KVM: MMU: Move kvm_free_some_pages() into critical section
If some other cpu steals mmu pages between our check and an attempt to
allocate, we can run out of mmu pages. Fix by moving the check into the
same critical section as the allocation.
Signed-off-by: Avi Kivity <avi@qumranet.com>
diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
index 834698d..c478ee2 100644
--- a/arch/x86/kvm/mmu.c
+++ b/arch/x86/kvm/mmu.c
@@ -291,7 +291,6 @@
{
int r;
- kvm_mmu_free_some_pages(vcpu);
r = mmu_topup_memory_cache(&vcpu->arch.mmu_pte_chain_cache,
pte_chain_cache, 4);
if (r)
@@ -569,9 +568,6 @@
{
struct kvm_mmu_page *sp;
- if (!vcpu->kvm->arch.n_free_mmu_pages)
- return NULL;
-
sp = mmu_memory_cache_alloc(&vcpu->arch.mmu_page_header_cache, sizeof *sp);
sp->spt = mmu_memory_cache_alloc(&vcpu->arch.mmu_page_cache, PAGE_SIZE);
sp->gfns = mmu_memory_cache_alloc(&vcpu->arch.mmu_page_cache, PAGE_SIZE);
@@ -1024,6 +1020,7 @@
page = gfn_to_page(vcpu->kvm, gfn);
spin_lock(&vcpu->kvm->mmu_lock);
+ kvm_mmu_free_some_pages(vcpu);
r = __nonpaging_map(vcpu, v, write, gfn, page);
spin_unlock(&vcpu->kvm->mmu_lock);
@@ -1275,6 +1272,7 @@
if (r)
goto out;
spin_lock(&vcpu->kvm->mmu_lock);
+ kvm_mmu_free_some_pages(vcpu);
mmu_alloc_roots(vcpu);
spin_unlock(&vcpu->kvm->mmu_lock);
kvm_x86_ops->set_cr3(vcpu, vcpu->arch.mmu.root_hpa);
@@ -1413,6 +1411,7 @@
pgprintk("%s: gpa %llx bytes %d\n", __FUNCTION__, gpa, bytes);
mmu_guess_page_from_pte_write(vcpu, gpa, new, bytes);
spin_lock(&vcpu->kvm->mmu_lock);
+ kvm_mmu_free_some_pages(vcpu);
++vcpu->kvm->stat.mmu_pte_write;
kvm_mmu_audit(vcpu, "pre pte write");
if (gfn == vcpu->arch.last_pt_write_gfn
@@ -1505,7 +1504,6 @@
void __kvm_mmu_free_some_pages(struct kvm_vcpu *vcpu)
{
- spin_lock(&vcpu->kvm->mmu_lock);
while (vcpu->kvm->arch.n_free_mmu_pages < KVM_REFILL_PAGES) {
struct kvm_mmu_page *sp;
@@ -1514,7 +1512,6 @@
kvm_mmu_zap_page(vcpu->kvm, sp);
++vcpu->kvm->stat.mmu_recycled;
}
- spin_unlock(&vcpu->kvm->mmu_lock);
}
int kvm_mmu_page_fault(struct kvm_vcpu *vcpu, gva_t cr2, u32 error_code)
