[v5,7/9] init-dom0less: allocate xenstore page is not already allocated

Commit Message

Stefano Stabellini Feb. 6, 2025, 1:08 a.m. UTC

We check if the xenstore page is already allocated. If yes, there is
nothing to do. If no, we proceed allocating it.

Signed-off-by: Stefano Stabellini <[e-mail]>
---
 tools/helpers/init-dom0less.c | 54 +++++++++++++++++++++++++++++++++--
 1 file changed, 51 insertions(+), 3 deletions(-)

Comments

Jan Beulich Feb. 6, 2025, 12:37 p.m. UTC | #1

On 06.02.2025 02:08, Stefano Stabellini wrote:
> --- a/tools/helpers/init-dom0less.c
> +++ b/tools/helpers/init-dom0less.c
> @@ -16,8 +16,35 @@
>  
>  #include "init-dom-json.h"
>  
> +#define XENSTORE_PFN_OFFSET 1
>  #define STR_MAX_LENGTH 128
>  
> +
> +static int alloc_xs_page(struct xc_interface_core *xch,

While this isn't my area of maintainership, may I nevertheless ask that you
please avoid introducing double blank lines?

Jan

Stefano Stabellini Feb. 6, 2025, 11:14 p.m. UTC | #2

On Thu, 6 Feb 2025, Jan Beulich wrote:
> On 06.02.2025 02:08, Stefano Stabellini wrote:
> > --- a/tools/helpers/init-dom0less.c
> > +++ b/tools/helpers/init-dom0less.c
> > @@ -16,8 +16,35 @@
> >  
> >  #include "init-dom-json.h"
> >  
> > +#define XENSTORE_PFN_OFFSET 1
> >  #define STR_MAX_LENGTH 128
> >  
> > +
> > +static int alloc_xs_page(struct xc_interface_core *xch,
> 
> While this isn't my area of maintainership, may I nevertheless ask that you
> please avoid introducing double blank lines?

Sure, thanks Jan

Patch

diff --git a/tools/helpers/init-dom0less.c b/tools/helpers/init-dom0less.c
index 2b51965fa7..3cee325358 100644
--- a/tools/helpers/init-dom0less.c
+++ b/tools/helpers/init-dom0less.c
@@ -16,8 +16,35 @@ 
 
 #include "init-dom-json.h"
 
+#define XENSTORE_PFN_OFFSET 1
 #define STR_MAX_LENGTH 128
 
+
+static int alloc_xs_page(struct xc_interface_core *xch,
+                         libxl_dominfo *info,
+                         uint64_t *xenstore_pfn)
+{
+    int rc;
+    const xen_pfn_t base = GUEST_MAGIC_BASE >> XC_PAGE_SHIFT;
+    xen_pfn_t p2m = (GUEST_MAGIC_BASE >> XC_PAGE_SHIFT) + XENSTORE_PFN_OFFSET;
+
+    rc = xc_domain_setmaxmem(xch, info->domid,
+                             info->max_memkb + (XC_PAGE_SIZE/1024));
+    if (rc < 0)
+        return rc;
+
+    rc = xc_domain_populate_physmap_exact(xch, info->domid, 1, 0, 0, &p2m);
+    if (rc < 0)
+        return rc;
+
+    *xenstore_pfn = base + XENSTORE_PFN_OFFSET;
+    rc = xc_clear_domain_page(xch, info->domid, *xenstore_pfn);
+    if (rc < 0)
+        return rc;
+
+    return 0;
+}
+
 static int get_xs_page(struct xc_interface_core *xch, libxl_dominfo *info,
                        uint64_t *xenstore_pfn)
 {
@@ -233,9 +260,30 @@  static int init_domain(struct xs_handle *xsh,
         return 0;
 
     /* Get xenstore page */
-    if (get_xs_page(xch, info, &xenstore_pfn) != 0) {
-        printf("Error on getting xenstore page\n");
-        return 1;
+    if (get_xs_page(xch, info, &xenstore_pfn) != 0 || xenstore_pfn == ~0ULL) {
+        struct xenstore_domain_interface *intf;
+
+        rc = alloc_xs_page(xch, info, &xenstore_pfn);
+        if (rc != 0) {
+            printf("Error on getting xenstore page\n");
+            return 1;
+        }
+
+        intf = xenforeignmemory_map(xfh, info->domid, PROT_READ | PROT_WRITE, 1,
+                                    &xenstore_pfn, NULL);
+        if (!intf) {
+            printf("Error mapping xenstore page\n");
+            return 1;
+        }
+
+        intf->connection = XENSTORE_RECONNECT;
+        xenforeignmemory_unmap(xfh, intf, 1);
+
+        /* Now everything is ready: set HVM_PARAM_STORE_PFN */
+        rc = xc_hvm_param_set(xch, info->domid, HVM_PARAM_STORE_PFN,
+                xenstore_pfn);
+        if (rc < 0)
+            return rc;
     }
 
     rc = xc_dom_gnttab_seed(xch, info->domid, true,