On Tue, Sep 25, 2018 at 07:58:41PM +0200, Vitaly Kuznetsov wrote:
> In preparation to MMU reconfiguration avoidance we need a space to
> cache source data. As this partially intersects with kvm_mmu_page_role,
> create 64bit sized union kvm_mmu_role holding both base and extended data.
> No functional change.
>
> Signed-off-by: Vitaly Kuznetsov <vkuznets@xxxxxxxxxx>
> ---
One nit below, other than that...
Reviewed-by: Sean Christopherson <sean.j.christopherson@xxxxxxxxx>
> diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
> index e59e5f49c8c2..bb1ef0f68f8e 100644
> --- a/arch/x86/kvm/mmu.c
> +++ b/arch/x86/kvm/mmu.c
> @@ -2359,7 +2359,7 @@ static struct kvm_mmu_page *kvm_mmu_get_page(struct kvm_vcpu *vcpu,
> int collisions = 0;
> LIST_HEAD(invalid_list);
>
> - role = vcpu->arch.mmu->base_role;
> + role = vcpu->arch.mmu->mmu_role.base;
> role.level = level;
> role.direct = direct;
> if (role.direct)
> @@ -4407,7 +4407,8 @@ static void reset_rsvds_bits_mask_ept(struct kvm_vcpu *vcpu,
> void
> reset_shadow_zero_bits_mask(struct kvm_vcpu *vcpu, struct kvm_mmu *context)
> {
> - bool uses_nx = context->nx || context->base_role.smep_andnot_wp;
> + bool uses_nx = context->nx ||
> + context->mmu_role.base.smep_andnot_wp;
> struct rsvd_bits_validate *shadow_zero_check;
> int i;
>
> @@ -4726,7 +4727,7 @@ static void init_kvm_tdp_mmu(struct kvm_vcpu *vcpu)
> {
> struct kvm_mmu *context = vcpu->arch.mmu;
>
> - context->base_role.word = mmu_base_role_mask.word &
> + context->mmu_role.base.word = mmu_base_role_mask.word &
> kvm_calc_tdp_mmu_root_page_role(vcpu).word;
> context->page_fault = tdp_page_fault;
> context->sync_page = nonpaging_sync_page;
> @@ -4807,7 +4808,7 @@ void kvm_init_shadow_mmu(struct kvm_vcpu *vcpu)
> else
> paging32_init_context(vcpu, context);
>
> - context->base_role.word = mmu_base_role_mask.word &
> + context->mmu_role.base.word = mmu_base_role_mask.word &
> kvm_calc_shadow_mmu_root_page_role(vcpu).word;
> reset_shadow_zero_bits_mask(vcpu, context);
> }
> @@ -4816,7 +4817,7 @@ EXPORT_SYMBOL_GPL(kvm_init_shadow_mmu);
> static union kvm_mmu_page_role
> kvm_calc_shadow_ept_root_page_role(struct kvm_vcpu *vcpu, bool accessed_dirty)
> {
> - union kvm_mmu_page_role role = vcpu->arch.mmu->base_role;
> + union kvm_mmu_page_role role = vcpu->arch.mmu->mmu_role.base;
>
> role.level = PT64_ROOT_4LEVEL;
> role.direct = false;
> @@ -4846,7 +4847,8 @@ void kvm_init_shadow_ept_mmu(struct kvm_vcpu *vcpu, bool execonly,
> context->update_pte = ept_update_pte;
> context->root_level = PT64_ROOT_4LEVEL;
> context->direct_map = false;
> - context->base_role.word = root_page_role.word & mmu_base_role_mask.word;
> + context->mmu_role.base.word =
> + root_page_role.word & mmu_base_role_mask.word;
> context->get_pdptr = kvm_pdptr_read;
>
> update_permission_bitmask(vcpu, context, true);
> @@ -5161,10 +5163,13 @@ static void kvm_mmu_pte_write(struct kvm_vcpu *vcpu, gpa_t gpa,
>
> local_flush = true;
> while (npte--) {
> + unsigned int base_role =
Nit: should this be a u32 to match mmu_role.base.word?
> + vcpu->arch.mmu->mmu_role.base.word;
> +
> entry = *spte;
> mmu_page_zap_pte(vcpu->kvm, sp, spte);
> if (gentry &&
> - !((sp->role.word ^ vcpu->arch.mmu->base_role.word)
> + !((sp->role.word ^ base_role)
> & mmu_base_role_mask.word) && rmap_can_add(vcpu))
> mmu_pte_write_new_pte(vcpu, sp, spte, &gentry);
> if (need_remote_flush(entry, *spte))
> @@ -5861,6 +5866,16 @@ int kvm_mmu_module_init(void)
> {
> int ret = -ENOMEM;
>
> + /*
> + * MMU roles use union aliasing which is, generally speaking, an
> + * undefined behavior. However, we supposedly know how compilers behave
> + * and the current status quo is unlikely to change. Guardians below are
> + * supposed to let us know if the assumption becomes false.
> + */
> + BUILD_BUG_ON(sizeof(union kvm_mmu_page_role) != sizeof(u32));
> + BUILD_BUG_ON(sizeof(union kvm_mmu_extended_role) != sizeof(u32));
> + BUILD_BUG_ON(sizeof(union kvm_mmu_role) != sizeof(u64));
> +
> kvm_mmu_reset_all_pte_masks();
>
> pte_list_desc_cache = kmem_cache_create("pte_list_desc",
> diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
> index 93ff08136fc1..c56a80c15c4f 100644
> --- a/arch/x86/kvm/vmx.c
> +++ b/arch/x86/kvm/vmx.c
> @@ -9321,7 +9321,7 @@ static int nested_vmx_eptp_switching(struct kvm_vcpu *vcpu,
>
> kvm_mmu_unload(vcpu);
> mmu->ept_ad = accessed_dirty;
> - mmu->base_role.ad_disabled = !accessed_dirty;
> + mmu->mmu_role.base.ad_disabled = !accessed_dirty;
> vmcs12->ept_pointer = address;
> /*
> * TODO: Check what's the correct approach in case
> --
> 2.17.1
>
