linux-kernel - Re: [PATCH v5 11/19] KVM:VMX: Emulate read and write to CET MSRs

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <27a14f56-3d5a-9d66-83be-e5893d5f0a9e@intel.com>
Date:   Wed, 9 Aug 2023 11:05:03 +0800
From:   "Yang, Weijiang" <weijiang.yang@...el.com>
To:     Paolo Bonzini <pbonzini@...hat.com>
CC:     <rick.p.edgecombe@...el.com>, <chao.gao@...el.com>,
        <binbin.wu@...ux.intel.com>, <seanjc@...gle.com>,
        <peterz@...radead.org>, <john.allen@....com>,
        <kvm@...r.kernel.org>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v5 11/19] KVM:VMX: Emulate read and write to CET MSRs

On 8/5/2023 5:40 AM, Paolo Bonzini wrote:
> On 8/3/23 06:27, Yang Weijiang wrote:
>> +        if (msr_info->index == MSR_KVM_GUEST_SSP)
>> +            msr_info->data = vmcs_readl(GUEST_SSP);
>
> Accesses to MSR_KVM_(GUEST_)SSP must be rejected unless host-initiated.
Yes, it's kept, in v5 it's folded in:

+static bool kvm_cet_is_msr_accessible(struct kvm_vcpu *vcpu,

+struct msr_data *msr)

+{

+if (is_shadow_stack_msr(msr->index)) {

+if (!kvm_cpu_cap_has(X86_FEATURE_SHSTK))

+return false;

+

+if (msr->index == MSR_KVM_GUEST_SSP)

+return msr->host_initiated;

+

+return msr->host_initiated ||

+guest_cpuid_has(vcpu, X86_FEATURE_SHSTK);

+}

+

+if (!kvm_cpu_cap_has(X86_FEATURE_SHSTK) &&

+!kvm_cpu_cap_has(X86_FEATURE_IBT))

+return false;

+

+return msr->host_initiated ||

+guest_cpuid_has(vcpu, X86_FEATURE_IBT) ||

+guest_cpuid_has(vcpu, X86_FEATURE_SHSTK); }

+

> Paolo
>