is_host_cpu_intel() should return TRUE if the host cpu in Intel based, otherwise
it should return FALSE. Currently, it returns zero (FALSE) when the host CPU
is INTEL and non-zero otherwise. Fix the function so that it agrees more with
the semantics. Adjust the calling logic accordingly. RAPL needs Intel host cpus.
If the host CPU is not Intel baseed, we should report error.
Signed-off-by: Ani Sinha <anisinha@redhat.com>
Link: https://lore.kernel.org/r/20240903080004.33746-1-anisinha@redhat.com
[While touching the code remove too many spaces from the second part of the
error. - Paolo]
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Fix leaking memory of file handle in case of error
Erase unused "pid = -1"
Add clearer error_report
Should fix Coverity CID 1558557.
Signed-off-by: Anthony Harivel <aharivel@redhat.com>
Link: https://lore.kernel.org/r/20240726102632.1324432-3-aharivel@redhat.com
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Starting with the "Sandy Bridge" generation, Intel CPUs provide a RAPL
interface (Running Average Power Limit) for advertising the accumulated
energy consumption of various power domains (e.g. CPU packages, DRAM,
etc.).
The consumption is reported via MSRs (model specific registers) like
MSR_PKG_ENERGY_STATUS for the CPU package power domain. These MSRs are
64 bits registers that represent the accumulated energy consumption in
micro Joules. They are updated by microcode every ~1ms.
For now, KVM always returns 0 when the guest requests the value of
these MSRs. Use the KVM MSR filtering mechanism to allow QEMU handle
these MSRs dynamically in userspace.
To limit the amount of system calls for every MSR call, create a new
thread in QEMU that updates the "virtual" MSR values asynchronously.
Each vCPU has its own vMSR to reflect the independence of vCPUs. The
thread updates the vMSR values with the ratio of energy consumed of
the whole physical CPU package the vCPU thread runs on and the
thread's utime and stime values.
All other non-vCPU threads are also taken into account. Their energy
consumption is evenly distributed among all vCPUs threads running on
the same physical CPU package.
To overcome the problem that reading the RAPL MSR requires priviliged
access, a socket communication between QEMU and the qemu-vmsr-helper is
mandatory. You can specified the socket path in the parameter.
This feature is activated with -accel kvm,rapl=true,path=/path/sock.sock
Actual limitation:
- Works only on Intel host CPU because AMD CPUs are using different MSR
adresses.
- Only the Package Power-Plane (MSR_PKG_ENERGY_STATUS) is reported at
the moment.
Signed-off-by: Anthony Harivel <aharivel@redhat.com>
Link: https://lore.kernel.org/r/20240522153453.1230389-4-aharivel@redhat.com
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
