[Xen-devel] [PATCH v2 16/23] vixen: pass grant table operations through to the outer Xen

[Anthony Liguori <aliguori@xxxxxxxx>]

From: Anthony Liguori <aliguori@xxxxxxxxxx>

The grant table is a region of guest memory that contains GMFNs
which in PV are MFNs but are PFNs in HVM.  Since a Vixen guest MFN
is an HVM PFN, we can pass this table directly through to the outer
Xen which cuts down considerably on overhead.

We do not forward most of the hypercalls since we only intend on
Vixen to be used for normal guests, not driver domains.

Signed-off-by: Anthony Liguori <aliguori@xxxxxxxxxx>
---
v1 -> v2
 - move to using reserved memory space for grant table instead of heap
 - use a dispatch function instead of modifying all calls
---
 xen/arch/x86/guest/vixen.c |   4 ++
 xen/common/grant_table.c   | 101 +++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 105 insertions(+)

diff --git a/xen/arch/x86/guest/vixen.c b/xen/arch/x86/guest/vixen.c
index 7c886a2..2437c92 100644
--- a/xen/arch/x86/guest/vixen.c
+++ b/xen/arch/x86/guest/vixen.c
@@ -22,10 +22,14 @@
 #include <asm/guest/vixen.h>
 #include <public/version.h>
 #include <public/hvm/hvm_info_table.h>
+#include <xen/grant_table.h>
+
+#define PCI_DEVICE_ID_XENSOURCE_PLATFORM       0x0001
 
 #define X86_HVM_END_SPECIAL_REGION  0xff000u
 
 #define SHARED_INFO_PFN                (X86_HVM_END_SPECIAL_REGION + 0)
+#define GRANT_TABLE_PFN_0      (X86_HVM_END_SPECIAL_REGION + 1)
 
 static int in_vixen;
 static int vixen_domid = 1;
diff --git a/xen/common/grant_table.c b/xen/common/grant_table.c
index 250450b..60a7941 100644
--- a/xen/common/grant_table.c
+++ b/xen/common/grant_table.c
@@ -39,6 +39,7 @@
 #include <xen/vmap.h>
 #include <xsm/xsm.h>
 #include <asm/flushtlb.h>
+#include <asm/guest.h>
 
 /* Per-domain grant information. */
 struct grant_table {
@@ -1801,6 +1802,56 @@ grant_table_init(struct domain *d, struct grant_table 
*gt,
 }
 
 static long
+vixen_gnttab_setup_table(
+    XEN_GUEST_HANDLE_PARAM(gnttab_setup_table_t) uop, unsigned int count)
+{
+    long rc;
+
+    struct gnttab_setup_table op;
+    xen_pfn_t *frame_list = NULL;
+    XEN_GUEST_HANDLE(xen_pfn_t) old_frame_list;
+
+    if ( count != 1 )
+        return -EINVAL;
+
+    if ( unlikely(copy_from_guest(&op, uop, 1) != 0) )
+    {
+        gdprintk(XENLOG_INFO, "Fault while reading gnttab_setup_table_t.\n");
+        return -EFAULT;
+    }
+
+    if ( op.nr_frames > 0 ) {
+        frame_list = xzalloc_array(xen_pfn_t, op.nr_frames);
+        if ( frame_list == NULL )
+            return -ENOMEM;
+    }
+
+    old_frame_list = op.frame_list;
+    op.frame_list.p = frame_list;
+
+    rc = HYPERVISOR_grant_table_op(GNTTABOP_setup_table, &op, count);
+    op.frame_list = old_frame_list;
+
+    if ( rc >= 0 ) {
+        if ( op.status == 0 && op.nr_frames &&
+             copy_to_guest(old_frame_list, frame_list, op.nr_frames) != 0 ) {
+            rc = -EFAULT;
+            goto out;
+        }
+
+        if ( unlikely(copy_to_guest(uop, &op, 1)) != 0 ) {
+            rc = -EFAULT;
+            goto out;
+        }
+    }
+
+ out:
+    xfree(frame_list);
+
+    return rc;
+}
+
+static long
 gnttab_setup_table(
     XEN_GUEST_HANDLE_PARAM(gnttab_setup_table_t) uop, unsigned int count,
     unsigned int limit_max)
@@ -1892,6 +1943,26 @@ gnttab_setup_table(
 }
 
 static long
+vixen_gnttab_query_size(
+    XEN_GUEST_HANDLE_PARAM(gnttab_query_size_t) uop, unsigned int count)
+{
+    struct gnttab_query_size op;
+    int rc;
+
+    if ( count != 1 )
+        return -EINVAL;
+
+    if ( unlikely(copy_from_guest(&op, uop, 1)) != 0)
+        return -EFAULT;
+
+    rc = HYPERVISOR_grant_table_op(GNTTABOP_query_size, &op, count);
+    if (rc == 0 && unlikely(__copy_to_guest(uop, &op, 1)) )
+        rc = -EFAULT;
+
+    return rc;
+}
+
+static long
 gnttab_query_size(
     XEN_GUEST_HANDLE_PARAM(gnttab_query_size_t) uop, unsigned int count)
 {
@@ -3311,6 +3382,33 @@ 
gnttab_cache_flush(XEN_GUEST_HANDLE_PARAM(gnttab_cache_flush_t) uop,
     return 0;
 }
 
+static long
+vixen_do_grant_table_op(
+    unsigned int cmd, XEN_GUEST_HANDLE_PARAM(void) uop, unsigned int count)
+{
+    long rc;
+
+    rc = -EFAULT;
+    switch ( cmd )
+    {
+    case GNTTABOP_setup_table:
+        rc = vixen_gnttab_setup_table(
+            guest_handle_cast(uop, gnttab_setup_table_t), count);
+        break;
+
+    case GNTTABOP_query_size:
+        rc = vixen_gnttab_query_size(
+            guest_handle_cast(uop, gnttab_query_size_t), count);
+        break;
+
+    default:
+        rc = -ENOSYS;
+        break;
+    }
+
+    return rc;
+ }
+
 long
 do_grant_table_op(
     unsigned int cmd, XEN_GUEST_HANDLE_PARAM(void) uop, unsigned int count)
@@ -3324,6 +3422,9 @@ do_grant_table_op(
     if ( (cmd &= GNTTABOP_CMD_MASK) != GNTTABOP_cache_flush && opaque_in )
         return -EINVAL;
 
+    if ( is_vixen() )
+        return vixen_do_grant_table_op(cmd, uop, count);
+
     rc = -EFAULT;
     switch ( cmd )
     {
-- 
1.9.1


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