linux-kernel - [PATCH 6/6] x86/platform/uv/BAU: Implement uv4_wait_completion with read

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Date:   Thu,  9 Mar 2017 10:42:14 -0600
From:   Andrew Banman <abanman@....com>
To:     mingo@...hat.com
Cc:     akpm@...ux-foundation.org, tglx@...utronix.de, hpa@...or.com,
        mike.travis@....com, rja@....com, sivanich@....com, x86@...nel.org,
        linux-kernel@...r.kernel.org, abanman@....com
Subject: [PATCH 6/6] x86/platform/uv/BAU: Implement uv4_wait_completion with read_status

UV4 does not employ a software-timeout as in previous generations so a new
wait_completion routine without this logic is required. Certain completion
statuses require the AUX status bit in addition to ERROR and BUSY.

Add the read_status routine to construct the full completion status. Use
read_status in the uv4_wait_completion routine to handle all possible
completion statuses.

Signed-off-by: Andrew Banman <abanman@....com>
Acked-by: Mike Travis <mike.travis@....com>
---
 arch/x86/platform/uv/tlb_uv.c | 58 ++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 57 insertions(+), 1 deletion(-)

diff --git a/arch/x86/platform/uv/tlb_uv.c b/arch/x86/platform/uv/tlb_uv.c
index 2a826dd..42e65fe 100644
--- a/arch/x86/platform/uv/tlb_uv.c
+++ b/arch/x86/platform/uv/tlb_uv.c
@@ -687,6 +687,62 @@ static int uv2_3_wait_completion(struct bau_desc *bau_desc,
 }
 
 /*
+ * Returns the status of current BAU message for cpu desc as a bit field
+ * [Error][Busy][Aux]
+ */
+static u64 read_status(u64 status_mmr, int index, int desc)
+{
+	u64 stat;
+
+	stat = ((read_lmmr(status_mmr) >> index) & UV_ACT_STATUS_MASK) << 1;
+	stat |= (read_lmmr(UVH_LB_BAU_SB_ACTIVATION_STATUS_2) >> desc) & 0x1;
+
+	return stat;
+}
+
+static int uv4_wait_completion(struct bau_desc *bau_desc,
+				struct bau_control *bcp, long try)
+{
+	struct ptc_stats *stat = bcp->statp;
+	u64 descriptor_stat;
+	u64 mmr = bcp->status_mmr;
+	int index = bcp->status_index;
+	int desc = bcp->uvhub_cpu;
+
+	descriptor_stat = read_status(mmr, index, desc);
+
+	/* spin on the status MMR, waiting for it to go idle */
+	while (descriptor_stat != UV2H_DESC_IDLE) {
+		switch (descriptor_stat) {
+		case UV2H_DESC_SOURCE_TIMEOUT:
+			stat->s_stimeout++;
+			return FLUSH_GIVEUP;
+
+		case UV2H_DESC_DEST_TIMEOUT:
+			stat->s_dtimeout++;
+			bcp->conseccompletes = 0;
+			return FLUSH_RETRY_TIMEOUT;
+
+		case UV2H_DESC_DEST_STRONG_NACK:
+			stat->s_plugged++;
+			bcp->conseccompletes = 0;
+			return FLUSH_RETRY_PLUGGED;
+
+		case UV2H_DESC_DEST_PUT_ERR:
+			bcp->conseccompletes = 0;
+			return FLUSH_GIVEUP;
+
+		default:
+			/* descriptor_stat is still BUSY */
+			cpu_relax();
+		}
+		descriptor_stat = read_status(mmr, index, desc);
+	}
+	bcp->conseccompletes++;
+	return FLUSH_COMPLETE;
+}
+
+/*
  * Our retries are blocked by all destination sw ack resources being
  * in use, and a timeout is pending. In that case hardware immediately
  * returns the ERROR that looks like a destination timeout.
@@ -2157,7 +2213,7 @@ static int __init init_per_cpu(int nuvhubs, int base_part_pnode)
 	.write_g_sw_ack          = write_gmmr_proc_sw_ack,
 	.write_payload_first     = write_mmr_proc_payload_first,
 	.write_payload_last      = write_mmr_proc_payload_last,
-	.wait_completion	 = uv2_3_wait_completion,
+	.wait_completion         = uv4_wait_completion,
 };
 
 /*
-- 
1.8.2.1