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authorRoger Pau Monne <roger.pau@citrix.com>2022-01-20 18:25:27 +0300
committerJuergen Gross <jgross@suse.com>2022-02-10 13:10:17 +0300
commite07e98da924e61e814bdaaa3ebc6e72b60dbf9ed (patch)
tree2e5604a8522eb851766669509f8921504eae9386 /arch
parentf34c4f2dd2445ab89e5373fff2990fab36578bd3 (diff)
downloadlinux-e07e98da924e61e814bdaaa3ebc6e72b60dbf9ed.tar.xz
xen/x86: detect support for extended destination ID
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>
Diffstat (limited to 'arch')
-rw-r--r--arch/x86/include/asm/xen/cpuid.h7
-rw-r--r--arch/x86/xen/enlighten_hvm.c6
2 files changed, 13 insertions, 0 deletions
diff --git a/arch/x86/include/asm/xen/cpuid.h b/arch/x86/include/asm/xen/cpuid.h
index a9630104f1c4..78e667a31d6c 100644
--- a/arch/x86/include/asm/xen/cpuid.h
+++ b/arch/x86/include/asm/xen/cpuid.h
@@ -100,6 +100,13 @@
/* 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)
diff --git a/arch/x86/xen/enlighten_hvm.c b/arch/x86/xen/enlighten_hvm.c
index 6448c5071117..945363d9cdba 100644
--- a/arch/x86/xen/enlighten_hvm.c
+++ b/arch/x86/xen/enlighten_hvm.c
@@ -248,6 +248,11 @@ static __init bool xen_x2apic_available(void)
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
@@ -310,6 +315,7 @@ struct hypervisor_x86 x86_hyper_xen_hvm __initdata = {
.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,
};