From nobody Sun Sep 7 12:21:37 2025 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 4B947CDB482 for ; Mon, 16 Oct 2023 16:33:15 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234258AbjJPQdO (ORCPT ); Mon, 16 Oct 2023 12:33:14 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:35626 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233597AbjJPQck (ORCPT ); Mon, 16 Oct 2023 12:32:40 -0400 Received: from mgamail.intel.com (mgamail.intel.com [192.55.52.136]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 3CF541FD0; Mon, 16 Oct 2023 09:17:51 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1697473071; x=1729009071; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=I8aUBHRSHQVF5uV6/44+BSCA3XBIOfQ0qDRGPet2e38=; b=A18oT6rYIWemRNIg7Fs11vsri2aLyesq+TW0HqXJtxbdYXDCGbud/807 4BNndqMYXbjDcDZpZX/AvHDNk/Ww4IrLgCgNYc7GSTrpfQjH/IT7IGnrU Q7hOv54JLgWwBZ08rUrf6m2cv+xAd9yaSclu5RONeSQUcOgZ1rJE92zv+ JYLVuzK3w2zuXV60ix7cfJLwnAiyLkpzJb8mhHXD5K7G2630z2G1ryDr2 7sWdNItsZT42TwRoEvbObiYEVjtNu7d6gtrL0C8/G53AtprAioE0t37Bj whm0ZHJHavh1gqZH+DwDSq19LDsBF3t45LkuNiN803t0VPubg4TkvpC61 Q==; X-IronPort-AV: E=McAfee;i="6600,9927,10865"; a="364921863" X-IronPort-AV: E=Sophos;i="6.03,229,1694761200"; d="scan'208";a="364921863" Received: from fmsmga003.fm.intel.com ([10.253.24.29]) by fmsmga106.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 16 Oct 2023 09:15:51 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=McAfee;i="6600,9927,10865"; a="846448185" X-IronPort-AV: E=Sophos;i="6.03,229,1694761200"; d="scan'208";a="846448185" Received: from ls.sc.intel.com (HELO localhost) ([172.25.112.31]) by fmsmga003-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 16 Oct 2023 09:15:50 -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 , chen.bo@intel.com, hang.yuan@intel.com, tina.zhang@intel.com Subject: [PATCH v16 063/116] KVM: TDX: vcpu_run: save/restore host state(host kernel gs) Date: Mon, 16 Oct 2023 09:14:15 -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 | 42 ++++++++++++++++++++++++++++++++++++++ arch/x86/kvm/vmx/tdx.h | 4 ++++ arch/x86/kvm/vmx/x86_ops.h | 4 ++++ 4 files changed, 78 insertions(+), 2 deletions(-) diff --git a/arch/x86/kvm/vmx/main.c b/arch/x86/kvm/vmx/main.c index c45b8fc3e8d3..bc75ed8ff371 100644 --- a/arch/x86/kvm/vmx/main.c +++ b/arch/x86/kvm/vmx/main.c @@ -169,6 +169,32 @@ 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)) @@ -304,9 +330,9 @@ 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 7b5d0556ad95..add9a0083adb 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 @@ -392,6 +393,7 @@ u8 tdx_get_mt_mask(struct kvm_vcpu *vcpu, gfn_t gfn, bo= ol is_mmio) int tdx_vcpu_create(struct kvm_vcpu *vcpu) { struct kvm_tdx *kvm_tdx =3D to_kvm_tdx(vcpu->kvm); + struct vcpu_tdx *tdx =3D to_tdx(vcpu); =20 /* * On cpu creation, cpuid entry is blank. Forcibly enable @@ -420,9 +422,47 @@ int tdx_vcpu_create(struct kvm_vcpu *vcpu) if ((kvm_tdx->xfam & XFEATURE_MASK_XTILE) =3D=3D XFEATURE_MASK_XTILE) vcpu->arch.xfd_no_write_intercept =3D true; =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; + + ++vcpu->stat.host_state_reload; + + 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); @@ -543,6 +583,8 @@ fastpath_t tdx_vcpu_run(struct kvm_vcpu *vcpu) =20 tdx_vcpu_enter_exit(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 04942488e6d1..610bd3f4e952 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 87cfa1c5afa3..02da72dfb2cf 100644 --- a/arch/x86/kvm/vmx/x86_ops.h +++ b/arch/x86/kvm/vmx/x86_ops.h @@ -151,6 +151,8 @@ 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); @@ -179,6 +181,8 @@ 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