always clear the X2APIC_ENABLE bit for PV guest

[ Upstream commit 5268c8f39e0efef81af2aaed160272d9eb507beb ]

Commit e657fccb 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: NTalons Lee <xin.li@citrix.com>
Reviewed-by: NJuergen Gross <jgross@suse.com>
Signed-off-by: NBoris Ostrovsky <boris.ostrovsky@oracle.com>
Signed-off-by: NSasha Levin <sashal@kernel.org>

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;