[Xen-devel] [PATCH v3 3/7] libxl: In libxl_set_vcpuonline check for maximum number of VCPUs against the cpumap.

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

There is no sense in trying to online (or offline) CPUs when the size of
cpumap is greater than the maximum number of VCPUs the guest can go to.

As such fail the operation if the count of CPUs to online is greater
than what the guest started with. For the offline case we do not
check (as the bits are unset in the cpumap) and let it go through.

Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
---
 tools/libxl/libxl.c | 27 ++++++++++++++++++++++++---
 1 file changed, 24 insertions(+), 3 deletions(-)

diff --git a/tools/libxl/libxl.c b/tools/libxl/libxl.c
index 4152ee4..d2b5ff3 100644
--- a/tools/libxl/libxl.c
+++ b/tools/libxl/libxl.c
@@ -5449,6 +5449,20 @@ int libxl_domain_get_nodeaffinity(libxl_ctx *ctx, 
uint32_t domid,
     return 0;
 }
 
+static int libxl__check_max(libxl__gc *gc, libxl_dominfo *info,
+                            libxl_bitmap *cpumap)
+{
+    int maxcpus = libxl_bitmap_count_set(cpumap);
+
+    if (maxcpus > info->vcpu_max_id + 1)
+    {
+        LOGE(ERROR, "You have a max of %d vCPUs and you want %d vCPUs!",
+             info->vcpu_max_id + 1, maxcpus);
+        return ERROR_FAIL;
+    }
+    return 0;
+}
+
 static int libxl__set_vcpuonline_xenstore(libxl__gc *gc, uint32_t domid,
                                          libxl_bitmap *cpumap)
 {
@@ -5464,6 +5478,9 @@ static int libxl__set_vcpuonline_xenstore(libxl__gc *gc, 
uint32_t domid,
         LOGE(ERROR, "getting domain info list");
         goto out;
     }
+    rc = libxl__check_max(gc, &info, cpumap);
+    if (rc)
+        goto out;
     rc = ERROR_FAIL;
     if (!(dompath = libxl__xs_get_dompath(gc, domid)))
         goto out;
@@ -5495,9 +5512,11 @@ static int libxl__set_vcpuonline_qmp(libxl__gc *gc, 
uint32_t domid,
     rc = libxl_domain_info(CTX, &info, domid);
     if (rc < 0) {
         LOGE(ERROR, "getting domain info list");
-        libxl_dominfo_dispose(&info);
-        return rc;
+        goto out;
     }
+    rc = libxl__check_max(gc, &info, cpumap);
+    if (rc)
+        goto out;
     for (i = 0; i <= info.vcpu_max_id; i++) {
         if (libxl_bitmap_test(cpumap, i)) {
             /* Return value is ignore because it does not tell anything useful
@@ -5508,8 +5527,10 @@ static int libxl__set_vcpuonline_qmp(libxl__gc *gc, 
uint32_t domid,
             libxl__qmp_cpu_add(gc, domid, i);
         }
     }
+    rc = 0;
+out:
     libxl_dominfo_dispose(&info);
-    return 0;
+    return rc;
 }
 
 int libxl_set_vcpuonline(libxl_ctx *ctx, uint32_t domid, libxl_bitmap *cpumap)
-- 
2.1.0


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