KVM legacy LBR patches have been merged in kernel 5.12, this patchset
is to expose the feature to guest from the perf capability MSR. Qemu can
add LBR format in cpu option to achieve it, e.g., -cpu host,lbr-fmt=0x5,
the format should match host value in IA32_PERF_CAPABILITIES.
Note, KVM legacy LBR solution accelerates guest perf performace by LBR MSR
passthrough so it requires guest cpu model matches that of host's, i.e.,
only -cpu host is supported.
Change in v5:
1. This patchset is rebased on tip : 6621441db5
2. No functional change since v4.
Yang Weijiang (2):
qdev-properties: Add a new macro with bitmask check for uint64_t
property
target/i386: Add lbr-fmt vPMU option to support guest LBR
hw/core/qdev-properties.c | 19 +++++++++++++++++
include/hw/qdev-properties.h | 12 +++++++++++
target/i386/cpu.c | 40 ++++++++++++++++++++++++++++++++++++
target/i386/cpu.h | 10 +++++++++
4 files changed, 81 insertions(+)
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2.27.0
