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

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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: Zenghui Yu <yuzenghui@huawei.com>
Acked-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20231026205306.3045075-1-oliver.upton@linux.dev
Signed-off-by: Oliver Upton <oliver.upton@linux.dev>
This commit is contained in:
Oliver Upton 2023-10-26 20:53:06 +00:00
parent 06899aa5dd
commit d11974dc5f
2 changed files with 28 additions and 1 deletions
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4
arch/arm64/kvm/mmio.c
View File

@ -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;
}

25
arch/arm64/kvm/trace_arm.h
View File

@ -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),