Re: [libvirt] [PATCH 2/5] util: introduce virHostCPUGetMicrocodeVersion

On Thu, Jan 04, 2018 at 15:58:09 +0100, Jiri Denemark wrote: > From: Paolo Bonzini <pbonzini(a)redhat.com&gt; > > This new API reads host's CPU microcode version from /proc/cpuinfo. > > Unfortunately, there is no other way of reading microcode version which > would be usable from both system and session daemon. > > Signed-off-by: Paolo Bonzini <pbonzini(a)redhat.com&gt; > Signed-off-by: Jiri Denemark <jdenemar(a)redhat.com&gt; > --- > src/libvirt_private.syms | 1 + > src/util/virhostcpu.c | 43 +++++++++++++++++++++++++++++++++++++++++++ > src/util/virhostcpu.h | 2 ++ > 3 files changed, 46 insertions(+) > > diff --git a/src/libvirt_private.syms b/src/libvirt_private.syms > index 8d583e3e74..a705fa846d 100644 > --- a/src/libvirt_private.syms > +++ b/src/libvirt_private.syms > @@ -1869,6 +1869,7 @@ virHostCPUGetCount; > virHostCPUGetInfo; > virHostCPUGetKVMMaxVCPUs; > virHostCPUGetMap; > +virHostCPUGetMicrocodeVersion; > virHostCPUGetOnline; > virHostCPUGetOnlineBitmap; > virHostCPUGetPresentBitmap; > diff --git a/src/util/virhostcpu.c b/src/util/virhostcpu.c > index c485a97211..713fdec553 100644 > --- a/src/util/virhostcpu.c > +++ b/src/util/virhostcpu.c > @@ -1206,3 +1206,46 @@ virHostCPUGetKVMMaxVCPUs(void) > return -1; > } > #endif /* HAVE_LINUX_KVM_H */ > + > + > +#ifdef __linux__ > + > +unsigned int > +virHostCPUGetMicrocodeVersion(void) > +{ > + char *outbuf = NULL; > + char *cur; > + unsigned int version = 0; > + > + if (virFileReadHeaderQuiet(CPUINFO_PATH, 4096, &outbuf) < 0) { In other places we read 1MiB of /proc/cpuinfo: src/util/virsysinfo.c:#define CPUINFO_FILE_LEN (1024*1024) /* 1MB limit for /proc/cpuinfo file */ Will this be enough?

> + char ebuf[1024]; > + VIR_DEBUG("Failed to read microcode version from %s: %s", > + CPUINFO_PATH, virStrerror(errno, ebuf, sizeof(ebuf))); Formatting the error message into a debug message does not make much sense. I'd just log 'errno' in raw since this function does not really return any errors.

ACK with pointless error formatting removed.