From: Eric Blake <eblake@redhat.com>
To: Shivaprasad G Bhat <sbhat@linux.ibm.com>,
david@gibson.dropbear.id.au, groug@kaod.org, qemu-ppc@nongnu.org,
ehabkost@redhat.com, marcel.apfelbaum@gmail.com, mst@redhat.com,
imammedo@redhat.com, xiaoguangrong.eric@gmail.com,
peter.maydell@linaro.org, qemu-arm@nongnu.org,
richard.henderson@linaro.org, pbonzini@redhat.com,
stefanha@redhat.com, haozhong.zhang@intel.com,
shameerali.kolothum.thodi@huawei.com, kwangwoo.lee@sk.com,
armbru@redhat.com
Cc: linux-nvdimm@lists.01.org, aneesh.kumar@linux.ibm.com,
qemu-devel@nongnu.org, kvm-ppc@vger.kernel.org,
shivaprasadbhat@gmail.com, bharata@linux.vnet.ibm.com
Subject: Re: [PATCH v4 3/3] nvdimm: Enable sync-dax device property for nvdimm
Date: Mon, 3 May 2021 13:27:22 -0500 [thread overview]
Message-ID: <f035a4ce-c070-6bb9-5792-da0a2d9d0a99@redhat.com> (raw)
In-Reply-To: <161966813983.652.5749368609701495826.stgit@17be908f7c1c>
On 4/28/21 10:49 PM, Shivaprasad G Bhat wrote:
> The patch adds the 'sync-dax' property to the nvdimm device.
>
> When the sync-dax is 'direct' indicates the backend is synchronous DAX
> capable and no explicit flush requests are required. When the mode is
> set to 'writeback' it indicates the backend is not synhronous DAX
synchronous
> capable and explicit flushes to Hypervisor are required.
>
> On PPC where the flush requests from guest can be honoured by the qemu,
s/the qemu/qemu/
> the 'writeback' mode is supported and set as the default. The device
> tree property "hcall-flush-required" is added to the nvdimm node which
> makes the guest to issue H_SCM_FLUSH hcalls to request for flushes
s/to issue/issue/
s/request for/request/
> explicitly. This would be the default behaviour without sync-dax
> property set for the nvdimm device. For old pSeries machine, the
> default is 'unsafe'.
>
> For non-PPC platforms, the mode is set to 'unsafe' as the default.
>
> Signed-off-by: Shivaprasad G Bhat <sbhat@linux.ibm.com>
> ---
> +++ b/qapi/common.json
> @@ -197,3 +197,23 @@
> { 'enum': 'GrabToggleKeys',
> 'data': [ 'ctrl-ctrl', 'alt-alt', 'shift-shift','meta-meta', 'scrolllock',
> 'ctrl-scrolllock' ] }
> +
> +##
> +# @NvdimmSyncModes:
> +#
> +# Indicates the mode of flush to be used to ensure persistence in case
> +# of power failures.
> +#
> +# @unsafe: This is to indicate, the data on the backend device not be
> +# consistent in power failure scenarios.
s/This is to indicate, the/This indicates that/
s/device not/device might not/
> +# @direct: This is to indicate the backend device supports synchronous DAX
> +# and no explicit flush requests from the guest is required.
This indicates the backend device supports synchronous DAX, and no
explicit flush requests from the guest are required.
> +# @writeback: To be used when the backend device doesn't support synchronous
> +# DAX. The hypervisor issues flushes to the disk when requested
> +# by the guest.
> +# Since: 6.0
6.1
> +#
> +##
> +{ 'enum': 'NvdimmSyncModes',
> + 'data': [ 'unsafe', 'writeback',
> + { 'name': 'direct', 'if': 'defined(CONFIG_LIBPMEM)' } ] }
>
>
--
Eric Blake, Principal Software Engineer
Red Hat, Inc. +1-919-301-3226
Virtualization: qemu.org | libvirt.org
next prev parent reply other threads:[~2021-05-03 18:28 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-04-29 3:48 [PATCH v4 0/3] nvdimm: Enable sync-dax property for nvdimm Shivaprasad G Bhat
2021-04-29 3:48 ` [PATCH v4 1/3] spapr: nvdimm: Forward declare and move the definitions Shivaprasad G Bhat
2021-05-03 18:23 ` Eric Blake
2021-05-04 1:21 ` David Gibson
2021-04-29 3:48 ` [PATCH v4 2/3] spapr: nvdimm: Implement H_SCM_FLUSH hcall Shivaprasad G Bhat
2021-04-29 3:49 ` [PATCH v4 3/3] nvdimm: Enable sync-dax device property for nvdimm Shivaprasad G Bhat
2021-05-03 18:27 ` Eric Blake [this message]
2021-04-29 15:55 ` [PATCH v4 0/3] nvdimm: Enable sync-dax " Stefan Hajnoczi
2021-04-29 16:32 ` Aneesh Kumar K.V
2021-04-30 4:27 ` David Gibson
2021-04-30 15:08 ` Stefan Hajnoczi
2021-04-30 19:14 ` Dan Williams
2021-05-01 13:55 ` Aneesh Kumar K.V
2021-05-03 14:05 ` Shivaprasad G Bhat
2021-05-03 19:41 ` Dan Williams
2021-05-04 4:59 ` Aneesh Kumar K.V
2021-05-04 5:43 ` Pankaj Gupta
2021-05-04 9:02 ` Aneesh Kumar K.V
2021-05-05 0:12 ` Dan Williams
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