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

Signed-off-by: Avi Kivity <avi@qumranet.com>
Acked-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

diff --git a/drivers/kvm/mmu.c b/drivers/kvm/mmu.c
index e96362a..7761089 100644 (file)
--- a/drivers/kvm/mmu.c
+++ b/drivers/kvm/mmu.c
@@ -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 kvm_mmu_memory_cache *mc)
                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 kvm_vcpu *vcpu, gva_t gva,
 {
        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_vcpu *vcpu)
        r = init_kvm_mmu(vcpu);
        if (r < 0)
                goto out;
-       mmu_topup_memory_caches(vcpu);
+       r = mmu_topup_memory_caches(vcpu);
 out:
        return r;
 }

diff --git a/drivers/kvm/paging_tmpl.h b/drivers/kvm/paging_tmpl.h
index 4e6670f..32b3851 100644 (file)
--- a/drivers/kvm/paging_tmpl.h
+++ b/drivers/kvm/paging_tmpl.h
@@ -339,7 +339,8 @@ static int FNAME(fix_write_pf)(struct kvm_vcpu *vcpu,
  *   - 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_vcpu *vcpu, gva_t addr,
        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.

diff --git a/drivers/kvm/svm.c b/drivers/kvm/svm.c
index 9925001..af1e7b3 100644 (file)
--- a/drivers/kvm/svm.c
+++ b/drivers/kvm/svm.c
@@ -852,6 +852,7 @@ static int pf_interception(struct kvm_vcpu *vcpu, struct kvm_run *kvm_run)
        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_vcpu *vcpu, struct kvm_run *kvm_run)
 
        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 *vcpu, struct kvm_run *kvm_run)
        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)

diff --git a/drivers/kvm/vmx.c b/drivers/kvm/vmx.c
index 59178ad..ed39567 100644 (file)
--- a/drivers/kvm/vmx.c
+++ b/drivers/kvm/vmx.c
@@ -1289,6 +1289,7 @@ static int handle_exception(struct kvm_vcpu *vcpu, struct kvm_run *kvm_run)
        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_vcpu *vcpu, struct kvm_run *kvm_run)
                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 *vcpu, struct kvm_run *kvm_run)
        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)