From: Sean Christopherson <seanjc@google.com>
To: Chao Gao <chao.gao@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, linux-kernel@vger.kernel.org,
Zeng Guang <guang.zeng@intel.com>,
Maxim Levitsky <mlevitsk@redhat.com>
Subject: Re: [PATCH 09/11] KVM: x86: Treat x2APIC's ICR as a 64-bit register, not two 32-bit regs
Date: Tue, 15 Feb 2022 16:40:03 +0000 [thread overview]
Message-ID: <YgvXY98ah4uIECee@google.com> (raw)
In-Reply-To: <20220215032712.GB28478@gao-cwp>
On Tue, Feb 15, 2022, Chao Gao wrote:
> > case APIC_SELF_IPI:
> >- if (apic_x2apic_mode(apic)) {
> >- kvm_lapic_reg_write(apic, APIC_ICR,
> >- APIC_DEST_SELF | (val & APIC_VECTOR_MASK));
> >- } else
> >+ if (apic_x2apic_mode(apic))
> >+ kvm_x2apic_icr_write(apic, APIC_DEST_SELF | (val & APIC_VECTOR_MASK));
> >+ else
>
> The original code looks incorrect. Emulating writes to SELF_IPI by writes to
> ICR has an unwanted side-effect: the value of ICR in vAPIC page gets changed.
>
> It is better to use kvm_apic_send_ipi() directly.
Agreed, the SDM lists SELF_IPI as write-only, with no associated MMIO offset, so
it should have no visible side effect in the vAPIC. I'll add a patch to fix this.
Thanks!
next prev parent reply other threads:[~2022-02-15 16:40 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-02-04 21:41 [PATCH 00/11] KVM: x86: Prep work for VMX IPI virtualization Sean Christopherson
2022-02-04 21:41 ` [PATCH 01/11] Revert "svm: Add warning message for AVIC IPI invalid target" Sean Christopherson
2022-02-07 16:44 ` Paolo Bonzini
2022-02-04 21:41 ` [PATCH 02/11] KVM: VMX: Handle APIC-write offset wrangling in VMX code Sean Christopherson
2022-02-15 2:22 ` Chao Gao
2022-02-15 16:30 ` Sean Christopherson
2022-02-04 21:41 ` [PATCH 03/11] KVM: x86: Use "raw" APIC register read for handling APIC-write VM-Exit Sean Christopherson
2022-02-04 21:41 ` [PATCH 04/11] KVM: SVM: Use common kvm_apic_write_nodecode() for AVIC write traps Sean Christopherson
2022-02-04 23:14 ` kernel test robot
2022-02-07 16:16 ` Sean Christopherson
2022-02-04 21:41 ` [PATCH 05/11] KVM: SVM: Don't rewrite guest ICR on AVIC IPI virtualization failure Sean Christopherson
2022-02-04 21:42 ` [PATCH 06/11] KVM: x86: WARN if KVM emulates an IPI without clearing the BUSY flag Sean Christopherson
2022-02-04 21:42 ` [PATCH 07/11] KVM: x86: Make kvm_lapic_reg_{read,write}() static Sean Christopherson
2022-02-04 21:42 ` [PATCH 08/11] KVM: x86: Add helpers to handle 64-bit APIC MSR read/writes Sean Christopherson
2022-02-04 21:42 ` [PATCH 09/11] KVM: x86: Treat x2APIC's ICR as a 64-bit register, not two 32-bit regs Sean Christopherson
2022-02-15 3:27 ` Chao Gao
2022-02-15 16:40 ` Sean Christopherson [this message]
2022-02-04 21:42 ` [PATCH 10/11] KVM: x86: Make kvm_lapic_set_reg() a "private" xAPIC helper Sean Christopherson
2022-02-04 21:42 ` [PATCH 11/11] KVM: selftests: Add test to verify KVM handles x2APIC ICR=>ICR2 dance Sean Christopherson
2022-02-24 14:58 ` [PATCH 00/11] KVM: x86: Prep work for VMX IPI virtualization Paolo Bonzini
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