Daniel Prilik d49adc9005 sys_util: add MemoryMappingArena ... There is a hard-limit to the number of MemoryMaps that can be added to a KVM VM, a arch-dependent number defined as KVM_USER_MEM_SLOTS. e.g: on x86 this is 509 (512 - 3 internal slots). For most purposes, this isn't too much of an issue, but there are some cases where one might want to share a lot of mmaps with a Guest. e.g: virtio-fs uses a large cache region for mapping in slices of file fds directly into guest memory. If one tries to add a new KVM memory region for each mmap, the number of available slots is quickly exhausted. MemoryMappingArena is a way to work around this limitation by allocating a single KVM memory region for a large slice of memory, and then using mmap with MAP_FIXED to override slices of this "arena" hostside, thereby achieving the same effect without quickly exhausting the number of KVM memory region slots. BUG=chromium:936567 TEST=cargo test -p sys_util Change-Id: I89cc3b22cdba6756b2d76689176d7147cf238f07 Reviewed-on: https://chromium-review.googlesource.com/1546600 Commit-Ready: ChromeOS CL Exonerator Bot <chromiumos-cl-exonerator@appspot.gserviceaccount.com> Tested-by: kokoro <noreply+kokoro@google.com> Reviewed-by: Zach Reizner <zachr@chromium.org>		2019-04-12 14:50:03 -07:00
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src	sys_util: add MemoryMappingArena	2019-04-12 14:50:03 -07:00
tests	memory: Add methods to return error on short writes and reads	2019-01-13 03:23:13 -08:00
Cargo.toml	cargo: Sort all dependency lists in Cargo.toml	2019-04-09 01:55:14 -07:00