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arm64: KVM: Add trapped system register access tracepoint 

We're pretty blind when it comes to system register tracing,
and rely on the ESR value displayed by kvm_handle_sys, which
isn't much.

Instead, let's add an actual name to the sysreg entries, so that
we can finally print it as we're about to perform the access
itself.

The new tracepoint is conveniently called kvm_sys_access.

Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
hifive-unleashed-5.1
Marc Zyngier 2018-12-04 10:44:22 +00:00
parent da6f16662a
commit 599d79dcd1
3 changed files with 41 additions and 0 deletions
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2
arch/arm64/kvm/sys_regs.c
View File

@ -1850,6 +1850,8 @@ static void perform_access(struct kvm_vcpu *vcpu,
struct sys_reg_params *params,
const struct sys_reg_desc *r)
{
trace_kvm_sys_access(*vcpu_pc(vcpu), params, r);
/*
* Not having an accessor means that we have configured a trap
* that we don't know how to handle. This certainly qualifies

4
arch/arm64/kvm/sys_regs.h
View File

@ -35,6 +35,9 @@ struct sys_reg_params {
};
struct sys_reg_desc {
/* Sysreg string for debug */
const char *name;
/* MRS/MSR instruction which accesses it. */
u8 Op0;
u8 Op1;
@ -130,6 +133,7 @@ const struct sys_reg_desc *find_reg_by_id(u64 id,
#define Op2(_x) .Op2 = _x
#define SYS_DESC(reg) \
.name = #reg, \
Op0(sys_reg_Op0(reg)), Op1(sys_reg_Op1(reg)), \
CRn(sys_reg_CRn(reg)), CRm(sys_reg_CRm(reg)), \
Op2(sys_reg_Op2(reg))

35
arch/arm64/kvm/trace.h
View File

@ -3,6 +3,7 @@
#define _TRACE_ARM64_KVM_H
#include <linux/tracepoint.h>
#include "sys_regs.h"
#undef TRACE_SYSTEM
#define TRACE_SYSTEM kvm
@ -152,6 +153,40 @@ TRACE_EVENT(kvm_handle_sys_reg,
TP_printk("HSR 0x%08lx", __entry->hsr)
);
TRACE_EVENT(kvm_sys_access,
TP_PROTO(unsigned long vcpu_pc, struct sys_reg_params *params, const struct sys_reg_desc *reg),
TP_ARGS(vcpu_pc, params, reg),
TP_STRUCT__entry(
__field(unsigned long, vcpu_pc)
__field(bool, is_write)
__field(const char *, name)
__field(u8, Op0)
__field(u8, Op1)
__field(u8, CRn)
__field(u8, CRm)
__field(u8, Op2)
),
TP_fast_assign(
__entry->vcpu_pc = vcpu_pc;
__entry->is_write = params->is_write;
__entry->name = reg->name;
__entry->Op0 = reg->Op0;
__entry->Op0 = reg->Op0;
__entry->Op1 = reg->Op1;
__entry->CRn = reg->CRn;
__entry->CRm = reg->CRm;
__entry->Op2 = reg->Op2;
),
TP_printk("PC: %lx %s (%d,%d,%d,%d,%d) %s",
__entry->vcpu_pc, __entry->name ?: "UNKN",
__entry->Op0, __entry->Op1, __entry->CRn,
__entry->CRm, __entry->Op2,
__entry->is_write ? "write" : "read")
);
TRACE_EVENT(kvm_set_guest_debug,
TP_PROTO(struct kvm_vcpu *vcpu, __u32 guest_debug),
TP_ARGS(vcpu, guest_debug),