From: Sean Christopherson <seanjc@google.com>
To: Maxim Levitsky <mlevitsk@redhat.com>
Cc: nikunj@amd.com, John Allen <john.allen@amd.com>,
kvm@vger.kernel.org, linux-kernel@vger.kernel.org,
pbonzini@redhat.com, weijiang.yang@intel.com,
rick.p.edgecombe@intel.com, x86@kernel.org,
thomas.lendacky@amd.com, bp@alien8.de
Subject: Re: [PATCH 3/9] KVM: x86: SVM: Pass through shadow stack MSRs
Date: Tue, 7 Nov 2023 15:10:02 -0800 [thread overview]
Message-ID: <ZUrDyqXAQZsQzCzl@google.com> (raw)
In-Reply-To: <2b27196c2b5d10625e10ea73e9f270c7ef0bf5a0.camel@redhat.com>
On Tue, Nov 07, 2023, Maxim Levitsky wrote:
> Since no sane L1 hypervisor will ever allow access to all its msrs from L2,
> it might make sense to always use a dedicated MSR bitmap for L2.
Hmm, there might be a full passthrough use case out there, but in general, yeah,
I agree. I think even kernel hardening use cases where the "hypervisor" is just
a lowvisor would utilize MSR bitmaps to prevent modifying the de-privileged
kernel from modifying select MSRs.
> Also since all sane L1 hypervisors do use a msr bitmap means that
> dedicated code path that doesn't use it is not well tested.
>
> On VMX if I am not mistaken, this is not an issue because either all
> MSRS are intercepted or a bitmap is used.
Yep, if the MSR bitmaps aren't used then all MSR accesses are intercepted.
next prev parent reply other threads:[~2023-11-07 23:10 UTC|newest]
Thread overview: 36+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-10-10 20:02 [PATCH 0/9] SVM guest shadow stack support John Allen
2023-10-10 20:02 ` [PATCH 1/9] KVM: x86: SVM: Emulate reads and writes to shadow stack MSRs John Allen
2023-11-02 18:00 ` Maxim Levitsky
2023-10-10 20:02 ` [PATCH 2/9] KVM: x86: SVM: Update dump_vmcb with shadow stack save area additions John Allen
2023-11-02 18:00 ` Maxim Levitsky
2023-10-10 20:02 ` [PATCH 3/9] KVM: x86: SVM: Pass through shadow stack MSRs John Allen
2023-10-12 9:01 ` Nikunj A. Dadhania
2023-10-17 18:17 ` John Allen
2023-10-18 11:27 ` Nikunj A. Dadhania
2023-11-02 18:05 ` Maxim Levitsky
2023-11-06 16:45 ` Sean Christopherson
2023-11-07 18:20 ` Maxim Levitsky
2023-11-07 23:10 ` Sean Christopherson [this message]
2023-10-10 20:02 ` [PATCH 4/9] KVM: SVM: Rename vmplX_ssp -> plX_ssp John Allen
2023-11-02 18:06 ` Maxim Levitsky
2023-10-10 20:02 ` [PATCH 5/9] KVM: SVM: Save shadow stack host state on VMRUN John Allen
2023-11-02 18:07 ` Maxim Levitsky
2024-02-26 16:56 ` John Allen
2023-10-10 20:02 ` [PATCH 6/9] KVM: SVM: Add MSR_IA32_XSS to the GHCB for hypervisor kernel John Allen
2023-10-14 0:31 ` Sean Christopherson
2023-11-02 18:10 ` Maxim Levitsky
2023-11-02 23:22 ` Sean Christopherson
2023-11-07 18:20 ` Maxim Levitsky
2024-02-15 17:39 ` John Allen
2024-02-20 16:20 ` Sean Christopherson
2024-02-20 16:33 ` John Allen
2024-02-21 16:38 ` John Allen
2023-10-10 20:02 ` [PATCH 7/9] x86/sev-es: Include XSS value in GHCB CPUID request John Allen
2023-10-12 12:59 ` Borislav Petkov
2023-10-17 18:12 ` John Allen
2023-10-17 18:49 ` Borislav Petkov
2023-11-02 18:14 ` Maxim Levitsky
2023-10-10 20:02 ` [PATCH 8/9] KVM: SVM: Use KVM-governed features to track SHSTK John Allen
2023-11-02 18:07 ` Maxim Levitsky
2023-10-10 20:02 ` [PATCH 9/9] KVM: SVM: Add CET features to supported_xss John Allen
2023-11-02 18:07 ` Maxim Levitsky
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