[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [RFC XEN PATCH v2 00/15] Add vNVDIMM support to HVM domains
On Sat, Apr 1, 2017 at 4:54 AM, Konrad Rzeszutek Wilk <konrad@xxxxxxxxxx> wrote: > ..snip.. >> >> Is there a resource I can read more about why the hypervisor needs to >> >> have this M2P mapping for nvdimm support? >> > >> > M2P is basically an array of frame numbers. It's indexed by the host >> > page frame number, or the machine frame number (MFN) in Xen's >> > definition. The n'th entry records the guest page frame number that is >> > mapped to MFN n. M2P is one of the core data structures used in Xen >> > memory management, and is used to convert MFN to guest PFN. A >> > read-only version of M2P is also exposed as part of ABI to guest. In >> > the previous design discussion, we decided to put the management of >> > NVDIMM in the existing Xen memory management as much as possible, so >> > we need to build M2P for NVDIMM as well. >> > >> >> Thanks, but what I don't understand is why this M2P lookup is needed? > > Xen uses it to construct the EPT page tables for the guests. > >> Does Xen establish this metadata for PCI mmio ranges as well? What Xen > > It doesn't have that (M2P) for PCI MMIO ranges. For those it has an > ranges construct (since those are usually contingous and given > in ranges to a guest). So, I'm confused again. This patchset / enabling requires both M2P and contiguous PMEM ranges. If the PMEM is contiguous it seems you don't need M2P and can just reuse the MMIO enabling, or am I missing something? _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxx https://lists.xen.org/xen-devel
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