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From: Sean Christopherson <seanjc@google.com>
To: Chao Gao <chao.gao@intel.com>
Cc: Jason Wang <jasowang@redhat.com>, Cindy Lu <lulu@redhat.com>,
	 Paolo Bonzini <pbonzini@redhat.com>,
	Vitaly Kuznetsov <vkuznets@redhat.com>,
	 Thomas Gleixner <tglx@linutronix.de>,
	Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
	 Dave Hansen <dave.hansen@linux.intel.com>,
	 "maintainer:X86 ARCHITECTURE (32-BIT AND 64-BIT)"
	<x86@kernel.org>, "H. Peter Anvin" <hpa@zytor.com>,
	 "Peter Zijlstra (Intel)" <peterz@infradead.org>,
	"Kirill A. Shutemov" <kas@kernel.org>,
	"Xin Li (Intel)" <xin@zytor.com>,
	 Rik van Riel <riel@surriel.com>,
	"Ahmed S. Darwish" <darwi@linutronix.de>,
	 "open list:KVM PARAVIRT (KVM/paravirt)" <kvm@vger.kernel.org>,
	 "open list:X86 ARCHITECTURE (32-BIT AND 64-BIT)"
	<linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v1] kvm: x86: implement PV send_IPI method
Date: Fri, 18 Jul 2025 08:22:54 -0700	[thread overview]
Message-ID: <aHpmzhaU5JNqhp75@google.com> (raw)
In-Reply-To: <aHplCKOxhBL0O4xr@intel.com>

On Fri, Jul 18, 2025, Chao Gao wrote:
> >> >> >> From: Jason Wang <jasowang@redhat.com>
> >If xAPIC vs. x2APIC is stable when
> >kvm_setup_pv_ipi() runs, maybe key off of that?
> 
> But the guest doesn't know if APICv is enabled or even IPI virtualization
> is enabled.

Oh yeah, duh.  Given that KVM emulates x2APIC irrespective of hardware support,
and that Linux leans heavily towards x2APIC (thanks MMIO stale data!), my vote
is to leave things as they are.

      reply	other threads:[~2025-07-18 15:22 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2025-07-18  6:24 [PATCH v1] kvm: x86: implement PV send_IPI method Cindy Lu
2025-07-18  7:52 ` Jason Wang
2025-07-18 11:00   ` Chao Gao
2025-07-18 11:15     ` Jason Wang
2025-07-18 12:19       ` Chao Gao
2025-07-18 14:01         ` Sean Christopherson
2025-07-18 15:15           ` Chao Gao
2025-07-18 15:22             ` Sean Christopherson [this message]

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