Currently we give all the v7-and-up CPUs a PMU with 4 counters. This
means that we don't provide the 6 counters that are required by the
Arm BSA (Base System Architecture) specification if the CPU supports
the Virtualization extensions.
Instead of having a single PMCR_NUM_COUNTERS, make each CPU type
specify the PMCR reset value (obtained from the appropriate TRM), and
use the 'N' field of that value to define the number of counters
provided.
This means that we now supply 6 counters instead of 4 for:
Cortex-A9, Cortex-A15, Cortex-A53, Cortex-A57, Cortex-A72,
Cortex-A76, Neoverse-N1, '-cpu max'
These CPUs remain with 4 counters:
Cortex-A7, Cortex-A8
This CPU goes down from 4 to 3 counters:
Cortex-R5
TODO: A64FX -- I don't know the correct PMCR_EL0 reset value.
Note that because we now use the PMCR reset value of the specific
implementation, we no longer set the LC bit out of reset. This has
an UNKNOWN value out of reset for all cores with any AArch32 support,
so guest software should be setting it anyway if it wants it.
This change was originally landed in commit f7fb73b8cdd3f7 (during
the 6.0 release cycle) but was then reverted by commit
21c2dd77a6aa517 before that release because it did not work with KVM.
This version fixes that by creating the scratch vCPU in
kvm_arm_get_host_cpu_features() with the KVM_ARM_VCPU_PMU_V3 feature
if KVM supports it, and then only asking KVM for the PMCR_EL0 value
if the vCPU has a PMU.
Signed-off-by: Peter Maydell<peter.maydell@linaro.org>
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I'd forgotten that we'd dropped this fix in the 6.0 timeframe
and never picked it back up again until Alex reminded me of it...
Changes since original attempt:
-- rebased
-- fix the code in kvm_arm_get_host_cpu_features() that reads PMCR_EL0
-- set PMCR value for new CPUs cortex-a76, neoverse-n1
-- set PMCR value for now-separated-out aarch32 -cpu max
-- TODO comment for a64fx
Shuuichirou, Itaru: this is another patch where we need to know
an A64FX register value...
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