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authorOliver Upton <oliver.upton@linux.dev>2024-12-20 01:41:14 +0300
committerMarc Zyngier <maz@kernel.org>2024-12-20 12:04:14 +0300
commit8c02c2bbd64375e603df79449f0eb2c57e1a597c (patch)
tree37c3a89ba887f1ee2e740c5fd716e40ead2e7797 /arch/arm64/kvm
parentb0ee51033ae35461ae98c465426f0002b8370679 (diff)
downloadlinux-8c02c2bbd64375e603df79449f0eb2c57e1a597c.tar.xz
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>
Diffstat (limited to 'arch/arm64/kvm')
-rw-r--r--arch/arm64/kvm/debug.c3
-rw-r--r--arch/arm64/kvm/hyp/include/hyp/debug-sr.h17
2 files changed, 7 insertions, 13 deletions
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);