@@ -17,6 +17,8 @@
#include <linux/kvm_host.h>
#include <linux/trace_events.h>
+#include <asm/kvm_emulate.h>
+
typedef int (*perf_trace_callback_fn)(struct kvm *kvm, bool enable);
struct kvm_trace_hook {
@@ -24,7 +26,37 @@ struct kvm_trace_hook {
perf_trace_callback_fn setup_fn;
};
+static int tlb_invalidate_trap(struct kvm *kvm, bool enable)
+{
+ int i;
+ struct kvm_vcpu *vcpu;
+
+ /*
+ * Halt the VM to ensure atomic update across all vcpus (this
+ * avoids racy behaviour against other modifications of
+ * HCR_EL2 such as kvm_toggle_cache/kvm_set_way_flush).
+ */
+ kvm_arm_halt_guest(kvm);
+ kvm_for_each_vcpu(i, vcpu, kvm) {
+ unsigned long hcr = vcpu_get_hcr(vcpu);
+
+ if (enable)
+ hcr |= HCR_TTLB;
+ else
+ hcr &= ~HCR_TTLB;
+
+ vcpu_set_hcr(vcpu, hcr);
+ }
+ kvm_arm_resume_guest(kvm);
+
+ return 0;
+}
+
static struct kvm_trace_hook trace_hook[] = {
+ {
+ .key = "kvm_tlb_invalidate",
+ .setup_fn = tlb_invalidate_trap,
+ },
{ },
};
The TTLB bit of Hypervisor Control Register controls the trapping of guest TLB maintenance instructions. Taking the trap requires a switch to the hypervisor and is an expensive operation. Enable selective trapping of guest TLB instructions when the associated perf trace event is enabled for a specific virtual machine. Signed-off-by: Punit Agrawal <punit.agrawal@arm.com> Cc: Christoffer Dall <christoffer.dall@linaro.org> Cc: Marc Zyngier <marc.zyngier@arm.com> --- virt/kvm/arm/perf_trace.c | 32 ++++++++++++++++++++++++++++++++ 1 file changed, 32 insertions(+)