From: Keith Busch <kbusch@kernel.org>
Date: Thu, 14 Oct 2021 09:45:42 -0700
Subject: nvme-pci: clear shadow doorbell memory on resets
Patch-mainline: v5.16-rc1
Git-commit: 58847f12fe7823c56f844218abcca6920901097d
References: jsc#PED-1183

The host memory doorbell and event buffers need to be initialized on
each reset so the driver doesn't observe stale values from the previous
instantiation.

Signed-off-by: Keith Busch <kbusch@kernel.org>
Tested-by: John Levon <john.levon@nutanix.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Acked-by: Daniel Wagner <dwagner@suse.de>
---
 drivers/nvme/host/pci.c |    9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

--- a/drivers/nvme/host/pci.c
+++ b/drivers/nvme/host/pci.c
@@ -245,8 +245,15 @@ static int nvme_dbbuf_dma_alloc(struct n
 {
 	unsigned int mem_size = nvme_dbbuf_size(dev);
 
-	if (dev->dbbuf_dbs)
+	if (dev->dbbuf_dbs) {
+		/*
+		 * Clear the dbbuf memory so the driver doesn't observe stale
+		 * values from the previous instantiation.
+		 */
+		memset(dev->dbbuf_dbs, 0, mem_size);
+		memset(dev->dbbuf_eis, 0, mem_size);
 		return 0;
+	}
 
 	dev->dbbuf_dbs = dma_alloc_coherent(dev->dev, mem_size,
 					    &dev->dbbuf_dbs_dma_addr,