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References: <20210715223505.GA29329@linuxonhyperv3.guj3yctzbm1etfxqx2vob5hsef.xx.internal.cloudapp.net>
 <CAM9Jb+g5viRiogvv2Mms+nBVWrYQXKofC9pweADUAW8-C6+iOw@mail.gmail.com> <20210720063510.GB8476@linuxonhyperv3.guj3yctzbm1etfxqx2vob5hsef.xx.internal.cloudapp.net>
In-Reply-To: <20210720063510.GB8476@linuxonhyperv3.guj3yctzbm1etfxqx2vob5hsef.xx.internal.cloudapp.net>
From: Pankaj Gupta <pankaj.gupta@ionos.com>
Date: Tue, 20 Jul 2021 08:51:04 +0200
Message-ID: <CALzYo30-fzcQMDVEhKMAGmzXO5hvtd-J6CtavesAUzaQjcpDcg@mail.gmail.com>
Subject: Re: [PATCH v2 1/2] virtio-pmem: Support PCI BAR-relative addresses
To: Taylor Stark <tstark@linux.microsoft.com>
Cc: Pankaj Gupta <pankaj.gupta.linux@gmail.com>, Dan Williams <dan.j.williams@intel.com>, 
	Vishal Verma <vishal.l.verma@intel.com>, Dave Jiang <dave.jiang@intel.com>, 
	Ira Weiny <ira.weiny@intel.com>, nvdimm@lists.linux.dev, apais@microsoft.com, 
	tyhicks@microsoft.com, jamorris@microsoft.com, benhill@microsoft.com, 
	sunilmut@microsoft.com, grahamwo@microsoft.com, tstark@microsoft.com, 
	"Michael S . Tsirkin" <mst@redhat.com>
Content-Type: text/plain; charset="UTF-8"

> > >
> > > -       virtio_cread_le(vpmem->vdev, struct virtio_pmem_config,
> > > -                       start, &vpmem->start);
> > > -       virtio_cread_le(vpmem->vdev, struct virtio_pmem_config,
> > > -                       size, &vpmem->size);
> > > +       /* Retrieve the pmem device's address and size. It may have been supplied
> > > +        * as a PCI BAR-relative shared memory region, or as a guest absolute address.
> > > +        */
> > > +       have_shm_region = virtio_get_shm_region(vpmem->vdev, &pmem_region,
> > > +                                               VIRTIO_PMEM_SHMCAP_ID_PMEM_REGION);
> >
> > Current implementation of Virtio pmem device in Qemu does not expose
> > it as PCI BAR.
> > So, can't test it. Just curious if device side implementation is also
> > tested for asynchronous
> > flush case?
> >
> > Thanks,
> > Pankaj
>
> Yes, I tested the async flush case as well. We basically call
> FlushFileBuffers on the backing file, which is Windows' equivalent of
> fsync. I also briefly tested with qemu to ensure that still works with
> the patch.

Thank you for the confirmation. This sounds really good.
I am also getting back to pending items for virtio-pmem.

On a side question: Do you guys have any or plan for Windows guest
implementation
for virtio-pmem?

Thanks,
Pankaj