From: Roger Pau Monné <roger.pau@citrix.com>
Date: Fri, 20 Dec 2019 15:28:27 +0000 (+0100)
Subject: x86/smp: check APIC ID on AP bringup
X-Git-Tag: archive/raspbian/4.14.0+80-gd101b417b7-1+rpi1^2~63^2~1006
X-Git-Url: https://dgit.raspbian.org/?a=commitdiff_plain;h=3d05407025ed1f83f492f81ba8175fa26b1e2fb3;p=xen.git

x86/smp: check APIC ID on AP bringup

Check that the processor to be woken up APIC ID is addressable in the
current APIC mode.

Note that in practice systems with APIC IDs > 255 should already have
x2APIC enabled by the firmware, and hence this is mostly a safety
belt.

Signed-off-by: Roger Pau Monné <roger.pau@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
---

diff --git a/xen/arch/x86/smpboot.c b/xen/arch/x86/smpboot.c
index fa691b6ba0..e439845802 100644
--- a/xen/arch/x86/smpboot.c
+++ b/xen/arch/x86/smpboot.c
@@ -1317,6 +1317,14 @@ int __cpu_up(unsigned int cpu)
     if ( (apicid = x86_cpu_to_apicid[cpu]) == BAD_APICID )
         return -ENODEV;
 
+    if ( (!x2apic_enabled && apicid >= APIC_ALL_CPUS) ||
+         (!iommu_intremap && (apicid >> 8)) )
+    {
+        printk("Unsupported: APIC ID %#x in xAPIC mode w/o interrupt remapping\n",
+               apicid);
+        return -EINVAL;
+    }
+
     if ( (ret = do_boot_cpu(apicid, cpu)) != 0 )
         return ret;