diff options
| author | Oliver Upton <oliver.upton@linux.dev> | 2024-12-19 14:41:14 -0800 |
|---|---|---|
| committer | Marc Zyngier <maz@kernel.org> | 2024-12-20 09:04:14 +0000 |
| commit | 8c02c2bbd64375e603df79449f0eb2c57e1a597c (patch) | |
| tree | 37c3a89ba887f1ee2e740c5fd716e40ead2e7797 | |
| parent | b0ee51033ae35461ae98c465426f0002b8370679 (diff) | |
KVM: arm64: Avoid reading ID_AA64DFR0_EL1 for debug save/restore
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>
| -rw-r--r-- | arch/arm64/include/asm/kvm_host.h | 4 | ||||
| -rw-r--r-- | arch/arm64/kvm/debug.c | 3 | ||||
| -rw-r--r-- | arch/arm64/kvm/hyp/include/hyp/debug-sr.h | 17 |
3 files changed, 11 insertions, 13 deletions
diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h index d48516de778d..e7c740c99ee3 100644 --- a/arch/arm64/include/asm/kvm_host.h +++ b/arch/arm64/include/asm/kvm_host.h @@ -661,6 +661,10 @@ struct kvm_host_data { /* Number of programmable event counters (PMCR_EL0.N) for this CPU */ unsigned int nr_event_counters; + + /* Number of debug breakpoints/watchpoints for this CPU (minus 1) */ + unsigned int debug_brps; + unsigned int debug_wrps; }; struct kvm_host_psci_config { diff --git a/arch/arm64/kvm/debug.c b/arch/arm64/kvm/debug.c index 7d3c71d65518..d921e7f7bd59 100644 --- a/arch/arm64/kvm/debug.c +++ b/arch/arm64/kvm/debug.c @@ -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; diff --git a/arch/arm64/kvm/hyp/include/hyp/debug-sr.h b/arch/arm64/kvm/hyp/include/hyp/debug-sr.h index c14586d87361..502a5b73ee70 100644 --- a/arch/arm64/kvm/hyp/include/hyp/debug-sr.h +++ b/arch/arm64/kvm/hyp/include/hyp/debug-sr.h @@ -106,12 +106,8 @@ static struct kvm_guest_debug_arch *__vcpu_debug_regs(struct kvm_vcpu *vcpu) static void __debug_save_state(struct kvm_guest_debug_arch *dbg, struct kvm_cpu_context *ctxt) { - u64 aa64dfr0; - int brps, wrps; - - aa64dfr0 = read_sysreg(id_aa64dfr0_el1); - brps = (aa64dfr0 >> 12) & 0xf; - wrps = (aa64dfr0 >> 20) & 0xf; + int brps = *host_data_ptr(debug_brps); + int wrps = *host_data_ptr(debug_wrps); save_debug(dbg->dbg_bcr, dbgbcr, brps); save_debug(dbg->dbg_bvr, dbgbvr, brps); @@ -124,13 +120,8 @@ static void __debug_save_state(struct kvm_guest_debug_arch *dbg, static void __debug_restore_state(struct kvm_guest_debug_arch *dbg, struct kvm_cpu_context *ctxt) { - u64 aa64dfr0; - int brps, wrps; - - aa64dfr0 = read_sysreg(id_aa64dfr0_el1); - - brps = (aa64dfr0 >> 12) & 0xf; - wrps = (aa64dfr0 >> 20) & 0xf; + int brps = *host_data_ptr(debug_brps); + int wrps = *host_data_ptr(debug_wrps); restore_debug(dbg->dbg_bcr, dbgbcr, brps); restore_debug(dbg->dbg_bvr, dbgbvr, brps); |