[Patch v2 4/4] x86/platform/UV: use efi_runtime_sem to serialise BIOS calls

[Hedi Berriche]

Calls into UV firmware must be protected against concurrency, use the
now visible efi_runtime_sem lock to serialise them.

Cc: Russ Anderson <rja@xxxxxxx>
Cc: Mike Travis <mike.travis@xxxxxxx>
Cc: Dimitri Sivanich <sivanich@xxxxxxx>
Cc: Steve Wahl <steve.wahl@xxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Hedi Berriche <hedi.berriche@xxxxxxx>
---
 arch/x86/include/asm/uv/bios.h |  3 ++-
 arch/x86/platform/uv/bios_uv.c | 23 +++++++++++++++++++++--
 2 files changed, 23 insertions(+), 3 deletions(-)

diff --git a/arch/x86/include/asm/uv/bios.h b/arch/x86/include/asm/uv/bios.h
index 4eee646544b2..581e2978a16c 100644
--- a/arch/x86/include/asm/uv/bios.h
+++ b/arch/x86/include/asm/uv/bios.h
@@ -48,7 +48,8 @@ enum {
 	BIOS_STATUS_SUCCESS		=  0,
 	BIOS_STATUS_UNIMPLEMENTED	= -ENOSYS,
 	BIOS_STATUS_EINVAL		= -EINVAL,
-	BIOS_STATUS_UNAVAIL		= -EBUSY
+	BIOS_STATUS_UNAVAIL		= -EBUSY,
+	BIOS_STATUS_ABORT		= -EINTR,
 };
 
 /* Address map parameters */
diff --git a/arch/x86/platform/uv/bios_uv.c b/arch/x86/platform/uv/bios_uv.c
index 8bace0ca9e57..e779b2a128ea 100644
--- a/arch/x86/platform/uv/bios_uv.c
+++ b/arch/x86/platform/uv/bios_uv.c
@@ -29,7 +29,8 @@
 
 struct uv_systab *uv_systab;
 
-s64 uv_bios_call(enum uv_bios_cmd which, u64 a1, u64 a2, u64 a3, u64 a4, u64 a5)
+static 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;
@@ -51,6 +52,19 @@ s64 uv_bios_call(enum uv_bios_cmd which, u64 a1, u64 a2, u64 a3, u64 a4, u64 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_runtime_sem))
+		return BIOS_STATUS_ABORT;
+
+	ret = __uv_bios_call(which, a1, a2, a3, a4, a5);
+	up(&efi_runtime_sem);
+
+	return ret;
+}
 EXPORT_SYMBOL_GPL(uv_bios_call);
 
 s64 uv_bios_call_irqsave(enum uv_bios_cmd which, u64 a1, u64 a2, u64 a3,
@@ -59,10 +73,15 @@ 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_runtime_sem))
+		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_runtime_sem);
+
 	return ret;
 }
 
-- 
2.20.1