From f80fad16afa5aebb8cce919e87f6c58fa03d16e6 Mon Sep 17 00:00:00 2001
From: David Woodhouse <dwmw@amazon.co.uk>
Date: Tue, 10 Jan 2023 00:03:49 +0000
Subject: hw/xen: Pass grant ref to gnttab unmap operation
The previous commit introduced redirectable gnttab operations fairly
much like-for-like, with the exception of the extra arguments to the
->open() call which were always NULL/0 anyway.
This *changes* the arguments to the ->unmap() operation to include the
original ref# that was mapped. Under real Xen it isn't necessary; all we
need to do from QEMU is munmap(), then the kernel will release the grant,
and Xen does the tracking/refcounting for the guest.
When we have emulated grant tables though, we need to do all that for
ourselves. So let's have the back ends keep track of what they mapped
and pass it in to the ->unmap() method for us.
Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
Reviewed-by: Paul Durrant <paul@xen.org>
---
hw/xen/xen-operations.c | 9 ++++++++-
1 file changed, 8 insertions(+), 1 deletion(-)
(limited to 'hw/xen/xen-operations.c')
diff --git a/hw/xen/xen-operations.c b/hw/xen/xen-operations.c
index 2e74a28..c5956d2 100644
--- a/hw/xen/xen-operations.c
+++ b/hw/xen/xen-operations.c
@@ -200,6 +200,13 @@ static xengnttab_handle *libxengnttab_backend_open(void)
return xengnttab_open(NULL, 0);
}
+static int libxengnttab_backend_unmap(xengnttab_handle *xgt,
+ void *start_address, uint32_t *refs,
+ uint32_t count)
+{
+ return xengnttab_unmap(xgt, start_address, count);
+}
+
static struct gnttab_backend_ops libxengnttab_backend_ops = {
.features = XEN_GNTTAB_OP_FEATURE_MAP_MULTIPLE,
@@ -208,7 +215,7 @@ static struct gnttab_backend_ops libxengnttab_backend_ops = {
.grant_copy = libxengnttab_fallback_grant_copy,
.set_max_grants = xengnttab_set_max_grants,
.map_refs = xengnttab_map_domain_grant_refs,
- .unmap = xengnttab_unmap,
+ .unmap = libxengnttab_backend_unmap,
};
void setup_xen_backend_ops(void)
--
cgit v1.1