vhost: correctly set bits of dirty pages

Fix two bugs in dirty page logging:
When counting pages we should increase address by 1 instead of
VHOST_PAGE_SIZE. Make log_write() correctly process requests
that cross pages with write_address not starting at page boundary.

Reported-by: Jason Wang <jasowang@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c
index 94701ff3a23ad957a9c675bd3ccd74418c2f989e..159c77a5746fecfd6c6eeb687cf11e747e194fba 100644 (file)
--- a/drivers/vhost/vhost.c
+++ b/drivers/vhost/vhost.c
@@ -884,6 +884,7 @@ static int log_write(void __user *log_base,
        int r;
        if (!write_length)
                return 0;
+       write_length += write_address % VHOST_PAGE_SIZE;
        write_address /= VHOST_PAGE_SIZE;
        for (;;) {
                u64 base = (u64)(unsigned long)log_base;
@@ -897,7 +898,7 @@ static int log_write(void __user *log_base,
                if (write_length <= VHOST_PAGE_SIZE)
                        break;
                write_length -= VHOST_PAGE_SIZE;
-               write_address += VHOST_PAGE_SIZE;
+               write_address += 1;
        }
        return r;
 }