linux-kernel - Re: [PATCH 2/4] KVM: VMX: Handle #MCs on VM-Enter/TD-Enter outside of the fastpath

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Message-ID: <a84c72849f021c4fec99caadd0a681146d8e5b6e.camel@intel.com>
Date: Mon, 17 Nov 2025 16:30:38 +0000
From: "Edgecombe, Rick P" <rick.p.edgecombe@...el.com>
To: "tony.lindgren@...ux.intel.com" <tony.lindgren@...ux.intel.com>,
	"seanjc@...gle.com" <seanjc@...gle.com>
CC: "kvm@...r.kernel.org" <kvm@...r.kernel.org>, "pbonzini@...hat.com"
	<pbonzini@...hat.com>, "Kohler, Jon" <jon@...anix.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 2/4] KVM: VMX: Handle #MCs on VM-Enter/TD-Enter outside of
 the fastpath

On Mon, 2025-11-17 at 14:38 +0200, Tony Lindgren wrote:
> I bisected kvm-x86/next down to this change for a TDX guest not
> booting and host producing errors like:
> 
> watchdog: CPU118: Watchdog detected hard LOCKUP on cpu 118
> 
> Dropping the is_td_vcpu(vcpu) check above fixes the issue. Earlier
> the call for vmx_handle_exit_irqoff() was unconditional.
> 
> Probably the (u16) cast above can be dropped too? It was never used
> for TDX looking at the patch.

Ah! Thanks for picking this up. I had almost got there but lost my TDX
machine for a bit.