On Wed, 2022-02-23 at 16:53 +0000, Sean Christopherson wrote: > Don't actually set a request bit in vcpu->requests when making a request > purely to force a vCPU to exit the guest. Logging a request but not > actually consuming it would cause the vCPU to get stuck in an infinite > loop during KVM_RUN because KVM would see the pending request and bail > from VM-Enter to service the request. > > Note, it's currently impossible for KVM to set KVM_REQ_GPC_INVALIDATE as > nothing in KVM is wired up to set guest_uses_pa=true. But, it'd be all > too easy for arch code to introduce use of kvm_gfn_to_pfn_cache_init() > without implementing handling of the request, especially since getting > test coverage of MMU notifier interaction with specific KVM features > usually requires a directed test. > > Opportunistically rename gfn_to_pfn_cache_invalidate_start()'s wake_vcpus > to evict_vcpus. The purpose of the request is to get vCPUs out of guest > mode, it's supposed to _avoid_ waking vCPUs that are blocking. > > Opportunistically rename KVM_REQ_GPC_INVALIDATE to be more specific as to > what it wants to accomplish, and to genericize the name so that it can > used for similar but unrelated scenarios, should they arise in the future. > Add a comment and documentation to explain why the "no action" request > exists. > > Add compile-time assertions to help detect improper usage. Use the inner > assertless helper in the one s390 path that makes requests without a > hardcoded request. > > Cc: David Woodhouse <dwmw@xxxxxxxxxxxx> > Signed-off-by: Sean Christopherson <seanjc@xxxxxxxxxx> > --- > > v2: > - Rewrite changelog and drop Fixes:, no bug currently exists. [David] > - Rebase to kvm/queue. Acked-by: David Woodhouse <dwmw@xxxxxxxxxxxx> But please could you rebase it on your other patch, which I have included into my xen-evtchn-kernel branch https://git.infradead.org/users/dwmw2/linux.git/commitdiff/48bc5fddd6ed https://git.infradead.org/users/dwmw2/linux.git/shortlog/refs/heads/xen-evtchn-kernel I'll be sending that out as a proper 'v1' series just as soon as I've finished writing the unit tests; the rest I think is ready (and working with actual guests in testing).
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