[PATCH 4.9 068/148] x86/platform/uv/BAU: Fix HUB errors by remove initial write to sw-ack register

[Greg Kroah-Hartman]

4.9-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Andrew Banman <abanman@xxxxxxx>


[ Upstream commit 1b17c6df852851b40c3c27c66b8fa2fd99cf25d8 ]

Writing to the software acknowledge clear register when there are no
pending messages causes a HUB error to assert. The original intent of this
write was to clear the pending bits before start of operation, but this is
an incorrect method and has been determined to be unnecessary.

Signed-off-by: Andrew Banman <abanman@xxxxxxx>
Acked-by: Mike Travis <mike.travis@xxxxxxx>
Cc: Andy Lutomirski <luto@xxxxxxxxxx>
Cc: Borislav Petkov <bp@xxxxxxxxx>
Cc: Brian Gerst <brgerst@xxxxxxxxx>
Cc: Denys Vlasenko <dvlasenk@xxxxxxxxxx>
Cc: H. Peter Anvin <hpa@xxxxxxxxx>
Cc: Josh Poimboeuf <jpoimboe@xxxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: akpm@xxxxxxxxxxxxxxxxxxxx
Cc: rja@xxxxxxx
Cc: sivanich@xxxxxxx
Link: http://lkml.kernel.org/r/1487351269-181133-1-git-send-email-abanman@xxxxxxx
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
Signed-off-by: Sasha Levin <alexander.levin@xxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
 arch/x86/platform/uv/tlb_uv.c |    1 -
 1 file changed, 1 deletion(-)

--- a/arch/x86/platform/uv/tlb_uv.c
+++ b/arch/x86/platform/uv/tlb_uv.c
@@ -1848,7 +1848,6 @@ static void pq_init(int node, int pnode)
 
 	ops.write_payload_first(pnode, first);
 	ops.write_payload_last(pnode, last);
-	ops.write_g_sw_ack(pnode, 0xffffUL);
 
 	/* in effect, all msg_type's are set to MSG_NOOP */
 	memset(pqp, 0, sizeof(struct bau_pq_entry) * DEST_Q_SIZE);