vmw_vmci: Convert driver to use get_user_pages_fast()

Convert vmci_host_setup_notify() and qp_host_get_user_memory() to use
get_user_pages_fast() instead of get_user_pages(). Note that
qp_host_get_user_memory() was using mmap_sem for writing without an
apparent reason.

CC: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/misc/vmw_vmci/vmci_host.c

@@ -243,11 +243,7 @@ static int vmci_host_setup_notify(struct vmci_ctx *context,
 	/*
 	 * Lock physical page backing a given user VA.
 	 */
-	down_read(&current->mm->mmap_sem);
-	retval = get_user_pages(current, current->mm,
-				PAGE_ALIGN(uva),
-				1, 1, 0, &page, NULL);
-	up_read(&current->mm->mmap_sem);
+	retval = get_user_pages_fast(PAGE_ALIGN(uva), 1, 1, &page);
 	if (retval != 1)
 		return VMCI_ERROR_GENERIC;
 

drivers/misc/vmw_vmci/vmci_queue_pair.c

@@ -732,13 +732,9 @@ static int qp_host_get_user_memory(u64 produce_uva,
 	int retval;
 	int err = VMCI_SUCCESS;
 
-	down_write(&current->mm->mmap_sem);
-	retval = get_user_pages(current,
-				current->mm,
-				(uintptr_t) produce_uva,
-				produce_q->kernel_if->num_pages,
-				1, 0,
-				produce_q->kernel_if->u.h.header_page, NULL);
+	retval = get_user_pages_fast((uintptr_t) produce_uva,
+				     produce_q->kernel_if->num_pages, 1,
+				     produce_q->kernel_if->u.h.header_page);
 	if (retval < produce_q->kernel_if->num_pages) {
 		pr_warn("get_user_pages(produce) failed (retval=%d)", retval);
 		qp_release_pages(produce_q->kernel_if->u.h.header_page,
@@ -747,12 +743,9 @@ static int qp_host_get_user_memory(u64 produce_uva,
 		goto out;
 	}
 
-	retval = get_user_pages(current,
-				current->mm,
-				(uintptr_t) consume_uva,
-				consume_q->kernel_if->num_pages,
-				1, 0,
-				consume_q->kernel_if->u.h.header_page, NULL);
+	retval = get_user_pages_fast((uintptr_t) consume_uva,
+				     consume_q->kernel_if->num_pages, 1,
+				     consume_q->kernel_if->u.h.header_page);
 	if (retval < consume_q->kernel_if->num_pages) {
 		pr_warn("get_user_pages(consume) failed (retval=%d)", retval);
 		qp_release_pages(consume_q->kernel_if->u.h.header_page,
@@ -763,8 +756,6 @@ static int qp_host_get_user_memory(u64 produce_uva,
 	}
 
  out:
-	up_write(&current->mm->mmap_sem);
-
 	return err;
 }