[RFC PATCH 08/16] KVM: PPC: Book3S HV: add a GET_TIMA_FD control to XIVE native device

["Cédric Le Goater" <clg@kaod.org>]

This will let the guest create a memory mapping to expose the XIVE
MMIO region (TIMA) used for interrupt management at the CPU level.

Signed-off-by: Cédric Le Goater <clg@kaod.org>
---
 arch/powerpc/include/uapi/asm/kvm.h   |  1 +
 arch/powerpc/kvm/book3s_xive_native.c | 49 +++++++++++++++++++++++++++++++++++
 2 files changed, 50 insertions(+)

diff --git a/arch/powerpc/include/uapi/asm/kvm.h b/arch/powerpc/include/uapi/asm/kvm.h
index cf54fad1faf6..c564ee892cac 100644
--- a/arch/powerpc/include/uapi/asm/kvm.h
+++ b/arch/powerpc/include/uapi/asm/kvm.h
@@ -677,6 +677,7 @@ struct kvm_ppc_cpu_char {
 #define KVM_DEV_XIVE_GRP_SOURCES	1	/* 64-bit source attributes */
 #define KVM_DEV_XIVE_GRP_CTRL		2
 #define   KVM_DEV_XIVE_GET_ESB_FD	1
+#define   KVM_DEV_XIVE_GET_TIMA_FD	2
 
 /* Layout of 64-bit XIVE source attribute values */
 #define  KVM_XIVE_LEVEL_SENSITIVE	(1ULL << 0)
diff --git a/arch/powerpc/kvm/book3s_xive_native.c b/arch/powerpc/kvm/book3s_xive_native.c
index 395298c5fca8..cfce8ba327ca 100644
--- a/arch/powerpc/kvm/book3s_xive_native.c
+++ b/arch/powerpc/kvm/book3s_xive_native.c
@@ -321,6 +321,52 @@ static int kvmppc_xive_native_get_esb_fd(struct kvmppc_xive *xive, u64 addr)
 	return put_user(ret, ubufp);
 }
 
+static int xive_native_tima_fault(struct vm_fault *vmf)
+{
+	struct vm_area_struct *vma = vmf->vma;
+
+	if (vmf->pgoff)
+		return VM_FAULT_SIGBUS;
+
+	vm_insert_pfn(vma, vmf->address, (unsigned long)
+		      local_paca->kvm_hstate.xive_tima_phys >> PAGE_SHIFT);
+	return VM_FAULT_NOPAGE;
+}
+
+static const struct vm_operations_struct xive_native_tima_vmops = {
+	.fault = xive_native_tima_fault,
+};
+
+static int xive_native_tima_mmap(struct file *file, struct vm_area_struct *vma)
+{
+	unsigned long len = vma->vm_end - vma->vm_start;
+
+	if (len != (1 << PAGE_SHIFT))
+		return -EINVAL;
+
+	vma->vm_flags |= VM_IO | VM_PFNMAP;
+	vma->vm_page_prot = pgprot_noncached_wc(vma->vm_page_prot);
+	vma->vm_ops = &xive_native_tima_vmops;
+	return 0;
+}
+
+static const struct file_operations xive_native_tima_fops = {
+	.mmap = xive_native_tima_mmap,
+};
+
+static int kvmppc_xive_native_get_tima_fd(struct kvmppc_xive *xive, u64 addr)
+{
+	u64 __user *ubufp = (u64 __user *) addr;
+	int ret;
+
+	ret = anon_inode_getfd("tima", &xive_native_tima_fops, xive,
+			       O_RDWR | O_CLOEXEC);
+	if (ret < 0)
+		return ret;
+
+	return put_user(ret, ubufp);
+}
+
 static int kvmppc_xive_native_set_attr(struct kvm_device *dev,
 				       struct kvm_device_attr *attr)
 {
@@ -344,6 +390,8 @@ static int kvmppc_xive_native_get_attr(struct kvm_device *dev,
 		switch (attr->attr) {
 		case KVM_DEV_XIVE_GET_ESB_FD:
 			return kvmppc_xive_native_get_esb_fd(xive, attr->addr);
+		case KVM_DEV_XIVE_GET_TIMA_FD:
+			return kvmppc_xive_native_get_tima_fd(xive, attr->addr);
 		}
 		break;
 	}
@@ -362,6 +410,7 @@ static int kvmppc_xive_native_has_attr(struct kvm_device *dev,
 	case KVM_DEV_XIVE_GRP_CTRL:
 		switch (attr->attr) {
 		case KVM_DEV_XIVE_GET_ESB_FD:
+		case KVM_DEV_XIVE_GET_TIMA_FD:
 			return 0;
 		}
 		break;
-- 
2.13.6