Commit d11974dc authored by Oliver Upton's avatar Oliver Upton
Browse files

KVM: arm64: Add tracepoint for MMIO accesses where ISV==0 



It is a pretty well known fact that KVM does not support MMIO emulation
without valid instruction syndrome information (ESR_EL2.ISV == 0). The
current kvm_pr_unimpl() is pretty useless, as it contains zero context
to relate the event to a vCPU.

Replace it with a precise tracepoint that dumps the relevant context
so the user can make sense of what the guest is doing.

Acked-by: default avatarZenghui Yu <yuzenghui@huawei.com>
Acked-by: default avatarMarc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20231026205306.3045075-1-oliver.upton@linux.dev


Signed-off-by: default avatarOliver Upton <oliver.upton@linux.dev>
parent 06899aa5

arch/arm64/kvm/mmio.c

+3 −1
Original line number Diff line number Diff line
@@ -135,6 +135,9 @@ int io_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa) 
	 * volunteered to do so, and bail out otherwise.

	 */

	if (!kvm_vcpu_dabt_isvalid(vcpu)) {

		trace_kvm_mmio_nisv(*vcpu_pc(vcpu), kvm_vcpu_get_esr(vcpu),

				    kvm_vcpu_get_hfar(vcpu), fault_ipa);



		if (test_bit(KVM_ARCH_FLAG_RETURN_NISV_IO_ABORT_TO_USER,

			     &vcpu->kvm->arch.flags)) {

			run->exit_reason = KVM_EXIT_ARM_NISV;
@@ -143,7 +146,6 @@ int io_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa) 
			return 0;

		}



		kvm_pr_unimpl("Data abort outside memslots with no valid syndrome info\n");

		return -ENOSYS;

	}

arch/arm64/kvm/trace_arm.h

+25 −0
Original line number Diff line number Diff line
@@ -136,6 +136,31 @@ TRACE_EVENT(kvm_mmio_emulate, 
		  __entry->vcpu_pc, __entry->instr, __entry->cpsr)

);



TRACE_EVENT(kvm_mmio_nisv,

	TP_PROTO(unsigned long vcpu_pc, unsigned long esr,

		 unsigned long far, unsigned long ipa),

	TP_ARGS(vcpu_pc, esr, far, ipa),



	TP_STRUCT__entry(

		__field(	unsigned long,	vcpu_pc		)

		__field(	unsigned long,	esr		)

		__field(	unsigned long,	far		)

		__field(	unsigned long,	ipa		)

	),



	TP_fast_assign(

		__entry->vcpu_pc		= vcpu_pc;

		__entry->esr			= esr;

		__entry->far			= far;

		__entry->ipa			= ipa;

	),



	TP_printk("ipa %#016lx, esr %#016lx, far %#016lx, pc %#016lx",

		  __entry->ipa, __entry->esr,

		  __entry->far, __entry->vcpu_pc)

);





TRACE_EVENT(kvm_set_way_flush,

	    TP_PROTO(unsigned long vcpu_pc, bool cache),

	    TP_ARGS(vcpu_pc, cache),