linux-kernel - Re: [PATCH v2 00/10] KVM: x86: Fix ICR handling when x2AVIC is active

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Message-ID: <172506346660.337709.9371266874053711771.b4-ty@google.com>
Date: Fri, 30 Aug 2024 17:20:55 -0700
From: Sean Christopherson <seanjc@...gle.com>
To: Sean Christopherson <seanjc@...gle.com>, Paolo Bonzini <pbonzini@...hat.com>
Cc: kvm@...r.kernel.org, linux-kernel@...r.kernel.org, 
	Maxim Levitsky <mlevitsk@...hat.com>, Suravee Suthikulpanit <suravee.suthikulpanit@....com>
Subject: Re: [PATCH v2 00/10] KVM: x86: Fix ICR handling when x2AVIC is active

On Fri, 19 Jul 2024 16:50:57 -0700, Sean Christopherson wrote:
> I made the mistake of expanding my testing to run with and without AVIC
> enabled, and to my surprise (wow, sarcasm), x2AVIC failed hard on the
> xapic_state_test due to ICR issues.
> 
> AFAICT, the issue is that AMD splits the 64-bit ICR into the legacy ICR
> and ICR2 fields when storing the ICR in the vAPIC (apparently "it's a
> single 64-bit register" is open to intepretation).  Aside from causing
> the selftest failure and potential live migration issues, botching the
> format is quite bad, as KVM will mishandle incomplete virtualized IPIs,
> e.g. generate IRQs to the wrong vCPU, drop IRQs, etc.
> 
> [...]

Applied to kvm-x86 misc, thanks!

[01/10] KVM: x86: Enforce x2APIC's must-be-zero reserved ICR bits
        https://github.com/kvm-x86/linux/commit/71bf395a276f
[02/10] KVM: x86: Move x2APIC ICR helper above kvm_apic_write_nodecode()
        https://github.com/kvm-x86/linux/commit/d33234342f8b
[03/10] KVM: x86: Re-split x2APIC ICR into ICR+ICR2 for AMD (x2AVIC)
        https://github.com/kvm-x86/linux/commit/73b42dc69be8
[04/10] KVM: selftests: Open code vcpu_run() equivalent in guest_printf test
        https://github.com/kvm-x86/linux/commit/d1c2cdca5a08
[05/10] KVM: selftests: Report unhandled exceptions on x86 as regular guest asserts
        https://github.com/kvm-x86/linux/commit/ed24ba6c2c34
[06/10] KVM: selftests: Add x86 helpers to play nice with x2APIC MSR #GPs
        https://github.com/kvm-x86/linux/commit/f2e91e874179
[07/10] KVM: selftests: Skip ICR.BUSY test in xapic_state_test if x2APIC is enabled
        https://github.com/kvm-x86/linux/commit/faf06a238254
[08/10] KVM: selftests: Test x2APIC ICR reserved bits
        https://github.com/kvm-x86/linux/commit/3426cb48adb4
[09/10] KVM: selftests: Verify the guest can read back the x2APIC ICR it wrote
        https://github.com/kvm-x86/linux/commit/0cb26ec32085
[10/10] KVM: selftests: Play nice with AMD's AVIC errata
        https://github.com/kvm-x86/linux/commit/5a7c7d148e48

--
https://github.com/kvm-x86/linux/tree/next