Revert "x86/platform/UV: Use efi_runtime_lock to serialise BIOS calls"

BugLink: https://bugs.launchpad.net/bugs/1822271

This reverts commit 7212e37cbdf99f48e4a6c689a42f4bda1ae69001.

Hedi Berriche <hedi.berriche@hpe.com> notes:

> In 4.4-stable efi_runtime_lock as defined in drivers/firmware/efi/runtime-wrappers.c
> is a spinlock (given it predates commit dce48e35) and commit
>
>         f331e766 x86/platform/UV: Use efi_runtime_lock to serialise BIOS calls
>
> which 7212e37cbdf9 is a backport of, needs it to be a semaphore.
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Stefan Bader <stefan.bader@canonical.com>
Acked-by: Juerg Haefliger <juerg.haefliger@canonical.com>
Signed-off-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com>

arch/x86/include/asm/uv/bios.h

@@ -48,8 +48,7 @@ enum {
 	BIOS_STATUS_SUCCESS		=  0,
 	BIOS_STATUS_UNIMPLEMENTED	= -ENOSYS,
 	BIOS_STATUS_EINVAL		= -EINVAL,
-	BIOS_STATUS_UNAVAIL		= -EBUSY,
-	BIOS_STATUS_ABORT		= -EINTR,
+	BIOS_STATUS_UNAVAIL		= -EBUSY
 };
 
 /*
@@ -112,9 +111,4 @@ extern long system_serial_number;
 
 extern struct kobject *sgi_uv_kobj;	/* /sys/firmware/sgi_uv */
 
-/*
- * EFI runtime lock; cf. firmware/efi/runtime-wrappers.c for details
- */
-extern struct semaphore __efi_uv_runtime_lock;
-
 #endif /* _ASM_X86_UV_BIOS_H */

arch/x86/platform/uv/bios_uv.c

@@ -28,8 +28,7 @@
 
 static struct uv_systab uv_systab;
 
-static s64 __uv_bios_call(enum uv_bios_cmd which, u64 a1, u64 a2, u64 a3,
-			u64 a4, u64 a5)
+s64 uv_bios_call(enum uv_bios_cmd which, u64 a1, u64 a2, u64 a3, u64 a4, u64 a5)
 {
 	struct uv_systab *tab = &uv_systab;
 	s64 ret;
@@ -44,19 +43,6 @@ static s64 __uv_bios_call(enum uv_bios_cmd which, u64 a1, u64 a2, u64 a3,
 			a1, a2, a3, a4, a5);
 	return ret;
 }
-
-s64 uv_bios_call(enum uv_bios_cmd which, u64 a1, u64 a2, u64 a3, u64 a4, u64 a5)
-{
-	s64 ret;
-
-	if (down_interruptible(&__efi_uv_runtime_lock))
-		return BIOS_STATUS_ABORT;
-
-	ret = __uv_bios_call(which, a1, a2, a3, a4, a5);
-	up(&__efi_uv_runtime_lock);
-
-	return ret;
-}
 EXPORT_SYMBOL_GPL(uv_bios_call);
 
 s64 uv_bios_call_irqsave(enum uv_bios_cmd which, u64 a1, u64 a2, u64 a3,
@@ -65,15 +51,10 @@ s64 uv_bios_call_irqsave(enum uv_bios_cmd which, u64 a1, u64 a2, u64 a3,
 	unsigned long bios_flags;
 	s64 ret;
 
-	if (down_interruptible(&__efi_uv_runtime_lock))
-		return BIOS_STATUS_ABORT;
-
 	local_irq_save(bios_flags);
-	ret = __uv_bios_call(which, a1, a2, a3, a4, a5);
+	ret = uv_bios_call(which, a1, a2, a3, a4, a5);
 	local_irq_restore(bios_flags);
 
-	up(&__efi_uv_runtime_lock);
-
 	return ret;
 }
 

drivers/firmware/efi/runtime-wrappers.c

@@ -87,13 +87,6 @@ static DEFINE_SPINLOCK(efi_runtime_lock);
  * context through efi_pstore_write().
  */
 
-/*
- * Expose the EFI runtime lock to the UV platform
- */
-#ifdef CONFIG_X86_UV
-extern struct semaphore __efi_uv_runtime_lock __alias(efi_runtime_lock);
-#endif
-
 /*
  * As per commit ef68c8f87ed1 ("x86: Serialize EFI time accesses on rtc_lock"),
  * the EFI specification requires that callers of the time related runtime