| Message ID | 20200916095150.755714-4-stefanha@redhat.com |
|---|---|
| State | New |
| Headers | show |
| Series | nvdimm: read-only file support | expand |
On Wed, 16 Sep 2020 10:51:50 +0100 Stefan Hajnoczi <stefanha@redhat.com> wrote: > Make it possible to present read-only files to the guest as "unarmed" > NVDIMMs. The Linux NVDIMM device (/dev/pmemX) is read-only. > > Acked-by: Michael S. Tsirkin <mst@redhat.com> > Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com> > Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com> > --- > docs/nvdimm.txt | 8 +++++++- > hw/mem/nvdimm.c | 4 ++++ > 2 files changed, 11 insertions(+), 1 deletion(-) > > diff --git a/docs/nvdimm.txt b/docs/nvdimm.txt > index c2c6e441b3..06c2008107 100644 > --- a/docs/nvdimm.txt > +++ b/docs/nvdimm.txt > @@ -17,7 +17,7 @@ following command line options: > > -machine pc,nvdimm > -m $RAM_SIZE,slots=$N,maxmem=$MAX_SIZE > - -object memory-backend-file,id=mem1,share=on,mem-path=$PATH,size=$NVDIMM_SIZE > + -object memory-backend-file,id=mem1,share=on,mem-path=$PATH,size=$NVDIMM_SIZE,readonly=off > -device nvdimm,id=nvdimm1,memdev=mem1 > > Where, > @@ -42,6 +42,12 @@ Where, > "share=off", then guest writes won't be applied to the backend > file and thus will be invisible to other guests. > > + "readonly=on/off" controls whether the file $PATH is opened read-only or > + read/write (default). "readonly=on" sets the ACPI NFIT NVDIMM Region Mapping > + Structure "NVDIMM State Flags" Bit 3 indicating that the device is "unarmed" > + and cannot accept persistent writes. Linux guest drivers set the device to > + read-only when this bit is present. > + > - "device nvdimm,id=nvdimm1,memdev=mem1" creates a virtual NVDIMM > device whose storage is provided by above memory backend device. > > diff --git a/hw/mem/nvdimm.c b/hw/mem/nvdimm.c > index e1574bc07c..848cd65917 100644 > --- a/hw/mem/nvdimm.c > +++ b/hw/mem/nvdimm.c > @@ -146,6 +146,10 @@ static void nvdimm_prepare_memory_region(NVDIMMDevice *nvdimm, Error **errp) > return; > } > > + if (memory_region_is_rom(mr)) { > + nvdimm->unarmed = true; /* this device is read-only */ > + } we probably should error out in case 'backend,readonly=true + nvdimm,unarmed=false' instead of silently ignoring user's input > nvdimm->nvdimm_mr = g_new(MemoryRegion, 1); > memory_region_init_alias(nvdimm->nvdimm_mr, OBJECT(dimm), > "nvdimm-memory", mr, 0, pmem_size);
On Mon, Dec 14, 2020 at 12:19:05PM +0100, Igor Mammedov wrote: > On Wed, 16 Sep 2020 10:51:50 +0100 > Stefan Hajnoczi <stefanha@redhat.com> wrote: > > diff --git a/hw/mem/nvdimm.c b/hw/mem/nvdimm.c > > index e1574bc07c..848cd65917 100644 > > --- a/hw/mem/nvdimm.c > > +++ b/hw/mem/nvdimm.c > > @@ -146,6 +146,10 @@ static void nvdimm_prepare_memory_region(NVDIMMDevice *nvdimm, Error **errp) > > return; > > } > > > > + if (memory_region_is_rom(mr)) { > > + nvdimm->unarmed = true; /* this device is read-only */ > > + } > we probably should error out in case 'backend,readonly=true + nvdimm,unarmed=false' > instead of silently ignoring user's input Will fix.
diff --git a/docs/nvdimm.txt b/docs/nvdimm.txt index c2c6e441b3..06c2008107 100644 --- a/docs/nvdimm.txt +++ b/docs/nvdimm.txt @@ -17,7 +17,7 @@ following command line options: -machine pc,nvdimm -m $RAM_SIZE,slots=$N,maxmem=$MAX_SIZE - -object memory-backend-file,id=mem1,share=on,mem-path=$PATH,size=$NVDIMM_SIZE + -object memory-backend-file,id=mem1,share=on,mem-path=$PATH,size=$NVDIMM_SIZE,readonly=off -device nvdimm,id=nvdimm1,memdev=mem1 Where, @@ -42,6 +42,12 @@ Where, "share=off", then guest writes won't be applied to the backend file and thus will be invisible to other guests. + "readonly=on/off" controls whether the file $PATH is opened read-only or + read/write (default). "readonly=on" sets the ACPI NFIT NVDIMM Region Mapping + Structure "NVDIMM State Flags" Bit 3 indicating that the device is "unarmed" + and cannot accept persistent writes. Linux guest drivers set the device to + read-only when this bit is present. + - "device nvdimm,id=nvdimm1,memdev=mem1" creates a virtual NVDIMM device whose storage is provided by above memory backend device. diff --git a/hw/mem/nvdimm.c b/hw/mem/nvdimm.c index e1574bc07c..848cd65917 100644 --- a/hw/mem/nvdimm.c +++ b/hw/mem/nvdimm.c @@ -146,6 +146,10 @@ static void nvdimm_prepare_memory_region(NVDIMMDevice *nvdimm, Error **errp) return; } + if (memory_region_is_rom(mr)) { + nvdimm->unarmed = true; /* this device is read-only */ + } + nvdimm->nvdimm_mr = g_new(MemoryRegion, 1); memory_region_init_alias(nvdimm->nvdimm_mr, OBJECT(dimm), "nvdimm-memory", mr, 0, pmem_size);