On Thu, Jan 04, 2018 at 16:15:46 +0100, Peter Krempa wrote:
> On Thu, Jan 04, 2018 at 15:58:09 +0100, Jiri Denemark wrote:
> > From: Paolo Bonzini <pbonzini@xxxxxxxxxx>
> >
> > 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@xxxxxxxxxx>
> > Signed-off-by: Jiri Denemark <jdenemar@xxxxxxxxxx>
> > ---
> > 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?
Should be (TM) :-) We're only interested in the first CPU and the
microcode version is printed very early before the endlessly growing
list of CPU features.
>
>
> > + 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.
It's not pointless. It makes the log useful without having to look at
/usr/include/asm-generic/errno-base.h. And it will only be done once in
libvirtd lifetime so it's not really wasting CPU cycles or something.
Jirka
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