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    Subject[PATCH 30/33] KVM: MMU: Detect oom conditions and propagate error to userspace
    From
    Date
    Signed-off-by: Avi Kivity <avi@qumranet.com>

    Index: linux-2.6/drivers/kvm/mmu.c
    ===================================================================
    --- linux-2.6.orig/drivers/kvm/mmu.c
    +++ linux-2.6/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
    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)
    -
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