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KVM: arm64: Avoid reading ID_AA64DFR0_EL1 for debug save/restore

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Similar to other per-CPU profiling/debug features we handle, store the
number of breakpoints/watchpoints in kvm_host_data to avoid reading the
ID register 4 times on every guest entry/exit. And if you're in the
nested virt business that's quite a few avoidable exits to the L0
hypervisor.

Tested-by: James Clark <james.clark@linaro.org>
Signed-off-by: Oliver Upton <oliver.upton@linux.dev>
Link: https://lore.kernel.org/r/20241219224116.3941496-18-oliver.upton@linux.dev
Signed-off-by: Marc Zyngier <maz@kernel.org>
This commit is contained in:
Oliver Upton
2024-12-19 14:41:14 -08:00
committed by Marc Zyngier
parent b0ee51033a
commit 8c02c2bbd6
3 changed files with 11 additions and 13 deletions
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3
arch/arm64/kvm/debug.c
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@@ -71,6 +71,9 @@ void kvm_init_host_debug_data(void)
*host_data_ptr(nr_event_counters) = FIELD_GET(ARMV8_PMU_PMCR_N,
read_sysreg(pmcr_el0));
*host_data_ptr(debug_brps) = SYS_FIELD_GET(ID_AA64DFR0_EL1, BRPs, dfr0);
*host_data_ptr(debug_wrps) = SYS_FIELD_GET(ID_AA64DFR0_EL1, WRPs, dfr0);
if (has_vhe())
return;