[PATCH 22/50] KVM: Allow dynamic allocation of the mmu shadow cache size
From: Avi Kivity
Date: Sun Dec 23 2007 - 09:58:24 EST
From: Izik Eidus <izike@xxxxxxxxxxxx>
The user is now able to set how many mmu pages will be allocated to the guest.
Signed-off-by: Izik Eidus <izike@xxxxxxxxxxxx>
Signed-off-by: Avi Kivity <avi@xxxxxxxxxxxx>
---
drivers/kvm/kvm.h | 7 ++++++-
drivers/kvm/kvm_main.c | 47 +++++++++++++++++++++++++++++++++++++++++++++++
drivers/kvm/mmu.c | 40 ++++++++++++++++++++++++++++++++++++++--
include/linux/kvm.h | 3 +++
4 files changed, 94 insertions(+), 3 deletions(-)
diff --git a/drivers/kvm/kvm.h b/drivers/kvm/kvm.h
index 1965438..9f10c37 100644
--- a/drivers/kvm/kvm.h
+++ b/drivers/kvm/kvm.h
@@ -40,6 +40,8 @@
#define KVM_MAX_VCPUS 4
#define KVM_ALIAS_SLOTS 4
#define KVM_MEMORY_SLOTS 8
+#define KVM_PERMILLE_MMU_PAGES 20
+#define KVM_MIN_ALLOC_MMU_PAGES 64
#define KVM_NUM_MMU_PAGES 1024
#define KVM_MIN_FREE_MMU_PAGES 5
#define KVM_REFILL_PAGES 25
@@ -418,7 +420,9 @@ struct kvm {
* Hash table of struct kvm_mmu_page.
*/
struct list_head active_mmu_pages;
- int n_free_mmu_pages;
+ unsigned int n_free_mmu_pages;
+ unsigned int n_requested_mmu_pages;
+ unsigned int n_alloc_mmu_pages;
struct hlist_head mmu_page_hash[KVM_NUM_MMU_PAGES];
struct kvm_vcpu *vcpus[KVM_MAX_VCPUS];
unsigned long rmap_overflow;
@@ -547,6 +551,7 @@ void kvm_mmu_set_nonpresent_ptes(u64 trap_pte, u64 notrap_pte);
int kvm_mmu_reset_context(struct kvm_vcpu *vcpu);
void kvm_mmu_slot_remove_write_access(struct kvm *kvm, int slot);
void kvm_mmu_zap_all(struct kvm *kvm);
+void kvm_mmu_change_mmu_pages(struct kvm *kvm, unsigned int kvm_nr_mmu_pages);
hpa_t gpa_to_hpa(struct kvm_vcpu *vcpu, gpa_t gpa);
#define HPA_MSB ((sizeof(hpa_t) * 8) - 1)
diff --git a/drivers/kvm/kvm_main.c b/drivers/kvm/kvm_main.c
index 3d1972e..d220e63 100644
--- a/drivers/kvm/kvm_main.c
+++ b/drivers/kvm/kvm_main.c
@@ -743,6 +743,24 @@ static int kvm_vm_ioctl_set_memory_region(struct kvm *kvm,
if (mem->slot >= kvm->nmemslots)
kvm->nmemslots = mem->slot + 1;
+ if (!kvm->n_requested_mmu_pages) {
+ unsigned int n_pages;
+
+ if (npages) {
+ n_pages = npages * KVM_PERMILLE_MMU_PAGES / 1000;
+ kvm_mmu_change_mmu_pages(kvm, kvm->n_alloc_mmu_pages +
+ n_pages);
+ } else {
+ unsigned int nr_mmu_pages;
+
+ n_pages = old.npages * KVM_PERMILLE_MMU_PAGES / 1000;
+ nr_mmu_pages = kvm->n_alloc_mmu_pages - n_pages;
+ nr_mmu_pages = max(nr_mmu_pages,
+ (unsigned int) KVM_MIN_ALLOC_MMU_PAGES);
+ kvm_mmu_change_mmu_pages(kvm, nr_mmu_pages);
+ }
+ }
+
*memslot = new;
kvm_mmu_slot_remove_write_access(kvm, mem->slot);
@@ -760,6 +778,26 @@ out:
return r;
}
+static int kvm_vm_ioctl_set_nr_mmu_pages(struct kvm *kvm,
+ u32 kvm_nr_mmu_pages)
+{
+ if (kvm_nr_mmu_pages < KVM_MIN_ALLOC_MMU_PAGES)
+ return -EINVAL;
+
+ mutex_lock(&kvm->lock);
+
+ kvm_mmu_change_mmu_pages(kvm, kvm_nr_mmu_pages);
+ kvm->n_requested_mmu_pages = kvm_nr_mmu_pages;
+
+ mutex_unlock(&kvm->lock);
+ return 0;
+}
+
+static int kvm_vm_ioctl_get_nr_mmu_pages(struct kvm *kvm)
+{
+ return kvm->n_alloc_mmu_pages;
+}
+
/*
* Get (and clear) the dirty memory log for a memory slot.
*/
@@ -3071,6 +3109,14 @@ static long kvm_vm_ioctl(struct file *filp,
goto out;
break;
}
+ case KVM_SET_NR_MMU_PAGES:
+ r = kvm_vm_ioctl_set_nr_mmu_pages(kvm, arg);
+ if (r)
+ goto out;
+ break;
+ case KVM_GET_NR_MMU_PAGES:
+ r = kvm_vm_ioctl_get_nr_mmu_pages(kvm);
+ break;
case KVM_GET_DIRTY_LOG: {
struct kvm_dirty_log log;
@@ -3278,6 +3324,7 @@ static long kvm_dev_ioctl(struct file *filp,
switch (ext) {
case KVM_CAP_IRQCHIP:
case KVM_CAP_HLT:
+ case KVM_CAP_MMU_SHADOW_CACHE_CONTROL:
r = 1;
break;
default:
diff --git a/drivers/kvm/mmu.c b/drivers/kvm/mmu.c
index 72757db..6cda1fe 100644
--- a/drivers/kvm/mmu.c
+++ b/drivers/kvm/mmu.c
@@ -747,6 +747,40 @@ static void kvm_mmu_zap_page(struct kvm *kvm,
kvm_mmu_reset_last_pte_updated(kvm);
}
+/*
+ * Changing the number of mmu pages allocated to the vm
+ * Note: if kvm_nr_mmu_pages is too small, you will get dead lock
+ */
+void kvm_mmu_change_mmu_pages(struct kvm *kvm, unsigned int kvm_nr_mmu_pages)
+{
+ /*
+ * If we set the number of mmu pages to be smaller be than the
+ * number of actived pages , we must to free some mmu pages before we
+ * change the value
+ */
+
+ if ((kvm->n_alloc_mmu_pages - kvm->n_free_mmu_pages) >
+ kvm_nr_mmu_pages) {
+ int n_used_mmu_pages = kvm->n_alloc_mmu_pages
+ - kvm->n_free_mmu_pages;
+
+ while (n_used_mmu_pages > kvm_nr_mmu_pages) {
+ struct kvm_mmu_page *page;
+
+ page = container_of(kvm->active_mmu_pages.prev,
+ struct kvm_mmu_page, link);
+ kvm_mmu_zap_page(kvm, page);
+ n_used_mmu_pages--;
+ }
+ kvm->n_free_mmu_pages = 0;
+ }
+ else
+ kvm->n_free_mmu_pages += kvm_nr_mmu_pages
+ - kvm->n_alloc_mmu_pages;
+
+ kvm->n_alloc_mmu_pages = kvm_nr_mmu_pages;
+}
+
static int kvm_mmu_unprotect_page(struct kvm_vcpu *vcpu, gfn_t gfn)
{
unsigned index;
@@ -1297,8 +1331,10 @@ static int alloc_mmu_pages(struct kvm_vcpu *vcpu)
ASSERT(vcpu);
- vcpu->kvm->n_free_mmu_pages = KVM_NUM_MMU_PAGES;
-
+ if (vcpu->kvm->n_requested_mmu_pages)
+ vcpu->kvm->n_free_mmu_pages = vcpu->kvm->n_requested_mmu_pages;
+ else
+ vcpu->kvm->n_free_mmu_pages = vcpu->kvm->n_alloc_mmu_pages;
/*
* When emulating 32-bit mode, cr3 is only 32 bits even on x86_64.
* Therefore we need to allocate shadow page tables in the first
diff --git a/include/linux/kvm.h b/include/linux/kvm.h
index 057a7f3..d2fd973 100644
--- a/include/linux/kvm.h
+++ b/include/linux/kvm.h
@@ -347,11 +347,14 @@ struct kvm_signal_mask {
*/
#define KVM_CAP_IRQCHIP 0
#define KVM_CAP_HLT 1
+#define KVM_CAP_MMU_SHADOW_CACHE_CONTROL 2
/*
* ioctls for VM fds
*/
#define KVM_SET_MEMORY_REGION _IOW(KVMIO, 0x40, struct kvm_memory_region)
+#define KVM_SET_NR_MMU_PAGES _IO(KVMIO, 0x44)
+#define KVM_GET_NR_MMU_PAGES _IO(KVMIO, 0x45)
/*
* KVM_CREATE_VCPU receives as a parameter the vcpu slot, and returns
* a vcpu fd.
--
1.5.3.7
--
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