linux-kernel - Re: [RFC PATCH v5 100/104] KVM: TDX: Silently discard SMI request

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: Windows password security audit tool. GUI, reports in PDF.

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

Message-ID: <26ec85d5-dd44-2364-1f8c-064de262cf8f@redhat.com>
Date:   Tue, 5 Apr 2022 17:41:51 +0200
From:   Paolo Bonzini <pbonzini@...hat.com>
To:     isaku.yamahata@...el.com, kvm@...r.kernel.org,
        linux-kernel@...r.kernel.org
Cc:     isaku.yamahata@...il.com, Jim Mattson <jmattson@...gle.com>,
        erdemaktas@...gle.com, Connor Kuehl <ckuehl@...hat.com>,
        Sean Christopherson <seanjc@...gle.com>
Subject: Re: [RFC PATCH v5 100/104] KVM: TDX: Silently discard SMI request

On 3/4/22 20:49, isaku.yamahata@...el.com wrote:
> From: Isaku Yamahata <isaku.yamahata@...el.com>
> 
> TDX doesn't support system-management mode (SMM) and system-management
> interrupt (SMI) in guest TDs.  Because guest state (vcpu state, memory
> state) is protected, it must go through the TDX module APIs to change guest
> state, injecting SMI and changing vcpu mode into SMM.  The TDX module
> doesn't provide a way for VMM to inject SMI into guest TD and a way for VMM
> to switch guest vcpu mode into SMM.
> 
> We have two options in KVM when handling SMM or SMI in the guest TD or the
> device model (e.g. QEMU): 1) silently ignore the request or 2) return a
> meaningful error.
> 
> For simplicity, we implemented the option 1).

Please also:

1) return zero from vmx_has_emulated_msr(MSR_IA32_SMBASE) for TDX 
virtual machines.

2) do a check for static_call(kvm_x86_has_emulated_msr)(kvm, 
MSR_IA32_SMBASE) in kvm_vcpu_ioctl_smi and __apic_accept_irq.

3) WARN_ON_ONCE in tdx_smi_allowed and tdx_enable_smi_window.

Paolo