From: Sean Christopherson Date: Fri, 11 Oct 2024 02:10:45 +0000 (-0700) Subject: KVM: x86/mmu: Process only valid TDP MMU roots when aging a gfn range X-Git-Tag: v6.13-rc1~97^2~13^2~15 X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=526e609f05676c21aeed6c04115ae777c40081ec;p=thirdparty%2Fkernel%2Flinux.git KVM: x86/mmu: Process only valid TDP MMU roots when aging a gfn range Skip invalid TDP MMU roots when aging a gfn range. There is zero reason to process invalid roots, as they by definition hold stale information. E.g. if a root is invalid because its from a previous memslot generation, in the unlikely event the root has a SPTE for the gfn, then odds are good that the gfn=>hva mapping is different, i.e. doesn't map to the hva that is being aged by the primary MMU. Link: https://lore.kernel.org/r/20241011021051.1557902-14-seanjc@google.com Signed-off-by: Sean Christopherson --- diff --git a/arch/x86/kvm/mmu/tdp_mmu.c b/arch/x86/kvm/mmu/tdp_mmu.c index f77927b57962b..e8c061bf94ec8 100644 --- a/arch/x86/kvm/mmu/tdp_mmu.c +++ b/arch/x86/kvm/mmu/tdp_mmu.c @@ -1205,9 +1205,11 @@ static __always_inline bool kvm_tdp_mmu_handle_gfn(struct kvm *kvm, /* * Don't support rescheduling, none of the MMU notifiers that funnel - * into this helper allow blocking; it'd be dead, wasteful code. + * into this helper allow blocking; it'd be dead, wasteful code. Note, + * this helper must NOT be used to unmap GFNs, as it processes only + * valid roots! */ - for_each_tdp_mmu_root(kvm, root, range->slot->as_id) { + for_each_valid_tdp_mmu_root(kvm, root, range->slot->as_id) { rcu_read_lock(); tdp_root_for_each_leaf_pte(iter, root, range->start, range->end)