[PATCH] cxl: Fix memory page not handled

[Christophe Lombard]

The a in-kernel 'library' API can be called by drivers to help
interaction with an IBM XSL on a POWER9 system.

The cxllib_handle_fault() API is used to handle memory fault. All memory
pages of the specified buffer have to be handled but the last page is
never touched, and the address the adapter is trying to access is never
sent to the kernel for resolution.

This patch updates the loop on the memory pages to be handled.

Signed-off-by: Christophe Lombard <clombard at linux.vnet.ibm.com>

Fixes: 3ced8d730063 ("cxl: Export library to support IBM XSL");
---
 drivers/misc/cxl/cxllib.c | 13 +++++++++++--
 1 file changed, 11 insertions(+), 2 deletions(-)

diff --git a/drivers/misc/cxl/cxllib.c b/drivers/misc/cxl/cxllib.c
index 5dba23c..0c1eaf0 100644
--- a/drivers/misc/cxl/cxllib.c
+++ b/drivers/misc/cxl/cxllib.c
@@ -219,8 +219,17 @@ int cxllib_handle_fault(struct mm_struct *mm, u64 addr, u64 size, u64 flags)
 
 	down_read(&mm->mmap_sem);
 
-	for (dar = addr; dar < addr + size; dar += page_size) {
-		if (!vma || dar < vma->vm_start || dar > vma->vm_end) {
+	vma = find_vma(mm, addr);
+	if (!vma) {
+		pr_err("Can't find vma for addr %016llx\n", addr);
+		rc = -EFAULT;
+		goto out;
+	}
+	/* get the size of the pages allocated */
+	page_size = vma_kernel_pagesize(vma);
+
+	for (dar = (addr & ~(page_size - 1)); dar <= (addr + size); dar += page_size) {
+		if (dar < vma->vm_start || dar > vma->vm_end) {
 			vma = find_vma(mm, addr);
 			if (!vma) {
 				pr_err("Can't find vma for addr %016llx\n", addr);
-- 
2.7.4