size of the array atomic_t count; // number of entries used -- 2.20.1

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