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

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

[Christoph Hellwig]

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.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 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 d690d5593a8095..e2bacd369a88a0 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);
 
-- 
2.26.2


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

[Keith Busch]

On Tue, Jun 09, 2020 at 06:10:53PM +0200, Christoph Hellwig wrote:
> 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.
> 
> Signed-off-by: Christoph Hellwig <hch@lst.de>

Looks good. Stable ought to pick this up too.

>  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 d690d5593a8095..e2bacd369a88a0 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);
>  
> -- 

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

[Keith Busch]

On Wed, Jun 10, 2020 at 01:29:53AM +0900, Keith Busch wrote:
> On Tue, Jun 09, 2020 at 06:10:53PM +0200, Christoph Hellwig wrote:
> > 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.
> > 
> > Signed-off-by: Christoph Hellwig <hch@lst.de>
> 
> Looks good. Stable ought to pick this up too.

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

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

[Sagi Grimberg]

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

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

[Christoph Hellwig]

On Wed, Jun 10, 2020 at 01:29:53AM +0900, Keith Busch wrote:
> On Tue, Jun 09, 2020 at 06:10:53PM +0200, Christoph Hellwig wrote:
> > 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.
> > 
> > Signed-off-by: Christoph Hellwig <hch@lst.de>
> 
> Looks good. Stable ought to pick this up too.

I've added a:

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

and added it to nvme-5.8.

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