Now that it is likely that CNTPCT_EL0 accesses will trap,
fast-track the emulation of the counter read which doesn't
need more that a simple offsetting.
One day, we'll have CNTPOFF everywhere. One day.
Suggested-by: Oliver Upton <oliver.upton@xxxxxxxxx>
Signed-off-by: Marc Zyngier <maz@xxxxxxxxxx>
---
arch/arm64/kvm/hyp/include/hyp/switch.h | 36 +++++++++++++++++++++++++
1 file changed, 36 insertions(+)
diff --git a/arch/arm64/kvm/hyp/include/hyp/switch.h b/arch/arm64/kvm/hyp/include/hyp/switch.h
index 07d37ff88a3f..9954368f639d 100644
--- a/arch/arm64/kvm/hyp/include/hyp/switch.h
+++ b/arch/arm64/kvm/hyp/include/hyp/switch.h
@@ -26,6 +26,7 @@
#include <asm/kvm_emulate.h>
#include <asm/kvm_hyp.h>
#include <asm/kvm_mmu.h>
+#include <asm/kvm_nested.h>
#include <asm/fpsimd.h>
#include <asm/debug-monitors.h>
#include <asm/processor.h>
@@ -326,6 +327,38 @@ static bool kvm_hyp_handle_ptrauth(struct kvm_vcpu *vcpu, u64 *exit_code)
return true;
}
+static bool kvm_hyp_handle_cntpct(struct kvm_vcpu *vcpu)
+{
+ struct arch_timer_context *ctxt;
+ u32 sysreg;
+ u64 val;
+
+ /*
+ * We only get here for 64bit guests, 32bit guests will hit
+ * the long and winding road all the way to the standard
+ * handling. Yes, it sucks to be irrelevant.
+ */
+ sysreg = esr_sys64_to_sysreg(kvm_vcpu_get_esr(vcpu));
+
+ switch (sysreg) {
+ case SYS_CNTPCT_EL0:
+ case SYS_CNTPCTSS_EL0:
+ ctxt = vcpu_ptimer(vcpu);
+ break;
+ default:
+ return false;
+ }
+
+ val = arch_timer_read_cntpct_el0();
+
+ if (ctxt->offset.vm_offset)
+ val -= *kern_hyp_va(ctxt->offset.vm_offset);
+
+ vcpu_set_reg(vcpu, kvm_vcpu_sys_get_rt(vcpu), val);
+ __kvm_skip_instr(vcpu);
+ return true;
+}
+
static bool kvm_hyp_handle_sysreg(struct kvm_vcpu *vcpu, u64 *exit_code)
{
if (cpus_have_final_cap(ARM64_WORKAROUND_CAVIUM_TX2_219_TVM) &&
@@ -339,6 +372,9 @@ static bool kvm_hyp_handle_sysreg(struct kvm_vcpu *vcpu, u64 *exit_code)
if (esr_is_ptrauth_trap(kvm_vcpu_get_esr(vcpu)))
return kvm_hyp_handle_ptrauth(vcpu, exit_code);
+ if (kvm_hyp_handle_cntpct(vcpu))
+ return true;
+
return false;
}
--
2.34.1
