[Xen-devel] [PATCH 12/16] tools: introduce a new parameter to set a predefined rdm boundary

[Ian Jackson <ian.jackson@xxxxxxxxxxxxx>]

From: Tiejun Chen <tiejun.chen@xxxxxxxxx>

Previously we always fix that predefined boundary as 2G to handle
conflict between memory and rdm, but now this predefined boundar
can be changes with the parameter "rdm_mem_boundary" in .cfg file.

CC: Ian Jackson <ian.jackson@xxxxxxxxxxxxx>
CC: Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>
CC: Ian Campbell <ian.campbell@xxxxxxxxxx>
CC: Wei Liu <wei.liu2@xxxxxxxxxx>
Signed-off-by: Tiejun Chen <tiejun.chen@xxxxxxxxx>
Acked-by: Wei Liu <wei.liu2@xxxxxxxxxx>
Acked-by: Ian Jackson <ian.jackson@xxxxxxxxxxxxx>
Checked-by: Ian Jackson <ian.jackson@xxxxxxxxxxxxx>
---
 docs/man/xl.cfg.pod.5       |   22 ++++++++++++++++++++++
 tools/libxl/libxl.h         |    6 ++++++
 tools/libxl/libxl_create.c  |    4 ++++
 tools/libxl/libxl_dom.c     |    8 +-------
 tools/libxl/libxl_types.idl |    1 +
 tools/libxl/xl_cmdimpl.c    |    3 +++
 6 files changed, 37 insertions(+), 7 deletions(-)

diff --git a/docs/man/xl.cfg.pod.5 b/docs/man/xl.cfg.pod.5
index e6e0f70..ce7ce85 100644
--- a/docs/man/xl.cfg.pod.5
+++ b/docs/man/xl.cfg.pod.5
@@ -845,6 +845,28 @@ More information about Xen gfx_passthru feature is 
available
 on the XenVGAPassthrough L<http://wiki.xen.org/wiki/XenVGAPassthrough>
 wiki page.
 
+=item B<rdm_mem_boundary=MBYTES>
+
+Number of megabytes to set a boundary for checking rdm conflict.
+
+When RDM conflicts with RAM, RDM probably scatter the whole RAM space.
+Especially multiple RDM entries would worsen this to lead a complicated
+memory layout. So here we're trying to figure out a simple solution to
+avoid breaking existing layout. So when a conflict occurs,
+
+    #1. Above a predefined boundary
+        - move lowmem_end below reserved region to solve conflict;
+
+    #2. Below a predefined boundary
+        - Check strict/relaxed policy.
+        "strict" policy leads to fail libxl. Note when both policies
+        are specified on a given region, 'strict' is always preferred.
+        "relaxed" policy issue a warning message and also mask this
+        entry INVALID to indicate we shouldn't expose this entry to
+        hvmloader.
+
+Here the default is 2G.
+
 =item B<dtdev=[ "DTDEV_PATH", "DTDEV_PATH", ... ]>
 
 Specifies the host device tree nodes to passthrough to this guest. Each
diff --git a/tools/libxl/libxl.h b/tools/libxl/libxl.h
index 5a7308d..927b2d8 100644
--- a/tools/libxl/libxl.h
+++ b/tools/libxl/libxl.h
@@ -909,6 +909,12 @@ const char *libxl_defbool_to_string(libxl_defbool b);
 #define LIBXL_TIMER_MODE_DEFAULT -1
 #define LIBXL_MEMKB_DEFAULT ~0ULL
 
+/*
+ * We'd like to set a memory boundary to determine if we need to check
+ * any overlap with reserved device memory.
+ */
+#define LIBXL_RDM_MEM_BOUNDARY_MEMKB_DEFAULT (2048 * 1024)
+
 #define LIBXL_MS_VM_GENID_LEN 16
 typedef struct {
     uint8_t bytes[LIBXL_MS_VM_GENID_LEN];
diff --git a/tools/libxl/libxl_create.c b/tools/libxl/libxl_create.c
index 5b57062..b27c53a 100644
--- a/tools/libxl/libxl_create.c
+++ b/tools/libxl/libxl_create.c
@@ -54,6 +54,10 @@ void libxl__rdm_setdefault(libxl__gc *gc, 
libxl_domain_build_info *b_info)
 {
     if (b_info->u.hvm.rdm.policy == LIBXL_RDM_RESERVE_POLICY_INVALID)
         b_info->u.hvm.rdm.policy = LIBXL_RDM_RESERVE_POLICY_RELAXED;
+
+    if (b_info->u.hvm.rdm_mem_boundary_memkb == LIBXL_MEMKB_DEFAULT)
+        b_info->u.hvm.rdm_mem_boundary_memkb =
+                            LIBXL_RDM_MEM_BOUNDARY_MEMKB_DEFAULT;
 }
 
 int libxl__domain_build_info_setdefault(libxl__gc *gc,
diff --git a/tools/libxl/libxl_dom.c b/tools/libxl/libxl_dom.c
index 9af3b21..0b7c39d 100644
--- a/tools/libxl/libxl_dom.c
+++ b/tools/libxl/libxl_dom.c
@@ -930,12 +930,6 @@ int libxl__build_hvm(libxl__gc *gc, uint32_t domid,
     int ret, rc = ERROR_FAIL;
     uint64_t mmio_start, lowmem_end, highmem_end;
     libxl_domain_build_info *const info = &d_config->b_info;
-    /*
-     * Currently we fix this as 2G to guarantee how to handle
-     * our rdm policy. But we'll provide a parameter to set
-     * this dynamically.
-     */
-    uint64_t rdm_mem_boundary = 0x80000000;
 
     memset(&args, 0, sizeof(struct xc_hvm_build_args));
     /* The params from the configuration file are in Mb, which are then
@@ -974,7 +968,7 @@ int libxl__build_hvm(libxl__gc *gc, uint32_t domid,
     args.mmio_start = mmio_start;
 
     rc = libxl__domain_device_construct_rdm(gc, d_config,
-                                            rdm_mem_boundary,
+                                            
info->u.hvm.rdm_mem_boundary_memkb*1024,
                                             &args);
     if (rc) {
         LOG(ERROR, "checking reserved device memory failed");
diff --git a/tools/libxl/libxl_types.idl b/tools/libxl/libxl_types.idl
index 157fa59..9caaf44 100644
--- a/tools/libxl/libxl_types.idl
+++ b/tools/libxl/libxl_types.idl
@@ -503,6 +503,7 @@ libxl_domain_build_info = Struct("domain_build_info",[
                                        ("ms_vm_genid",      libxl_ms_vm_genid),
                                        ("serial_list",      libxl_string_list),
                                        ("rdm", libxl_rdm_reserve),
+                                       ("rdm_mem_boundary_memkb", MemKB),
                                        ])),
                  ("pv", Struct(None, [("kernel", string),
                                       ("slack_memkb", MemKB),
diff --git a/tools/libxl/xl_cmdimpl.c b/tools/libxl/xl_cmdimpl.c
index 5c6d1b0..615b78b 100644
--- a/tools/libxl/xl_cmdimpl.c
+++ b/tools/libxl/xl_cmdimpl.c
@@ -1581,6 +1581,9 @@ static void parse_config_data(const char *config_source,
                     exit(1);
             }
         }
+
+        if (!xlu_cfg_get_long (config, "rdm_mem_boundary", &l, 0))
+            b_info->u.hvm.rdm_mem_boundary_memkb = l * 1024;
         break;
     case LIBXL_DOMAIN_TYPE_PV:
     {
-- 
1.7.10.4


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