Merge tag 'for-upstream' of https://gitlab.com/bonzini/qemu into staging

* target/i386/kvm: support for reading RAPL MSRs using a helper program
* hpet: emulation improvements

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Merge tag 'for-upstream' of https://gitlab.com/bonzini/qemu into staging

* target/i386/kvm: support for reading RAPL MSRs using a helper program
* hpet: emulation improvements

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# gpg: Signature made Tue 23 Jul 2024 03:19:58 AM AEST
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# gpg: Good signature from "Paolo Bonzini <bonzini@gnu.org>" [full]
# gpg: aka "Paolo Bonzini <pbonzini@redhat.com>" [full]

* tag 'for-upstream' of https://gitlab.com/bonzini/qemu:
hpet: avoid timer storms on periodic timers
hpet: store full 64-bit target value of the counter
hpet: accept 64-bit reads and writes
hpet: place read-only bits directly in "new_val"
hpet: remove unnecessary variable "index"
hpet: ignore high bits of comparator in 32-bit mode
hpet: fix and cleanup persistence of interrupt status
Add support for RAPL MSRs in KVM/Qemu
tools: build qemu-vmsr-helper
qio: add support for SO_PEERCRED for socket channel
target/i386: do not crash if microvm guest uses SGX CPUID leaves

Signed-off-by: Richard Henderson <richard.henderson@linaro.org>

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Add support for RAPL MSRs in KVM/Qemu

Starting with the "Sandy Bridge" generation, Intel CPUs provide a RAPL
interface (Running Average Power Limit) for advertising the accumulated
energy consumptio

Add support for RAPL MSRs in KVM/Qemu

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>

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