linux-kernel - [PATCH] xen/privcmd: Support correctly 64KB page granularity when mapping memory

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Date:   Wed, 31 May 2017 14:03:57 +0100
From:   Julien Grall <julien.grall@....com>
To:     xen-devel@...ts.xen.org
Cc:     sstabellini@...nel.org, boris.ostrovsky@...cle.com,
        jgross@...e.com, linux-kernel@...r.kernel.org,
        Julien Grall <julien.grall@....com>, stable@...r.kernel.org,
        Feng Kan <fkan@....com>
Subject: [PATCH] xen/privcmd: Support correctly 64KB page granularity when mapping memory

Commit 5995a68 "xen/privcmd: Add support for Linux 64KB page granularity" did
not go far enough to support 64KB in mmap_batch_fn.

The variable 'nr' is the number of 4KB chunk to map. However, when Linux
is using 64KB page granularity the array of pages (vma->vm_private_data)
contain one page per 64KB. Fix it by incrementing st->index correctly.

Furthermore, st->va is not correctly incremented as PAGE_SIZE !=
XEN_PAGE_SIZE.

Fixes: 5995a68 ("xen/privcmd: Add support for Linux 64KB page granularity")
CC: stable@...r.kernel.org
Reported-by: Feng Kan <fkan@....com>
Signed-off-by: Julien Grall <julien.grall@....com>
---
 drivers/xen/privcmd.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/xen/privcmd.c b/drivers/xen/privcmd.c
index 7a92a5e1d40c..feca75b07fdd 100644
--- a/drivers/xen/privcmd.c
+++ b/drivers/xen/privcmd.c
@@ -362,8 +362,8 @@ static int mmap_batch_fn(void *data, int nr, void *state)
 				st->global_error = 1;
 		}
 	}
-	st->va += PAGE_SIZE * nr;
-	st->index += nr;
+	st->va += XEN_PAGE_SIZE * nr;
+	st->index += nr / XEN_PFN_PER_PAGE;
 
 	return 0;
 }
-- 
2.11.0