Track regions of the TVM guest physical address space #4
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Just like std::vec::Vec::insert. Signed-off-by: Andrew Bresticker <abrestic@rivosinc.com>
So that we can get a mutable iterator to the underlying vector. Also use
as{,_mut}_slice() to avoid the unsafe block.
Signed-off-by: Andrew Bresticker <abrestic@rivosinc.com>
copy_and_add_data_pages_builder() intializes and maps pages one-by-one so if copy_from_guest() fails in the middle of the range, we end up with a partially-mapped range of pages. Fix this by intializing the entire range first before mapping. Signed-off-by: Andrew Bresticker <abrestic@rivosinc.com>
dgreid
reviewed
Jun 28, 2022
In preparation for demand-filled pages, shared memory, and emulated MMIO introduce VmRegionList which keeps track of the regions in the guest physical address space. For now the only type of region we have is the memory that's fully populated prior to VM finalization. The region list is backed by an extra page that the host must donate during TvmCreate. Note that this could also be accomplished in the page table itself by flagging PTEs. That wastes much more memory however, in particular for regions which will never be populated (MMIO) or will likely only be sparsely populated (shared memory). Signed-off-by: Andrew Bresticker <abrestic@rivosinc.com>
There's no demand faulting currently and the direction we've decided to take going forward (for both shared memory and zero-fill-on-demand pages) is to forward the page fault to the host so that it can handle it by inserting a page. Signed-off-by: Andrew Bresticker <abrestic@rivosinc.com>
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LGTM, thanks! |
dgreid
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Jun 29, 2022
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Introduce
VmRegionListwhich tracks the distinct regions in a TVM's guest physical address space, similar in principle to KVMmemslots. This will be used in follow-on patches to support demand faulting of zero pages and emulated MMIO (and can also be used to support shared memory).Patches 1 and 2 are minor
PageVecfixes, patch 3 fixes an error path when mapping pages, patch 4 introduces the VM region tracking, and patch 5 removes hooks for handling demand faults when copying to/from the guest address space.