KVM: PPC: Book3S HV: XIVE: Add a TIMA mapping

Each thread has an associated Thread Interrupt Management context
composed of a set of registers. These registers let the thread handle
priority management and interrupt acknowledgment. The most important
are :

    - Interrupt Pending Buffer     (IPB)
    - Current Processor Priority   (CPPR)
    - Notification Source Register (NSR)

They are exposed to software in four different pages each proposing a
view with a different privilege. The first page is for the physical
thread context and the second for the hypervisor. Only the third
(operating system) and the fourth (user level) are exposed the guest.

A custom VM fault handler will populate the VMA with the appropriate
pages, which should only be the OS page for now.

Signed-off-by: Cédric Le Goater <clg@kaod.org>
Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Paul Mackerras <paulus@ozlabs.org>

1 files changed, 39 insertions, 0 deletions

diff --git a/arch/powerpc/kvm/book3s_xive_native.c b/arch/powerpc/kvm/book3s_xive_native.c
index 2f9d5e9439a6..f5314da0cb45 100644
--- a/arch/powerpc/kvm/book3s_xive_native.c
+++ b/arch/powerpc/kvm/book3s_xive_native.c
@@ -165,6 +165,44 @@ bail:
 	return rc;
 }
 
+static vm_fault_t xive_native_tima_fault(struct vm_fault *vmf)
+{
+	struct vm_area_struct *vma = vmf->vma;
+
+	switch (vmf->pgoff - vma->vm_pgoff) {
+	case 0: /* HW - forbid access */
+	case 1: /* HV - forbid access */
+		return VM_FAULT_SIGBUS;
+	case 2: /* OS */
+		vmf_insert_pfn(vma, vmf->address, xive_tima_os >> PAGE_SHIFT);
+		return VM_FAULT_NOPAGE;
+	case 3: /* USER - TODO */
+	default:
+		return VM_FAULT_SIGBUS;
+	}
+}
+
+static const struct vm_operations_struct xive_native_tima_vmops = {
+	.fault = xive_native_tima_fault,
+};
+
+static int kvmppc_xive_native_mmap(struct kvm_device *dev,
+				   struct vm_area_struct *vma)
+{
+	/* We only allow mappings at fixed offset for now */
+	if (vma->vm_pgoff == KVM_XIVE_TIMA_PAGE_OFFSET) {
+		if (vma_pages(vma) > 4)
+			return -EINVAL;
+		vma->vm_ops = &xive_native_tima_vmops;
+	} else {
+		return -EINVAL;
+	}
+
+	vma->vm_flags |= VM_IO | VM_PFNMAP;
+	vma->vm_page_prot = pgprot_noncached_wc(vma->vm_page_prot);
+	return 0;
+}
+
 static int kvmppc_xive_native_set_source(struct kvmppc_xive *xive, long irq,
 					 u64 addr)
 {
@@ -1050,6 +1088,7 @@ struct kvm_device_ops kvm_xive_native_ops = {
 	.set_attr = kvmppc_xive_native_set_attr,
 	.get_attr = kvmppc_xive_native_get_attr,
 	.has_attr = kvmppc_xive_native_has_attr,
+	.mmap = kvmppc_xive_native_mmap,
 };
 
 void kvmppc_xive_native_init_module(void)