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H A Dpmu_counters_test.cdiff 08a828249b16f69248652937be7f1b8dab340a22 Sat Mar 09 02:36:41 CET 2024 Sean Christopherson <seanjc@google.com> KVM: selftests: Verify post-RESET value of PERF_GLOBAL_CTRL in PMCs test

Add a guest assert in the PMU counters test to verify that KVM stuffs
the vCPU's post-RESET value to globally enable all general purpose
counters. Per Intel's SDM,

IA32_PERF_GLOBAL_CTRL: Sets bits n-1:0 and clears the upper bits.

and

Where "n" is the number of general-purpose counters available in
the processor.

For the edge case where there are zero GP counters, follow the spirit
of the architecture, not the SDM's literal wording, which doesn't account
for this possibility and would require the CPU to set _all_ bits in
PERF_GLOBAL_CTRL.

Reviewed-by: Dapeng Mi <dapeng1.mi@linux.intel.com>
Tested-by: Dapeng Mi <dapeng1.mi@linux.intel.com>
Link: https://lore.kernel.org/r/20240309013641.1413400-3-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>