Re: [Xen-devel] [PATCH] PVH linux: Use ballooning to allocate grant table pages

[Mukesh Rathor <mukesh.rathor@xxxxxxxxxx>]

On Thu, 31 Jan 2013 18:30:15 -0800
Mukesh Rathor <mukesh.rathor@xxxxxxxxxx> wrote:

> This patch fixes a fixme in Linux to use alloc_xenballooned_pages() to
> allocate pfns for grant table pages instead of kmalloc. This also
> simplifies add to physmap on the xen side a bit.

Looking at it again, I realized rc should be signed in gnttab_resume().
Below again. Thanks.

Signed-off-by: Mukesh Rathor <mukesh.rathor@xxxxxxxxxx>

diff --git a/drivers/xen/grant-table.c b/drivers/xen/grant-table.c
index 9c0019d..7a630bb 100644
--- a/drivers/xen/grant-table.c
+++ b/drivers/xen/grant-table.c
@@ -47,6 +47,7 @@
 #include <xen/grant_table.h>
 #include <xen/interface/memory.h>
 #include <xen/hvc-console.h>
+#include <xen/balloon.h>
 #include <asm/xen/hypercall.h>
 #include <asm/xen/interface.h>
 
@@ -1138,27 +1139,42 @@ static void gnttab_request_version(void)
                grant_table_version);
 }
 
+static int xlated_setup_gnttab_pages(int numpages, void **addr)
+{
+       int i, rc;
+       unsigned long pfns[numpages];
+       struct page *pages[numpages];
+
+       rc = alloc_xenballooned_pages(numpages, pages, 0);
+       if (rc != 0) {
+               pr_warn("%s Could not balloon alloc %d pfns rc:%d\n", __func__,
+                       numpages, rc);
+               return -ENOMEM;
+       }
+       for (i = 0; i < numpages; i++)
+               pfns[i] = page_to_pfn(pages[i]);
+
+       rc = arch_gnttab_map_shared(pfns, numpages, numpages, addr);
+       return rc;
+}
+
 int gnttab_resume(void)
 {
+       int rc;
        unsigned int max_nr_gframes;
-       char *kmsg = "Failed to kmalloc pages for pv in hvm grant frames\n";
 
        gnttab_request_version();
        max_nr_gframes = gnttab_max_grant_frames();
        if (max_nr_gframes < nr_grant_frames)
                return -ENOSYS;
 
-       /* PVH note: xen will free existing kmalloc'd mfn in
-        * XENMEM_add_to_physmap. TBD/FIXME: use xen ballooning instead of
-        * kmalloc(). */
        if (xen_pv_domain() && xen_feature(XENFEAT_auto_translated_physmap) &&
            !gnttab_shared.addr) {
-               gnttab_shared.addr =
-                       kmalloc(max_nr_gframes * PAGE_SIZE, GFP_KERNEL);
-               if (!gnttab_shared.addr) {
-                       pr_warn("%s", kmsg);
-                       return -ENOMEM;
-               }
+
+               rc = xlated_setup_gnttab_pages(max_nr_gframes,
+                                              &gnttab_shared.addr);
+               if (rc != 0)
+                       return rc;
        }
        if (xen_pv_domain())
                return gnttab_map(0, nr_grant_frames - 1);




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