x86/virt/tdx: KVM: Consolidate TDX CPU hotplug handling

The core kernel registers a CPU hotplug callback to do VMX and TDX init
and deinit while KVM registers a separate CPU offline callback to block
offlining the last online CPU in a socket.

Splitting TDX-related CPU hotplug handling across two components is odd
and adds unnecessary complexity.

Consolidate TDX-related CPU hotplug handling by integrating KVM's
tdx_offline_cpu() to the one in the core kernel.

Also move nr_configured_hkid to the core kernel because tdx_offline_cpu()
references it. Since HKID allocation and free are handled in the core
kernel, it's more natural to track used HKIDs there.

Reviewed-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Chao Gao <chao.gao@intel.com>
Tested-by: Chao Gao <chao.gao@intel.com>
Tested-by: Sagi Shahar <sagis@google.com>
Link: https://patch.msgid.link/20260214012702.2368778-14-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>

diff --git a/arch/x86/kvm/vmx/tdx.c b/arch/x86/kvm/vmx/tdx.c
index c0cd0d73015fd06690b41502b79deb3a8eb48bd8..520d85a2974aea694920c4b6f57bc96103055e3c 100644 (file)
--- a/arch/x86/kvm/vmx/tdx.c
+++ b/arch/x86/kvm/vmx/tdx.c
@@ -59,8 +59,6 @@ module_param_named(tdx, enable_tdx, bool, 0444);
 #define TDX_SHARED_BIT_PWL_5 gpa_to_gfn(BIT_ULL(51))
 #define TDX_SHARED_BIT_PWL_4 gpa_to_gfn(BIT_ULL(47))
 
-static enum cpuhp_state tdx_cpuhp_state __ro_after_init;
-
 static const struct tdx_sys_info *tdx_sysinfo;
 
 void tdh_vp_rd_failed(struct vcpu_tdx *tdx, char *uclass, u32 field, u64 err)
@@ -219,8 +217,6 @@ static int init_kvm_tdx_caps(const struct tdx_sys_info_td_conf *td_conf,
  */
 static DEFINE_MUTEX(tdx_lock);
 
-static atomic_t nr_configured_hkid;
-
 static bool tdx_operand_busy(u64 err)
 {
        return (err & TDX_SEAMCALL_STATUS_MASK) == TDX_OPERAND_BUSY;
@@ -268,7 +264,6 @@ static inline void tdx_hkid_free(struct kvm_tdx *kvm_tdx)
 {
        tdx_guest_keyid_free(kvm_tdx->hkid);
        kvm_tdx->hkid = -1;
-       atomic_dec(&nr_configured_hkid);
        misc_cg_uncharge(MISC_CG_RES_TDX, kvm_tdx->misc_cg, 1);
        put_misc_cg(kvm_tdx->misc_cg);
        kvm_tdx->misc_cg = NULL;
@@ -2398,8 +2393,6 @@ static int __tdx_td_init(struct kvm *kvm, struct td_params *td_params,
 
        ret = -ENOMEM;
 
-       atomic_inc(&nr_configured_hkid);
-
        tdr_page = alloc_page(GFP_KERNEL);
        if (!tdr_page)
                goto free_hkid;
@@ -3291,51 +3284,10 @@ int tdx_gmem_max_mapping_level(struct kvm *kvm, kvm_pfn_t pfn, bool is_private)
        return PG_LEVEL_4K;
 }
 
-static int tdx_online_cpu(unsigned int cpu)
-{
-       return 0;
-}
-
-static int tdx_offline_cpu(unsigned int cpu)
-{
-       int i;
-
-       /* No TD is running.  Allow any cpu to be offline. */
-       if (!atomic_read(&nr_configured_hkid))
-               return 0;
-
-       /*
-        * In order to reclaim TDX HKID, (i.e. when deleting guest TD), need to
-        * call TDH.PHYMEM.PAGE.WBINVD on all packages to program all memory
-        * controller with pconfig.  If we have active TDX HKID, refuse to
-        * offline the last online cpu.
-        */
-       for_each_online_cpu(i) {
-               /*
-                * Found another online cpu on the same package.
-                * Allow to offline.
-                */
-               if (i != cpu && topology_physical_package_id(i) ==
-                               topology_physical_package_id(cpu))
-                       return 0;
-       }
-
-       /*
-        * This is the last cpu of this package.  Don't offline it.
-        *
-        * Because it's hard for human operator to understand the
-        * reason, warn it.
-        */
-#define MSG_ALLPKG_ONLINE \
-       "TDX requires all packages to have an online CPU. Delete all TDs in order to offline all CPUs of a package.\n"
-       pr_warn_ratelimited(MSG_ALLPKG_ONLINE);
-       return -EBUSY;
-}
-
 static int __init __tdx_bringup(void)
 {
        const struct tdx_sys_info_td_conf *td_conf;
-       int r, i;
+       int i;
 
        for (i = 0; i < ARRAY_SIZE(tdx_uret_msrs); i++) {
                /*
@@ -3403,23 +3355,7 @@ static int __init __tdx_bringup(void)
        if (misc_cg_set_capacity(MISC_CG_RES_TDX, tdx_get_nr_guest_keyids()))
                return -EINVAL;
 
-       /*
-        * TDX-specific cpuhp callback to disallow offlining the last CPU in a
-        * packing while KVM is running one or more TDs.  Reclaiming HKIDs
-        * requires doing PAGE.WBINVD on every package, i.e. offlining all CPUs
-        * of a package would prevent reclaiming the HKID.
-        */
-       r = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "kvm/cpu/tdx:online",
-                             tdx_online_cpu, tdx_offline_cpu);
-       if (r < 0)
-               goto err_cpuhup;
-
-       tdx_cpuhp_state = r;
        return 0;
-
-err_cpuhup:
-       misc_cg_set_capacity(MISC_CG_RES_TDX, 0);
-       return r;
 }
 
 int __init tdx_bringup(void)
@@ -3487,7 +3423,6 @@ void tdx_cleanup(void)
                return;
 
        misc_cg_set_capacity(MISC_CG_RES_TDX, 0);
-       cpuhp_remove_state(tdx_cpuhp_state);
 }
 
 void __init tdx_hardware_setup(void)

diff --git a/arch/x86/virt/vmx/tdx/tdx.c b/arch/x86/virt/vmx/tdx/tdx.c
index a5937b0b76b2e920567857d03ae9fdfc7396e17f..3a1dddec6843dc2fd4e2dd49ff29220ec0e4b1d2 100644 (file)
--- a/arch/x86/virt/vmx/tdx/tdx.c
+++ b/arch/x86/virt/vmx/tdx/tdx.c
@@ -59,6 +59,8 @@ static LIST_HEAD(tdx_memlist);
 static struct tdx_sys_info tdx_sysinfo __ro_after_init;
 static bool tdx_module_initialized __ro_after_init;
 
+static atomic_t nr_configured_hkid;
+
 typedef void (*sc_err_func_t)(u64 fn, u64 err, struct tdx_module_args *args);
 
 static inline void seamcall_err(u64 fn, u64 err, struct tdx_module_args *args)
@@ -186,6 +188,40 @@ static int tdx_online_cpu(unsigned int cpu)
 
 static int tdx_offline_cpu(unsigned int cpu)
 {
+       int i;
+
+       /* No TD is running.  Allow any cpu to be offline. */
+       if (!atomic_read(&nr_configured_hkid))
+               goto done;
+
+       /*
+        * In order to reclaim TDX HKID, (i.e. when deleting guest TD), need to
+        * call TDH.PHYMEM.PAGE.WBINVD on all packages to program all memory
+        * controller with pconfig.  If we have active TDX HKID, refuse to
+        * offline the last online cpu.
+        */
+       for_each_online_cpu(i) {
+               /*
+                * Found another online cpu on the same package.
+                * Allow to offline.
+                */
+               if (i != cpu && topology_physical_package_id(i) ==
+                               topology_physical_package_id(cpu))
+                       goto done;
+       }
+
+       /*
+        * This is the last cpu of this package.  Don't offline it.
+        *
+        * Because it's hard for human operator to understand the
+        * reason, warn it.
+        */
+#define MSG_ALLPKG_ONLINE \
+       "TDX requires all packages to have an online CPU. Delete all TDs in order to offline all CPUs of a package.\n"
+       pr_warn_ratelimited(MSG_ALLPKG_ONLINE);
+       return -EBUSY;
+
+done:
        x86_virt_put_ref(X86_FEATURE_VMX);
        return 0;
 }
@@ -1506,15 +1542,22 @@ EXPORT_SYMBOL_FOR_KVM(tdx_get_nr_guest_keyids);
 
 int tdx_guest_keyid_alloc(void)
 {
-       return ida_alloc_range(&tdx_guest_keyid_pool, tdx_guest_keyid_start,
-                              tdx_guest_keyid_start + tdx_nr_guest_keyids - 1,
-                              GFP_KERNEL);
+       int ret;
+
+       ret = ida_alloc_range(&tdx_guest_keyid_pool, tdx_guest_keyid_start,
+                             tdx_guest_keyid_start + tdx_nr_guest_keyids - 1,
+                             GFP_KERNEL);
+       if (ret >= 0)
+               atomic_inc(&nr_configured_hkid);
+
+       return ret;
 }
 EXPORT_SYMBOL_FOR_KVM(tdx_guest_keyid_alloc);
 
 void tdx_guest_keyid_free(unsigned int keyid)
 {
        ida_free(&tdx_guest_keyid_pool, keyid);
+       atomic_dec(&nr_configured_hkid);
 }
 EXPORT_SYMBOL_FOR_KVM(tdx_guest_keyid_free);