linux-kernel - Re: [PATCH v3] KVM: TDX: Force split irqchip for TDX at irqchip creation time

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Message-ID: <ce2f31af27a07faebf55055b392e706464a803f1.camel@intel.com>
Date: Thu, 28 Aug 2025 11:20:30 +0000
From: "Huang, Kai" <kai.huang@...el.com>
To: "seanjc@...gle.com" <seanjc@...gle.com>, "dave.hansen@...ux.intel.com"
	<dave.hansen@...ux.intel.com>, "binbin.wu@...ux.intel.com"
	<binbin.wu@...ux.intel.com>, "sagis@...gle.com" <sagis@...gle.com>,
	"bp@...en8.de" <bp@...en8.de>, "mingo@...hat.com" <mingo@...hat.com>,
	"tglx@...utronix.de" <tglx@...utronix.de>, "Weiny, Ira"
	<ira.weiny@...el.com>, "pbonzini@...hat.com" <pbonzini@...hat.com>,
	"hpa@...or.com" <hpa@...or.com>
CC: "Li, Xiaoyao" <xiaoyao.li@...el.com>, "kvm@...r.kernel.org"
	<kvm@...r.kernel.org>, "linux-kernel@...r.kernel.org"
	<linux-kernel@...r.kernel.org>, "x86@...nel.org" <x86@...nel.org>
Subject: Re: [PATCH v3] KVM: TDX: Force split irqchip for TDX at irqchip
 creation time

On Wed, 2025-08-27 at 17:30 -0700, Sagi Shahar wrote:
> TDX module protects the EOI-bitmap which prevents the use of in-kernel
> I/O APIC. See more details in the original patch [1]
						      ^
						      missing a period
> 
> The current implementation already enforces the use of split irqchip for
> TDX but it does so at the vCPU creation time which is generally to late
								  ^
								  too
> to fallback to split irqchip.
> 
> This patch follows Sean's recommendation from [2] and adds a check if
> I/O APIC is supported for the VM at irqchip creation time.
> 
> [1] https://lore.kernel.org/lkml/20250222014757.897978-11-binbin.wu@linux.intel.com/
> [2] https://lore.kernel.org/lkml/aK3vZ5HuKKeFuuM4@google.com/
> 
> Suggested-by: Sean Christopherson <seanjc@...gle.com>
> Reviewed-by: Binbin Wu <binbin.wu@...ux.intel.com>
> Reviewed-by: Xiaoyao Li <xiaoyao.li@...el.com>
> Signed-off-by: Sagi Shahar <sagis@...gle.com>

Acked-by: Kai Huang <kai.huang@...el.com>