amd_iommu: Check APIC ID > 255 for XTSup

The XTSup mode enables x2APIC support for AMD IOMMU, which is needed
to support vcpu w/ APIC ID > 255.

Reviewed-by: Alejandro Jimenez <alejandro.j.jimenez@oracle.com>
Signed-off-by: Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>
Signed-off-by: Santosh Shukla <santosh.shukla@amd.com>
Message-Id: <20240927172913.121477-6-santosh.shukla@amd.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

diff --git a/hw/i386/amd_iommu.c b/hw/i386/amd_iommu.c
index 38297376e7a9073d4f226ba6d6343f943d4a5349..13af7211e11d7eb665a1899ef15a3ce5f9346985 100644 (file)
--- a/hw/i386/amd_iommu.c
+++ b/hw/i386/amd_iommu.c
@@ -32,6 +32,7 @@
 #include "trace.h"
 #include "hw/i386/apic-msidef.h"
 #include "hw/qdev-properties.h"
+#include "kvm/kvm_i386.h"
 
 /* used AMD-Vi MMIO registers */
 const char *amdvi_mmio_low[] = {
@@ -1651,6 +1652,16 @@ static void amdvi_sysbus_realize(DeviceState *dev, Error **errp)
     memory_region_add_subregion_overlap(&s->mr_sys, AMDVI_INT_ADDR_FIRST,
                                         &s->mr_ir, 1);
 
+    /* AMD IOMMU with x2APIC mode requires xtsup=on */
+    if (x86ms->apic_id_limit > 255 && !s->xtsup) {
+        error_report("AMD IOMMU with x2APIC confguration requires xtsup=on");
+        exit(EXIT_FAILURE);
+    }
+    if (s->xtsup && kvm_irqchip_is_split() && !kvm_enable_x2apic()) {
+        error_report("AMD IOMMU xtsup=on requires support on the KVM side");
+        exit(EXIT_FAILURE);
+    }
+
     pci_setup_iommu(bus, &amdvi_iommu_ops, s);
     amdvi_init(s);
 }