Commit e9adde43 authored by Marc Zyngier's avatar Marc Zyngier
Browse files

KVM: arm64: timers: Fast-track CNTPCT_EL0 trap handling 



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: default avatarOliver Upton <oliver.upton@linux.dev>
Signed-off-by: default avatarMarc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20230330174800.2677007-14-maz@kernel.org
parent 1a6511eb

arch/arm64/kvm/hyp/include/hyp/switch.h

+36 −0
Original line number Diff line number Diff line
@@ -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;

}