From: Isaku Yamahata <isaku.yamahata@xxxxxxxxx> Handle vCPUs dissociations by invoking SEAMCALL TDH.VP.FLUSH which flushes the address translation caches and cached TD VMCS of a TD vCPU in its associated pCPU. In TDX, a vCPUs can only be associated with one pCPU at a time, which is done by invoking SEAMCALL TDH.VP.ENTER. For a successful association, the vCPU must be dissociated from its previous associated pCPU. To facilitate vCPU dissociation, introduce a per-pCPU list associated_tdvcpus. Add a vCPU into this list when it's loaded into a new pCPU (i.e. when a vCPU is loaded for the first time or migrated to a new pCPU). vCPU dissociations can happen under below conditions: - On the op hardware_disable is called. This op is called when virtualization is disabled on a given pCPU, e.g. when hot-unplug a pCPU or machine shutdown/suspend. In this case, dissociate all vCPUs from the pCPU by iterating its per-pCPU list associated_tdvcpus. - On vCPU migration to a new pCPU. Before adding a vCPU into associated_tdvcpus list of the new pCPU, dissociation from its old pCPU is required, which is performed by issuing an IPI and executing SEAMCALL TDH.VP.FLUSH on the old pCPU. On a successful dissociation, the vCPU will be removed from the associated_tdvcpus list of its previously associated pCPU. - On tdx_mmu_release_hkid() is called. TDX mandates that all vCPUs must be disassociated prior to the release of an hkid. Therefore, dissociation of all vCPUs is a must before executing the SEAMCALL TDH.MNG.VPFLUSHDONE and subsequently freeing the hkid. Signed-off-by: Isaku Yamahata <isaku.yamahata@xxxxxxxxx> Co-developed-by: Yan Zhao <yan.y.zhao@xxxxxxxxx> Signed-off-by: Yan Zhao <yan.y.zhao@xxxxxxxxx> Signed-off-by: Rick Edgecombe <rick.p.edgecombe@xxxxxxxxx> --- TDX MMU part 2 v1: - Changed title to "KVM: TDX: Handle vCPU dissociation" . - Updated commit log. - Removed calling tdx_disassociate_vp_on_cpu() in tdx_vcpu_free() since no new TD enter would be called for vCPU association after tdx_mmu_release_hkid(), which is now called in vt_vm_destroy(), i.e. after releasing vcpu fd and kvm_unload_vcpu_mmus(), and before tdx_vcpu_free(). - TODO: include Isaku's fix https://eclists.intel.com/sympa/arc/kvm-qemu-review/2024-07/msg00359.html - Update for the wrapper functions for SEAMCALLs. (Sean) - Removed unnecessary pr_err() in tdx_flush_vp_on_cpu(). - Use KVM_BUG_ON() in tdx_flush_vp_on_cpu() for consistency. - Capitalize the first word of tile. (Binbin) - Minor fixed in changelog. (Binbin, Reinette(internal)) - Fix some comments. (Binbin, Reinette(internal)) - Rename arg_ to _arg (Binbin) - Updates from seamcall overhaul (Kai) - Remove lockdep_assert_preemption_disabled() in tdx_hardware_setup() since now hardware_enable() is not called via SMP func call anymore, but (per-cpu) CPU hotplug thread - Use KVM_BUG_ON() for SEAMCALLs in tdx_mmu_release_hkid() (Kai) - Update based on upstream commit "KVM: x86: Fold kvm_arch_sched_in() into kvm_arch_vcpu_load()" - Eliminate TDX_FLUSHVP_NOT_DONE error check because vCPUs were all freed. So the error won't happen. (Sean) --- arch/x86/kvm/vmx/main.c | 22 +++++- arch/x86/kvm/vmx/tdx.c | 151 +++++++++++++++++++++++++++++++++++-- arch/x86/kvm/vmx/tdx.h | 2 + arch/x86/kvm/vmx/x86_ops.h | 4 + 4 files changed, 169 insertions(+), 10 deletions(-) diff --git a/arch/x86/kvm/vmx/main.c b/arch/x86/kvm/vmx/main.c index 8f5dbab9099f..8171c1412c3b 100644 --- a/arch/x86/kvm/vmx/main.c +++ b/arch/x86/kvm/vmx/main.c @@ -10,6 +10,14 @@ #include "tdx.h" #include "tdx_arch.h" +static void vt_hardware_disable(void) +{ + /* Note, TDX *and* VMX need to be disabled if TDX is enabled. */ + if (enable_tdx) + tdx_hardware_disable(); + vmx_hardware_disable(); +} + static __init int vt_hardware_setup(void) { int ret; @@ -113,6 +121,16 @@ static void vt_vcpu_reset(struct kvm_vcpu *vcpu, bool init_event) vmx_vcpu_reset(vcpu, init_event); } +static void vt_vcpu_load(struct kvm_vcpu *vcpu, int cpu) +{ + if (is_td_vcpu(vcpu)) { + tdx_vcpu_load(vcpu, cpu); + return; + } + + vmx_vcpu_load(vcpu, cpu); +} + static void vt_flush_tlb_all(struct kvm_vcpu *vcpu) { /* @@ -217,7 +235,7 @@ struct kvm_x86_ops vt_x86_ops __initdata = { .hardware_unsetup = vmx_hardware_unsetup, .hardware_enable = vmx_hardware_enable, - .hardware_disable = vmx_hardware_disable, + .hardware_disable = vt_hardware_disable, .emergency_disable = vmx_emergency_disable, .has_emulated_msr = vmx_has_emulated_msr, @@ -234,7 +252,7 @@ struct kvm_x86_ops vt_x86_ops __initdata = { .vcpu_reset = vt_vcpu_reset, .prepare_switch_to_guest = vmx_prepare_switch_to_guest, - .vcpu_load = vmx_vcpu_load, + .vcpu_load = vt_vcpu_load, .vcpu_put = vmx_vcpu_put, .update_exception_bitmap = vmx_update_exception_bitmap, diff --git a/arch/x86/kvm/vmx/tdx.c b/arch/x86/kvm/vmx/tdx.c index 3083a66bb895..554154d3dd58 100644 --- a/arch/x86/kvm/vmx/tdx.c +++ b/arch/x86/kvm/vmx/tdx.c @@ -57,6 +57,14 @@ static DEFINE_MUTEX(tdx_lock); /* Maximum number of retries to attempt for SEAMCALLs. */ #define TDX_SEAMCALL_RETRIES 10000 +/* + * A per-CPU list of TD vCPUs associated with a given CPU. Used when a CPU + * is brought down to invoke TDH_VP_FLUSH on the appropriate TD vCPUS. + * Protected by interrupt mask. This list is manipulated in process context + * of vCPU and IPI callback. See tdx_flush_vp_on_cpu(). + */ +static DEFINE_PER_CPU(struct list_head, associated_tdvcpus); + 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); @@ -88,6 +96,22 @@ static inline bool is_td_finalized(struct kvm_tdx *kvm_tdx) return kvm_tdx->finalized; } +static inline void tdx_disassociate_vp(struct kvm_vcpu *vcpu) +{ + lockdep_assert_irqs_disabled(); + + list_del(&to_tdx(vcpu)->cpu_list); + + /* + * Ensure tdx->cpu_list is updated before setting vcpu->cpu to -1, + * otherwise, a different CPU can see vcpu->cpu = -1 and add the vCPU + * to its list before it's deleted from this CPU's list. + */ + smp_wmb(); + + vcpu->cpu = -1; +} + static void tdx_clear_page(unsigned long page_pa) { const void *zero_page = (const void *) __va(page_to_phys(ZERO_PAGE(0))); @@ -168,6 +192,83 @@ static void tdx_reclaim_control_page(unsigned long ctrl_page_pa) free_page((unsigned long)__va(ctrl_page_pa)); } +struct tdx_flush_vp_arg { + struct kvm_vcpu *vcpu; + u64 err; +}; + +static void tdx_flush_vp(void *_arg) +{ + struct tdx_flush_vp_arg *arg = _arg; + struct kvm_vcpu *vcpu = arg->vcpu; + u64 err; + + arg->err = 0; + lockdep_assert_irqs_disabled(); + + /* Task migration can race with CPU offlining. */ + if (unlikely(vcpu->cpu != raw_smp_processor_id())) + return; + + /* + * No need to do TDH_VP_FLUSH if the vCPU hasn't been initialized. The + * list tracking still needs to be updated so that it's correct if/when + * the vCPU does get initialized. + */ + if (is_td_vcpu_created(to_tdx(vcpu))) { + /* + * No need to retry. TDX Resources needed for TDH.VP.FLUSH are: + * TDVPR as exclusive, TDR as shared, and TDCS as shared. This + * vp flush function is called when destructing vCPU/TD or vCPU + * migration. No other thread uses TDVPR in those cases. + */ + err = tdh_vp_flush(to_tdx(vcpu)); + if (unlikely(err && err != TDX_VCPU_NOT_ASSOCIATED)) { + /* + * This function is called in IPI context. Do not use + * printk to avoid console semaphore. + * The caller prints out the error message, instead. + */ + if (err) + arg->err = err; + } + } + + tdx_disassociate_vp(vcpu); +} + +static void tdx_flush_vp_on_cpu(struct kvm_vcpu *vcpu) +{ + struct tdx_flush_vp_arg arg = { + .vcpu = vcpu, + }; + int cpu = vcpu->cpu; + + if (unlikely(cpu == -1)) + return; + + smp_call_function_single(cpu, tdx_flush_vp, &arg, 1); + if (KVM_BUG_ON(arg.err, vcpu->kvm)) + pr_tdx_error(TDH_VP_FLUSH, arg.err); +} + +void tdx_hardware_disable(void) +{ + int cpu = raw_smp_processor_id(); + struct list_head *tdvcpus = &per_cpu(associated_tdvcpus, cpu); + struct tdx_flush_vp_arg arg; + struct vcpu_tdx *tdx, *tmp; + unsigned long flags; + + local_irq_save(flags); + /* Safe variant needed as tdx_disassociate_vp() deletes the entry. */ + list_for_each_entry_safe(tdx, tmp, tdvcpus, cpu_list) { + arg.vcpu = &tdx->vcpu; + tdx_flush_vp(&arg); + } + local_irq_restore(flags); +} + static void smp_func_do_phymem_cache_wb(void *unused) { u64 err = 0; @@ -204,22 +305,21 @@ void tdx_mmu_release_hkid(struct kvm *kvm) bool packages_allocated, targets_allocated; struct kvm_tdx *kvm_tdx = to_kvm_tdx(kvm); cpumask_var_t packages, targets; - u64 err; + struct kvm_vcpu *vcpu; + unsigned long j; int i; + u64 err; if (!is_hkid_assigned(kvm_tdx)) return; - /* KeyID has been allocated but guest is not yet configured */ - if (!is_td_created(kvm_tdx)) { - tdx_hkid_free(kvm_tdx); - return; - } - packages_allocated = zalloc_cpumask_var(&packages, GFP_KERNEL); targets_allocated = zalloc_cpumask_var(&targets, GFP_KERNEL); cpus_read_lock(); + kvm_for_each_vcpu(j, vcpu, kvm) + tdx_flush_vp_on_cpu(vcpu); + /* * TDH.PHYMEM.CACHE.WB tries to acquire the TDX module global lock * and can fail with TDX_OPERAND_BUSY when it fails to get the lock. @@ -233,6 +333,16 @@ void tdx_mmu_release_hkid(struct kvm *kvm) * After the above flushing vps, there should be no more vCPU * associations, as all vCPU fds have been released at this stage. */ + err = tdh_mng_vpflushdone(kvm_tdx); + if (err == TDX_FLUSHVP_NOT_DONE) + goto out; + if (KVM_BUG_ON(err, kvm)) { + pr_tdx_error(TDH_MNG_VPFLUSHDONE, err); + pr_err("tdh_mng_vpflushdone() failed. HKID %d is leaked.\n", + kvm_tdx->hkid); + goto out; + } + for_each_online_cpu(i) { if (packages_allocated && cpumask_test_and_set_cpu(topology_physical_package_id(i), @@ -258,6 +368,7 @@ void tdx_mmu_release_hkid(struct kvm *kvm) tdx_hkid_free(kvm_tdx); } +out: mutex_unlock(&tdx_lock); cpus_read_unlock(); free_cpumask_var(targets); @@ -409,6 +520,26 @@ int tdx_vcpu_create(struct kvm_vcpu *vcpu) return 0; } +void tdx_vcpu_load(struct kvm_vcpu *vcpu, int cpu) +{ + struct vcpu_tdx *tdx = to_tdx(vcpu); + + if (vcpu->cpu == cpu) + return; + + tdx_flush_vp_on_cpu(vcpu); + + local_irq_disable(); + /* + * Pairs with the smp_wmb() in tdx_disassociate_vp() to ensure + * vcpu->cpu is read before tdx->cpu_list. + */ + smp_rmb(); + + list_add(&tdx->cpu_list, &per_cpu(associated_tdvcpus, cpu)); + local_irq_enable(); +} + void tdx_vcpu_free(struct kvm_vcpu *vcpu) { struct vcpu_tdx *tdx = to_tdx(vcpu); @@ -1977,7 +2108,7 @@ static int __init __do_tdx_bringup(void) static int __init __tdx_bringup(void) { const struct tdx_sys_info_td_conf *td_conf; - int r; + int r, i; if (!tdp_mmu_enabled || !enable_mmio_caching) return -EOPNOTSUPP; @@ -1987,6 +2118,10 @@ static int __init __tdx_bringup(void) return -EOPNOTSUPP; } + /* tdx_hardware_disable() uses associated_tdvcpus. */ + for_each_possible_cpu(i) + INIT_LIST_HEAD(&per_cpu(associated_tdvcpus, i)); + /* * Enabling TDX requires enabling hardware virtualization first, * as making SEAMCALLs requires CPU being in post-VMXON state. diff --git a/arch/x86/kvm/vmx/tdx.h b/arch/x86/kvm/vmx/tdx.h index 25a4aaede2ba..4b6fc25feeb6 100644 --- a/arch/x86/kvm/vmx/tdx.h +++ b/arch/x86/kvm/vmx/tdx.h @@ -39,6 +39,8 @@ struct vcpu_tdx { unsigned long *tdcx_pa; bool td_vcpu_created; + struct list_head cpu_list; + bool initialized; /* diff --git a/arch/x86/kvm/vmx/x86_ops.h b/arch/x86/kvm/vmx/x86_ops.h index d8a00ab4651c..f4aa0ec16980 100644 --- a/arch/x86/kvm/vmx/x86_ops.h +++ b/arch/x86/kvm/vmx/x86_ops.h @@ -119,6 +119,7 @@ void vmx_cancel_hv_timer(struct kvm_vcpu *vcpu); void vmx_setup_mce(struct kvm_vcpu *vcpu); #ifdef CONFIG_INTEL_TDX_HOST +void tdx_hardware_disable(void); int tdx_vm_init(struct kvm *kvm); void tdx_mmu_release_hkid(struct kvm *kvm); void tdx_vm_free(struct kvm *kvm); @@ -128,6 +129,7 @@ int tdx_vm_ioctl(struct kvm *kvm, void __user *argp); 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); +void tdx_vcpu_load(struct kvm_vcpu *vcpu, int cpu); u8 tdx_get_mt_mask(struct kvm_vcpu *vcpu, gfn_t gfn, bool is_mmio); int tdx_vcpu_ioctl(struct kvm_vcpu *vcpu, void __user *argp); @@ -145,6 +147,7 @@ void tdx_flush_tlb_current(struct kvm_vcpu *vcpu); void tdx_load_mmu_pgd(struct kvm_vcpu *vcpu, hpa_t root_hpa, int root_level); int tdx_gmem_private_max_mapping_level(struct kvm *kvm, kvm_pfn_t pfn); #else +static inline void tdx_hardware_disable(void) {} static inline int tdx_vm_init(struct kvm *kvm) { return -EOPNOTSUPP; } static inline void tdx_mmu_release_hkid(struct kvm *kvm) {} static inline void tdx_vm_free(struct kvm *kvm) {} @@ -154,6 +157,7 @@ static inline int tdx_vm_ioctl(struct kvm *kvm, void __user *argp) { return -EOP 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 void tdx_vcpu_load(struct kvm_vcpu *vcpu, int cpu) {} static inline u8 tdx_get_mt_mask(struct kvm_vcpu *vcpu, gfn_t gfn, bool is_mmio) { return 0; } static inline int tdx_vcpu_ioctl(struct kvm_vcpu *vcpu, void __user *argp) { return -EOPNOTSUPP; } -- 2.34.1
