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

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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>
This commit is contained in:
Chao Gao 2026-02-13 17:26:59 -08:00 committed by Sean Christopherson
parent 9900400e20
commit eac90a5ba0
2 changed files with 47 additions and 69 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

67
arch/x86/kvm/vmx/tdx.c
View File

@ -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)

49
arch/x86/virt/vmx/tdx/tdx.c
View File

@ -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);