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: Rick Edgecombe <rick.p.edgecombe@xxxxxxxxx>
Signed-off-by: Rick Edgecombe <rick.p.edgecombe@xxxxxxxxx>
Co-developed-by: Yan Zhao <yan.y.zhao@xxxxxxxxx>
Signed-off-by: Yan Zhao <yan.y.zhao@xxxxxxxxx>
Message-ID: <20241112073858.22312-1-yan.y.zhao@xxxxxxxxx>
Signed-off-by: Paolo Bonzini <pbonzini@xxxxxxxxxx>
---
arch/x86/kvm/vmx/main.c | 22 ++++-
arch/x86/kvm/vmx/tdx.c | 159 +++++++++++++++++++++++++++++++++++--
arch/x86/kvm/vmx/tdx.h | 2 +
arch/x86/kvm/vmx/x86_ops.h | 4 +
4 files changed, 177 insertions(+), 10 deletions(-)
diff --git a/arch/x86/kvm/vmx/main.c b/arch/x86/kvm/vmx/main.c
index 828168e67d4e..abb0fc723a0b 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_disable_virtualization_cpu(void)
+{
+ /* Note, TDX *and* VMX need to be disabled if TDX is enabled. */
+ if (enable_tdx)
+ tdx_disable_virtualization_cpu();
+ vmx_disable_virtualization_cpu();
+}
+
static __init int vt_hardware_setup(void)
{
int ret;
@@ -111,6 +119,16 @@ 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)
{
if (is_td_vcpu(vcpu)) {
@@ -199,7 +217,7 @@ struct kvm_x86_ops vt_x86_ops __initdata = {
.hardware_unsetup = vmx_hardware_unsetup,
.enable_virtualization_cpu = vmx_enable_virtualization_cpu,
- .disable_virtualization_cpu = vmx_disable_virtualization_cpu,
+ .disable_virtualization_cpu = vt_disable_virtualization_cpu,
.emergency_disable_virtualization_cpu = vmx_emergency_disable_virtualization_cpu,
.has_emulated_msr = vmx_has_emulated_msr,
@@ -216,7 +234,7 @@ 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 246f924ae6f6..a6696448cb53 100644
--- a/arch/x86/kvm/vmx/tdx.c
+++ b/arch/x86/kvm/vmx/tdx.c
@@ -162,6 +162,21 @@ static bool tdx_operand_busy(u64 err)
}
+/*
+ * A per-CPU list of TD vCPUs associated with a given CPU.
+ * Protected by interrupt mask. Only manipulated by the CPU owning this per-CPU
+ * list.
+ * - When a vCPU is loaded onto a CPU, it is removed from the per-CPU list of
+ * the old CPU during the IPI callback running on the old CPU, and then added
+ * to the per-CPU list of the new CPU.
+ * - When a TD is tearing down, all vCPUs are disassociated from their current
+ * running CPUs and removed from the per-CPU list during the IPI callback
+ * running on those CPUs.
+ * - When a CPU is brought down, traverse the per-CPU list to disassociate all
+ * associated TD vCPUs and remove them from the per-CPU list.
+ */
+static DEFINE_PER_CPU(struct list_head, associated_tdvcpus);
+
static inline void tdx_hkid_free(struct kvm_tdx *kvm_tdx)
{
tdx_guest_keyid_free(kvm_tdx->hkid);
@@ -177,6 +192,22 @@ static inline bool is_hkid_assigned(struct kvm_tdx *kvm_tdx)
return kvm_tdx->hkid > 0;
}
+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(struct page *page)
{
const void *zero_page = (const void *) page_to_virt(ZERO_PAGE(0));
@@ -243,6 +274,83 @@ static void tdx_reclaim_control_page(struct page *ctrl_page)
__free_page(ctrl_page);
}
+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 (to_tdx(vcpu)->state != VCPU_TD_STATE_UNINITIALIZED) {
+ /*
+ * 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)->vp);
+ 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_disable_virtualization_cpu(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);
+}
+
#define TDX_SEAMCALL_RETRIES 10000
static void smp_func_do_phymem_cache_wb(void *unused)
@@ -281,22 +389,21 @@ 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 (!kvm_tdx->td.tdr_page) {
- 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.
@@ -310,6 +417,16 @@ 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->td);
+ 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),
@@ -335,6 +452,7 @@ 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);
@@ -483,6 +601,27 @@ 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 || !is_hkid_assigned(to_kvm_tdx(vcpu->kvm)))
+ return;
+
+ tdx_flush_vp_on_cpu(vcpu);
+
+ KVM_BUG_ON(cpu != raw_smp_processor_id(), vcpu->kvm);
+ 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 kvm_tdx *kvm_tdx = to_kvm_tdx(vcpu->kvm);
@@ -2038,7 +2177,11 @@ void tdx_cleanup(void)
int __init tdx_bringup(void)
{
- int r;
+ int r, i;
+
+ /* tdx_disable_virtualization_cpu() uses associated_tdvcpus. */
+ for_each_possible_cpu(i)
+ INIT_LIST_HEAD(&per_cpu(associated_tdvcpus, i));
if (!enable_tdx)
return 0;
diff --git a/arch/x86/kvm/vmx/tdx.h b/arch/x86/kvm/vmx/tdx.h
index b71f8e9643e4..8ed96f980d9a 100644
--- a/arch/x86/kvm/vmx/tdx.h
+++ b/arch/x86/kvm/vmx/tdx.h
@@ -47,6 +47,8 @@ struct vcpu_tdx {
struct tdx_vp vp;
+ struct list_head cpu_list;
+
enum vcpu_tdx_state state;
};
diff --git a/arch/x86/kvm/vmx/x86_ops.h b/arch/x86/kvm/vmx/x86_ops.h
index bc3cf1c1da37..6ab10d3cdb6f 100644
--- a/arch/x86/kvm/vmx/x86_ops.h
+++ b/arch/x86/kvm/vmx/x86_ops.h
@@ -122,6 +122,7 @@ void vmx_cancel_hv_timer(struct kvm_vcpu *vcpu);
void vmx_setup_mce(struct kvm_vcpu *vcpu);
#ifdef CONFIG_INTEL_TDX_HOST
+void tdx_disable_virtualization_cpu(void);
int tdx_vm_init(struct kvm *kvm);
void tdx_mmu_release_hkid(struct kvm *kvm);
void tdx_vm_destroy(struct kvm *kvm);
@@ -129,6 +130,7 @@ 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_load(struct kvm_vcpu *vcpu, int cpu);
int tdx_vcpu_ioctl(struct kvm_vcpu *vcpu, void __user *argp);
@@ -146,6 +148,7 @@ void tdx_flush_tlb_all(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_disable_virtualization_cpu(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_destroy(struct kvm *kvm) {}
@@ -153,6 +156,7 @@ 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_load(struct kvm_vcpu *vcpu, int cpu) {}
static inline int tdx_vcpu_ioctl(struct kvm_vcpu *vcpu, void __user *argp) { return -EOPNOTSUPP; }
--
2.43.5
