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<lkp@xxxxxxxxx>.
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<butterflyhuangxx@xxxxxxxxx>.
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
