From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 9F3A017725 for ; Tue, 2 Jan 2024 22:34:28 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=redhat.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=redhat.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="d2EGr0LV" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1704234867; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=8Dz39R9pAkRItXAhKUr29BdCW8gCwDIwIhiTXdpehTI=; b=d2EGr0LV/me5t3Qiy8yRl/lSTFQHzQGwiYKefPQ1ZLOgrcqMd5UuMH9OCeUXHXl7MZQlH6 bc2QznhOE1Va5TOQIYAGb3EYH7iXpVEI/iDQX8KpDrcOCAJq07SpnP4EAnsEx2m7ESQyzm E3iJhuo2Z1k8ezR+F0kCOBXs+B98cOI= Received: from mail-wr1-f69.google.com (mail-wr1-f69.google.com [209.85.221.69]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-151-VUt3m1anNN663e3AMtmMdA-1; Tue, 02 Jan 2024 17:34:21 -0500 X-MC-Unique: VUt3m1anNN663e3AMtmMdA-1 Received: by mail-wr1-f69.google.com with SMTP id ffacd0b85a97d-336953e0fe7so5761357f8f.1 for ; Tue, 02 Jan 2024 14:34:21 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1704234860; x=1704839660; h=content-transfer-encoding:mime-version:user-agent:references :in-reply-to:date:cc:to:from:subject:message-id:x-gm-message-state :from:to:cc:subject:date:message-id:reply-to; bh=8Dz39R9pAkRItXAhKUr29BdCW8gCwDIwIhiTXdpehTI=; b=Yt2uWoppEhw5KRebvcTrCYitlUQrKR/8M59lzIdcZKGHGI3lNBf6GfBemYyAnCIVdY mTWpxbRXfUzxDOUsNFSLQ6d38b5MHux/Rp970PC8xAEmAmttlaH1LPZ/sZd5y0brWiCR PuG5t6qlkTJmr/l9sLlAdOGT6SHR5cLUZx4BN5s+hmAwTnKDMQMEH/dVzcgYeqGPJBbE /8ApSclJHkYOYFwwisFtElKLEZtX0igI8N7NLgDnnFk1uQr2E9A6ziTJtcgYVhqWJQY3 skQIhif6HUKDSQIPkZlhWjj0Dso8x8C9TGcZ0M9WnfSjEAN/Zemhx/M4ceeB7oXPs9Zh 7tSg== X-Gm-Message-State: AOJu0YwthUaW8NEKPvK46P1Km+dGZFSbO482pc/lWGJ2lCs22hfymiv8 WXnvw2KzLOkRn8yzdXCDM3GsWfgP95dmtfuQsRYtM7FINaqkZeQ7mlnYK1FAFGoLy2nf0cFiP3B fEUPlsHxxni5z9zZ7NjwiSQCAE0tffdzy X-Received: by 2002:a5d:598a:0:b0:337:161:6d81 with SMTP id n10-20020a5d598a000000b0033701616d81mr5680527wri.52.1704234860502; Tue, 02 Jan 2024 14:34:20 -0800 (PST) X-Google-Smtp-Source: AGHT+IHwNcYpeTiMWaP9qxjWQSEmPItktNdEZFwRfWo0MNeTrtE4XPftazTB0jgG/v2KAfOFCyCKAg== X-Received: by 2002:a5d:598a:0:b0:337:161:6d81 with SMTP id n10-20020a5d598a000000b0033701616d81mr5680521wri.52.1704234860177; Tue, 02 Jan 2024 14:34:20 -0800 (PST) Received: from starship ([147.235.223.38]) by smtp.gmail.com with ESMTPSA id m2-20020adfe0c2000000b00337464bf723sm3155670wri.18.2024.01.02.14.34.18 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 02 Jan 2024 14:34:19 -0800 (PST) Message-ID: Subject: Re: [PATCH v8 21/26] KVM: x86: Save and reload SSP to/from SMRAM From: Maxim Levitsky To: Yang Weijiang , seanjc@google.com, pbonzini@redhat.com, dave.hansen@intel.com, kvm@vger.kernel.org, linux-kernel@vger.kernel.org Cc: peterz@infradead.org, chao.gao@intel.com, rick.p.edgecombe@intel.com, john.allen@amd.com Date: Wed, 03 Jan 2024 00:34:18 +0200 In-Reply-To: <20231221140239.4349-22-weijiang.yang@intel.com> References: <20231221140239.4349-1-weijiang.yang@intel.com> <20231221140239.4349-22-weijiang.yang@intel.com> Content-Type: text/plain; charset="UTF-8" User-Agent: Evolution 3.36.5 (3.36.5-2.fc32) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 7bit On Thu, 2023-12-21 at 09:02 -0500, Yang Weijiang wrote: > Save CET SSP to SMRAM on SMI and reload it on RSM. KVM emulates HW arch > behavior when guest enters/leaves SMM mode,i.e., save registers to SMRAM > at the entry of SMM and reload them at the exit to SMM. Per SDM, SSP is > one of such registers on 64-bit Arch, and add the support for SSP. Note, > on 32-bit Arch, SSP is not defined in SMRAM, so fail 32-bit CET guest > launch. > > Suggested-by: Sean Christopherson > Suggested-by: Chao Gao > Signed-off-by: Yang Weijiang > --- > arch/x86/kvm/cpuid.c | 11 +++++++++++ > arch/x86/kvm/smm.c | 8 ++++++++ > arch/x86/kvm/smm.h | 2 +- > 3 files changed, 20 insertions(+), 1 deletion(-) > > diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c > index 3ab133530573..cfc0ac8ddb4a 100644 > --- a/arch/x86/kvm/cpuid.c > +++ b/arch/x86/kvm/cpuid.c > @@ -149,6 +149,17 @@ static int kvm_check_cpuid(struct kvm_vcpu *vcpu, > if (vaddr_bits != 48 && vaddr_bits != 57 && vaddr_bits != 0) > return -EINVAL; > } > + /* > + * Prevent 32-bit guest from being launched if CET is exposed as SSP > + * state is not defined for 32-bit SMRAM. > + */ > + best = cpuid_entry2_find(entries, nent, 0x80000001, > + KVM_CPUID_INDEX_NOT_SIGNIFICANT); > + if (best && !(best->edx & F(LM))) { > + best = cpuid_entry2_find(entries, nent, 0x7, 0); > + if (best && ((best->ecx & F(SHSTK)) || (best->edx & F(IBT)))) > + return -EINVAL; > + } I honestly prefer a check in enter_smm_save_state_32 because SMM might not even be enabled/used for the guest, and for consistency with SVM check that I added, but whatever. Reviewed-by: Maxim Levitsky Best regards, Maxim Levitsky > > /* > * Exposing dynamic xfeatures to the guest requires additional > diff --git a/arch/x86/kvm/smm.c b/arch/x86/kvm/smm.c > index 45c855389ea7..7aac9c54c353 100644 > --- a/arch/x86/kvm/smm.c > +++ b/arch/x86/kvm/smm.c > @@ -275,6 +275,10 @@ static void enter_smm_save_state_64(struct kvm_vcpu *vcpu, > enter_smm_save_seg_64(vcpu, &smram->gs, VCPU_SREG_GS); > > smram->int_shadow = static_call(kvm_x86_get_interrupt_shadow)(vcpu); > + > + if (guest_can_use(vcpu, X86_FEATURE_SHSTK)) > + KVM_BUG_ON(kvm_msr_read(vcpu, MSR_KVM_SSP, &smram->ssp), > + vcpu->kvm); > } > #endif > > @@ -564,6 +568,10 @@ static int rsm_load_state_64(struct x86_emulate_ctxt *ctxt, > static_call(kvm_x86_set_interrupt_shadow)(vcpu, 0); > ctxt->interruptibility = (u8)smstate->int_shadow; > > + if (guest_can_use(vcpu, X86_FEATURE_SHSTK)) > + KVM_BUG_ON(kvm_msr_write(vcpu, MSR_KVM_SSP, smstate->ssp), > + vcpu->kvm); > + > return X86EMUL_CONTINUE; > } > #endif > diff --git a/arch/x86/kvm/smm.h b/arch/x86/kvm/smm.h > index a1cf2ac5bd78..1e2a3e18207f 100644 > --- a/arch/x86/kvm/smm.h > +++ b/arch/x86/kvm/smm.h > @@ -116,8 +116,8 @@ struct kvm_smram_state_64 { > u32 smbase; > u32 reserved4[5]; > > - /* ssp and svm_* fields below are not implemented by KVM */ > u64 ssp; > + /* svm_* fields below are not implemented by KVM */ > u64 svm_guest_pat; > u64 svm_host_efer; > u64 svm_host_cr4; Best regards, Maxim Levitsky