From 3f0d4db7579c471ae9873e953e220943924c7ea0 Mon Sep 17 00:00:00 2001 From: Denys Vlasenko Date: Fri, 11 Aug 2017 22:11:58 +0200 Subject: [PATCH] KVM: SVM: delete avic_vm_id_bitmap (2 megabyte static array) MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit With lightly tweaked defconfig: text data bss dec hex filename 11259661 5109408 2981888 19350957 12745ad vmlinux.before 11259661 5109408 884736 17253805 10745ad vmlinux.after Only compile-tested. Signed-off-by: Denys Vlasenko Cc: Joerg Roedel Cc: pbonzini@redhat.com Cc: rkrcmar@redhat.com Cc: tglx@linutronix.de Cc: mingo@redhat.com Cc: hpa@zytor.com Cc: x86@kernel.org Cc: kvm@vger.kernel.org Cc: linux-kernel@vger.kernel.org Signed-off-by: Radim Krčmář --- arch/x86/kvm/svm.c | 61 ++++++++++++++++------------------------------ 1 file changed, 21 insertions(+), 40 deletions(-) diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c index a603d0c14a5a..36812876f371 100644 --- a/arch/x86/kvm/svm.c +++ b/arch/x86/kvm/svm.c @@ -280,10 +280,6 @@ module_param(avic, int, S_IRUGO); static int vls = true; module_param(vls, int, 0444); -/* AVIC VM ID bit masks and lock */ -static DECLARE_BITMAP(avic_vm_id_bitmap, AVIC_VM_ID_NR); -static DEFINE_SPINLOCK(avic_vm_id_lock); - static void svm_set_cr0(struct kvm_vcpu *vcpu, unsigned long cr0); static void svm_flush_tlb(struct kvm_vcpu *vcpu); static void svm_complete_interrupts(struct vcpu_svm *svm); @@ -989,6 +985,8 @@ static void disable_nmi_singlestep(struct vcpu_svm *svm) */ #define SVM_VM_DATA_HASH_BITS 8 static DEFINE_HASHTABLE(svm_vm_data_hash, SVM_VM_DATA_HASH_BITS); +static u32 next_vm_id = 0; +static bool next_vm_id_wrapped = 0; static DEFINE_SPINLOCK(svm_vm_data_hash_lock); /* Note: @@ -1387,34 +1385,6 @@ static int avic_init_backing_page(struct kvm_vcpu *vcpu) return 0; } -static inline int avic_get_next_vm_id(void) -{ - int id; - - spin_lock(&avic_vm_id_lock); - - /* AVIC VM ID is one-based. */ - id = find_next_zero_bit(avic_vm_id_bitmap, AVIC_VM_ID_NR, 1); - if (id <= AVIC_VM_ID_MASK) - __set_bit(id, avic_vm_id_bitmap); - else - id = -EAGAIN; - - spin_unlock(&avic_vm_id_lock); - return id; -} - -static inline int avic_free_vm_id(int id) -{ - if (id <= 0 || id > AVIC_VM_ID_MASK) - return -EINVAL; - - spin_lock(&avic_vm_id_lock); - __clear_bit(id, avic_vm_id_bitmap); - spin_unlock(&avic_vm_id_lock); - return 0; -} - static void avic_vm_destroy(struct kvm *kvm) { unsigned long flags; @@ -1423,8 +1393,6 @@ static void avic_vm_destroy(struct kvm *kvm) if (!avic) return; - avic_free_vm_id(vm_data->avic_vm_id); - if (vm_data->avic_logical_id_table_page) __free_page(vm_data->avic_logical_id_table_page); if (vm_data->avic_physical_id_table_page) @@ -1438,19 +1406,16 @@ static void avic_vm_destroy(struct kvm *kvm) static int avic_vm_init(struct kvm *kvm) { unsigned long flags; - int vm_id, err = -ENOMEM; + int err = -ENOMEM; struct kvm_arch *vm_data = &kvm->arch; struct page *p_page; struct page *l_page; + struct kvm_arch *ka; + u32 vm_id; if (!avic) return 0; - vm_id = avic_get_next_vm_id(); - if (vm_id < 0) - return vm_id; - vm_data->avic_vm_id = (u32)vm_id; - /* Allocating physical APIC ID table (4KB) */ p_page = alloc_page(GFP_KERNEL); if (!p_page) @@ -1468,6 +1433,22 @@ static int avic_vm_init(struct kvm *kvm) clear_page(page_address(l_page)); spin_lock_irqsave(&svm_vm_data_hash_lock, flags); + again: + vm_id = next_vm_id = (next_vm_id + 1) & AVIC_VM_ID_MASK; + if (vm_id == 0) { /* id is 1-based, zero is not okay */ + next_vm_id_wrapped = 1; + goto again; + } + /* Is it still in use? Only possible if wrapped at least once */ + if (next_vm_id_wrapped) { + hash_for_each_possible(svm_vm_data_hash, ka, hnode, vm_id) { + struct kvm *k2 = container_of(ka, struct kvm, arch); + struct kvm_arch *vd2 = &k2->arch; + if (vd2->avic_vm_id == vm_id) + goto again; + } + } + vm_data->avic_vm_id = vm_id; hash_add(svm_vm_data_hash, &vm_data->hnode, vm_data->avic_vm_id); spin_unlock_irqrestore(&svm_vm_data_hash_lock, flags);