[PATCH 35/34] KVM: Prepare for handling only shared mappings in mmu_notifier events
From: Paolo Bonzini <pbonzini@redhat.com>
Date: 2023-11-05 16:35:44
Also in:
kvm, kvm-riscv, kvmarm, linux-arm-kernel, linux-fsdevel, linux-mips, linux-mm, linux-riscv, lkml
Subsystem:
kernel virtual machine (kvm), the rest · Maintainers:
Paolo Bonzini, Linus Torvalds
From: Sean Christopherson <seanjc@google.com> Add flags to "struct kvm_gfn_range" to let notifier events target only shared and only private mappings, and write up the existing mmu_notifier events to be shared-only (private memory is never associated with a userspace virtual address, i.e. can't be reached via mmu_notifiers). Add two flags so that KVM can handle the three possibilities (shared, private, and shared+private) without needing something like a tri-state enum. Link: https://lore.kernel.org/all/ZJX0hk+KpQP0KUyB@google.com (local) Signed-off-by: Sean Christopherson <seanjc@google.com> Message-Id: [ref] Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> --- include/linux/kvm_host.h | 2 ++ virt/kvm/kvm_main.c | 17 +++++++++++++++++ 2 files changed, 19 insertions(+)
diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index 3ebc6912c54a..4d5d139b0bde 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h@@ -264,6 +264,8 @@ struct kvm_gfn_range { gfn_t start; gfn_t end; union kvm_mmu_notifier_arg arg; + bool only_private; + bool only_shared; bool may_block; }; bool kvm_unmap_gfn_range(struct kvm *kvm, struct kvm_gfn_range *range);
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 8758cb799e18..9170a61ea99f 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c@@ -635,6 +635,13 @@ static __always_inline kvm_mn_ret_t __kvm_handle_hva_range(struct kvm *kvm, * the second or later invocation of the handler). */ gfn_range.arg = range->arg; + + /* + * HVA-based notifications provide a userspace address, + * and as such are only relevant for shared mappings. + */ + gfn_range.only_private = false; + gfn_range.only_shared = true; gfn_range.may_block = range->may_block; /*
@@ -2493,6 +2500,16 @@ static __always_inline void kvm_handle_gfn_range(struct kvm *kvm, gfn_range.arg = range->arg; gfn_range.may_block = range->may_block; + /* + * If/when KVM supports more attributes beyond private .vs shared, this + * _could_ set only_{private,shared} appropriately if the entire target + * range already has the desired private vs. shared state (it's unclear + * if that is a net win). For now, KVM reaches this point if and only + * if the private flag is being toggled, i.e. all mappings are in play. + */ + gfn_range.only_private = false; + gfn_range.only_shared = false; + for (i = 0; i < kvm_arch_nr_memslot_as_ids(kvm); i++) { slots = __kvm_memslots(kvm, i);
--
2.39.1