xen/pvh: Use ballooning to allocate grant table pages [v2]

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.

Signed-off-by: Mukesh Rathor <mukesh.rathor@oracle.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
[v1: Rebase on xen/grant-table: correctly initialize grant table version 1]

diff --git a/drivers/xen/grant-table.c b/drivers/xen/grant-table.c
index c5c2eb3bce5c9c55852673719aab9a6d216bbfa2..f4e067b05303ae1bfac36cdc589b69c1eb6403ee 100644 (file)
--- 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>
 
@@ -1026,10 +1027,22 @@ static void gnttab_unmap_frames_v2(void)
        arch_gnttab_unmap(grstatus, nr_status_frames(nr_grant_frames));
 }
 
+static xen_pfn_t pvh_get_grant_pfn(int grant_idx)
+{
+       unsigned long vaddr;
+       unsigned int level;
+       pte_t *pte;
+
+       vaddr = (unsigned long)(gnttab_shared.addr) + grant_idx * PAGE_SIZE;
+       pte = lookup_address(vaddr, &level);
+       BUG_ON(pte == NULL);
+       return pte_mfn(*pte);
+}
+
 static int gnttab_map(unsigned int start_idx, unsigned int end_idx)
 {
        struct gnttab_setup_table setup;
-       unsigned long start_gpfn;
+       unsigned long start_gpfn = 0;
        xen_pfn_t *frames;
        unsigned int nr_gframes = end_idx + 1;
        int rc;
@@ -1041,8 +1054,6 @@ static int gnttab_map(unsigned int start_idx, unsigned int end_idx)
 
                if (xen_hvm_domain())
                        start_gpfn = xen_hvm_resume_frames >> PAGE_SHIFT;
-               else
-                       start_gpfn = virt_to_pfn(gnttab_shared.addr);
                /*
                 * Loop backwards, so that the first hypercall has the largest
                 * index, ensuring that the table will grow only once.
@@ -1051,7 +1062,11 @@ static int gnttab_map(unsigned int start_idx, unsigned int end_idx)
                        xatp.domid = DOMID_SELF;
                        xatp.idx = i;
                        xatp.space = XENMAPSPACE_grant_table;
-                       xatp.gpfn = start_gpfn + i;
+                       if (xen_hvm_domain())
+                               xatp.gpfn = start_gpfn + i;
+                       else
+                               xatp.gpfn = pvh_get_grant_pfn(i);
+
                        rc = HYPERVISOR_memory_op(XENMEM_add_to_physmap, &xatp);
                        if (rc != 0) {
                                printk(KERN_WARNING
@@ -1141,26 +1156,50 @@ static void gnttab_request_version(void)
                grant_table_version);
 }
 
+/*
+ * PVH: we need three things: virtual address, pfns, and mfns. The pfns
+ * are allocated via ballooning, then we call arch_gnttab_map_shared to
+ * allocate the VA and put pfn's in the pte's for the VA. The mfn's are
+ * finally allocated in gnttab_map() by xen which also populates the P2M.
+ */
+static int xlated_setup_gnttab_pages(unsigned long 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 Couldn't balloon alloc %ld pfns rc:%d\n", __func__,
+                       numpages, rc);
+               return rc;
+       }
+       for (i = 0; i < numpages; i++)
+               pfns[i] = page_to_pfn(pages[i]);
+
+       rc = arch_gnttab_map_shared(pfns, numpages, numpages, addr);
+       if (rc != 0)
+               free_xenballooned_pages(numpages, pages);
+
+       return rc;
+}
+
 static int gnttab_setup(void)
 {
+       int rc;
        unsigned int max_nr_gframes;
-       char *kmsg = "Failed to kmalloc pages for pv in hvm grant frames\n";
 
        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((unsigned long)max_nr_gframes,
+                                              &gnttab_shared.addr);
+               if (rc != 0)
+                       return rc;
        }
        if (xen_pv_domain())
                return gnttab_map(0, nr_grant_frames - 1);