On 11/21/21 13:54, David Woodhouse wrote:
Introduce the basic concept of 2 level event channels for kernel delivery, which is just a simple matter of a few test_and_set_bit calls on a mapped shared info page.This can be used for routing MSI of passthrough devices to PIRQ event channels in a Xen guest, and we can build on it for delivering IPIs and timers directly from the kernel too. v1: Use kvm_map_gfn() although I didn't quite see how it works. v2: Avoid kvm_map_gfn() and implement a safe mapping with invalidation support for myself. v3: Reinvent gfn_to_pfn_cache with sane invalidation semantics, for my use case as well as nesting. v4: Rework dirty handling, as it became apparently that we need an active vCPU context to mark pages dirty so it can't be done from the MMU notifier duing the invalidation; it has to happen on unmap. v5: Fix sparse warnings reported by kernel test robot<l...@intel.com>. Fix revalidation when memslots change but the resulting HVA stays the same. We can use the same kernel mapping in that case, if the HVA → PFN translation was valid before. So that probably means we shouldn't unmap the "old_hva". Augment the test case to exercise that one too. Include the fix for the dirty ring vs. Xen shinfo oops reported by butt3rflyh4ck<butterflyhuan...@gmail.com>. As in the previous two rounds, the last patch (this time patch 12) is included as illustration of how we*might* use this for fixing the UAF bugs in nesting, but isn't intended to be applied as-is. Patches 1-11 are.
Queued 1-7, will be on kvm/next tomorrow though. Paolo
