From: "Huang, Kai" <kai.huang@intel.com>
To: "x86@kernel.org" <x86@kernel.org>,
"pbonzini@redhat.com" <pbonzini@redhat.com>,
"tglx@kernel.org" <tglx@kernel.org>,
"seanjc@google.com" <seanjc@google.com>,
"mingo@redhat.com" <mingo@redhat.com>,
"bp@alien8.de" <bp@alien8.de>,
"dave.hansen@linux.intel.com" <dave.hansen@linux.intel.com>
Cc: "hpa@zytor.com" <hpa@zytor.com>,
"kvm@vger.kernel.org" <kvm@vger.kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"yosry@kernel.org" <yosry@kernel.org>
Subject: Re: [PATCH] x86/apic: KVM: Use cpu_physical_id() to get APIC ID of running vCPU for AVIC
Date: Mon, 15 Jun 2026 02:00:35 +0000 [thread overview]
Message-ID: <1a254f5df4cc66952a7a7f2e9b669da334fb3525.camel@intel.com> (raw)
In-Reply-To: <20260612185459.591892-1-seanjc@google.com>
On Fri, 2026-06-12 at 11:54 -0700, Sean Christopherson wrote:
> Use cpu_physical_id() instead of default_cpu_present_to_apicid() when
> getting the APIC ID of the pCPU on which a vCPU is running/loaded, as the
> kernel has gone way off the rails if a vCPU is loaded on a pCPU that has
> been physically removed from the system. Even if the impossible were to
> happen, the absolutely worst case scenario is that hardware will ring the
> AIVC doorbell on the wrong pCPU, i.e. a severely broken system will
> experience mild performance issues.
>
> Kill off KVM's superfluous kvm_cpu_get_apicid() wrapper along with the
> for-KVM export of default_cpu_present_to_apicid(), as they existed purely
> for the wonky AVIC usage.
>
> Cc: Kai Huang <kai.huang@intel.com>
> Cc: Yosry Ahmed <yosry@kernel.org>
> Signed-off-by: Sean Christopherson <seanjc@google.com>
Reviewed-by: Kai Huang <kai.huang@intel.com>
next prev parent reply other threads:[~2026-06-15 2:00 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-06-12 18:54 Sean Christopherson
2026-06-12 21:26 ` Yosry Ahmed
2026-06-15 2:00 ` Huang, Kai [this message]
2026-06-16 7:57 ` Naveen N Rao
2026-06-24 9:22 ` Paolo Bonzini
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