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(a)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(a)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