diff options
| author | Ben Gardon <bgardon@google.com> | 2021-05-18 10:34:14 -0700 |
|---|---|---|
| committer | Paolo Bonzini <pbonzini@redhat.com> | 2021-06-17 13:09:27 -0400 |
| commit | d501f747ef5c0ac0c917f9a6781d04ae4ae39d63 (patch) | |
| tree | 4e083219aaff30031d8df1fb0463279ba0cba222 /arch/x86/kvm/mmu/tdp_mmu.c | |
| parent | e2209710ccc5d28d8b88c822d2f3e03b269a2856 (diff) | |
KVM: x86/mmu: Lazily allocate memslot rmaps
If the TDP MMU is in use, wait to allocate the rmaps until the shadow
MMU is actually used. (i.e. a nested VM is launched.) This saves memory
equal to 0.2% of guest memory in cases where the TDP MMU is used and
there are no nested guests involved.
Signed-off-by: Ben Gardon <bgardon@google.com>
Message-Id: <20210518173414.450044-8-bgardon@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'arch/x86/kvm/mmu/tdp_mmu.c')
| -rw-r--r-- | arch/x86/kvm/mmu/tdp_mmu.c | 6 |
1 files changed, 4 insertions, 2 deletions
diff --git a/arch/x86/kvm/mmu/tdp_mmu.c b/arch/x86/kvm/mmu/tdp_mmu.c index 6b6dfcdcb179..cc13e001f3de 100644 --- a/arch/x86/kvm/mmu/tdp_mmu.c +++ b/arch/x86/kvm/mmu/tdp_mmu.c @@ -14,10 +14,10 @@ static bool __read_mostly tdp_mmu_enabled = false; module_param_named(tdp_mmu, tdp_mmu_enabled, bool, 0644); /* Initializes the TDP MMU for the VM, if enabled. */ -void kvm_mmu_init_tdp_mmu(struct kvm *kvm) +bool kvm_mmu_init_tdp_mmu(struct kvm *kvm) { if (!tdp_enabled || !READ_ONCE(tdp_mmu_enabled)) - return; + return false; /* This should not be changed for the lifetime of the VM. */ kvm->arch.tdp_mmu_enabled = true; @@ -25,6 +25,8 @@ void kvm_mmu_init_tdp_mmu(struct kvm *kvm) INIT_LIST_HEAD(&kvm->arch.tdp_mmu_roots); spin_lock_init(&kvm->arch.tdp_mmu_pages_lock); INIT_LIST_HEAD(&kvm->arch.tdp_mmu_pages); + + return true; } static __always_inline void kvm_lockdep_assert_mmu_lock_held(struct kvm *kvm, |