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Subject[PATCH 37/52] KVM: Recalculate mmu pages needed for every memory region change
Date
From: Zhang Xiantao <xiantao.zhang@intel.com>

Instead of incrementally changing the mmu cache size for every memory slot
operation, recalculate it from scratch. This is simpler and safer.

Signed-off-by: Zhang Xiantao <xiantao.zhang@intel.com>
Signed-off-by: Avi Kivity <avi@qumranet.com>
---
drivers/kvm/kvm_main.c | 21 ++++-----------------
drivers/kvm/mmu.c | 19 +++++++++++++++++++
drivers/kvm/x86.h | 1 +
3 files changed, 24 insertions(+), 17 deletions(-)
diff --git a/drivers/kvm/kvm_main.c b/drivers/kvm/kvm_main.c
index f06fa3a..6a702e1 100644
--- a/drivers/kvm/kvm_main.c
+++ b/drivers/kvm/kvm_main.c
@@ -333,26 +333,13 @@ int __kvm_set_memory_region(struct kvm *kvm,
if (mem->slot >= kvm->nmemslots)
kvm->nmemslots = mem->slot + 1;

+ *memslot = new;
+
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);
- }
+ unsigned int nr_mmu_pages = kvm_mmu_calculate_mmu_pages(kvm);
+ kvm_mmu_change_mmu_pages(kvm, nr_mmu_pages);
}

- *memslot = new;
-
kvm_mmu_slot_remove_write_access(kvm, mem->slot);
kvm_flush_remote_tlbs(kvm);

diff --git a/drivers/kvm/mmu.c b/drivers/kvm/mmu.c
index 4624f37..101cd53 100644
--- a/drivers/kvm/mmu.c
+++ b/drivers/kvm/mmu.c
@@ -1535,6 +1535,25 @@ nomem:
return -ENOMEM;
}

+/*
+ * Caculate mmu pages needed for kvm.
+ */
+unsigned int kvm_mmu_calculate_mmu_pages(struct kvm *kvm)
+{
+ int i;
+ unsigned int nr_mmu_pages;
+ unsigned int nr_pages = 0;
+
+ for (i = 0; i < kvm->nmemslots; i++)
+ nr_pages += kvm->memslots[i].npages;
+
+ nr_mmu_pages = nr_pages * KVM_PERMILLE_MMU_PAGES / 1000;
+ nr_mmu_pages = max(nr_mmu_pages,
+ (unsigned int) KVM_MIN_ALLOC_MMU_PAGES);
+
+ return nr_mmu_pages;
+}
+
#ifdef AUDIT

static const char *audit_msg;
diff --git a/drivers/kvm/x86.h b/drivers/kvm/x86.h
index 90b791b..71f2477 100644
--- a/drivers/kvm/x86.h
+++ b/drivers/kvm/x86.h
@@ -236,6 +236,7 @@ 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);
+unsigned int kvm_mmu_calculate_mmu_pages(struct kvm *kvm);
void kvm_mmu_change_mmu_pages(struct kvm *kvm, unsigned int kvm_nr_mmu_pages);

enum emulation_result {
--
1.5.3.7


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