From: Sean Christopherson <seanjc@google.com>
To: Zeng Guang <guang.zeng@intel.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>,
Vitaly Kuznetsov <vkuznets@redhat.com>,
Wanpeng Li <wanpengli@tencent.com>,
Jim Mattson <jmattson@google.com>, Joerg Roedel <joro@8bytes.org>,
kvm@vger.kernel.org, Dave Hansen <dave.hansen@linux.intel.com>,
Tony Luck <tony.luck@intel.com>,
Kan Liang <kan.liang@linux.intel.com>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
"H. Peter Anvin" <hpa@zytor.com>,
Kim Phillips <kim.phillips@amd.com>,
Jarkko Sakkinen <jarkko@kernel.org>,
Jethro Beekman <jethro@fortanix.com>,
Kai Huang <kai.huang@intel.com>,
x86@kernel.org, linux-kernel@vger.kernel.org,
Robert Hu <robert.hu@intel.com>, Gao Chao <chao.gao@intel.com>,
Maxim Levitsky <mlevitsk@redhat.com>
Subject: Re: [PATCH v8 6/9] KVM: x86: lapic: don't allow to change APIC ID unconditionally
Date: Fri, 15 Apr 2022 14:39:48 +0000 [thread overview]
Message-ID: <YlmDtC73u/AouMsu@google.com> (raw)
In-Reply-To: <20220411090447.5928-7-guang.zeng@intel.com>
On Mon, Apr 11, 2022, Zeng Guang wrote:
> From: Maxim Levitsky <mlevitsk@redhat.com>
>
> No normal guest has any reason to change physical APIC IDs, and
> allowing this introduces bugs into APIC acceleration code.
>
> And Intel recent hardware just ignores writes to APIC_ID in
> xAPIC mode. More background can be found at:
> https://lore.kernel.org/lkml/Yfw5ddGNOnDqxMLs@google.com/
>
> Looks there is no much value to support writable xAPIC ID in
> guest except supporting some old and crazy use cases which
> probably would fail on real hardware. So, make xAPIC ID
> read-only for KVM guests.
AFAIK, the plan is to add a capability to let userspace opt-in to a fully read-only
APIC ID[*], but I haven't seen patches...
Maxim?
[*] https://lore.kernel.org/all/c903e82ed2a1e98f66910c35b5aabdcf56e08e72.camel@redhat.com
next prev parent reply other threads:[~2022-04-15 14:40 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-04-11 9:04 [PATCH v8 0/9] IPI virtualization support for VM Zeng Guang
2022-04-11 9:04 ` [PATCH v8 1/9] x86/cpu: Add new VMX feature, Tertiary VM-Execution control Zeng Guang
2022-04-11 9:04 ` [PATCH v8 2/9] KVM: VMX: Extend BUILD_CONTROLS_SHADOW macro to support 64-bit variation Zeng Guang
2022-04-11 9:04 ` [PATCH v8 3/9] KVM: VMX: Detect Tertiary VM-Execution control when setup VMCS config Zeng Guang
2022-04-11 9:04 ` [PATCH v8 4/9] KVM: VMX: Report tertiary_exec_control field in dump_vmcs() Zeng Guang
2022-04-11 9:04 ` [PATCH v8 5/9] KVM: x86: Add support for vICR APIC-write VM-Exits in x2APIC mode Zeng Guang
2022-04-11 9:04 ` [PATCH v8 6/9] KVM: x86: lapic: don't allow to change APIC ID unconditionally Zeng Guang
2022-04-15 14:39 ` Sean Christopherson [this message]
2022-04-19 14:07 ` Maxim Levitsky
2022-04-26 8:14 ` Maxim Levitsky
2022-04-26 14:00 ` Chao Gao
2022-04-11 9:04 ` [PATCH v8 7/9] KVM: Move kvm_arch_vcpu_precreate() under kvm->lock Zeng Guang
2022-04-15 15:00 ` Sean Christopherson
2022-04-15 15:11 ` Sean Christopherson
2022-04-11 9:04 ` [PATCH v8 8/9] KVM: x86: Allow userspace set maximum VCPU id for VM Zeng Guang
2022-04-15 15:01 ` Sean Christopherson
2022-04-11 9:04 ` [PATCH v8 9/9] KVM: VMX: enable IPI virtualization Zeng Guang
2022-04-15 15:25 ` Sean Christopherson
2022-04-18 9:25 ` Chao Gao
2022-04-18 15:14 ` Sean Christopherson
2022-04-19 0:00 ` Chao Gao
2022-04-18 12:49 ` Zeng Guang
2022-04-15 15:45 ` Sean Christopherson
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