[Xen-devel] [PATCH 1/3] x86/ioapic: only use dest32 with x2apic and interrupt remapping enabled

[Roger Pau Monne <roger.pau@xxxxxxxxxx>]

The IO-APIC code assumes that x2apic being enabled also implies
interrupt remapping being enabled, and hence will use the 32bit
destination field in the IO-APIC entry.

This is safe now, but there's no reason to not enable x2APIC even
without interrupt remapping, and hence the IO-APIC code needs to use
the 32 bit destination field only when both interrupt remapping and
x2APIC are enabled.

Signed-off-by: Roger Pau Monné <roger.pau@xxxxxxxxxx>
---
 xen/arch/x86/io_apic.c | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/xen/arch/x86/io_apic.c b/xen/arch/x86/io_apic.c
index 732b57995c..9d38568fba 100644
--- a/xen/arch/x86/io_apic.c
+++ b/xen/arch/x86/io_apic.c
@@ -964,7 +964,7 @@ static hw_irq_controller ioapic_edge_type;
 #define IOAPIC_LEVEL   1
 
 #define SET_DEST(ent, mode, val) do { \
-    if (x2apic_enabled) \
+    if (x2apic_enabled && iommu_intremap) \
         (ent).dest.dest32 = (val); \
     else \
         (ent).dest.mode.mode##_dest = (val); \
@@ -1194,14 +1194,14 @@ static void /*__init*/ __print_IO_APIC(bool boot)
        printk(KERN_DEBUG ".... IRQ redirection table:\n");
 
        printk(KERN_DEBUG " NR %s Msk Trg IRR Pol Stat DstM DelM Vec\n",
-               x2apic_enabled ? " DestID" : "Dst");
+               (x2apic_enabled && iommu_intremap) ? " DestID" : "Dst");
 
        for (i = 0; i <= reg_01.bits.entries; i++) {
             struct IO_APIC_route_entry entry;
 
             entry = ioapic_read_entry(apic, i, 0);
 
-            if ( x2apic_enabled )
+            if ( x2apic_enabled && iommu_intremap )
                 printk(KERN_DEBUG " %02x %08x", i, entry.dest.dest32);
             else
                 printk(KERN_DEBUG " %02x  %02x ", i,
@@ -2504,9 +2504,9 @@ void dump_ioapic_irq_info(void)
                    rte.dest_mode ? 'L' : 'P',
                    rte.delivery_status, rte.polarity, rte.irr,
                    rte.trigger ? 'L' : 'E', rte.mask,
-                   x2apic_enabled ? 8 : 2,
-                   x2apic_enabled ? rte.dest.dest32
-                                  : rte.dest.logical.logical_dest);
+                   (x2apic_enabled && iommu_intremap) ? 8 : 2,
+                   (x2apic_enabled && iommu_intremap) ?
+                       rte.dest.dest32 : rte.dest.logical.logical_dest);
 
             if ( entry->next == 0 )
                 break;
-- 
2.24.0


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