[Xen-changelog] [xen master] x86/smp: check APIC ID on AP bringup

[patchbot@xxxxxxx]

commit 3d05407025ed1f83f492f81ba8175fa26b1e2fb3
Author:     Roger Pau Monné <roger.pau@xxxxxxxxxx>
AuthorDate: Fri Dec 20 16:28:27 2019 +0100
Commit:     Jan Beulich <jbeulich@xxxxxxxx>
CommitDate: Fri Dec 20 16:28:27 2019 +0100

    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@xxxxxxxxxx>
    Reviewed-by: Jan Beulich <jbeulich@xxxxxxxx>
---
 xen/arch/x86/smpboot.c | 8 ++++++++
 1 file changed, 8 insertions(+)

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;
 
--
generated by git-patchbot for /home/xen/git/xen.git#master

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