[Xen-devel] [PATCH] Qemu: Add sanity check for vcpu config

["Liu, Jinsong" <jinsong.liu@xxxxxxxxx>]

>From 4d483620c863f626543fdc407c2951ceef49623e Mon Sep 17 00:00:00 2001
From: Liu, Jinsong <jinsong.liu@xxxxxxxxx>
Date: Sun, 21 Mar 2010 22:48:04 +0800
Subject: [PATCH] Qemu: Add sanity check for vcpu config

Currently Xen/Qemu support max 128 vcpus. To avoid mis-setting
at config file, this patch add sanity check for vcpu config.
1. maxvcpus and vcpus should no more than HVM_MAX_VCPUS (128)
2. vcpus should no more than maxvcpus.

Signed-off-by: Liu, Jinsong <jinsong.liu@xxxxxxxxx>
---
 vl.c |   30 ++++++++++++++++++++++++++++++
 1 files changed, 30 insertions(+), 0 deletions(-)

diff --git a/vl.c b/vl.c
index 30debd7..d69d90c 100644
--- a/vl.c
+++ b/vl.c
@@ -4706,6 +4706,34 @@ static void termsig_setup(void)
 
 #endif
 
+/* 32bit Hamming weight */
+unsigned int hweight32(unsigned int w)
+{
+       unsigned int res = w - ((w >> 1) & 0x55555555);
+       res = (res & 0x33333333) + ((res >> 2) & 0x33333333);
+       res = (res + (res >> 4)) & 0x0F0F0F0F;
+       res = res + (res >> 8);
+       return (res + (res >> 16)) & 0x000000FF;
+}
+
+static void vcpu_sanity_check(void)
+{
+    int i, vcpu_avail_weight = 0;
+
+    for (i=0; i<((HVM_MAX_VCPUS + 31)/32); i++)
+        vcpu_avail_weight += hweight32(vcpu_avail[i]);
+
+    if (vcpus > HVM_MAX_VCPUS) {
+        fprintf(stderr, "maxvcpus and vcpus should not more than %d\n",
+                         HVM_MAX_VCPUS);
+        exit(EXIT_FAILURE);
+    }
+    if (vcpu_avail_weight > vcpus) {
+        fprintf(stderr, "vcpus should not more than maxvcpus\n");
+        exit(EXIT_FAILURE);
+    }
+}
+
 #define STEP   8   /* 8 characters fill uint32_t bitmap */
 #define SPACE  8   /* space for non-hex characters in vcpu str */
 #define MAX_VCPU_STR_LEN    ((HVM_MAX_VCPUS + 3)/4 + SPACE)
@@ -5569,6 +5597,8 @@ int main(int argc, char **argv, char **envp)
         exit(1);
     }
 
+    vcpu_sanity_check();
+
     if (nographic) {
        if (serial_device_index == 0)
            serial_devices[0] = "stdio";
-- 
1.5.6.4

Attachment: qemu-vcpu-sanity-check.patch
Description: qemu-vcpu-sanity-check.patch

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