[PATCH AUTOSEL 5.4 262/266] nvme-pci: use simple suspend when a HMB is enabled

[Sasha Levin]

From: Christoph Hellwig <hch@xxxxxx>

[ Upstream commit b97120b15ebd3de51325084136d3b9c3cce656d6 ]

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@xxxxxx>
Reviewed-by: Keith Busch <kbusch@xxxxxxxxxx>
Reviewed-by: Sagi Grimberg <sagi@xxxxxxxxxxx>
Signed-off-by: Jens Axboe <axboe@xxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
 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 cd64ddb129e5..acbdf21b76ed 100644
--- a/drivers/nvme/host/pci.c
+++ b/drivers/nvme/host/pci.c
@@ -2962,9 +2962,15 @@ 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);
 
-- 
2.25.1