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nvdimm: check -object memory-backend-file, readonly=on option
Check that -device nvdimm,unarmed=on is used when -object memory-backend-file,readonly=on and document that -device nvdimm,unarmed=on|off controls whether the NVDIMM appears read-only to the guest. Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com> Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com> Reviewed-by: Liam Merwick <liam.merwick@oracle.com> Acked-by: Michael S. Tsirkin <mst@redhat.com> Message-Id: <20210104171320.575838-4-stefanha@redhat.com> Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
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@ -17,8 +17,8 @@ following command line options:
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-machine pc,nvdimm
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-m $RAM_SIZE,slots=$N,maxmem=$MAX_SIZE
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-object memory-backend-file,id=mem1,share=on,mem-path=$PATH,size=$NVDIMM_SIZE
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-device nvdimm,id=nvdimm1,memdev=mem1
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-object memory-backend-file,id=mem1,share=on,mem-path=$PATH,size=$NVDIMM_SIZE,readonly=off
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-device nvdimm,id=nvdimm1,memdev=mem1,unarmed=off
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Where,
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@ -31,9 +31,10 @@ Where,
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of normal RAM devices and vNVDIMM devices, e.g. $MAX_SIZE should be
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>= $RAM_SIZE + $NVDIMM_SIZE here.
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- "object memory-backend-file,id=mem1,share=on,mem-path=$PATH,size=$NVDIMM_SIZE"
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creates a backend storage of size $NVDIMM_SIZE on a file $PATH. All
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accesses to the virtual NVDIMM device go to the file $PATH.
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- "object memory-backend-file,id=mem1,share=on,mem-path=$PATH,
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size=$NVDIMM_SIZE,readonly=off" creates a backend storage of size
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$NVDIMM_SIZE on a file $PATH. All accesses to the virtual NVDIMM device go
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to the file $PATH.
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"share=on/off" controls the visibility of guest writes. If
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"share=on", then guest writes will be applied to the backend
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@ -42,8 +43,17 @@ Where,
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"share=off", then guest writes won't be applied to the backend
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file and thus will be invisible to other guests.
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- "device nvdimm,id=nvdimm1,memdev=mem1" creates a virtual NVDIMM
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device whose storage is provided by above memory backend device.
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"readonly=on/off" controls whether the file $PATH is opened read-only or
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read/write (default).
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- "device nvdimm,id=nvdimm1,memdev=mem1,unarmed=off" creates a read/write
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virtual NVDIMM device whose storage is provided by above memory backend
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device.
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"unarmed" controls the ACPI NFIT NVDIMM Region Mapping Structure "NVDIMM
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State Flags" Bit 3 indicating that the device is "unarmed" and cannot accept
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persistent writes. Linux guest drivers set the device to read-only when this
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bit is present. Set unarmed to on when the memdev has readonly=on.
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Multiple vNVDIMM devices can be created if multiple pairs of "-object"
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and "-device" are provided.
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@ -146,6 +146,15 @@ static void nvdimm_prepare_memory_region(NVDIMMDevice *nvdimm, Error **errp)
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return;
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}
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if (!nvdimm->unarmed && memory_region_is_rom(mr)) {
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HostMemoryBackend *hostmem = dimm->hostmem;
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error_setg(errp, "'unarmed' property must be off since memdev %s "
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"is read-only",
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object_get_canonical_path_component(OBJECT(hostmem)));
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return;
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}
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nvdimm->nvdimm_mr = g_new(MemoryRegion, 1);
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memory_region_init_alias(nvdimm->nvdimm_mr, OBJECT(dimm),
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"nvdimm-memory", mr, 0, pmem_size);
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