[PATCH v5 00/12] KVM: x86/xen: Add in-kernel Xen event channel delivery
pbonzini at redhat.com
Thu Dec 9 10:34:45 PST 2021
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 at 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<butterflyhuangxx at 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.
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