ocxl: Add AFU interrupt support

Add user APIs through ioctl to allocate, free, and be notified of an
AFU interrupt.

For opencapi, an AFU can trigger an interrupt on the host by sending a
specific command targeting a 64-bit object handle. On POWER9, this is
implemented by mapping a special page in the address space of a
process and a write to that page will trigger an interrupt.

Signed-off-by: Frederic Barrat <fbarrat@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

1 files changed, 49 insertions, 2 deletions

diff --git a/drivers/misc/ocxl/context.c b/drivers/misc/ocxl/context.c
index b34b836f924c..269149490063 100644
--- a/drivers/misc/ocxl/context.c
+++ b/drivers/misc/ocxl/context.c
@@ -31,6 +31,8 @@ int ocxl_context_init(struct ocxl_context *ctx, struct ocxl_afu *afu,
 	mutex_init(&ctx->mapping_lock);
 	init_waitqueue_head(&ctx->events_wq);
 	mutex_init(&ctx->xsl_error_lock);
+	mutex_init(&ctx->irq_lock);
+	idr_init(&ctx->irq_idr);
 	/*
 	 * Keep a reference on the AFU to make sure it's valid for the
 	 * duration of the life of the context
@@ -80,6 +82,19 @@ out:
 	return rc;
 }
 
+static int map_afu_irq(struct vm_area_struct *vma, unsigned long address,
+		u64 offset, struct ocxl_context *ctx)
+{
+	u64 trigger_addr;
+
+	trigger_addr = ocxl_afu_irq_get_addr(ctx, offset);
+	if (!trigger_addr)
+		return VM_FAULT_SIGBUS;
+
+	vm_insert_pfn(vma, address, trigger_addr >> PAGE_SHIFT);
+	return VM_FAULT_NOPAGE;
+}
+
 static int map_pp_mmio(struct vm_area_struct *vma, unsigned long address,
 		u64 offset, struct ocxl_context *ctx)
 {
@@ -118,7 +133,10 @@ static int ocxl_mmap_fault(struct vm_fault *vmf)
 	pr_debug("%s: pasid %d address 0x%lx offset 0x%llx\n", __func__,
 		ctx->pasid, vmf->address, offset);
 
-	rc = map_pp_mmio(vma, vmf->address, offset, ctx);
+	if (offset < ctx->afu->irq_base_offset)
+		rc = map_pp_mmio(vma, vmf->address, offset, ctx);
+	else
+		rc = map_afu_irq(vma, vmf->address, offset, ctx);
 	return rc;
 }
 
@@ -126,6 +144,30 @@ static const struct vm_operations_struct ocxl_vmops = {
 	.fault = ocxl_mmap_fault,
 };
 
+static int check_mmap_afu_irq(struct ocxl_context *ctx,
+			struct vm_area_struct *vma)
+{
+	/* only one page */
+	if (vma_pages(vma) != 1)
+		return -EINVAL;
+
+	/* check offset validty */
+	if (!ocxl_afu_irq_get_addr(ctx, vma->vm_pgoff << PAGE_SHIFT))
+		return -EINVAL;
+
+	/*
+	 * trigger page should only be accessible in write mode.
+	 *
+	 * It's a bit theoretical, as a page mmaped with only
+	 * PROT_WRITE is currently readable, but it doesn't hurt.
+	 */
+	if ((vma->vm_flags & VM_READ) || (vma->vm_flags & VM_EXEC) ||
+		!(vma->vm_flags & VM_WRITE))
+		return -EINVAL;
+	vma->vm_flags &= ~(VM_MAYREAD | VM_MAYEXEC);
+	return 0;
+}
+
 static int check_mmap_mmio(struct ocxl_context *ctx,
 			struct vm_area_struct *vma)
 {
@@ -139,7 +181,10 @@ int ocxl_context_mmap(struct ocxl_context *ctx, struct vm_area_struct *vma)
 {
 	int rc;
 
-	rc = check_mmap_mmio(ctx, vma);
+	if ((vma->vm_pgoff << PAGE_SHIFT) < ctx->afu->irq_base_offset)
+		rc = check_mmap_mmio(ctx, vma);
+	else
+		rc = check_mmap_afu_irq(ctx, vma);
 	if (rc)
 		return rc;
 
@@ -224,6 +269,8 @@ void ocxl_context_free(struct ocxl_context *ctx)
 	idr_remove(&ctx->afu->contexts_idr, ctx->pasid);
 	mutex_unlock(&ctx->afu->contexts_lock);
 
+	ocxl_afu_irq_free_all(ctx);
+	idr_destroy(&ctx->irq_idr);
 	/* reference to the AFU taken in ocxl_context_init */
 	ocxl_afu_put(ctx->afu);
 	kfree(ctx);