[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 14:35, 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. Thanks, Haozhong _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxx http://lists.xen.org/xen-devel
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