On Tue, May 21, 2013 at 1:50 AM, Xiao Guangrong
<xiaoguangrong@xxxxxxxxxxxxxxxxxx> wrote:
> On 05/19/2013 12:52 PM, Jun Nakajima wrote:
>> From: Nadav Har'El <nyh@xxxxxxxxxx>
>>
>> KVM's existing shadow MMU code already supports nested TDP. To use it, we
>> need to set up a new "MMU context" for nested EPT, and create a few callbacks
>> for it (nested_ept_*()). This context should also use the EPT versions of
>> the page table access functions (defined in the previous patch).
>> Then, we need to switch back and forth between this nested context and the
>> regular MMU context when switching between L1 and L2 (when L1 runs this L2
>> with EPT).
>>
>> Signed-off-by: Nadav Har'El <nyh@xxxxxxxxxx>
>> Signed-off-by: Jun Nakajima <jun.nakajima@xxxxxxxxx>
>> Signed-off-by: Xinhao Xu <xinhao.xu@xxxxxxxxx>
>> ---
>> arch/x86/kvm/mmu.c | 38 ++++++++++++++++++++++++++++++++++++++
>> arch/x86/kvm/mmu.h | 1 +
>> arch/x86/kvm/vmx.c | 54 +++++++++++++++++++++++++++++++++++++++++++++++++++++-
>> 3 files changed, 92 insertions(+), 1 deletion(-)
>>
>> diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
>> index 6c1670f..37f8d7f 100644
>> --- a/arch/x86/kvm/mmu.c
>> +++ b/arch/x86/kvm/mmu.c
>> @@ -3653,6 +3653,44 @@ int kvm_init_shadow_mmu(struct kvm_vcpu *vcpu, struct kvm_mmu *context)
>> }
>> EXPORT_SYMBOL_GPL(kvm_init_shadow_mmu);
>>
>> +int kvm_init_shadow_EPT_mmu(struct kvm_vcpu *vcpu, struct kvm_mmu *context)
>> +{
>> + ASSERT(vcpu);
>> + ASSERT(!VALID_PAGE(vcpu->arch.mmu.root_hpa));
>> +
>> + context->shadow_root_level = kvm_x86_ops->get_tdp_level();
>
> That means L1 guest always uses page-walk length == 4? But in your previous patch,
> it can be 2.
We want to support "page-walk length == 4" only.
>
>> +
>> + context->nx = is_nx(vcpu); /* TODO: ? */
>
> Hmm? EPT always support NX.
>
>> + context->new_cr3 = paging_new_cr3;
>> + context->page_fault = EPT_page_fault;
>> + context->gva_to_gpa = EPT_gva_to_gpa;
>> + context->sync_page = EPT_sync_page;
>> + context->invlpg = EPT_invlpg;
>> + context->update_pte = EPT_update_pte;
>> + context->free = paging_free;
>> + context->root_level = context->shadow_root_level;
>> + context->root_hpa = INVALID_PAGE;
>> + context->direct_map = false;
>> +
>> + /* TODO: reset_rsvds_bits_mask() is not built for EPT, we need
>> + something different.
>> + */
>
> Exactly. :)
>
>> + reset_rsvds_bits_mask(vcpu, context);
>> +
>> +
>> + /* TODO: I copied these from kvm_init_shadow_mmu, I don't know why
>> + they are done, or why they write to vcpu->arch.mmu and not context
>> + */
>> + vcpu->arch.mmu.base_role.cr4_pae = !!is_pae(vcpu);
>> + vcpu->arch.mmu.base_role.cr0_wp = is_write_protection(vcpu);
>> + vcpu->arch.mmu.base_role.smep_andnot_wp =
>> + kvm_read_cr4_bits(vcpu, X86_CR4_SMEP) &&
>> + !is_write_protection(vcpu);
>
> I guess we need not care these since the permission of EPT page does not depend
> on these.
Right. I'll clean up this.
>
>> +
>> + return 0;
>> +}
>> +EXPORT_SYMBOL_GPL(kvm_init_shadow_EPT_mmu);
>> +
>> static int init_kvm_softmmu(struct kvm_vcpu *vcpu)
>> {
>> int r = kvm_init_shadow_mmu(vcpu, vcpu->arch.walk_mmu);
>> diff --git a/arch/x86/kvm/mmu.h b/arch/x86/kvm/mmu.h
>> index 2adcbc2..8fc94dd 100644
>> --- a/arch/x86/kvm/mmu.h
>> +++ b/arch/x86/kvm/mmu.h
>> @@ -54,6 +54,7 @@ int kvm_mmu_get_spte_hierarchy(struct kvm_vcpu *vcpu, u64 addr, u64 sptes[4]);
>> void kvm_mmu_set_mmio_spte_mask(u64 mmio_mask);
>> int handle_mmio_page_fault_common(struct kvm_vcpu *vcpu, u64 addr, bool direct);
>> int kvm_init_shadow_mmu(struct kvm_vcpu *vcpu, struct kvm_mmu *context);
>> +int kvm_init_shadow_EPT_mmu(struct kvm_vcpu *vcpu, struct kvm_mmu *context);
>>
>> static inline unsigned int kvm_mmu_available_pages(struct kvm *kvm)
>> {
>> diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
>> index fb9cae5..a88432f 100644
>> --- a/arch/x86/kvm/vmx.c
>> +++ b/arch/x86/kvm/vmx.c
>> @@ -1045,6 +1045,11 @@ static inline bool nested_cpu_has_virtual_nmis(struct vmcs12 *vmcs12,
>> return vmcs12->pin_based_vm_exec_control & PIN_BASED_VIRTUAL_NMIS;
>> }
>>
>> +static inline int nested_cpu_has_ept(struct vmcs12 *vmcs12)
>> +{
>> + return nested_cpu_has2(vmcs12, SECONDARY_EXEC_ENABLE_EPT);
>> +}
>> +
>> static inline bool is_exception(u32 intr_info)
>> {
>> return (intr_info & (INTR_INFO_INTR_TYPE_MASK | INTR_INFO_VALID_MASK))
>> @@ -7311,6 +7316,46 @@ static void vmx_set_supported_cpuid(u32 func, struct kvm_cpuid_entry2 *entry)
>> entry->ecx |= bit(X86_FEATURE_VMX);
>> }
>>
>> +/* Callbacks for nested_ept_init_mmu_context: */
>> +
>> +static unsigned long nested_ept_get_cr3(struct kvm_vcpu *vcpu)
>> +{
>> + /* return the page table to be shadowed - in our case, EPT12 */
>> + return get_vmcs12(vcpu)->ept_pointer;
>> +}
>> +
>> +static void nested_ept_inject_page_fault(struct kvm_vcpu *vcpu,
>> + struct x86_exception *fault)
>> +{
>> + struct vmcs12 *vmcs12;
>> + nested_vmx_vmexit(vcpu);
>> + vmcs12 = get_vmcs12(vcpu);
>> + /*
>> + * Note no need to set vmcs12->vm_exit_reason as it is already copied
>> + * from vmcs02 in nested_vmx_vmexit() above, i.e., EPT_VIOLATION.
>> + */
>> + vmcs12->exit_qualification = fault->error_code;
>
> Hmm, you directly copy the error code from FNAME(walk_addr_generic),
> but its format is different and i did not see you cook the error code
> in the previous patches.
>
Right. Basically this is the original code from Nadav, and 12, 13
fix/cook the error code.
--
Jun
Intel Open Source Technology Center
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