linux-kernel - Re: [PATCH v1 3/4] KVM: VMX: Handle the immediate form of MSR instructions

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Message-ID: <aItNtifaItfXhXnu@intel.com>
Date: Thu, 31 Jul 2025 19:04:22 +0800
From: Chao Gao <chao.gao@...el.com>
To: "Xin Li (Intel)" <xin@...or.com>
CC: <linux-kernel@...r.kernel.org>, <kvm@...r.kernel.org>,
	<pbonzini@...hat.com>, <seanjc@...gle.com>, <tglx@...utronix.de>,
	<mingo@...hat.com>, <bp@...en8.de>, <dave.hansen@...ux.intel.com>,
	<x86@...nel.org>, <hpa@...or.com>
Subject: Re: [PATCH v1 3/4] KVM: VMX: Handle the immediate form of MSR
 instructions

On Wed, Jul 30, 2025 at 10:46:04AM -0700, Xin Li (Intel) wrote:
>Handle two newly introduced VM exit reasons associated with the
>immediate form of MSR instructions.
>
>For proper virtualization of the immediate form of MSR instructions,
>Intel VMX architecture adds the following changes:

The CPUID feature bit also indicates support for the two new VM-exit reasons.
Therefore, KVM needs to reflect EXIT_REASON_MSR_READ/WRITE_IMM VM-exits to
L1 guests in nested cases if KVM claims it supports the new form of MSR
instructions.

I'm also wondering if the emulator needs to support this new instruction. I
suppose it does.