[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 <r...@hpe.com>
Cc: Mike Travis <mike.tra...@hpe.com>
Cc: Dimitri Sivanich <sivan...@hpe.com>
Cc: Steve Wahl <steve.w...@hpe.com>
Cc: sta...@vger.kernel.org
Signed-off-by: Hedi Berriche <hedi.berri...@hpe.com>
---
 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