[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [PATCH 0/4] add support for vNVDIMM
On 01/20/16 14:54, Andrew Cooper wrote: > On 20/01/16 14:47, Zhang, Haozhong wrote: > > On 01/20/16 14:35, Stefano Stabellini wrote: > >> On Wed, 20 Jan 2016, Zhang, Haozhong wrote: > >>> On 01/20/16 12:43, Stefano Stabellini wrote: > >>>> On Wed, 20 Jan 2016, Tian, Kevin wrote: > >>>>>> From: Zhang, Haozhong > >>>>>> Sent: Tuesday, December 29, 2015 7:32 PM > >>>>>> > >>>>>> This patch series is the Xen part patch to provide virtual NVDIMM to > >>>>>> guest. The corresponding QEMU patch series is sent separately with the > >>>>>> title "[PATCH 0/2] add vNVDIMM support for Xen". > >>>>>> > >>>>>> * Background > >>>>>> > >>>>>> NVDIMM (Non-Volatile Dual In-line Memory Module) is going to be > >>>>>> supported on Intel's platform. NVDIMM devices are discovered via ACPI > >>>>>> and configured by _DSM method of NVDIMM device in ACPI. Some > >>>>>> documents can be found at > >>>>>> [1] ACPI 6: > >>>>>> http://www.uefi.org/sites/default/files/resources/ACPI_6.0.pdf > >>>>>> [2] NVDIMM Namespace: > >>>>>> http://pmem.io/documents/NVDIMM_Namespace_Spec.pdf > >>>>>> [3] DSM Interface Example: > >>>>>> http://pmem.io/documents/NVDIMM_DSM_Interface_Example.pdf > >>>>>> [4] Driver Writer's Guide: > >>>>>> http://pmem.io/documents/NVDIMM_Driver_Writers_Guide.pdf > >>>>>> > >>>>>> The upstream QEMU (commits 5c42eef ~ 70d1fb9) has added support to > >>>>>> provide virtual NVDIMM in PMEM mode, in which NVDIMM devices are > >>>>>> mapped into CPU's address space and are accessed via normal memory > >>>>>> read/write and three special instructions (clflushopt/clwb/pcommit). > >>>>>> > >>>>>> This patch series and the corresponding QEMU patch series enable Xen > >>>>>> to provide vNVDIMM devices to HVM domains. > >>>>>> > >>>>>> * Design > >>>>>> > >>>>>> Supporting vNVDIMM in PMEM mode has three requirements. > >>>>>> > >>>>> Although this design is about vNVDIMM, some background of how pNVDIMM > >>>>> is managed in Xen would be helpful to understand the whole design since > >>>>> in PMEM mode you need map pNVDIMM into GFN addr space so there's > >>>>> a matter of how pNVDIMM is allocated. > >>>> Yes, some background would be very helpful. Given that there are so many > >>>> moving parts on this (Xen, the Dom0 kernel, QEMU, hvmloader, libxl) > >>>> I suggest that we start with a design document for this feature. > >>> Let me prepare a design document. Basically, it would include > >>> following contents. Please let me know if you want anything additional > >>> to be included. > >> Thank you! > >> > >> > >>> * What NVDIMM is and how it is used > >>> * Software interface of NVDIMM > >>> - ACPI NFIT: what parameters are recorded and their usage > >>> - ACPI SSDT: what _DSM methods are provided and their functionality > >>> - New instructions: clflushopt/clwb/pcommit > >>> * How the linux kernel drives NVDIMM > >>> - ACPI parsing > >>> - Block device interface > >>> - Partition NVDIMM devices > >>> * How KVM/QEMU implements vNVDIMM > >> This is a very good start. > >> > >> > >>> * What I propose to implement vNVDIMM in Xen > >>> - Xen hypervisor/toolstack: new instruction enabling and address mapping > >>> - Dom0 Linux kernel: host NVDIMM driver > >>> - QEMU: virtual NFIT/SSDT, _DSM handling, and role in address mapping > >> This is OK. It might be also good to list other options that were > >> discussed, but it is certainly not necessary in first instance. > > I'll include them. > > > > And one thing missed above: > > * What I propose to implement vNVDIMM in Xen > > - Building vNFIT and vSSDT: copy them from QEMU to Xen toolstack > > > > I know it is controversial and will record other options and my reason > > for this choice. > > Please would you split the subjects of "how to architect guest NVDIMM > support in Xen" from "how to get suitable ACPI tables into a guest". > The former depends on the latter, but they are two different problems to > solve and shouldn't be conflated in one issue. > > ~Andrew > Sure. Haozhong _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxx http://lists.xen.org/xen-devel
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