Commit eac90a5b authored by Chao Gao's avatar Chao Gao Committed by Sean Christopherson
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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: default avatarDan Williams <dan.j.williams@intel.com>
Signed-off-by: default avatarChao Gao <chao.gao@intel.com>
Tested-by: default avatarChao Gao <chao.gao@intel.com>
Tested-by: default avatarSagi Shahar <sagis@google.com>
Link: https://patch.msgid.link/20260214012702.2368778-14-seanjc@google.com


Signed-off-by: default avatarSean Christopherson <seanjc@google.com>
parent 9900400e

arch/x86/kvm/vmx/tdx.c

+1 −66
Original line number Diff line number Diff line
@@ -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)

arch/x86/virt/vmx/tdx/tdx.c

+46 −3
Original line number Diff line number Diff line
@@ -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,

	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);