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Re: [libvirt] [RFC v3 PATCH 3/5] PowerPC : Add support for ppc64 qemu



Hi Stefan,
Thanks for reviewing the patch.

On 11/29/2011 10:25 PM, Stefan Berger wrote:
On 11/29/2011 09:59 AM, Prerna Saxena wrote:
From: Prerna Saxena<prerna linux vnet ibm com>
Date: Mon, 3 Oct 2011 06:01:33 -0700
Subject: [PATCH 3/5] Add support for ppc64 qemu

This enables libvirt to select the correct qemu binary
(qemu-system-ppc64)
for a guest vm based on arch 'ppc64'.
Also, libvirt is enabled to correctly parse the list of supported PowerPC
CPUs, generated by running 'qemu-system-ppc64 -cpu ?'

Signed-off-by: Prerna Saxena<prerna linux vnet ibm com>
---
src/qemu/qemu_capabilities.c | 64
++++++++++++++++++++++++++++++++++++++++++
1 files changed, 64 insertions(+), 0 deletions(-)

diff --git a/src/qemu/qemu_capabilities.c b/src/qemu/qemu_capabilities.c
index c5fe41d..c2d3d93 100644
--- a/src/qemu/qemu_capabilities.c
+++ b/src/qemu/qemu_capabilities.c
@@ -185,6 +185,7 @@ static const struct qemu_arch_info const
arch_info_hvm[] = {
{ "mipsel", 32, NULL, "qemu-system-mipsel", NULL, NULL, 0 },
{ "sparc", 32, NULL, "qemu-system-sparc", NULL, NULL, 0 },
{ "ppc", 32, NULL, "qemu-system-ppc", NULL, NULL, 0 },
+ { "ppc64", 64, NULL, "qemu-system-ppc64", NULL, NULL, 0 },
{ "itanium", 64, NULL, "qemu-system-ia64", NULL, NULL, 0 },
{ "s390x", 64, NULL, "qemu-system-s390x", NULL, NULL, 0 },
};
@@ -477,6 +478,67 @@ error:
return -1;
}

+/* ppc64 parser.
+ * Format : PowerPC<machine> <description>
+ */
+static int
+qemuCapsParsePPCModels(const char *output,
+ unsigned int *retcount,
+ const char ***retcpus)
+{
+ const char *p = output;
+ const char *next;
+ unsigned int count = 0;
+ const char **cpus = NULL;
+ int i;
+ do {
+ const char *t;
+
+ if ((next = strchr(p, '\n')))
+ next++;
+
+ if (!STRPREFIX(p, "PowerPC "))
+ continue;
If what you are parsing here is indeed corrupted, you may end up in an
endless loop with p not moving anymore. You have to advance 'p' at least
by 1 and have a check before whether *p == '\0' to get out of it. You
may also want to put this check before the calculation of 'next'.

When the execution gets to a 'continue', the do..while loop will resume execution from next iteration after processing the conditional check. In this case, whe condition in 'while' loop is :
while ((p =next))
which automatically advances 'p'.

+
+ /* Skip the preceding sub-string "PowerPC " */
+ p += 8;
+
+ /*Malformed string, does not obey the format 'PowerPC<model> <desc>'*/
+ if (!(t = strchr(p, ' ')) || (next&& t>= next))
+ continue;
+
+ if (*p == '\0' || *p == '\n')
+ continue;
*p = '\0' presumably is end-of-string -- shouldn't we 'break' here ?

Agree. The reason it works fine in its present form is 'cos when p becomes empty, 'next' is empty too, and the loop condition fails which causes the do..while loop to terminate.

+
+ if (retcpus) {
if retcpus is not provided you may want to return -1 earlier
+ unsigned int len;
+
+ if (VIR_REALLOC_N(cpus, count + 1)< 0)
virReportOOMError();
+ goto error;
+
+ if (t)
+ len = t - p - 1;
len would remain uninitialized if t is not set, but t at this point must
be set due to the check above. Remove 'if(t)'.

Will do.

+
+ if (!(cpus[count] = strndup(p, len)))
virReportOOMError();

I need to explicitly free cpus[] array, hence hadnt invoked this routine.
I'll call this just before return '-1'.
+ goto error;
+ }
+ count++;
+ } while ((p = next));
+
+ if (retcount)
+ *retcount = count;
+ if (retcpus)
+ *retcpus = cpus;
+ return 0;
+
+error:
+ if (cpus) {
+ for (i = 0; i< count; i++)
+ VIR_FREE(cpus[i]);
+ }
+ VIR_FREE(cpus);
+ return -1;
+}

int
qemuCapsProbeCPUModels(const char *qemu,
@@ -497,6 +559,8 @@ qemuCapsProbeCPUModels(const char *qemu,

if (STREQ(arch, "i686") || STREQ(arch, "x86_64"))
parse = qemuCapsParseX86Models;
+ else if (STREQ(arch, "ppc64"))
+ parse = qemuCapsParsePPCModels;
else {
VIR_DEBUG("don't know how to parse %s CPU models", arch);
return 0;



--
Prerna Saxena

Linux Technology Centre,
IBM Systems and Technology Lab,
Bangalore, India


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