libxc: add xc_domain_remove_from_physmap to wrap XENMEM_remove_from_physmap

This is for the proposal "Allow setting up shared memory areas between VMs
from xl config file". See:

  https://lists.xen.org/archives/html/xen-devel/2017-08/msg03242.html

Then plan is to use XENMEM_add_to_physmap_batch to map the shared pages from
one domU to another and use XENMEM_remove_from_physmap to cancel the sharing.
A wrapper to XENMEM_add_to_physmap_batch was added in the following commit:

  commit 20e725e9364cff4a29945f66986ecd88cca8743d

Now add the wrapper to XENMEM_remove_from_physmap.

Signed-off-by: Zhongze Liu <blackskygg@gmail.com>
Reviewed-by: Stefano Stabellini <sstabellini@kernel.org>
Acked-by: Wei Liu <wei.liu2@citrix.com>

diff --git a/tools/libxc/include/xenctrl.h b/tools/libxc/include/xenctrl.h
index 235b8bb8479e9709f405deab928b431afde6ca12..543abfcb3468c0d5f1edccaa58a0340751e127ab 100644 (file)
--- a/tools/libxc/include/xenctrl.h
+++ b/tools/libxc/include/xenctrl.h
@@ -1416,6 +1416,10 @@ int xc_domain_add_to_physmap_batch(xc_interface *xch,
                                    xen_pfn_t *gfpns,
                                    int *errs);
 
+int xc_domain_remove_from_physmap(xc_interface *xch,
+                                  uint32_t domid,
+                                  xen_pfn_t gpfn);
+
 int xc_domain_populate_physmap(xc_interface *xch,
                                uint32_t domid,
                                unsigned long nr_extents,

diff --git a/tools/libxc/xc_domain.c b/tools/libxc/xc_domain.c
index da0aa2f6a8770366f3b400b7f57620601a061a98..ea3df1ef316572b2846ffe1fb365700e0b593801 100644 (file)
--- a/tools/libxc/xc_domain.c
+++ b/tools/libxc/xc_domain.c
@@ -1090,6 +1090,17 @@ out:
     return rc;
 }
 
+int xc_domain_remove_from_physmap(xc_interface *xch,
+                                  uint32_t domid,
+                                  xen_pfn_t gpfn)
+{
+    struct xen_remove_from_physmap xrfp = {
+        .domid = domid,
+        .gpfn = gpfn,
+    };
+    return do_memory_op(xch, XENMEM_remove_from_physmap, &xrfp, sizeof(xrfp));
+}
+
 int xc_domain_claim_pages(xc_interface *xch,
                                uint32_t domid,
                                unsigned long nr_pages)