[PATCH 30/33] KVM: MMU: Detect oom conditions and propagate error to userspace

Avi Kivity
2007-01-04T16:19:07Z

@@ -166,19 +166,20 @@ static int is_rmap_pte(u64 pte)
== (PT_WRITABLE_MASK | PT_PRESENT_MASK);
}

-static void mmu_topup_memory_cache(struct kvm_mmu_memory_cache *cache,
- size_t objsize, int min)
+static int mmu_topup_memory_cache(struct kvm_mmu_memory_cache *cache,
+ size_t objsize, int min)
{
void *obj;

if (cache->nobjs >= min)
- return;
+ return 0;
while (cache->nobjs < ARRAY_SIZE(cache->objects)) {
obj = kzalloc(objsize, GFP_NOWAIT);
if (!obj)
- BUG();
+ return -ENOMEM;
cache->objects[cache->nobjs++] = obj;
}
+ return 0;
}

static void mmu_free_memory_cache(struct kvm_mmu_memory_cache *mc)
@@ -187,12 +188,18 @@ static void mmu_free_memory_cache(struct
kfree(mc->objects[--mc->nobjs]);
}

-static void mmu_topup_memory_caches(struct kvm_vcpu *vcpu)
+static int mmu_topup_memory_caches(struct kvm_vcpu *vcpu)
{
- mmu_topup_memory_cache(&vcpu->mmu_pte_chain_cache,
- sizeof(struct kvm_pte_chain), 4);
- mmu_topup_memory_cache(&vcpu->mmu_rmap_desc_cache,
- sizeof(struct kvm_rmap_desc), 1);
+ int r;
+
+ r = mmu_topup_memory_cache(&vcpu->mmu_pte_chain_cache,
+ sizeof(struct kvm_pte_chain), 4);
+ if (r)
+ goto out;
+ r = mmu_topup_memory_cache(&vcpu->mmu_rmap_desc_cache,
+ sizeof(struct kvm_rmap_desc), 1);
+out:
+ return r;
}

static void mmu_free_memory_caches(struct kvm_vcpu *vcpu)
@@ -824,8 +831,11 @@ static int nonpaging_page_fault(struct k
{
gpa_t addr = gva;
hpa_t paddr;
+ int r;

- mmu_topup_memory_caches(vcpu);
+ r = mmu_topup_memory_caches(vcpu);
+ if (r)
+ return r;

ASSERT(vcpu);
ASSERT(VALID_PAGE(vcpu->mmu.root_hpa));
@@ -1052,7 +1062,7 @@ int kvm_mmu_reset_context(struct kvm_vcp
r = init_kvm_mmu(vcpu);
if (r < 0)
goto out;
- mmu_topup_memory_caches(vcpu);
+ r = mmu_topup_memory_caches(vcpu);
out:
return r;
}
Index: linux-2.6/drivers/kvm/svm.c
===================================================================
--- linux-2.6.orig/drivers/kvm/svm.c
+++ linux-2.6/drivers/kvm/svm.c
@@ -852,6 +852,7 @@ static int pf_interception(struct kvm_vc
u64 fault_address;
u32 error_code;
enum emulation_result er;
+ int r;

if (is_external_interrupt(exit_int_info))
push_irq(vcpu, exit_int_info & SVM_EVTINJ_VEC_MASK);
@@ -860,7 +861,12 @@ static int pf_interception(struct kvm_vc

fault_address = vcpu->svm->vmcb->control.exit_info_2;
error_code = vcpu->svm->vmcb->control.exit_info_1;
- if (!kvm_mmu_page_fault(vcpu, fault_address, error_code)) {
+ r = kvm_mmu_page_fault(vcpu, fault_address, error_code);
+ if (r < 0) {
+ spin_unlock(&vcpu->kvm->lock);
+ return r;
+ }
+ if (!r) {
spin_unlock(&vcpu->kvm->lock);
return 1;
}
@@ -1398,6 +1404,7 @@ static int svm_vcpu_run(struct kvm_vcpu
u16 fs_selector;
u16 gs_selector;
u16 ldt_selector;
+ int r;

again:
do_interrupt_requests(vcpu, kvm_run);
@@ -1565,7 +1572,8 @@ again:
return 0;
}

- if (handle_exit(vcpu, kvm_run)) {
+ r = handle_exit(vcpu, kvm_run);
+ if (r > 0) {
if (signal_pending(current)) {
++kvm_stat.signal_exits;
post_kvm_run_save(vcpu, kvm_run);
@@ -1581,7 +1589,7 @@ again:
goto again;
}
post_kvm_run_save(vcpu, kvm_run);
- return 0;
+ return r;
}

static void svm_flush_tlb(struct kvm_vcpu *vcpu)
Index: linux-2.6/drivers/kvm/paging_tmpl.h
===================================================================
--- linux-2.6.orig/drivers/kvm/paging_tmpl.h
+++ linux-2.6/drivers/kvm/paging_tmpl.h
@@ -339,7 +339,8 @@ static int FNAME(fix_write_pf)(struct kv
* - normal guest page fault due to the guest pte marked not present, not
* writable, or not executable
*
- * Returns: 1 if we need to emulate the instruction, 0 otherwise
+ * Returns: 1 if we need to emulate the instruction, 0 otherwise, or
+ * a negative value on error.
*/
static int FNAME(page_fault)(struct kvm_vcpu *vcpu, gva_t addr,
u32 error_code)
@@ -351,10 +352,13 @@ static int FNAME(page_fault)(struct kvm_
u64 *shadow_pte;
int fixed;
int write_pt = 0;
+ int r;

pgprintk("%s: addr %lx err %x\n", __FUNCTION__, addr, error_code);

- mmu_topup_memory_caches(vcpu);
+ r = mmu_topup_memory_caches(vcpu);
+ if (r)
+ return r;

/*
* Look up the shadow pte for the faulting address.
Index: linux-2.6/drivers/kvm/vmx.c
===================================================================
--- linux-2.6.orig/drivers/kvm/vmx.c
+++ linux-2.6/drivers/kvm/vmx.c
@@ -1289,6 +1289,7 @@ static int handle_exception(struct kvm_v
unsigned long cr2, rip;
u32 vect_info;
enum emulation_result er;
+ int r;

vect_info = vmcs_read32(IDT_VECTORING_INFO_FIELD);
intr_info = vmcs_read32(VM_EXIT_INTR_INFO);
@@ -1317,7 +1318,12 @@ static int handle_exception(struct kvm_v
cr2 = vmcs_readl(EXIT_QUALIFICATION);

spin_lock(&vcpu->kvm->lock);
- if (!kvm_mmu_page_fault(vcpu, cr2, error_code)) {
+ r = kvm_mmu_page_fault(vcpu, cr2, error_code);
+ if (r < 0) {
+ spin_unlock(&vcpu->kvm->lock);
+ return r;
+ }
+ if (!r) {
spin_unlock(&vcpu->kvm->lock);
return 1;
}
@@ -1680,6 +1686,7 @@ static int vmx_vcpu_run(struct kvm_vcpu
u8 fail;
u16 fs_sel, gs_sel, ldt_sel;
int fs_gs_ldt_reload_needed;
+ int r;

again:
/*
@@ -1853,6 +1860,7 @@ again:
if (fail) {
kvm_run->exit_type = KVM_EXIT_TYPE_FAIL_ENTRY;
kvm_run->exit_reason = vmcs_read32(VM_INSTRUCTION_ERROR);
+ r = 0;
} else {
if (fs_gs_ldt_reload_needed) {
load_ldt(ldt_sel);
@@ -1872,7 +1880,8 @@ again:
}
vcpu->launched = 1;
kvm_run->exit_type = KVM_EXIT_TYPE_VM_EXIT;
- if (kvm_handle_exit(kvm_run, vcpu)) {
+ r = kvm_handle_exit(kvm_run, vcpu);
+ if (r > 0) {
/* Give scheduler a change to reschedule. */
if (signal_pending(current)) {
++kvm_stat.signal_exits;
@@ -1892,7 +1901,7 @@ again:
}

post_kvm_run_save(vcpu, kvm_run);
- return 0;
+ return r;
}

static void vmx_flush_tlb(struct kvm_vcpu *vcpu)