[Qemu-devel] [PATCH 5/5] intel_iommu: do not allow EIM without KVM support

[Radim Krčmář]

Cluster x2APIC cannot work without KVM's x2apic API when the maximal
APIC ID is > 8.  Make the code simpler by completely forbidding EIM
without KVM's x2apic API.

Signed-off-by: Radim Krčmář <address@hidden>
---
  I think it the dependency would be nicer in the eim setter, but the
  other dependency, for interrupt remapping, isn't there and I didn't
  venture for reasons.
---
 hw/i386/intel_iommu.c  |  7 +++++++
 target-i386/kvm-stub.c |  5 +++++
 target-i386/kvm.c      | 13 +++++++++++++
 target-i386/kvm_i386.h |  1 +
 4 files changed, 26 insertions(+)

diff --git a/hw/i386/intel_iommu.c b/hw/i386/intel_iommu.c
index 269e37e71af4..0304a1bf6f1d 100644
--- a/hw/i386/intel_iommu.c
+++ b/hw/i386/intel_iommu.c
@@ -32,6 +32,7 @@
 #include "hw/pci-host/q35.h"
 #include "sysemu/kvm.h"
 #include "hw/i386/apic_internal.h"
+#include "kvm_i386.h"
 
 /*#define DEBUG_INTEL_IOMMU*/
 #ifdef DEBUG_INTEL_IOMMU
@@ -2485,6 +2486,12 @@ static void vtd_realize(DeviceState *dev, Error **errp)
                      "kernel-irqchip=on, please use 'split|off'.");
         exit(1);
     }
+
+    if (s->eim_supported && kvm_irqchip_in_kernel() &&
+        !kvm_enable_x2apic()) {
+        error_report("EIM requires support from the KVM side (X2APIC_API).");
+        exit(1);
+    }
 }
 
 static void vtd_class_init(ObjectClass *klass, void *data)
diff --git a/target-i386/kvm-stub.c b/target-i386/kvm-stub.c
index cdf15061091d..bda4dc2f0c57 100644
--- a/target-i386/kvm-stub.c
+++ b/target-i386/kvm-stub.c
@@ -25,6 +25,11 @@ bool kvm_has_smm(void)
     return 1;
 }
 
+bool kvm_enable_x2apic(void)
+{
+    return false;
+}
+
 /* This function is only called inside conditionals which we
  * rely on the compiler to optimize out when CONFIG_KVM is not
  * defined.
diff --git a/target-i386/kvm.c b/target-i386/kvm.c
index f1ad805665ad..4c0a4df5eaea 100644
--- a/target-i386/kvm.c
+++ b/target-i386/kvm.c
@@ -128,6 +128,19 @@ bool kvm_allows_irq0_override(void)
     return !kvm_irqchip_in_kernel() || kvm_has_gsi_routing();
 }
 
+static bool kvm_x2apic_api_set_flags(uint64_t flags)
+{
+    KVMState *s = KVM_STATE(current_machine->accelerator);
+
+    return !kvm_vm_enable_cap(s, KVM_CAP_X2APIC_API, 0, flags);
+}
+
+bool kvm_enable_x2apic(void)
+{
+    return kvm_x2apic_api_set_flags(KVM_X2APIC_API_USE_32BIT_IDS |
+                                    KVM_X2APIC_API_DISABLE_BROADCAST_QUIRK);
+}
+
 static int kvm_get_tsc(CPUState *cs)
 {
     X86CPU *cpu = X86_CPU(cs);
diff --git a/target-i386/kvm_i386.h b/target-i386/kvm_i386.h
index 42b00af1b1c3..559dd8b5acd2 100644
--- a/target-i386/kvm_i386.h
+++ b/target-i386/kvm_i386.h
@@ -41,4 +41,5 @@ int kvm_device_msix_set_vector(KVMState *s, uint32_t dev_id, 
uint32_t vector,
 int kvm_device_msix_assign(KVMState *s, uint32_t dev_id);
 int kvm_device_msix_deassign(KVMState *s, uint32_t dev_id);
 
+bool kvm_enable_x2apic(void);
 #endif
-- 
2.10.0