linux-kernel - [PATCH AUTOSEL 4.19 57/83] always clear the X2APIC

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Message-Id: <20190213023701.20286-57-sashal@kernel.org>
Date:   Tue, 12 Feb 2019 21:36:35 -0500
From:   Sasha Levin <sashal@...nel.org>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:     Talons Lee <xin.li@...rix.com>,
        Boris Ostrovsky <boris.ostrovsky@...cle.com>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH AUTOSEL 4.19 57/83] always clear the X2APIC_ENABLE bit for PV guest

From: Talons Lee <xin.li@...rix.com>

[ Upstream commit 5268c8f39e0efef81af2aaed160272d9eb507beb ]

Commit e657fcc clears cpu capability bit instead of using fake cpuid
value, the EXTD should always be off for PV guest without depending
on cpuid value. So remove the cpuid check in xen_read_msr_safe() to
always clear the X2APIC_ENABLE bit.

Signed-off-by: Talons Lee <xin.li@...rix.com>
Reviewed-by: Juergen Gross <jgross@...e.com>
Signed-off-by: Boris Ostrovsky <boris.ostrovsky@...cle.com>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 arch/x86/xen/enlighten_pv.c | 5 +----
 1 file changed, 1 insertion(+), 4 deletions(-)

diff --git a/arch/x86/xen/enlighten_pv.c b/arch/x86/xen/enlighten_pv.c
index 52a7c3faee0c..782f98b332f0 100644
--- a/arch/x86/xen/enlighten_pv.c
+++ b/arch/x86/xen/enlighten_pv.c
@@ -899,10 +899,7 @@ static u64 xen_read_msr_safe(unsigned int msr, int *err)
 	val = native_read_msr_safe(msr, err);
 	switch (msr) {
 	case MSR_IA32_APICBASE:
-#ifdef CONFIG_X86_X2APIC
-		if (!(cpuid_ecx(1) & (1 << (X86_FEATURE_X2APIC & 31))))
-#endif
-			val &= ~X2APIC_ENABLE;
+		val &= ~X2APIC_ENABLE;
 		break;
 	}
 	return val;
-- 
2.19.1