[PATCH 3/7] virHostCPUGetCPUID: Add comment on how KVM_GET_SUPPORTED_CPUID works

The commit adding the code fetching host CPU flags via the KVM_GET_SUPPORTED_CPUID didn't describe at all why such an alghorithm is needed. Add a comment from the documentation outlining how the userspace function is expected to allocate memory here. Signed-off-by: Peter Krempa <pkrempa(a)redhat.com&gt; --- src/util/virhostcpu.c | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/src/util/virhostcpu.c b/src/util/virhostcpu.c index 011ef8a153..6be00a5b76 100644 --- a/src/util/virhostcpu.c +++ b/src/util/virhostcpu.c @@ -1327,6 +1327,13 @@ virHostCPUGetCPUID(void) return NULL; } + /* Userspace invokes KVM_GET_SUPPORTED_CPUID by passing a kvm_cpuid2 structure + * with the 'nent' field indicating the number of entries in the variable-size + * array 'entries'. If the number of entries is too low to describe the cpu + * capabilities, an error (E2BIG) is returned. If the number is too high, + * the 'nent' field is adjusted and an error (ENOMEM) is returned. If the + * number is just right, the 'nent' field is adjusted to the number of valid + * entries in the 'entries' array, which is then filled. */ for (i = 1; i < INT32_MAX; i *= 2) { g_autofree struct kvm_cpuid2 *kvm_cpuid = NULL; kvm_cpuid = g_malloc0(sizeof(struct kvm_cpuid2) + -- 2.35.1