On Mon, Jan 22, 2024 at 03:53:00PM -0800, isaku.yamahata@xxxxxxxxx wrote:
> From: Isaku Yamahata <isaku.yamahata@xxxxxxxxx>
>
> As the first step to create TDX guest, create/destroy VM struct. Assign
> TDX private Host Key ID (HKID) to the TDX guest for memory encryption and
> allocate extra pages for the TDX guest. On destruction, free allocated
> pages, and HKID.
>
> Before tearing down private page tables, TDX requires some resources of the
> guest TD to be destroyed (i.e. HKID must have been reclaimed, etc). Add
> mmu notifier release callback before tearing down private page tables for
> it.
>
> Add vm_free() of kvm_x86_ops hook at the end of kvm_arch_destroy_vm()
> because some per-VM TDX resources, e.g. TDR, need to be freed after other
> TDX resources, e.g. HKID, were freed.
>
> Co-developed-by: Kai Huang <kai.huang@xxxxxxxxx>
> Signed-off-by: Kai Huang <kai.huang@xxxxxxxxx>
> Signed-off-by: Sean Christopherson <sean.j.christopherson@xxxxxxxxx>
> Signed-off-by: Isaku Yamahata <isaku.yamahata@xxxxxxxxx>
>
> ---
> v18:
> - Use TDH.SYS.RD() instead of struct tdsysinfo_struct.
> - Rename tdx_reclaim_td_page() to tdx_reclaim_control_page()
> - return -EAGAIN on TDX_RND_NO_ENTROPY of TDH.MNG.CREATE(), TDH.MNG.ADDCX()
> - fix comment to remove extra the.
> - use true instead of 1 for boolean.
> - remove an extra white line.
>
> v16:
> - Simplified tdx_reclaim_page()
> - Reorganize the locking of tdx_release_hkid(), and use smp_call_mask()
> instead of smp_call_on_cpu() to hold spinlock to race with invalidation
> on releasing guest memfd
> ---
> arch/x86/include/asm/kvm-x86-ops.h | 2 +
> arch/x86/include/asm/kvm_host.h | 2 +
> arch/x86/kvm/Kconfig | 3 +-
> arch/x86/kvm/mmu/mmu.c | 7 +
> arch/x86/kvm/vmx/main.c | 26 +-
> arch/x86/kvm/vmx/tdx.c | 474 ++++++++++++++++++++++++++++-
> arch/x86/kvm/vmx/tdx.h | 6 +-
> arch/x86/kvm/vmx/x86_ops.h | 6 +
> arch/x86/kvm/x86.c | 1 +
> 9 files changed, 519 insertions(+), 8 deletions(-)
...
> +
> +static int __tdx_reclaim_page(hpa_t pa)
> +{
> + struct tdx_module_args out;
> + u64 err;
> +
> + do {
> + err = tdh_phymem_page_reclaim(pa, &out);
> + /*
> + * TDH.PHYMEM.PAGE.RECLAIM is allowed only when TD is shutdown.
> + * state. i.e. destructing TD.
> + * TDH.PHYMEM.PAGE.RECLAIM requires TDR and target page.
> + * Because we're destructing TD, it's rare to contend with TDR.
> + */
> + } while (unlikely(err == (TDX_OPERAND_BUSY | TDX_OPERAND_ID_RCX)));
v16 changed to tdx module 1.5, so here should be TDX_OPERAND_ID_TDR, value 128ULL.
> + if (WARN_ON_ONCE(err)) {
> + pr_tdx_error(TDH_PHYMEM_PAGE_RECLAIM, err, &out);
> + return -EIO;
> + }
> +
> + return 0;
> +}
> +
> +static int tdx_reclaim_page(hpa_t pa)
> +{
> + int r;
> +
> + r = __tdx_reclaim_page(pa);
> + if (!r)
> + tdx_clear_page(pa);
> + return r;
> +}
> +
> +static void tdx_reclaim_control_page(unsigned long td_page_pa)
> +{
> + WARN_ON_ONCE(!td_page_pa);
> +
> + /*
> + * TDCX are being reclaimed. TDX module maps TDCX with HKID
> + * assigned to the TD. Here the cache associated to the TD
> + * was already flushed by TDH.PHYMEM.CACHE.WB before here, So
> + * cache doesn't need to be flushed again.
> + */
> + if (tdx_reclaim_page(td_page_pa))
> + /*
> + * Leak the page on failure:
> + * tdx_reclaim_page() returns an error if and only if there's an
> + * unexpected, fatal error, e.g. a SEAMCALL with bad params,
> + * incorrect concurrency in KVM, a TDX Module bug, etc.
> + * Retrying at a later point is highly unlikely to be
> + * successful.
> + * No log here as tdx_reclaim_page() already did.
> + */
> + return;
> + free_page((unsigned long)__va(td_page_pa));
> +}
> +
> +static void tdx_do_tdh_phymem_cache_wb(void *unused)
> +{
> + u64 err = 0;
> +
> + do {
> + err = tdh_phymem_cache_wb(!!err);
> + } while (err == TDX_INTERRUPTED_RESUMABLE);
> +
> + /* Other thread may have done for us. */
> + if (err == TDX_NO_HKID_READY_TO_WBCACHE)
> + err = TDX_SUCCESS;
> + if (WARN_ON_ONCE(err))
> + pr_tdx_error(TDH_PHYMEM_CACHE_WB, err, NULL);
> +}
> +
> +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;
> + int i;
> +
> + if (!is_hkid_assigned(kvm_tdx))
> + return;
> +
> + 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();
> +
> + /*
> + * We can destroy multiple guest TDs simultaneously. Prevent
> + * tdh_phymem_cache_wb from returning TDX_BUSY by serialization.
> + */
> + mutex_lock(&tdx_lock);
> +
> + /*
> + * Go through multiple TDX HKID state transitions with three SEAMCALLs
> + * to make TDH.PHYMEM.PAGE.RECLAIM() usable. Make the transition atomic
> + * to other functions to operate private pages and Secure-EPT pages.
> + *
> + * Avoid race for kvm_gmem_release() to call kvm_mmu_unmap_gfn_range().
> + * This function is called via mmu notifier, mmu_release().
> + * kvm_gmem_release() is called via fput() on process exit.
> + */
> + write_lock(&kvm->mmu_lock);
> +
> + for_each_online_cpu(i) {
> + if (packages_allocated &&
> + cpumask_test_and_set_cpu(topology_physical_package_id(i),
> + packages))
> + continue;
> + if (targets_allocated)
> + cpumask_set_cpu(i, targets);
> + }
> + if (targets_allocated)
> + on_each_cpu_mask(targets, tdx_do_tdh_phymem_cache_wb, NULL, true);
> + else
> + on_each_cpu(tdx_do_tdh_phymem_cache_wb, NULL, true);
> + /*
> + * In the case of error in tdx_do_tdh_phymem_cache_wb(), the following
> + * tdh_mng_key_freeid() will fail.
> + */
> + err = tdh_mng_key_freeid(kvm_tdx->tdr_pa);
> + if (WARN_ON_ONCE(err)) {
> + pr_tdx_error(TDH_MNG_KEY_FREEID, err, NULL);
> + pr_err("tdh_mng_key_freeid() failed. HKID %d is leaked.\n",
> + kvm_tdx->hkid);
> + } else
> + tdx_hkid_free(kvm_tdx);
> +
> + write_unlock(&kvm->mmu_lock);
> + mutex_unlock(&tdx_lock);
> + cpus_read_unlock();
> + free_cpumask_var(targets);
> + free_cpumask_var(packages);
> +}
> +
> +void tdx_vm_free(struct kvm *kvm)
> +{
> + struct kvm_tdx *kvm_tdx = to_kvm_tdx(kvm);
> + u64 err;
> + int i;
> +
> + /*
> + * tdx_mmu_release_hkid() failed to reclaim HKID. Something went wrong
> + * heavily with TDX module. Give up freeing TD pages. As the function
> + * already warned, don't warn it again.
> + */
> + if (is_hkid_assigned(kvm_tdx))
> + return;
> +
> + if (kvm_tdx->tdcs_pa) {
> + for (i = 0; i < tdx_info->nr_tdcs_pages; i++) {
> + if (kvm_tdx->tdcs_pa[i])
> + tdx_reclaim_control_page(kvm_tdx->tdcs_pa[i]);
> + }
> + kfree(kvm_tdx->tdcs_pa);
> + kvm_tdx->tdcs_pa = NULL;
> + }
> +
> + if (!kvm_tdx->tdr_pa)
> + return;
> + if (__tdx_reclaim_page(kvm_tdx->tdr_pa))
> + return;
> + /*
> + * TDX module maps TDR with TDX global HKID. TDX module may access TDR
> + * while operating on TD (Especially reclaiming TDCS). Cache flush with
> + * TDX global HKID is needed.
> + */
> + err = tdh_phymem_page_wbinvd(set_hkid_to_hpa(kvm_tdx->tdr_pa,
> + tdx_global_keyid));
> + if (WARN_ON_ONCE(err)) {
> + pr_tdx_error(TDH_PHYMEM_PAGE_WBINVD, err, NULL);
> + return;
> + }
> + tdx_clear_page(kvm_tdx->tdr_pa);
> +
> + free_page((unsigned long)__va(kvm_tdx->tdr_pa));
> + kvm_tdx->tdr_pa = 0;
> +}
> +
> +static int tdx_do_tdh_mng_key_config(void *param)
> +{
> + hpa_t *tdr_p = param;
> + u64 err;
> +
> + do {
> + err = tdh_mng_key_config(*tdr_p);
> +
> + /*
> + * If it failed to generate a random key, retry it because this
> + * is typically caused by an entropy error of the CPU's random
> + * number generator.
> + */
> + } while (err == TDX_KEY_GENERATION_FAILED);
> +
> + if (WARN_ON_ONCE(err)) {
> + pr_tdx_error(TDH_MNG_KEY_CONFIG, err, NULL);
> + return -EIO;
> + }
> +
> + return 0;
> +}
> +
> +static int __tdx_td_init(struct kvm *kvm);
> +
> +int tdx_vm_init(struct kvm *kvm)
> +{
> + /*
> + * TDX has its own limit of the number of vcpus in addition to
> + * KVM_MAX_VCPUS.
> + */
> + kvm->max_vcpus = min(kvm->max_vcpus, TDX_MAX_VCPUS);
> +
> + /* Place holder for TDX specific logic. */
> + return __tdx_td_init(kvm);
> +}
> +
> static int tdx_get_capabilities(struct kvm_tdx_cmd *cmd)
> {
> struct kvm_tdx_capabilities __user *user_caps;
> @@ -181,6 +459,176 @@ static int tdx_get_capabilities(struct kvm_tdx_cmd *cmd)
> return ret;
> }
>
> +static int __tdx_td_init(struct kvm *kvm)
> +{
> + struct kvm_tdx *kvm_tdx = to_kvm_tdx(kvm);
> + cpumask_var_t packages;
> + unsigned long *tdcs_pa = NULL;
> + unsigned long tdr_pa = 0;
> + unsigned long va;
> + int ret, i;
> + u64 err;
> +
> + ret = tdx_guest_keyid_alloc();
> + if (ret < 0)
> + return ret;
> + kvm_tdx->hkid = ret;
> +
> + va = __get_free_page(GFP_KERNEL_ACCOUNT);
> + if (!va)
> + goto free_hkid;
> + tdr_pa = __pa(va);
> +
> + tdcs_pa = kcalloc(tdx_info->nr_tdcs_pages, sizeof(*kvm_tdx->tdcs_pa),
> + GFP_KERNEL_ACCOUNT | __GFP_ZERO);
> + if (!tdcs_pa)
> + goto free_tdr;
> + for (i = 0; i < tdx_info->nr_tdcs_pages; i++) {
> + va = __get_free_page(GFP_KERNEL_ACCOUNT);
> + if (!va)
> + goto free_tdcs;
> + tdcs_pa[i] = __pa(va);
> + }
> +
> + if (!zalloc_cpumask_var(&packages, GFP_KERNEL)) {
> + ret = -ENOMEM;
> + goto free_tdcs;
> + }
> + cpus_read_lock();
> + /*
> + * Need at least one CPU of the package to be online in order to
> + * program all packages for host key id. Check it.
> + */
> + for_each_present_cpu(i)
> + cpumask_set_cpu(topology_physical_package_id(i), packages);
> + for_each_online_cpu(i)
> + cpumask_clear_cpu(topology_physical_package_id(i), packages);
> + if (!cpumask_empty(packages)) {
> + ret = -EIO;
> + /*
> + * Because it's hard for human operator to figure out the
> + * reason, warn it.
> + */
> +#define MSG_ALLPKG "All packages need to have online CPU to create TD. Online CPU and retry.\n"
> + pr_warn_ratelimited(MSG_ALLPKG);
> + goto free_packages;
> + }
Generate/release hkid both requests to have "cpumask of at least 1
cpu per each node", how about add one helper for this ? The helper also
checks the cpus_read_lock() is held and return the cpumask if at least
1 cpu is online per node, thus this init funciotn can be simplified and
become more easy to review.
> +
> + /*
> + * Acquire global lock to avoid TDX_OPERAND_BUSY:
> + * TDH.MNG.CREATE and other APIs try to lock the global Key Owner
> + * Table (KOT) to track the assigned TDX private HKID. It doesn't spin
> + * to acquire the lock, returns TDX_OPERAND_BUSY instead, and let the
> + * caller to handle the contention. This is because of time limitation
> + * usable inside the TDX module and OS/VMM knows better about process
> + * scheduling.
> + *
> + * APIs to acquire the lock of KOT:
> + * TDH.MNG.CREATE, TDH.MNG.KEY.FREEID, TDH.MNG.VPFLUSHDONE, and
> + * TDH.PHYMEM.CACHE.WB.
> + */
> + mutex_lock(&tdx_lock);
> + err = tdh_mng_create(tdr_pa, kvm_tdx->hkid);
> + mutex_unlock(&tdx_lock);
> + if (err == TDX_RND_NO_ENTROPY) {
> + ret = -EAGAIN;
> + goto free_packages;
> + }
> + if (WARN_ON_ONCE(err)) {
> + pr_tdx_error(TDH_MNG_CREATE, err, NULL);
> + ret = -EIO;
> + goto free_packages;
> + }
> + kvm_tdx->tdr_pa = tdr_pa;
> +
> + for_each_online_cpu(i) {
> + int pkg = topology_physical_package_id(i);
> +
> + if (cpumask_test_and_set_cpu(pkg, packages))
> + continue;
> +
> + /*
> + * Program the memory controller in the package with an
> + * encryption key associated to a TDX private host key id
> + * assigned to this TDR. Concurrent operations on same memory
> + * controller results in TDX_OPERAND_BUSY. Avoid this race by
> + * mutex.
> + */
> + mutex_lock(&tdx_mng_key_config_lock[pkg]);
> + ret = smp_call_on_cpu(i, tdx_do_tdh_mng_key_config,
> + &kvm_tdx->tdr_pa, true);
> + mutex_unlock(&tdx_mng_key_config_lock[pkg]);
> + if (ret)
> + break;
> + }
> + cpus_read_unlock();
> + free_cpumask_var(packages);
> + if (ret) {
> + i = 0;
> + goto teardown;
> + }
> +
> + kvm_tdx->tdcs_pa = tdcs_pa;
> + for (i = 0; i < tdx_info->nr_tdcs_pages; i++) {
> + err = tdh_mng_addcx(kvm_tdx->tdr_pa, tdcs_pa[i]);
> + if (err == TDX_RND_NO_ENTROPY) {
> + /* Here it's hard to allow userspace to retry. */
> + ret = -EBUSY;
> + goto teardown;
> + }
> + if (WARN_ON_ONCE(err)) {
> + pr_tdx_error(TDH_MNG_ADDCX, err, NULL);
> + ret = -EIO;
> + goto teardown;
> + }
> + }
> +
> + /*
> + * Note, TDH_MNG_INIT cannot be invoked here. TDH_MNG_INIT requires a dedicated
> + * ioctl() to define the configure CPUID values for the TD.
> + */
> + return 0;
> +
> + /*
> + * The sequence for freeing resources from a partially initialized TD
> + * varies based on where in the initialization flow failure occurred.
> + * Simply use the full teardown and destroy, which naturally play nice
> + * with partial initialization.
> + */
> +teardown:
> + for (; i < tdx_info->nr_tdcs_pages; i++) {
> + if (tdcs_pa[i]) {
> + free_page((unsigned long)__va(tdcs_pa[i]));
> + tdcs_pa[i] = 0;
> + }
> + }
> + if (!kvm_tdx->tdcs_pa)
> + kfree(tdcs_pa);
> + tdx_mmu_release_hkid(kvm);
> + tdx_vm_free(kvm);
> + return ret;
> +
> +free_packages:
> + cpus_read_unlock();
> + free_cpumask_var(packages);
> +free_tdcs:
> + for (i = 0; i < tdx_info->nr_tdcs_pages; i++) {
> + if (tdcs_pa[i])
> + free_page((unsigned long)__va(tdcs_pa[i]));
> + }
> + kfree(tdcs_pa);
> + kvm_tdx->tdcs_pa = NULL;
> +
> +free_tdr:
> + if (tdr_pa)
> + free_page((unsigned long)__va(tdr_pa));
> + kvm_tdx->tdr_pa = 0;
> +free_hkid:
> + if (is_hkid_assigned(kvm_tdx))
> + tdx_hkid_free(kvm_tdx);
> + return ret;
> +}
> +
> int tdx_vm_ioctl(struct kvm *kvm, void __user *argp)
> {
> struct kvm_tdx_cmd tdx_cmd;
> @@ -212,12 +660,13 @@ int tdx_vm_ioctl(struct kvm *kvm, void __user *argp)
>
> static int __init tdx_module_setup(void)
> {
> - u16 num_cpuid_config;
> + u16 num_cpuid_config, tdcs_base_size;
> int ret;
> u32 i;
>
> struct tdx_md_map mds[] = {
> TDX_MD_MAP(NUM_CPUID_CONFIG, &num_cpuid_config),
> + TDX_MD_MAP(TDCS_BASE_SIZE, &tdcs_base_size),
> };
>
> #define TDX_INFO_MAP(_field_id, _member) \
> @@ -272,6 +721,8 @@ static int __init tdx_module_setup(void)
> c->edx = ecx_edx >> 32;
> }
>
> + tdx_info->nr_tdcs_pages = tdcs_base_size / PAGE_SIZE;
> +
> return 0;
>
> error_sys_rd:
> @@ -319,13 +770,27 @@ int __init tdx_hardware_setup(struct kvm_x86_ops *x86_ops)
> struct vmx_tdx_enabled vmx_tdx = {
> .err = ATOMIC_INIT(0),
> };
> + int max_pkgs;
> int r = 0;
> + int i;
>
> + if (!cpu_feature_enabled(X86_FEATURE_MOVDIR64B)) {
> + pr_warn("MOVDIR64B is reqiured for TDX\n");
> + return -EOPNOTSUPP;
> + }
> if (!enable_ept) {
> pr_warn("Cannot enable TDX with EPT disabled\n");
> return -EINVAL;
> }
>
> + max_pkgs = topology_max_packages();
> + tdx_mng_key_config_lock = kcalloc(max_pkgs, sizeof(*tdx_mng_key_config_lock),
> + GFP_KERNEL);
> + if (!tdx_mng_key_config_lock)
> + return -ENOMEM;
> + for (i = 0; i < max_pkgs; i++)
> + mutex_init(&tdx_mng_key_config_lock[i]);
> +
> if (!zalloc_cpumask_var(&vmx_tdx.vmx_enabled, GFP_KERNEL)) {
> r = -ENOMEM;
> goto out;
> @@ -350,4 +815,5 @@ int __init tdx_hardware_setup(struct kvm_x86_ops *x86_ops)
> void tdx_hardware_unsetup(void)
> {
> kfree(tdx_info);
> + kfree(tdx_mng_key_config_lock);
> }
> diff --git a/arch/x86/kvm/vmx/tdx.h b/arch/x86/kvm/vmx/tdx.h
> index 22c0b57f69ca..ae117f864cfb 100644
> --- a/arch/x86/kvm/vmx/tdx.h
> +++ b/arch/x86/kvm/vmx/tdx.h
> @@ -8,7 +8,11 @@
>
> struct kvm_tdx {
> struct kvm kvm;
> - /* TDX specific members follow. */
> +
> + unsigned long tdr_pa;
> + unsigned long *tdcs_pa;
> +
> + int hkid;
> };
>
> struct vcpu_tdx {
> diff --git a/arch/x86/kvm/vmx/x86_ops.h b/arch/x86/kvm/vmx/x86_ops.h
> index 3a3be66888da..5befcc2d58e1 100644
> --- a/arch/x86/kvm/vmx/x86_ops.h
> +++ b/arch/x86/kvm/vmx/x86_ops.h
> @@ -140,6 +140,9 @@ void tdx_hardware_unsetup(void);
> bool tdx_is_vm_type_supported(unsigned long type);
>
> int tdx_vm_enable_cap(struct kvm *kvm, struct kvm_enable_cap *cap);
> +int tdx_vm_init(struct kvm *kvm);
> +void tdx_mmu_release_hkid(struct kvm *kvm);
> +void tdx_vm_free(struct kvm *kvm);
> int tdx_vm_ioctl(struct kvm *kvm, void __user *argp);
> #else
> static inline int tdx_hardware_setup(struct kvm_x86_ops *x86_ops) { return -EOPNOTSUPP; }
> @@ -150,6 +153,9 @@ static inline int tdx_vm_enable_cap(struct kvm *kvm, struct kvm_enable_cap *cap)
> {
> return -EINVAL;
> };
> +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) {}
> static inline int tdx_vm_ioctl(struct kvm *kvm, void __user *argp) { return -EOPNOTSUPP; }
> #endif
>
> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> index a1389ddb1b33..3ab243d9fe9d 100644
> --- a/arch/x86/kvm/x86.c
> +++ b/arch/x86/kvm/x86.c
> @@ -12714,6 +12714,7 @@ void kvm_arch_destroy_vm(struct kvm *kvm)
> kvm_page_track_cleanup(kvm);
> kvm_xen_destroy_vm(kvm);
> kvm_hv_destroy_vm(kvm);
> + static_call_cond(kvm_x86_vm_free)(kvm);
> }
>
> static void memslot_rmap_free(struct kvm_memory_slot *slot)
> --
> 2.25.1
>
>
