From nobody Wed Dec 17 12:08:41 2025 Received: from mail.zytor.com (terminus.zytor.com [198.137.202.136]) (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 BD5DB1DB933; Fri, 28 Mar 2025 17:13:12 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=198.137.202.136 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1743181994; cv=none; b=f48+teHCqk4xP3RoNhXom8dT0CwvYtde5/Mww3lxPcD9XSkcRu8efQZl0wTf+RRMN0biFgT/6M43gmD7T+3/dOImcwuAuTijFs8WbfrlUpE1B1veXXZyuNwGNaD64haNW9/Tumi6ZuiYy1Dom/sRx98chm3ztCZKfCQlPPlAFZc= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1743181994; c=relaxed/simple; bh=nKtI0MoZljq8oJ474v4DSi5ng4WHDtrTqB1RNCxFzLA=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=AODKN6x4f8gzmPvetVF78eYVu5T1+j66Y6OEnhoDFWVRGGqyIuW5hisZ8VXFLJgp1BVVsJ0oyQj8xJYSd+MiqmOJ6EgcTfYn2h6mxh/njmQHPBq8oIpFoRCkbyCVrBgjf9XqgcBx1Otcn/yhcQRAM62/eabIa6IJVOK6nweMJSo= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=zytor.com; spf=pass smtp.mailfrom=zytor.com; dkim=pass (2048-bit key) header.d=zytor.com header.i=@zytor.com header.b=JG4AeK6f; arc=none smtp.client-ip=198.137.202.136 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=zytor.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=zytor.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=zytor.com header.i=@zytor.com header.b="JG4AeK6f" Received: from terminus.zytor.com (terminus.zytor.com [IPv6:2607:7c80:54:3:0:0:0:136]) (authenticated bits=0) by mail.zytor.com (8.18.1/8.17.1) with ESMTPSA id 52SHC6ve2029344 (version=TLSv1.3 cipher=TLS_AES_256_GCM_SHA384 bits=256 verify=NO); Fri, 28 Mar 2025 10:12:21 -0700 DKIM-Filter: OpenDKIM Filter v2.11.0 mail.zytor.com 52SHC6ve2029344 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=zytor.com; s=2025032001; t=1743181941; bh=QVjhEk8LANeNjTZnda/EOsJByuSCnzUke3jKUCxn4/g=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=JG4AeK6fQ1eiuzfHEDa8sD9MTCFg6tI1FuDg/jSKx5YVsN6CyIowc6hk82cPAtC9A +Z1zEiAASIumYqxyQ0m8J2cASkMjYBh6KogO9qTTtnw5UrABUrabywxyJrytiE7eyO 5fUjDCTR+7gEUyAnHAOzzk0ryC55Nb8XU1bXJDRkolIJpisgaW+zutIRKZElwMjQg9 EnQNMgPTsMQaGRc1DgWKNsuLTjKp211g7iDzGPyzEGPcjuTE9i5HnzZVS0a3GspL79 LvpclMnkvz4cuIrLoUk7PKdpIl1XLfFHJOmvwBJutJUlHXNma9oD38kS/nn5A6V6gh fATpJtwX/wGuA== From: "Xin Li (Intel)" To: pbonzini@redhat.com, seanjc@google.com, kvm@vger.kernel.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org Cc: corbet@lwn.net, tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, dave.hansen@linux.intel.com, x86@kernel.org, hpa@zytor.com, andrew.cooper3@citrix.com, luto@kernel.org, peterz@infradead.org, chao.gao@intel.com, xin3.li@intel.com Subject: [PATCH v4 08/19] KVM: VMX: Add support for FRED context save/restore Date: Fri, 28 Mar 2025 10:11:54 -0700 Message-ID: <20250328171205.2029296-9-xin@zytor.com> X-Mailer: git-send-email 2.48.1 In-Reply-To: <20250328171205.2029296-1-xin@zytor.com> References: <20250328171205.2029296-1-xin@zytor.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" From: Xin Li Handle FRED MSR access requests, allowing FRED context to be set/get from both host and guest. During VM save/restore and live migration, FRED context needs to be saved/restored, which requires FRED MSRs to be accessed from userspace, e.g., Qemu. Note, handling of MSR_IA32_FRED_SSP0, i.e., MSR_IA32_PL0_SSP, is not added yet, which is done in the KVM CET patch set. Signed-off-by: Xin Li Signed-off-by: Xin Li (Intel) Tested-by: Shan Kang --- Changes since v2: * Add a helper to convert FRED MSR index to VMCS field encoding to make the code more compact (Chao Gao). * Get rid of the "host_initiated" check because userspace has to set CPUID before MSRs (Chao Gao & Sean Christopherson). * Address a few cleanup comments (Sean Christopherson). Changes since v1: * Use kvm_cpu_cap_has() instead of cpu_feature_enabled() (Chao Gao). * Fail host requested FRED MSRs access if KVM cannot virtualize FRED (Chao Gao). * Handle the case FRED MSRs are valid but KVM cannot virtualize FRED (Chao Gao). * Add sanity checks when writing to FRED MSRs. --- arch/x86/kvm/vmx/vmx.c | 48 ++++++++++++++++++++++++++++++++++++++++++ arch/x86/kvm/x86.c | 28 ++++++++++++++++++++++++ 2 files changed, 76 insertions(+) diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c index 1fd32aa255f9..ae9712624413 100644 --- a/arch/x86/kvm/vmx/vmx.c +++ b/arch/x86/kvm/vmx/vmx.c @@ -1426,6 +1426,24 @@ static void vmx_write_guest_kernel_gs_base(struct vc= pu_vmx *vmx, u64 data) preempt_enable(); vmx->msr_guest_kernel_gs_base =3D data; } + +static u64 vmx_read_guest_fred_rsp0(struct vcpu_vmx *vmx) +{ + preempt_disable(); + if (vmx->guest_state_loaded) + vmx->msr_guest_fred_rsp0 =3D read_msr(MSR_IA32_FRED_RSP0); + preempt_enable(); + return vmx->msr_guest_fred_rsp0; +} + +static void vmx_write_guest_fred_rsp0(struct vcpu_vmx *vmx, u64 data) +{ + preempt_disable(); + if (vmx->guest_state_loaded) + wrmsrns(MSR_IA32_FRED_RSP0, data); + preempt_enable(); + vmx->msr_guest_fred_rsp0 =3D data; +} #endif =20 static void grow_ple_window(struct kvm_vcpu *vcpu) @@ -2039,6 +2057,24 @@ int vmx_get_feature_msr(u32 msr, u64 *data) } } =20 +#ifdef CONFIG_X86_64 +static u32 fred_msr_vmcs_fields[] =3D { + GUEST_IA32_FRED_RSP1, + GUEST_IA32_FRED_RSP2, + GUEST_IA32_FRED_RSP3, + GUEST_IA32_FRED_STKLVLS, + GUEST_IA32_FRED_SSP1, + GUEST_IA32_FRED_SSP2, + GUEST_IA32_FRED_SSP3, + GUEST_IA32_FRED_CONFIG, +}; + +static u32 fred_msr_to_vmcs(u32 msr) +{ + return fred_msr_vmcs_fields[msr - MSR_IA32_FRED_RSP1]; +} +#endif + /* * Reads an msr value (of 'msr_info->index') into 'msr_info->data'. * Returns 0 on success, non-0 otherwise. @@ -2061,6 +2097,12 @@ int vmx_get_msr(struct kvm_vcpu *vcpu, struct msr_da= ta *msr_info) case MSR_KERNEL_GS_BASE: msr_info->data =3D vmx_read_guest_kernel_gs_base(vmx); break; + case MSR_IA32_FRED_RSP0: + msr_info->data =3D vmx_read_guest_fred_rsp0(vmx); + break; + case MSR_IA32_FRED_RSP1 ... MSR_IA32_FRED_CONFIG: + msr_info->data =3D vmcs_read64(fred_msr_to_vmcs(msr_info->index)); + break; #endif case MSR_EFER: return kvm_get_msr_common(vcpu, msr_info); @@ -2268,6 +2310,12 @@ int vmx_set_msr(struct kvm_vcpu *vcpu, struct msr_da= ta *msr_info) vmx_update_exception_bitmap(vcpu); } break; + case MSR_IA32_FRED_RSP0: + vmx_write_guest_fred_rsp0(vmx, data); + break; + case MSR_IA32_FRED_RSP1 ... MSR_IA32_FRED_CONFIG: + vmcs_write64(fred_msr_to_vmcs(msr_index), data); + break; #endif case MSR_IA32_SYSENTER_CS: if (is_guest_mode(vcpu)) diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index c841817a914a..007577143337 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -318,6 +318,9 @@ static const u32 msrs_to_save_base[] =3D { MSR_STAR, #ifdef CONFIG_X86_64 MSR_CSTAR, MSR_KERNEL_GS_BASE, MSR_SYSCALL_MASK, MSR_LSTAR, + MSR_IA32_FRED_RSP0, MSR_IA32_FRED_RSP1, MSR_IA32_FRED_RSP2, + MSR_IA32_FRED_RSP3, MSR_IA32_FRED_STKLVLS, MSR_IA32_FRED_SSP1, + MSR_IA32_FRED_SSP2, MSR_IA32_FRED_SSP3, MSR_IA32_FRED_CONFIG, #endif MSR_IA32_TSC, MSR_IA32_CR_PAT, MSR_VM_HSAVE_PA, MSR_IA32_FEAT_CTL, MSR_IA32_BNDCFGS, MSR_TSC_AUX, @@ -1849,6 +1852,23 @@ static int __kvm_set_msr(struct kvm_vcpu *vcpu, u32 = index, u64 data, =20 data =3D (u32)data; break; + case MSR_IA32_FRED_RSP0 ... MSR_IA32_FRED_CONFIG: + if (!guest_cpu_cap_has(vcpu, X86_FEATURE_FRED)) + return 1; + + /* Bit 11, bits 5:4, and bit 2 of the IA32_FRED_CONFIG must be zero */ + if (index =3D=3D MSR_IA32_FRED_CONFIG && data & (BIT_ULL(11) | GENMASK_U= LL(5, 4) | BIT_ULL(2))) + return 1; + if (index !=3D MSR_IA32_FRED_STKLVLS && is_noncanonical_msr_address(data= , vcpu)) + return 1; + if ((index >=3D MSR_IA32_FRED_RSP0 && index <=3D MSR_IA32_FRED_RSP3) && + (data & GENMASK_ULL(5, 0))) + return 1; + if ((index >=3D MSR_IA32_FRED_SSP1 && index <=3D MSR_IA32_FRED_SSP3) && + (data & GENMASK_ULL(2, 0))) + return 1; + + break; } =20 msr.data =3D data; @@ -1893,6 +1913,10 @@ int __kvm_get_msr(struct kvm_vcpu *vcpu, u32 index, = u64 *data, !guest_cpu_cap_has(vcpu, X86_FEATURE_RDPID)) return 1; break; + case MSR_IA32_FRED_RSP0 ... MSR_IA32_FRED_CONFIG: + if (!guest_cpu_cap_has(vcpu, X86_FEATURE_FRED)) + return 1; + break; } =20 msr.index =3D index; @@ -7455,6 +7479,10 @@ static void kvm_probe_msr_to_save(u32 msr_index) if (!(kvm_get_arch_capabilities() & ARCH_CAP_TSX_CTRL_MSR)) return; break; + case MSR_IA32_FRED_RSP0 ... MSR_IA32_FRED_CONFIG: + if (!kvm_cpu_cap_has(X86_FEATURE_FRED)) + return; + break; default: break; } --=20 2.48.1