[Xen-devel] [PATCH v2 4/6] xen: use errno instead of rc for xc_domain_add_to_physmap

[Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>]

In Xen 4.6 commit cd2f100f0f61b3f333d52d1737dd73f02daee592
"libxc: Fix do_memory_op to return negative value on errors"
made the libxc API less odd-ball: On errors, return value is
-1 and error code is in errno. On success the return value
is either 0 or an positive value.

Since we could be running with an old toolstack in which the
Exx value is in rc or the newer, we add an wrapper around
the xc_domain_add_to_physmap (called xen_xc_domain_add_to_physmap)
which will always return the EXX.

Xen 4.6 did not change the libxc functions mentioned (same parameters)
so we piggyback on the fact that Xen 4.6 has a new function:
commit 504ed2053362381ac01b98db9313454488b7db40 "tools/libxc: Expose
new hypercall xc_reserved_device_memory_map" and check for that.

Suggested-by: Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
Reviewed-by: Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>
---
 configure                   | 26 ++++++++++++++++++++++++++
 include/hw/xen/xen_common.h | 22 ++++++++++++++++++++++
 xen-hvm.c                   |  4 ++--
 3 files changed, 50 insertions(+), 2 deletions(-)

diff --git a/configure b/configure
index d854936..f162025 100755
--- a/configure
+++ b/configure
@@ -1889,6 +1889,32 @@ int main(void) {
   xc_gnttab_open(NULL, 0);
   xc_domain_add_to_physmap(0, 0, XENMAPSPACE_gmfn, 0, 0);
   xc_hvm_inject_msi(xc, 0, 0xf0000000, 0x00000000);
+  xc_reserved_device_memory_map(xc, 0, 0, 0, 0, NULL, 0);
+  return 0;
+}
+EOF
+      compile_prog "" "$xen_libs"
+    then
+    xen_ctrl_version=460
+    xen=yes
+
+  elif
+      cat > $TMPC <<EOF &&
+#include <xenctrl.h>
+#include <xenstore.h>
+#include <stdint.h>
+#include <xen/hvm/hvm_info_table.h>
+#if !defined(HVM_MAX_VCPUS)
+# error HVM_MAX_VCPUS not defined
+#endif
+int main(void) {
+  xc_interface *xc;
+  xs_daemon_open();
+  xc = xc_interface_open(0, 0, 0);
+  xc_hvm_set_mem_type(0, 0, HVMMEM_ram_ro, 0, 0);
+  xc_gnttab_open(NULL, 0);
+  xc_domain_add_to_physmap(0, 0, XENMAPSPACE_gmfn, 0, 0);
+  xc_hvm_inject_msi(xc, 0, 0xf0000000, 0x00000000);
   xc_hvm_create_ioreq_server(xc, 0, 0, NULL);
   return 0;
 }
diff --git a/include/hw/xen/xen_common.h b/include/hw/xen/xen_common.h
index ed5fd3e..3cd5875 100644
--- a/include/hw/xen/xen_common.h
+++ b/include/hw/xen/xen_common.h
@@ -407,4 +407,26 @@ static inline int xen_set_ioreq_server_state(XenXC xc, 
domid_t dom,
 
 #endif
 
+#if CONFIG_XEN_CTRL_INTERFACE_VERSION < 460
+static inline int xen_xc_domain_add_to_physmap(XenXC xch, uint32_t domid,
+                                               unsigned int space,
+                                               unsigned long idx,
+                                               xen_pfn_t gpfn)
+{
+    return xc_domain_add_to_physmap(xch, domid, space, idx, gpfn);
+}
+#else
+static inline int xen_xc_domain_add_to_physmap(XenXC xch, uint32_t domid,
+                                               unsigned int space,
+                                               unsigned long idx,
+                                               xen_pfn_t gpfn)
+{
+    /* In Xen 4.6 rc is -1 and errno contains the error value. */
+    int rc = xc_domain_add_to_physmap(xch, domid, space, idx, gpfn);
+    if (rc == -1)
+        return errno;
+    return rc;
+}
+#endif
+
 #endif /* QEMU_HW_XEN_COMMON_H */
diff --git a/xen-hvm.c b/xen-hvm.c
index 0408462..fae2d22 100644
--- a/xen-hvm.c
+++ b/xen-hvm.c
@@ -345,7 +345,7 @@ go_physmap:
         unsigned long idx = pfn + i;
         xen_pfn_t gpfn = start_gpfn + i;
 
-        rc = xc_domain_add_to_physmap(xen_xc, xen_domid, XENMAPSPACE_gmfn, 
idx, gpfn);
+        rc = xen_xc_domain_add_to_physmap(xen_xc, xen_domid, XENMAPSPACE_gmfn, 
idx, gpfn);
         if (rc) {
             DPRINTF("add_to_physmap MFN %"PRI_xen_pfn" to PFN %"
                     PRI_xen_pfn" failed: %d\n", idx, gpfn, rc);
@@ -422,7 +422,7 @@ static int xen_remove_from_physmap(XenIOState *state,
         xen_pfn_t idx = start_addr + i;
         xen_pfn_t gpfn = phys_offset + i;
 
-        rc = xc_domain_add_to_physmap(xen_xc, xen_domid, XENMAPSPACE_gmfn, 
idx, gpfn);
+        rc = xen_xc_domain_add_to_physmap(xen_xc, xen_domid, XENMAPSPACE_gmfn, 
idx, gpfn);
         if (rc) {
             fprintf(stderr, "add_to_physmap MFN %"PRI_xen_pfn" to PFN %"
                     PRI_xen_pfn" failed: %d\n", idx, gpfn, rc);
-- 
2.1.0


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