From: Maciej S. Szmigiero Date: Mon, 6 Dec 2021 19:54:24 +0000 (+0100) Subject: KVM: x86: Use nr_memslot_pages to avoid traversing the memslots array X-Git-Url: http://git.osdn.net/view?a=commitdiff_plain;h=f5756029eef501bcd39ecd844968e4fb3055c1bd;p=uclinux-h8%2Flinux.git KVM: x86: Use nr_memslot_pages to avoid traversing the memslots array There is no point in recalculating from scratch the total number of pages in all memslots each time a memslot is created or deleted. Use KVM's cached nr_memslot_pages to compute the default max number of MMU pages. Note that even with nr_memslot_pages capped at ULONG_MAX we can't safely multiply it by KVM_PERMILLE_MMU_PAGES (20) since this operation can possibly overflow an unsigned long variable. Write this "* 20 / 1000" operation as "/ 50" instead to avoid such overflow. Signed-off-by: Maciej S. Szmigiero [sean: use common KVM field and rework changelog accordingly] Reviewed-by: Sean Christopherson Message-Id: --- diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h index d9f09535384b..552ed45f133b 100644 --- a/arch/x86/include/asm/kvm_host.h +++ b/arch/x86/include/asm/kvm_host.h @@ -135,7 +135,7 @@ #define KVM_HPAGE_MASK(x) (~(KVM_HPAGE_SIZE(x) - 1)) #define KVM_PAGES_PER_HPAGE(x) (KVM_HPAGE_SIZE(x) / PAGE_SIZE) -#define KVM_PERMILLE_MMU_PAGES 20 +#define KVM_MEMSLOT_PAGES_TO_MMU_PAGES_RATIO 50 #define KVM_MIN_ALLOC_MMU_PAGES 64UL #define KVM_MMU_HASH_SHIFT 12 #define KVM_NUM_MMU_PAGES (1 << KVM_MMU_HASH_SHIFT) @@ -1592,7 +1592,6 @@ void kvm_mmu_slot_leaf_clear_dirty(struct kvm *kvm, const struct kvm_memory_slot *memslot); void kvm_mmu_zap_all(struct kvm *kvm); void kvm_mmu_invalidate_mmio_sptes(struct kvm *kvm, u64 gen); -unsigned long kvm_mmu_calculate_default_mmu_pages(struct kvm *kvm); void kvm_mmu_change_mmu_pages(struct kvm *kvm, unsigned long kvm_nr_mmu_pages); int load_pdptrs(struct kvm_vcpu *vcpu, struct kvm_mmu *mmu, unsigned long cr3); diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c index e2e1d012df22..e41cf095f2d1 100644 --- a/arch/x86/kvm/mmu/mmu.c +++ b/arch/x86/kvm/mmu/mmu.c @@ -6150,30 +6150,6 @@ out: return ret; } -/* - * Calculate mmu pages needed for kvm. - */ -unsigned long kvm_mmu_calculate_default_mmu_pages(struct kvm *kvm) -{ - unsigned long nr_mmu_pages; - unsigned long nr_pages = 0; - struct kvm_memslots *slots; - struct kvm_memory_slot *memslot; - int i; - - for (i = 0; i < KVM_ADDRESS_SPACE_NUM; i++) { - slots = __kvm_memslots(kvm, i); - - kvm_for_each_memslot(memslot, slots) - nr_pages += memslot->npages; - } - - nr_mmu_pages = nr_pages * KVM_PERMILLE_MMU_PAGES / 1000; - nr_mmu_pages = max(nr_mmu_pages, KVM_MIN_ALLOC_MMU_PAGES); - - return nr_mmu_pages; -} - void kvm_mmu_destroy(struct kvm_vcpu *vcpu) { kvm_mmu_unload(vcpu); diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 29a030a3c797..73e0e40c94b6 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -11784,9 +11784,13 @@ void kvm_arch_commit_memory_region(struct kvm *kvm, enum kvm_mr_change change) { if (!kvm->arch.n_requested_mmu_pages && - (change == KVM_MR_CREATE || change == KVM_MR_DELETE)) - kvm_mmu_change_mmu_pages(kvm, - kvm_mmu_calculate_default_mmu_pages(kvm)); + (change == KVM_MR_CREATE || change == KVM_MR_DELETE)) { + unsigned long nr_mmu_pages; + + nr_mmu_pages = kvm->nr_memslot_pages / KVM_MEMSLOT_PAGES_TO_MMU_PAGES_RATIO; + nr_mmu_pages = max(nr_mmu_pages, KVM_MIN_ALLOC_MMU_PAGES); + kvm_mmu_change_mmu_pages(kvm, nr_mmu_pages); + } kvm_mmu_slot_apply_flags(kvm, old, new, change);