KVM: Enable snooping control for supported hardware
Memory aliases with different memory type is a problem for guest. For the guest
without assigned device, the memory type of guest memory would always been the
same as host(WB); but for the assigned device, some part of memory may be used
as DMA and then set to uncacheable memory type(UC/WC), which would be a conflict of
host memory type then be a potential issue.
Snooping control can guarantee the cache correctness of memory go through the
DMA engine of VT-d.
[avi: fix build on ia64]
Signed-off-by: Sheng Yang <sheng@linux.intel.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index 72d5684..bdce8e1 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -367,6 +367,9 @@
int kvm_request_irq_source_id(struct kvm *kvm);
void kvm_free_irq_source_id(struct kvm *kvm, int irq_source_id);
+/* For vcpu->arch.iommu_flags */
+#define KVM_IOMMU_CACHE_COHERENCY 0x1
+
#ifdef CONFIG_IOMMU_API
int kvm_iommu_map_pages(struct kvm *kvm, gfn_t base_gfn,
unsigned long npages);