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[35.185.214.157]) by smtp.gmail.com with ESMTPSA id v10sm4657125pfg.162.2021.11.08.13.31.43 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 08 Nov 2021 13:31:43 -0800 (PST) Date: Mon, 8 Nov 2021 21:31:39 +0000 From: Sean Christopherson To: Chenyi Qiang Cc: Paolo Bonzini , Vitaly Kuznetsov , Wanpeng Li , Jim Mattson , Joerg Roedel , Xiaoyao Li , kvm@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v5 6/7] KVM: VMX: Expose PKS to guest Message-ID: References: <20210811101126.8973-1-chenyi.qiang@intel.com> <20210811101126.8973-7-chenyi.qiang@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210811101126.8973-7-chenyi.qiang@intel.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Aug 11, 2021, Chenyi Qiang wrote: > diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c > index 739be5da3bca..dbee0d639db3 100644 > --- a/arch/x86/kvm/cpuid.c > +++ b/arch/x86/kvm/cpuid.c > @@ -458,7 +458,7 @@ void kvm_set_cpu_caps(void) > F(AVX512_VPOPCNTDQ) | F(UMIP) | F(AVX512_VBMI2) | F(GFNI) | > F(VAES) | F(VPCLMULQDQ) | F(AVX512_VNNI) | F(AVX512_BITALG) | > F(CLDEMOTE) | F(MOVDIRI) | F(MOVDIR64B) | 0 /*WAITPKG*/ | > - F(SGX_LC) | F(BUS_LOCK_DETECT) > + F(SGX_LC) | F(BUS_LOCK_DETECT) | 0 /*PKS*/ ... > ); > /* Set LA57 based on hardware capability. */ > if (cpuid_ecx(7) & F(LA57)) ... > @@ -7311,6 +7312,14 @@ static __init void vmx_set_cpu_caps(void) > > if (cpu_has_vmx_waitpkg()) > kvm_cpu_cap_check_and_set(X86_FEATURE_WAITPKG); > + > + /* > + * PKS is not yet implemented for shadow paging. > + * If not support VM_{ENTRY, EXIT}_LOAD_IA32_PKRS, > + * don't expose the PKS as well. > + */ > + if (enable_ept && cpu_has_load_ia32_pkrs()) > + kvm_cpu_cap_check_and_set(X86_FEATURE_PKS); I would rather handle the !TDP case in cpuid.c alongside the PKU. The decision to not support Protection Keys with legacy shadow paging is an x86 decision, not a VMX decision. And VMX's extra restriction on the VMCS support should not bleed into common x86. Can you also opportunistically update the comment (see below) to explain _why_ OSPKE needs to be enabled in order to advertise PKU? Thanks! diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c index 2d70edb0f323..c4ed6881857c 100644 --- a/arch/x86/kvm/cpuid.c +++ b/arch/x86/kvm/cpuid.c @@ -439,18 +439,23 @@ void kvm_set_cpu_caps(void) F(AVX512_VPOPCNTDQ) | F(UMIP) | F(AVX512_VBMI2) | F(GFNI) | F(VAES) | F(VPCLMULQDQ) | F(AVX512_VNNI) | F(AVX512_BITALG) | F(CLDEMOTE) | F(MOVDIRI) | F(MOVDIR64B) | 0 /*WAITPKG*/ | - F(SGX_LC) | F(BUS_LOCK_DETECT) + F(SGX_LC) | F(BUS_LOCK_DETECT) | F(PKS) ); /* Set LA57 based on hardware capability. */ if (cpuid_ecx(7) & F(LA57)) kvm_cpu_cap_set(X86_FEATURE_LA57); /* - * PKU not yet implemented for shadow paging and requires OSPKE - * to be set on the host. Clear it if that is not the case + * Protection Keys are not supported for shadow paging. PKU further + * requires OSPKE to be set on the host in order to use {RD,WR}PKRU to + * save/restore the guests PKRU. */ - if (!tdp_enabled || !boot_cpu_has(X86_FEATURE_OSPKE)) + if (!tdp_enabled) { kvm_cpu_cap_clear(X86_FEATURE_PKU); + kvm_cpu_cap_clear(X86_FEATURE_PKS); + } else if (!boot_cpu_has(X86_FEATURE_OSPKE)) { + kvm_cpu_cap_clear(X86_FEATURE_PKU); + } kvm_cpu_cap_mask(CPUID_7_EDX, F(AVX512_4VNNIW) | F(AVX512_4FMAPS) | F(SPEC_CTRL) | and then vmx.c only needs to handle clearing PKS when the VMCS controls aren't available.