linux-kernel - [RFC PATCH 6/6] x86/x2apic-savic: Not set APIC backing page if Secure AVIC is not enabled.

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Message-Id: <20250506130712.156583-7-ltykernel@gmail.com>
Date: Tue,  6 May 2025 09:07:11 -0400
From: Tianyu Lan <ltykernel@...il.com>
To: kys@...rosoft.com,
	haiyangz@...rosoft.com,
	wei.liu@...nel.org,
	decui@...rosoft.com,
	tglx@...utronix.de,
	mingo@...hat.com,
	bp@...en8.de,
	dave.hansen@...ux.intel.com,
	x86@...nel.org,
	hpa@...or.com,
	Neeraj.Upadhyay@....com,
	yuehaibing@...wei.com,
	kvijayab@....com,
	jacob.jun.pan@...ux.intel.com,
	jpoimboe@...nel.org,
	tiala@...rosoft.com
Cc: linux-hyperv@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: [RFC PATCH 6/6] x86/x2apic-savic: Not set APIC backing page if Secure AVIC is not enabled.

From: Tianyu Lan <tiala@...rosoft.com>

When Secure AVIC is not enabled, init_apic_page()
should return directly.

Signed-off-by: Tianyu Lan <tiala@...rosoft.com>
---
 arch/x86/kernel/apic/x2apic_savic.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/arch/x86/kernel/apic/x2apic_savic.c b/arch/x86/kernel/apic/x2apic_savic.c
index 0dd7e39931b0..fb09c0f9e276 100644
--- a/arch/x86/kernel/apic/x2apic_savic.c
+++ b/arch/x86/kernel/apic/x2apic_savic.c
@@ -333,6 +333,9 @@ static void init_apic_page(void)
 {
 	u32 apic_id;
 
+	if (!cc_platform_has(CC_ATTR_SNP_SECURE_AVIC))
+		return;
+
 	/*
 	 * Before Secure AVIC is enabled, APIC msr reads are intercepted.
 	 * APIC_ID msr read returns the value from the Hypervisor.
-- 
2.25.1