Merge tag 'kvm-x86-fixes-6.15-rcN' of https://github.com/kvm-x86/linux into HEAD

Merge tag 'kvm-x86-fixes-6.15-rcN' of https://github.com/kvm-x86/linux into HEAD

KVM x86 fixes for 6.15-rcN

 - Forcibly leave SMM on SHUTDOWN interception on AMD CPUs to avoid causing
   problems due to KVM stuffing INIT on SHUTDOWN (KVM needs to sanitize the
   VMCB as its state is undefined after SHUTDOWN, emulating INIT is the
   least awful choice).

 - Track the valid sync/dirty fields in kvm_run as a u64 to ensure KVM
   KVM doesn't goof a sanity check in the future.

 - Free obsolete roots when (re)loading the MMU to fix a bug where
   pre-faulting memory can get stuck due to always encountering a stale
   root.

 - When dumping GHCB state, use KVM's snapshot instead of the raw GHCB page
   to print state, so that KVM doesn't print stale/wrong information.

 - When changing memory attributes (e.g. shared <=> private), add potential
   hugepage ranges to the mmu_invalidate_range_{start,end} set so that KVM
   doesn't create a shared/private hugepage when the the corresponding
   attributes will become mixed (the attributes are commited *after* KVM
   finishes the invalidation).

 - Rework the SRSO mitigation to enable BP_SPEC_REDUCE only when KVM has at
   least one active VM.  Effectively BP_SPEC_REDUCE when KVM is loaded led
   to very measurable performance regressions for non-KVM workloads.