From: "Rafael J. Wysocki" <rafael@kernel.org>
To: Jason Gunthorpe <jgg@mellanox.com>
Cc: Christoph Hellwig <hch@infradead.org>,
Dan Williams <dan.j.williams@intel.com>,
"linux-nvdimm@lists.01.org" <linux-nvdimm@lists.01.org>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
"Rafael J. Wysocki" <rafael@kernel.org>,
Doug Ledford <dledford@redhat.com>, Pavel Machek <pavel@ucw.cz>,
Len Brown <len.brown@intel.com>,
ACPI Devel Maling List <linux-acpi@vger.kernel.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v2 11/12] PM, libnvdimm: Add 'mem-quiet' state and callback for firmware activation
Date: Thu, 9 Jul 2020 17:43:52 +0200 [thread overview]
Message-ID: <CAJZ5v0hW79nEe1P5YqNx0o0jHAMuPw-i02GY3TCvG_uFu48ETg@mail.gmail.com> (raw)
In-Reply-To: <20200709153854.GY23821@mellanox.com>
On Thu, Jul 9, 2020 at 5:39 PM Jason Gunthorpe <jgg@mellanox.com> wrote:
>
> On Thu, Jul 09, 2020 at 04:00:51PM +0100, Christoph Hellwig wrote:
> > On Mon, Jul 06, 2020 at 06:59:32PM -0700, Dan Williams wrote:
> > > The runtime firmware activation capability of Intel NVDIMM devices
> > > requires memory transactions to be disabled for 100s of microseconds.
> > > This timeout is large enough to cause in-flight DMA to fail and other
> > > application detectable timeouts. Arrange for firmware activation to be
> > > executed while the system is "quiesced", all processes and device-DMA
> > > frozen.
> > >
> > > It is already required that invoking device ->freeze() callbacks is
> > > sufficient to cease DMA. A device that continues memory writes outside
> > > of user-direction violates expectations of the PM core to be to
> > > establish a coherent hibernation image.
> > >
> > > That said, RDMA devices are an example of a device that access memory
> > > outside of user process direction.
>
> Are you saying freeze doesn't work for some RDMA drivers? That would
> be a driver bug, I think.
>
> The consequences of doing freeze are pretty serious, but it should
> still stop DMA.
Yes, it should. The "freeze" callbacks are expected to prevent any
DMA transfers from being carried out after they have been executed.
Thanks!
next prev parent reply other threads:[~2020-07-09 15:44 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-07-07 1:58 [PATCH v2 00/12] ACPI/NVDIMM: Runtime Firmware Activation Dan Williams
2020-07-07 1:58 ` [PATCH v2 01/12] libnvdimm: Validate command family indices Dan Williams
2020-07-07 1:58 ` [PATCH v2 02/12] ACPI: NFIT: Move bus_dsm_mask out of generic nvdimm_bus_descriptor Dan Williams
2020-07-07 1:58 ` [PATCH v2 03/12] ACPI: NFIT: Define runtime firmware activation commands Dan Williams
2020-07-07 1:58 ` [PATCH v2 04/12] tools/testing/nvdimm: Cleanup dimm index passing Dan Williams
2020-07-07 1:59 ` [PATCH v2 05/12] tools/testing/nvdimm: Add command debug messages Dan Williams
2020-07-07 1:59 ` [PATCH v2 06/12] tools/testing/nvdimm: Prepare nfit_ctl_test() for ND_CMD_CALL emulation Dan Williams
2020-07-07 1:59 ` [PATCH v2 07/12] tools/testing/nvdimm: Emulate firmware activation commands Dan Williams
2020-07-07 1:59 ` [PATCH v2 08/12] driver-core: Introduce DEVICE_ATTR_ADMIN_{RO,RW} Dan Williams
2020-07-07 1:59 ` [PATCH v2 09/12] libnvdimm: Convert to DEVICE_ATTR_ADMIN_RO() Dan Williams
2020-07-07 1:59 ` [PATCH v2 10/12] libnvdimm: Add runtime firmware activation sysfs interface Dan Williams
2020-07-07 1:59 ` [PATCH v2 11/12] PM, libnvdimm: Add 'mem-quiet' state and callback for firmware activation Dan Williams
2020-07-07 16:56 ` Pavel Machek
2020-07-09 14:57 ` Rafael J. Wysocki
2020-07-09 19:04 ` Dan Williams
2020-07-13 14:03 ` Rafael J. Wysocki
2020-07-09 15:00 ` Christoph Hellwig
2020-07-09 15:38 ` Jason Gunthorpe
2020-07-09 15:43 ` Rafael J. Wysocki [this message]
2020-07-09 16:10 ` Dan Williams
2020-07-09 16:34 ` Jason Gunthorpe
2020-07-09 15:56 ` Dan Williams
2020-07-07 1:59 ` [PATCH v2 12/12] ACPI: NFIT: Add runtime firmware activate support Dan Williams
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