[PATCH] port/xen: map memory directly in privcmd PRIVCMD_MMAPBATCH

[Roger Pau Monne <roger.pau%citrix.com@localhost>]

Instead of mapping memory when a pagefault happens in the memory
region, map the memory directly on the pivcmd call (as Linux does).
This fixes the problem with Qemu upstream, that changes the location
of the pfns after calling xc_map_foreign_bulk.

Signed-off-by: Roger Pau Monne <roger.pau%citrix.com@localhost>
---
 sys/arch/xen/xen/privcmd.c |   78 +++++++++++++++++++------------------------
 1 files changed, 35 insertions(+), 43 deletions(-)

diff --git a/sys/arch/xen/xen/privcmd.c b/sys/arch/xen/xen/privcmd.c
index f584913..033a37d 100644
--- a/sys/arch/xen/xen/privcmd.c
+++ b/sys/arch/xen/xen/privcmd.c
@@ -69,6 +69,8 @@ static void privpgop_detach(struct uvm_object *);
 static int privpgop_fault(struct uvm_faultinfo *, vaddr_t , struct vm_page **,
                         int, int, vm_prot_t, int);
 static int privcmd_map_obj(struct vm_map *, vaddr_t, paddr_t *, int, int);
+static int privcmd_map(pmap_t pmap, vaddr_t va0, u_long *mfn,
+                       vm_prot_t prot, int num, int domid);
 
 
 static int
@@ -371,16 +373,13 @@ privcmd_ioctl(void *v)
        }
        case IOCTL_PRIVCMD_MMAPBATCH:
        {
-               int i;
                privcmd_mmapbatch_t* pmb = ap->a_data;
-               vaddr_t va0, va;
-               u_long mfn;
-               paddr_t ma;
+               vaddr_t va0;
+               u_long *mfn;
                struct vm_map *vmm;
                struct vm_map_entry *entry;
                vm_prot_t prot;
                pmap_t pmap;
-               vaddr_t trymap;
 
                vmm = &curlwp->l_proc->p_vmspace->vm_map;
                pmap = vm_map_pmap(vmm);
@@ -400,48 +399,23 @@ privcmd_ioctl(void *v)
                }
                prot = entry->protection;
                vm_map_unlock_read(vmm);
-               
-               maddr = kmem_alloc(sizeof(paddr_t) * pmb->num, KM_SLEEP);
-               if (maddr == NULL)
-                       return ENOMEM;
-               /* get a page of KVA to check mappins */
-               trymap = uvm_km_alloc(kernel_map, PAGE_SIZE, PAGE_SIZE,
-                   UVM_KMF_VAONLY);
-               if (trymap == 0) {
-                       kmem_free(maddr, sizeof(paddr_t) * pmb->num);
-                       return ENOMEM;
-               }
 
-               for(i = 0; i < pmb->num; ++i) {
-                       va = va0 + (i * PAGE_SIZE);
-                       error = copyin(&pmb->arr[i], &mfn, sizeof(mfn));
-                       if (error != 0) {
-                               /* XXX: mappings */
-                               pmap_update(pmap_kernel());
-                               kmem_free(maddr, sizeof(paddr_t) * pmb->num);
-                               uvm_km_free(kernel_map, trymap, PAGE_SIZE,
-                                   UVM_KMF_VAONLY);
-                               return error;
-                       }
-                       ma = ((paddr_t)mfn) << PGSHIFT;
-                       if (pmap_enter_ma(pmap_kernel(), trymap, ma, 0,
-                           prot, PMAP_CANFAIL, pmb->dom)) {
-                               mfn |= 0xF0000000;
-                               copyout(&mfn, &pmb->arr[i], sizeof(mfn));
-                               maddr[i] = INVALID_PAGE;
-                       } else {
-                               pmap_remove(pmap_kernel(), trymap,
-                                   trymap + PAGE_SIZE);
-                               maddr[i] = ma;
-                       }
+               mfn = kmem_alloc(sizeof(u_long) * pmb->num, KM_SLEEP);
+               error = copyin(pmb->arr, mfn, sizeof(u_long) * pmb->num);
+               if (error != 0) {
+                       /* XXX: mappings */
+                       kmem_free(mfn, sizeof(u_long) * pmb->num);
+                       return error;
                }
-               pmap_update(pmap_kernel());
-
-               error = privcmd_map_obj(vmm, va0, maddr, pmb->num, pmb->dom);
-               uvm_km_free(kernel_map, trymap, PAGE_SIZE, UVM_KMF_VAONLY);
 
-               if (error != 0)
+               /* Map the memory region directly */
+               error = privcmd_map(pmap, va0, mfn, prot, pmb->num, pmb->dom);
+               if (error) {
+                       kmem_free(mfn, sizeof(u_long) * pmb->num);
                        return error;
+               }
+               copyout(mfn, pmb->arr, sizeof(u_long) * pmb->num);
+               kmem_free(mfn, sizeof(u_long) * pmb->num);
 
                break;
        }
@@ -452,6 +426,24 @@ privcmd_ioctl(void *v)
        return error;
 }
 
+static int privcmd_map(pmap_t pmap, vaddr_t va0, u_long *mfn,
+               vm_prot_t prot, int num, int domid)
+{
+       int i;
+       vaddr_t va;
+       paddr_t ma;
+
+       for(i = 0; i < num; ++i) {
+               va = va0 + (i * PAGE_SIZE);
+               ma = ((paddr_t)mfn[i]) << PGSHIFT;
+               if (pmap_enter_ma(pmap, va, ma, 0, prot, PMAP_CANFAIL, domid))
+                       mfn[i] |= 0xF0000000;
+       }
+       pmap_update(pmap);
+
+       return 0;
+}
+
 static struct uvm_pagerops privpgops = {
   .pgo_reference = privpgop_reference,
   .pgo_detach = privpgop_detach,