From: Christoph Hellwig <hch@lst.de>

Date: Wed, 3 Jun 2020 08:24:17 +0200

Subject: [PATCH] nvme-pci: use simple suspend when a HMB is enabled

Git-commit: b97120b15ebd3de51325084136d3b9c3cce656d6

Patch-mainline: v5.8-rc1

References: git-fixes

While the NVMe specification allows the device to access the host memory

buffer in host DRAM from all power states, hosts will fail access to

DRAM during S3 and similar power states.

Fixes: d916b1be94b6 ("nvme-pci: use host managed power state for suspend")

Signed-off-by: Christoph Hellwig <hch@lst.de>

Reviewed-by: Keith Busch <kbusch@kernel.org>

Reviewed-by: Sagi Grimberg <sagi@grimberg.me>

Signed-off-by: Jens Axboe <axboe@kernel.dk>

Acked-by: Hannes Reinecke <hare@suse.com>

---

 drivers/nvme/host/pci.c | 6 ++++++

 1 file changed, 6 insertions(+)

diff --git a/drivers/nvme/host/pci.c b/drivers/nvme/host/pci.c

index d690d5593a80..e2bacd369a88 100644

--- a/drivers/nvme/host/pci.c

+++ b/drivers/nvme/host/pci.c

@@ -2950,9 +2950,15 @@ static int nvme_suspend(struct device *dev)

 	 * the PCI bus layer to put it into D3 in order to take the PCIe link

 	 * down, so as to allow the platform to achieve its minimum low-power

 	 * state (which may not be possible if the link is up).

+	 *

+	 * If a host memory buffer is enabled, shut down the device as the NVMe

+	 * specification allows the device to access the host memory buffer in

+	 * host DRAM from all power states, but hosts will fail access to DRAM

+	 * during S3.

 	 */

 	if (pm_suspend_via_firmware() || !ctrl->npss ||

 	    !pcie_aspm_enabled(pdev) ||

+	    ndev->nr_host_mem_descs ||

 	    (ndev->ctrl.quirks & NVME_QUIRK_SIMPLE_SUSPEND))

 		return nvme_disable_prepare_reset(ndev, true);

-- 

2.29.2