From: Xin Li <xin@zytor.com>
To: Binbin Wu <binbin.wu@linux.intel.com>, Xiaoyao Li <xiaoyao.li@intel.com>
Cc: Sean Christopherson <seanjc@google.com>,
Paolo Bonzini <pbonzini@redhat.com>,
kvm@vger.kernel.org, linux-kernel@vger.kernel.org,
Borislav Petkov <bp@alien8.de>
Subject: Re: [PATCH v3 4/6] KVM: x86: Add support for RDMSR/WRMSRNS w/ immediate on Intel
Date: Mon, 1 Sep 2025 00:04:24 -0700 [thread overview]
Message-ID: <c4bc61da-c42c-453d-b484-f970b99cb616@zytor.com> (raw)
In-Reply-To: <849dd787-8821-41f1-8eef-26ede3032d90@linux.intel.com>
On 8/31/2025 11:34 PM, Binbin Wu wrote:
>> We need to inject #UD for !guest_cpu_has(X86_FEATURE_MSR_IMM)
>>
>
> Indeed.
Good catch!
>
> There is a virtualization hole of this feature for the accesses to the MSRs
> not
> intercepted. IIUIC, there is no other control in VMX for this feature. If the
> feature is supported in hardware, the guest will succeed when it accesses
> to the
> MSRs not intercepted even when the feature is not exposed to the guest, but
> the
> guest will get #UD when access to the MSRs intercepted if KVM injects #UD.
hpa mentioned this when I just started the work. But I managed to forget
it later... Sigh!
>
> But I guess this is the guest's fault by not following the CPUID, KVM should
> still follow the spec?
I think we should still inject #UD when a MSR is intercepted by KVM.
next prev parent reply other threads:[~2025-09-01 7:04 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-08-05 20:22 [PATCH v3 0/6] KVM: VMX: Handle the immediate form of MSR instructions Sean Christopherson
2025-08-05 20:22 ` [PATCH v3 1/6] x86/cpufeatures: Add a CPU feature bit for MSR immediate form instructions Sean Christopherson
2025-08-05 20:22 ` [PATCH v3 2/6] KVM: x86: Rename local "ecx" variables to "msr" and "pmc" as appropriate Sean Christopherson
2025-08-06 15:42 ` Xin Li
2025-08-05 20:22 ` [PATCH v3 3/6] KVM: x86: Rename handle_fastpath_set_msr_irqoff() to handle_fastpath_wrmsr() Sean Christopherson
2025-08-06 15:48 ` Xin Li
2025-08-05 20:22 ` [PATCH v3 4/6] KVM: x86: Add support for RDMSR/WRMSRNS w/ immediate on Intel Sean Christopherson
2025-09-01 4:13 ` Xiaoyao Li
2025-09-01 6:34 ` Binbin Wu
2025-09-01 7:04 ` Xin Li [this message]
2025-09-01 7:22 ` Xiaoyao Li
2025-09-02 14:50 ` Sean Christopherson
2025-09-02 15:46 ` Xin Li
2025-09-03 4:43 ` Xiaoyao Li
2025-09-18 18:33 ` Sean Christopherson
2025-08-05 20:22 ` [PATCH v3 5/6] KVM: VMX: Support the immediate form of WRMSRNS in the VM-Exit fastpath Sean Christopherson
2025-08-05 20:22 ` [PATCH v3 6/6] KVM: x86: Advertise support for the immediate form of MSR instructions Sean Christopherson
2025-08-06 15:38 ` [PATCH v3 0/6] KVM: VMX: Handle " Xin Li
2025-08-19 23:12 ` Sean Christopherson
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