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Message-Id: <20170811201158.24715-1-dvlasenk@redhat.com>
Date: Fri, 11 Aug 2017 22:11:58 +0200
From: Denys Vlasenko <dvlasenk@...hat.com>
To: Joerg Roedel <joro@...tes.org>
Cc: Denys Vlasenko <dvlasenk@...hat.com>, pbonzini@...hat.com,
rkrcmar@...hat.com, tglx@...utronix.de, mingo@...hat.com,
hpa@...or.com, x86@...nel.org, kvm@...r.kernel.org,
linux-kernel@...r.kernel.org
Subject: [PATCH] KVM: SVM: delete avic_vm_id_bitmap (2 megabyte static array)
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 <dvlasenk@...hat.com>
Cc: Joerg Roedel <joro@...tes.org>
Cc: pbonzini@...hat.com
Cc: rkrcmar@...hat.com
Cc: tglx@...utronix.de
Cc: mingo@...hat.com
Cc: hpa@...or.com
Cc: x86@...nel.org
Cc: kvm@...r.kernel.org
Cc: linux-kernel@...r.kernel.org
---
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 1107626..f575089 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);
--
2.9.2
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