Xen allows the usage of some previously reserved bits in the IO-APIC
RTE and the MSI address fields in order to store high bits for the
target APIC ID. Such feature is already implemented by QEMU/KVM and
HyperV, so in order to enable it just add the handler that checks for
it's presence.
Signed-off-by: Roger Pau Monné <roger.pau@citrix.com>
Reviewed-by: Juergen Gross <jgross@suse.com>
Link: https://lore.kernel.org/r/20220120152527.7524-3-roger.pau@citrix.com
Signed-off-by: Juergen Gross <jgross@suse.com>
/* Memory mapped from other domains has valid IOMMU entries */
#define XEN_HVM_CPUID_IOMMU_MAPPINGS (1u << 2)
#define XEN_HVM_CPUID_VCPU_ID_PRESENT (1u << 3) /* vcpu id is present in EBX */
+#define XEN_HVM_CPUID_DOMID_PRESENT (1u << 4) /* domid is present in ECX */
+/*
+ * Bits 55:49 from the IO-APIC RTE and bits 11:5 from the MSI address can be
+ * used to store high bits for the Destination ID. This expands the Destination
+ * ID field from 8 to 15 bits, allowing to target APIC IDs up 32768.
+ */
+#define XEN_HVM_CPUID_EXT_DEST_ID (1u << 5)
/*
* Leaf 6 (0x40000x05)
return x2apic_supported();
}
+static bool __init msi_ext_dest_id(void)
+{
+ return cpuid_eax(xen_cpuid_base() + 4) & XEN_HVM_CPUID_EXT_DEST_ID;
+}
+
static __init void xen_hvm_guest_late_init(void)
{
#ifdef CONFIG_XEN_PVH
.init.x2apic_available = xen_x2apic_available,
.init.init_mem_mapping = xen_hvm_init_mem_mapping,
.init.guest_late_init = xen_hvm_guest_late_init,
+ .init.msi_ext_dest_id = msi_ext_dest_id,
.runtime.pin_vcpu = xen_pin_vcpu,
.ignore_nopv = true,
};