From nobody Wed Feb 11 19:00:48 2026 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 60709C6FA99 for ; Sun, 12 Mar 2023 18:04:02 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231814AbjCLSEA (ORCPT ); Sun, 12 Mar 2023 14:04:00 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:39094 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231304AbjCLSCp (ORCPT ); Sun, 12 Mar 2023 14:02:45 -0400 Received: from mga12.intel.com (mga12.intel.com [192.55.52.136]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 539C34E5CE; Sun, 12 Mar 2023 10:59:29 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1678643969; x=1710179969; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=kmdl+EVzCwsZETsOPlf5vqG3hqbRCjmsE18QsAzTM30=; b=II75N05Nzwup/taE9fLqzI6kyQTmlUM2tMDHGS9WH6iPVbExh0xNDcwu X6QPzcer/VwZP0Z+TCs16tEIcdfPX0uGtO9fXmsgEjK8mrMAduJUuaMrd MatKKobABe2mlh2DtIUKW7+9RS+hCQmPIeIvotFnWEeHNIqC/pvvUe2gb HlNkl+sdMf2KT/XJIiV0e5wZpgL8D9bNZb3FmJRwUVvIXM0Maa8TtROg7 kEu3vD2XeO6Xv4FWwWJ1budeZbPsxZ84pNBrL3do6ZDWxf+aizh0sRD9M UjoedFQZiJs6zZ5zeEt7TJy2P2E4uL9CsKuUEi/3yGbDs6F0F74pYtdzt Q==; X-IronPort-AV: E=McAfee;i="6500,9779,10647"; a="316659956" X-IronPort-AV: E=Sophos;i="5.98,254,1673942400"; d="scan'208";a="316659956" Received: from fmsmga008.fm.intel.com ([10.253.24.58]) by fmsmga106.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 12 Mar 2023 10:58:09 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=McAfee;i="6500,9779,10647"; a="742596705" X-IronPort-AV: E=Sophos;i="5.98,254,1673942400"; d="scan'208";a="742596705" Received: from ls.sc.intel.com (HELO localhost) ([143.183.96.54]) by fmsmga008-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 12 Mar 2023 10:58:09 -0700 From: isaku.yamahata@intel.com To: kvm@vger.kernel.org, linux-kernel@vger.kernel.org Cc: isaku.yamahata@intel.com, isaku.yamahata@gmail.com, Paolo Bonzini , erdemaktas@google.com, Sean Christopherson , Sagi Shahar , David Matlack , Kai Huang , Zhi Wang Subject: [PATCH v13 065/113] KVM: TDX: vcpu_run: save/restore host state(host kernel gs) Date: Sun, 12 Mar 2023 10:56:29 -0700 Message-Id: X-Mailer: git-send-email 2.25.1 In-Reply-To: References: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" From: Isaku Yamahata On entering/exiting TDX vcpu, Preserved or clobbered CPU state is different from VMX case. Add TDX hooks to save/restore host/guest CPU state. Save/restore kernel GS base MSR. Signed-off-by: Isaku Yamahata Reviewed-by: Paolo Bonzini --- arch/x86/kvm/vmx/main.c | 30 ++++++++++++++++++++++++++-- arch/x86/kvm/vmx/tdx.c | 41 ++++++++++++++++++++++++++++++++++++++ arch/x86/kvm/vmx/tdx.h | 4 ++++ arch/x86/kvm/vmx/x86_ops.h | 4 ++++ 4 files changed, 77 insertions(+), 2 deletions(-) diff --git a/arch/x86/kvm/vmx/main.c b/arch/x86/kvm/vmx/main.c index 2fd6c954590d..4a3b42ff9701 100644 --- a/arch/x86/kvm/vmx/main.c +++ b/arch/x86/kvm/vmx/main.c @@ -170,6 +170,32 @@ static void vt_vcpu_reset(struct kvm_vcpu *vcpu, bool = init_event) vmx_vcpu_reset(vcpu, init_event); } =20 +static void vt_prepare_switch_to_guest(struct kvm_vcpu *vcpu) +{ + /* + * All host state is saved/restored across SEAMCALL/SEAMRET, and the + * guest state of a TD is obviously off limits. Deferring MSRs and DRs + * is pointless because the TDX module needs to load *something* so as + * not to expose guest state. + */ + if (is_td_vcpu(vcpu)) { + tdx_prepare_switch_to_guest(vcpu); + return; + } + + vmx_prepare_switch_to_guest(vcpu); +} + +static void vt_vcpu_put(struct kvm_vcpu *vcpu) +{ + if (is_td_vcpu(vcpu)) { + tdx_vcpu_put(vcpu); + return; + } + + vmx_vcpu_put(vcpu); +} + static int vt_vcpu_pre_run(struct kvm_vcpu *vcpu) { if (is_td_vcpu(vcpu)) @@ -307,9 +333,9 @@ struct kvm_x86_ops vt_x86_ops __initdata =3D { .vcpu_free =3D vt_vcpu_free, .vcpu_reset =3D vt_vcpu_reset, =20 - .prepare_switch_to_guest =3D vmx_prepare_switch_to_guest, + .prepare_switch_to_guest =3D vt_prepare_switch_to_guest, .vcpu_load =3D vmx_vcpu_load, - .vcpu_put =3D vmx_vcpu_put, + .vcpu_put =3D vt_vcpu_put, =20 .update_exception_bitmap =3D vmx_update_exception_bitmap, .get_msr_feature =3D vmx_get_msr_feature, diff --git a/arch/x86/kvm/vmx/tdx.c b/arch/x86/kvm/vmx/tdx.c index 28a19b14cbbc..321635a94bd5 100644 --- a/arch/x86/kvm/vmx/tdx.c +++ b/arch/x86/kvm/vmx/tdx.c @@ -1,5 +1,6 @@ // SPDX-License-Identifier: GPL-2.0 #include +#include =20 #include =20 @@ -372,6 +373,8 @@ u8 tdx_get_mt_mask(struct kvm_vcpu *vcpu, gfn_t gfn, bo= ol is_mmio) =20 int tdx_vcpu_create(struct kvm_vcpu *vcpu) { + struct vcpu_tdx *tdx =3D to_tdx(vcpu); + /* * On cpu creation, cpuid entry is blank. Forcibly enable * X2APIC feature to allow X2APIC. @@ -396,9 +399,45 @@ int tdx_vcpu_create(struct kvm_vcpu *vcpu) vcpu->arch.guest_state_protected =3D !(to_kvm_tdx(vcpu->kvm)->attributes & TDX_TD_ATTRIBUTE_DEBUG); =20 + tdx->host_state_need_save =3D true; + tdx->host_state_need_restore =3D false; + return 0; } =20 +void tdx_prepare_switch_to_guest(struct kvm_vcpu *vcpu) +{ + struct vcpu_tdx *tdx =3D to_tdx(vcpu); + + if (!tdx->host_state_need_save) + return; + + if (likely(is_64bit_mm(current->mm))) + tdx->msr_host_kernel_gs_base =3D current->thread.gsbase; + else + tdx->msr_host_kernel_gs_base =3D read_msr(MSR_KERNEL_GS_BASE); + + tdx->host_state_need_save =3D false; +} + +static void tdx_prepare_switch_to_host(struct kvm_vcpu *vcpu) +{ + struct vcpu_tdx *tdx =3D to_tdx(vcpu); + + tdx->host_state_need_save =3D true; + if (!tdx->host_state_need_restore) + return; + + wrmsrl(MSR_KERNEL_GS_BASE, tdx->msr_host_kernel_gs_base); + tdx->host_state_need_restore =3D false; +} + +void tdx_vcpu_put(struct kvm_vcpu *vcpu) +{ + vmx_vcpu_pi_put(vcpu); + tdx_prepare_switch_to_host(vcpu); +} + void tdx_vcpu_free(struct kvm_vcpu *vcpu) { struct vcpu_tdx *tdx =3D to_tdx(vcpu); @@ -465,6 +504,8 @@ fastpath_t tdx_vcpu_run(struct kvm_vcpu *vcpu) =20 tdx_vcpu_enter_exit(vcpu, tdx); =20 + tdx->host_state_need_restore =3D true; + vcpu->arch.regs_avail &=3D ~VMX_REGS_LAZY_LOAD_SET; trace_kvm_exit(vcpu, KVM_ISA_VMX); =20 diff --git a/arch/x86/kvm/vmx/tdx.h b/arch/x86/kvm/vmx/tdx.h index af29e1d89657..cd50d366b7ee 100644 --- a/arch/x86/kvm/vmx/tdx.h +++ b/arch/x86/kvm/vmx/tdx.h @@ -66,6 +66,10 @@ struct vcpu_tdx { =20 bool initialized; =20 + bool host_state_need_save; + bool host_state_need_restore; + u64 msr_host_kernel_gs_base; + /* * Dummy to make pmu_intel not corrupt memory. * TODO: Support PMU for TDX. Future work. diff --git a/arch/x86/kvm/vmx/x86_ops.h b/arch/x86/kvm/vmx/x86_ops.h index c939a9d4d927..ee697a3e9b14 100644 --- a/arch/x86/kvm/vmx/x86_ops.h +++ b/arch/x86/kvm/vmx/x86_ops.h @@ -156,6 +156,8 @@ int tdx_vcpu_create(struct kvm_vcpu *vcpu); void tdx_vcpu_free(struct kvm_vcpu *vcpu); void tdx_vcpu_reset(struct kvm_vcpu *vcpu, bool init_event); fastpath_t tdx_vcpu_run(struct kvm_vcpu *vcpu); +void tdx_prepare_switch_to_guest(struct kvm_vcpu *vcpu); +void tdx_vcpu_put(struct kvm_vcpu *vcpu); u8 tdx_get_mt_mask(struct kvm_vcpu *vcpu, gfn_t gfn, bool is_mmio); =20 int tdx_vcpu_ioctl(struct kvm_vcpu *vcpu, void __user *argp); @@ -183,6 +185,8 @@ static inline int tdx_vcpu_create(struct kvm_vcpu *vcpu= ) { return -EOPNOTSUPP; } static inline void tdx_vcpu_free(struct kvm_vcpu *vcpu) {} static inline void tdx_vcpu_reset(struct kvm_vcpu *vcpu, bool init_event) = {} static inline fastpath_t tdx_vcpu_run(struct kvm_vcpu *vcpu) { return EXIT= _FASTPATH_NONE; } +static inline void tdx_prepare_switch_to_guest(struct kvm_vcpu *vcpu) {} +static inline void tdx_vcpu_put(struct kvm_vcpu *vcpu) {} static inline u8 tdx_get_mt_mask(struct kvm_vcpu *vcpu, gfn_t gfn, bool is= _mmio) { return 0; } =20 static inline int tdx_vcpu_ioctl(struct kvm_vcpu *vcpu, void __user *argp)= { return -EOPNOTSUPP; } --=20 2.25.1