[PATCH v2] libxc: add xc_domain_remove_from_physmap to wrap XENMEM_remove_from_physmap

[PATCH v2] libxc: add xc_domain_remove_from_physmap to wrap XENMEM_remove_from_physmap

[Zhongze Liu]

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

  https://lists.xenproject.org/archives/html/xen-devel/2017-07/msg03047.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>
Cc: Ian Jackson <ian.jackson@eu.citrix.com>
Cc: Wei Liu <wei.liu2@citrix.com>
Cc: Stefano Stabellini <sstabellini@kernel.org>
Cc: Julien Grall <julien.grall@arm.com>
Cc: xen-devel@lists.xen.org
---
  v2: add the signed-off message
---
 tools/libxc/include/xenctrl.h |  4 ++++
 tools/libxc/xc_domain.c       | 11 +++++++++++
 2 files changed, 15 insertions(+)

diff --git a/tools/libxc/include/xenctrl.h b/tools/libxc/include/xenctrl.h
index c7710b8f36..0ff15a9255 100644
--- a/tools/libxc/include/xenctrl.h
+++ b/tools/libxc/include/xenctrl.h
@@ -1381,6 +1381,10 @@ 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,
+                                  domid_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 3bab4e8bab..e6b32792c0 100644
--- a/tools/libxc/xc_domain.c
+++ b/tools/libxc/xc_domain.c
@@ -1077,6 +1077,17 @@ out:
     return rc;
 }
 
+int xc_domain_remove_from_physmap(xc_interface *xch,
+                                  domid_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)
-- 
2.14.0


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Re: [PATCH v2] libxc: add xc_domain_remove_from_physmap to wrap XENMEM_remove_from_physmap

[Stefano Stabellini]

On Sat, 19 Aug 2017, Zhongze Liu wrote:
> This is for the proposal "Allow setting up shared memory areas between VMs
> from xl config file". See:
> 
>   https://lists.xenproject.org/archives/html/xen-devel/2017-07/msg03047.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>


> Cc: Ian Jackson <ian.jackson@eu.citrix.com>
> Cc: Wei Liu <wei.liu2@citrix.com>
> Cc: Stefano Stabellini <sstabellini@kernel.org>
> Cc: Julien Grall <julien.grall@arm.com>
> Cc: xen-devel@lists.xen.org
> ---
>   v2: add the signed-off message
> ---
>  tools/libxc/include/xenctrl.h |  4 ++++
>  tools/libxc/xc_domain.c       | 11 +++++++++++
>  2 files changed, 15 insertions(+)
> 
> diff --git a/tools/libxc/include/xenctrl.h b/tools/libxc/include/xenctrl.h
> index c7710b8f36..0ff15a9255 100644
> --- a/tools/libxc/include/xenctrl.h
> +++ b/tools/libxc/include/xenctrl.h
> @@ -1381,6 +1381,10 @@ 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,
> +                                  domid_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 3bab4e8bab..e6b32792c0 100644
> --- a/tools/libxc/xc_domain.c
> +++ b/tools/libxc/xc_domain.c
> @@ -1077,6 +1077,17 @@ out:
>      return rc;
>  }
>  
> +int xc_domain_remove_from_physmap(xc_interface *xch,
> +                                  domid_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)
> -- 
> 2.14.0
> 

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