From: Yang Weijiang <weijiang.yang@xxxxxxxxx> TDX module resets the TSX_CTRL MSR to 0 at TD exit if TSX is enabled for TD. Or it preserves the TSX_CTRL MSR if TSX is disabled for TD. VMM can rely on uret_msrs mechanism to defer the reload of host value until exiting to user space. Signed-off-by: Yang Weijiang <weijiang.yang@xxxxxxxxx> Signed-off-by: Isaku Yamahata <isaku.yamahata@xxxxxxxxx> --- arch/x86/kvm/vmx/tdx.c | 35 +++++++++++++++++++++++++++++++++-- arch/x86/kvm/vmx/tdx.h | 8 ++++++++ 2 files changed, 41 insertions(+), 2 deletions(-) diff --git a/arch/x86/kvm/vmx/tdx.c b/arch/x86/kvm/vmx/tdx.c index 5b5c68a1ece4..29aa53d530ca 100644 --- a/arch/x86/kvm/vmx/tdx.c +++ b/arch/x86/kvm/vmx/tdx.c @@ -496,14 +496,21 @@ static struct tdx_uret_msr tdx_uret_msrs[] = { {.msr = MSR_LSTAR,}, {.msr = MSR_TSC_AUX,}, }; +static unsigned int tdx_uret_tsx_ctrl_slot; -static void tdx_user_return_update_cache(void) +static void tdx_user_return_update_cache(struct kvm_vcpu *vcpu) { int i; for (i = 0; i < ARRAY_SIZE(tdx_uret_msrs); i++) kvm_user_return_update_cache(tdx_uret_msrs[i].slot, tdx_uret_msrs[i].defval); + /* + * TSX_CTRL is reset to 0 if guest TSX is supported. Otherwise + * preserved. + */ + if (to_kvm_tdx(vcpu->kvm)->tsx_supported) + kvm_user_return_update_cache(tdx_uret_tsx_ctrl_slot, 0); } static void tdx_restore_host_xsave_state(struct kvm_vcpu *vcpu) @@ -547,7 +554,7 @@ fastpath_t tdx_vcpu_run(struct kvm_vcpu *vcpu) tdx_vcpu_enter_exit(vcpu, tdx); - tdx_user_return_update_cache(); + tdx_user_return_update_cache(vcpu); tdx_restore_host_xsave_state(vcpu); tdx->host_state_need_restore = true; @@ -1021,6 +1028,24 @@ static int setup_tdparams_xfam(struct kvm_cpuid2 *cpuid, struct td_params *td_pa return 0; } +static bool tdparams_tsx_supported(struct kvm_cpuid2 *cpuid) +{ + const struct kvm_cpuid_entry2 *entry; + u64 mask; + u32 ebx; + + entry = kvm_find_cpuid_entry2(cpuid, 0x7, 0); + if (entry) + ebx = entry->ebx; + else + ebx = 0; + + mask = __feature_bit(X86_FEATURE_HLE) | __feature_bit(X86_FEATURE_RTM); + if (ebx & mask) + return true; + return false; +} + static int setup_tdparams(struct kvm *kvm, struct td_params *td_params, struct kvm_tdx_init_vm *init_vm) { @@ -1064,6 +1089,7 @@ static int setup_tdparams(struct kvm *kvm, struct td_params *td_params, MEMCPY_SAME_SIZE(td_params->mrowner, init_vm->mrowner); MEMCPY_SAME_SIZE(td_params->mrownerconfig, init_vm->mrownerconfig); + to_kvm_tdx(kvm)->tsx_supported = tdparams_tsx_supported(cpuid); return 0; } @@ -1693,6 +1719,11 @@ int __init tdx_hardware_setup(struct kvm_x86_ops *x86_ops) return -EIO; } } + tdx_uret_tsx_ctrl_slot = kvm_find_user_return_msr(MSR_IA32_TSX_CTRL); + if (WARN_ON_ONCE(tdx_uret_tsx_ctrl_slot == -1)) { + pr_err("MSR_IA32_TSX_CTRL isn't included by kvm_find_user_return_msr\n"); + return -EIO; + } max_pkgs = topology_max_packages(); tdx_mng_key_config_lock = kcalloc(max_pkgs, sizeof(*tdx_mng_key_config_lock), diff --git a/arch/x86/kvm/vmx/tdx.h b/arch/x86/kvm/vmx/tdx.h index cd50d366b7ee..6ce362c70e26 100644 --- a/arch/x86/kvm/vmx/tdx.h +++ b/arch/x86/kvm/vmx/tdx.h @@ -17,6 +17,14 @@ struct kvm_tdx { u64 xfam; int hkid; + /* + * Used on each TD-exit, see tdx_user_return_update_cache(). + * TSX_CTRL value on TD exit + * - set 0 if guest TSX enabled + * - preserved if guest TSX disabled + */ + u64 tsx_supported; + hpa_t source_pa; bool finalized; -- 2.25.1