Re: [PATCH v10 024/108] KVM: TDX: allocate/free TDX vcpu structure

Yuan Yao
2022-11-14T06:46:32Z

On Sat, Oct 29, 2022 at 11:22:25PM -0700, isaku.yamahata@intel.com wrote:
> From: Isaku Yamahata <isaku.yamahata@intel.com>
>
> The next step of TDX guest creation is to create vcpu. Allocate TDX vcpu
> structures, initialize it. Allocate pages of TDX vcpu for the TDX module.
>
> In the case of the conventional case, cpuid is empty at the initialization.
> and cpuid is configured after the vcpu initialization. Because TDX
> supports only X2APIC mode, cpuid is forcibly initialized to support X2APIC
> on the vcpu initialization.
>
> Signed-off-by: Isaku Yamahata <isaku.yamahata@intel.com>
> ---
> arch/x86/kvm/vmx/main.c | 40 +++++++++--
> arch/x86/kvm/vmx/tdx.c | 138 +++++++++++++++++++++++++++++++++++++
> arch/x86/kvm/vmx/x86_ops.h | 8 +++
> 3 files changed, 182 insertions(+), 4 deletions(-)
>
> diff --git a/arch/x86/kvm/vmx/main.c b/arch/x86/kvm/vmx/main.c
> index b4e4c6c677f6..c125b2e3e8b4 100644
> --- a/arch/x86/kvm/vmx/main.c
> +++ b/arch/x86/kvm/vmx/main.c
> @@ -63,6 +63,38 @@ static void vt_vm_free(struct kvm *kvm)
> return tdx_vm_free(kvm);
> }
>
> +static int vt_vcpu_precreate(struct kvm *kvm)
> +{
> + if (is_td(kvm))
> + return 0;
> +
> + return vmx_vcpu_precreate(kvm);
> +}
> +
> +static int vt_vcpu_create(struct kvm_vcpu *vcpu)
> +{
> + if (is_td_vcpu(vcpu))
> + return tdx_vcpu_create(vcpu);
> +
> + return vmx_vcpu_create(vcpu);
> +}
> +
> +static void vt_vcpu_free(struct kvm_vcpu *vcpu)
> +{
> + if (is_td_vcpu(vcpu))
> + return tdx_vcpu_free(vcpu);
> +
> + return vmx_vcpu_free(vcpu);
> +}
> +
> +static void vt_vcpu_reset(struct kvm_vcpu *vcpu, bool init_event)
> +{
> + if (is_td_vcpu(vcpu))
> + return tdx_vcpu_reset(vcpu, init_event);
> +
> + return vmx_vcpu_reset(vcpu, init_event);
> +}
> +
> static int vt_mem_enc_ioctl(struct kvm *kvm, void __user *argp)
> {
> if (!is_td(kvm))
> @@ -89,10 +121,10 @@ struct kvm_x86_ops vt_x86_ops __initdata = {
> .vm_destroy = vt_vm_destroy,
> .vm_free = vt_vm_free,
>
> - .vcpu_precreate = vmx_vcpu_precreate,
> - .vcpu_create = vmx_vcpu_create,
> - .vcpu_free = vmx_vcpu_free,
> - .vcpu_reset = vmx_vcpu_reset,
> + .vcpu_precreate = vt_vcpu_precreate,
> + .vcpu_create = vt_vcpu_create,
> + .vcpu_free = vt_vcpu_free,
> + .vcpu_reset = vt_vcpu_reset,
>
> .prepare_switch_to_guest = vmx_prepare_switch_to_guest,
> .vcpu_load = vmx_vcpu_load,
> diff --git a/arch/x86/kvm/vmx/tdx.c b/arch/x86/kvm/vmx/tdx.c
> index 54045e0576e7..0625c354b341 100644
> --- a/arch/x86/kvm/vmx/tdx.c
> +++ b/arch/x86/kvm/vmx/tdx.c
> @@ -49,6 +49,11 @@ static __always_inline hpa_t set_hkid_to_hpa(hpa_t pa, u16 hkid)
> return pa | ((hpa_t)hkid << boot_cpu_data.x86_phys_bits);
> }
>
> +static inline bool is_td_vcpu_created(struct vcpu_tdx *tdx)
> +{
> + return tdx->tdvpr.added;
> +}
> +
> static inline bool is_td_created(struct kvm_tdx *kvm_tdx)
> {
> return kvm_tdx->tdr.added;
> @@ -296,6 +301,139 @@ int tdx_vm_init(struct kvm *kvm)
> return 0;
> }
>
> +int tdx_vcpu_create(struct kvm_vcpu *vcpu)
> +{
> + struct vcpu_tdx *tdx = to_tdx(vcpu);
> + int ret, i;
> +
> + /* TDX only supports x2APIC, which requires an in-kernel local APIC. */
> + if (!vcpu->arch.apic)
> + return -EINVAL;
> +
> + fpstate_set_confidential(&vcpu->arch.guest_fpu);
> +
> + ret = tdx_alloc_td_page(&tdx->tdvpr);
> + if (ret)
> + return ret;
> +
> + tdx->tdvpx = kcalloc(tdx_caps.tdvpx_nr_pages, sizeof(*tdx->tdvpx),
> + GFP_KERNEL_ACCOUNT);
> + if (!tdx->tdvpx) {
> + ret = -ENOMEM;
> + goto free_tdvpr;
> + }
> + for (i = 0; i < tdx_caps.tdvpx_nr_pages; i++) {
> + ret = tdx_alloc_td_page(&tdx->tdvpx[i]);
> + if (ret)
> + goto free_tdvpx;
> + }
> +
> + vcpu->arch.efer = EFER_SCE | EFER_LME | EFER_LMA | EFER_NX;
> +
> + vcpu->arch.cr0_guest_owned_bits = -1ul;
> + vcpu->arch.cr4_guest_owned_bits = -1ul;
> +
> + vcpu->arch.tsc_offset = to_kvm_tdx(vcpu->kvm)->tsc_offset;
> + vcpu->arch.l1_tsc_offset = vcpu->arch.tsc_offset;
> + vcpu->arch.guest_state_protected =
> + !(to_kvm_tdx(vcpu->kvm)->attributes & TDX_TD_ATTRIBUTE_DEBUG);
> +
> + return 0;
> +
> +free_tdvpx:
> + /* @i points at the TDVPX page that failed allocation. */
> + for (--i; i >= 0; i--)
> + free_page(tdx->tdvpx[i].va);
> + kfree(tdx->tdvpx);
> + tdx->tdvpx = NULL;
> +free_tdvpr:
> + free_page(tdx->tdvpr.va);
> +
> + return ret;
> +}
> +
> +void tdx_vcpu_free(struct kvm_vcpu *vcpu)
> +{
> + struct vcpu_tdx *tdx = to_tdx(vcpu);
> + int i;
> +
> + /* Can't reclaim or free pages if teardown failed. */
> + if (is_hkid_assigned(to_kvm_tdx(vcpu->kvm)))
> + return;
> +
> + if (tdx->tdvpx) {
> + for (i = 0; i < tdx_caps.tdvpx_nr_pages; i++)
> + tdx_reclaim_td_page(&tdx->tdvpx[i]);
> + kfree(tdx->tdvpx);
> + tdx->tdvpx = NULL;
> + }
> + tdx_reclaim_td_page(&tdx->tdvpr);
> +}
> +
> +void tdx_vcpu_reset(struct kvm_vcpu *vcpu, bool init_event)
> +{
> + struct kvm_tdx *kvm_tdx = to_kvm_tdx(vcpu->kvm);
> + struct vcpu_tdx *tdx = to_tdx(vcpu);
> + struct msr_data apic_base_msr;
> + u64 err;
> + int i;
> +
> + /* TDX doesn't support INIT event. */
> + if (WARN_ON_ONCE(init_event))
> + goto td_bugged;
> + if (WARN_ON_ONCE(is_td_vcpu_created(tdx)))
> + goto td_bugged;
> +
> + err = tdh_vp_create(kvm_tdx->tdr.pa, tdx->tdvpr.pa);
> + if (WARN_ON_ONCE(err)) {
> + pr_tdx_error(TDH_VP_CREATE, err, NULL);
> + goto td_bugged;
> + }
> + tdx_mark_td_page_added(&tdx->tdvpr);
> +
> + for (i = 0; i < tdx_caps.tdvpx_nr_pages; i++) {
> + err = tdh_vp_addcx(tdx->tdvpr.pa, tdx->tdvpx[i].pa);
> + if (WARN_ON_ONCE(err)) {
> + pr_tdx_error(TDH_VP_ADDCX, err, NULL);
> + goto td_bugged;
> + }
> + tdx_mark_td_page_added(&tdx->tdvpx[i]);
> + }
> +
> + if (!vcpu->arch.cpuid_entries) {
> + /*
> + * On cpu creation, cpuid entry is blank. Forcibly enable
> + * X2APIC feature to allow X2APIC.
> + */
> + struct kvm_cpuid_entry2 *e;
> +
> + e = kvmalloc_array(1, sizeof(*e), GFP_KERNEL_ACCOUNT);

NULL checking is necessary for kvmalloc_array.

> + *e = (struct kvm_cpuid_entry2) {
> + .function = 1, /* Features for X2APIC */
> + .index = 0,
> + .eax = 0,
> + .ebx = 0,
> + .ecx = 1ULL << 21, /* X2APIC */
> + .edx = 0,
> + };
> + vcpu->arch.cpuid_entries = e;
> + vcpu->arch.cpuid_nent = 1;
> + }
> + apic_base_msr.data = APIC_DEFAULT_PHYS_BASE | LAPIC_MODE_X2APIC;
> + if (kvm_vcpu_is_reset_bsp(vcpu))
> + apic_base_msr.data |= MSR_IA32_APICBASE_BSP;
> + apic_base_msr.host_initiated = true;
> + if (WARN_ON_ONCE(kvm_set_apic_base(vcpu, &apic_base_msr)))
> + goto td_bugged;
> +
> + vcpu->arch.mp_state = KVM_MP_STATE_RUNNABLE;
> +
> + return;
> +
> +td_bugged:
> + vcpu->kvm->vm_bugged = true;
> +}
> +
> int tdx_dev_ioctl(void __user *argp)
> {
> struct kvm_tdx_capabilities __user *user_caps;
> diff --git a/arch/x86/kvm/vmx/x86_ops.h b/arch/x86/kvm/vmx/x86_ops.h
> index 93ffe2deb8e8..f6841c3dd12d 100644
> --- a/arch/x86/kvm/vmx/x86_ops.h
> +++ b/arch/x86/kvm/vmx/x86_ops.h
> @@ -141,6 +141,10 @@ int tdx_vm_init(struct kvm *kvm);
> void tdx_mmu_release_hkid(struct kvm *kvm);
> void tdx_vm_free(struct kvm *kvm);
>
> +int tdx_vcpu_create(struct kvm_vcpu *vcpu);
> +void tdx_vcpu_free(struct kvm_vcpu *vcpu);
> +void tdx_vcpu_reset(struct kvm_vcpu *vcpu, bool init_event);
> +
> int tdx_vm_ioctl(struct kvm *kvm, void __user *argp);
> #else
> static inline int tdx_hardware_setup(struct kvm_x86_ops *x86_ops) { return 0; }
> @@ -154,6 +158,10 @@ static inline void tdx_mmu_release_hkid(struct kvm *kvm) {}
> static inline void tdx_flush_shadow_all_private(struct kvm *kvm) {}
> static inline void tdx_vm_free(struct kvm *kvm) {}
>
> +static inline int tdx_vcpu_create(struct kvm_vcpu *vcpu) { return -EOPNOTSUPP; }
> +static inline void tdx_vcpu_free(struct kvm_vcpu *vcpu) {}
> +static inline void tdx_vcpu_reset(struct kvm_vcpu *vcpu, bool init_event) {}
> +
> static inline int tdx_vm_ioctl(struct kvm *kvm, void __user *argp) { return -EOPNOTSUPP; }
> #endif
>
> --
> 2.25.1
>