[PATCH v8 11/11] KVM: arm64: add trace points for guest_debug debug

Alex Bennée
2015-07-07T16:18:59Z

This includes trace points for:
kvm_arch_setup_guest_debug
kvm_arch_clear_guest_debug

I've also added some generic register setting trace events and also a
trace point to dump the array of hardware registers.

Signed-off-by: Alex Bennée <alex.bennee@linaro.org>

---
v3
- add trace event for debug access.
- remove short trace #define, rename trace events
- use __print_array with fixed array instead of own func
- rationalise trace points (only one per register changed)
- add vcpu ptr to the debug_setup trace
- remove :: in prints
v4
- u32/u64 split on debug registers
- fix for renames
- add tracing of traps/set_guest_debug
- remove handle_guest_debug trace
v5
- minor print fmt fix
- rm pstate traces
v6
- fix merge conflicts
- update control reg tracking to u64 (abi change)
v7
- fix merge conflicts from ioctl move
- fix other minor merge conflicts
- fixes for the re-factored sys_regs code
v8
- updates for sys_regs re-factor
---
arch/arm64/kvm/debug.c | 36 +++++++++++++-
arch/arm64/kvm/guest.c | 4 ++
arch/arm64/kvm/sys_regs.c | 17 +++++++
arch/arm64/kvm/trace.h | 123 ++++++++++++++++++++++++++++++++++++++++++++++
4 files changed, 179 insertions(+), 1 deletion(-)

diff --git a/arch/arm64/kvm/debug.c b/arch/arm64/kvm/debug.c
index 4a99e54..47e5f0f 100644
--- a/arch/arm64/kvm/debug.c
+++ b/arch/arm64/kvm/debug.c
@@ -18,12 +18,15 @@
*/

#include <linux/kvm_host.h>
+#include <linux/hw_breakpoint.h>

#include <asm/debug-monitors.h>
#include <asm/kvm_asm.h>
#include <asm/kvm_arm.h>
#include <asm/kvm_emulate.h>

+#include "trace.h"
+
/* These are the bits of MDSCR_EL1 we may manipulate */
#define MDSCR_EL1_DEBUG_MASK (DBG_MDSCR_SS | \
DBG_MDSCR_KDE | \
@@ -44,11 +47,17 @@ static DEFINE_PER_CPU(u32, mdcr_el2);
static void save_guest_debug_regs(struct kvm_vcpu *vcpu)
{
vcpu->arch.guest_debug_preserved.mdscr_el1 = vcpu_sys_reg(vcpu, MDSCR_EL1);
+
+ trace_kvm_arm_set_dreg32("Saved MDSCR_EL1",
+ vcpu->arch.guest_debug_preserved.mdscr_el1);
}

static void restore_guest_debug_regs(struct kvm_vcpu *vcpu)
{
vcpu_sys_reg(vcpu, MDSCR_EL1) = vcpu->arch.guest_debug_preserved.mdscr_el1;
+
+ trace_kvm_arm_set_dreg32("Restored MDSCR_EL1",
+ vcpu_sys_reg(vcpu, MDSCR_EL1));
}

/**
@@ -99,6 +108,8 @@ void kvm_arm_setup_debug(struct kvm_vcpu *vcpu)
{
bool trap_debug = !(vcpu->arch.debug_flags & KVM_ARM64_DEBUG_DIRTY);

+ trace_kvm_arm_setup_debug(vcpu, vcpu->guest_debug);
+
vcpu->arch.mdcr_el2 = __this_cpu_read(mdcr_el2) & MDCR_EL2_HPMN_MASK;
vcpu->arch.mdcr_el2 |= (MDCR_EL2_TPM |
MDCR_EL2_TPMCR |
@@ -140,6 +151,8 @@ void kvm_arm_setup_debug(struct kvm_vcpu *vcpu)
vcpu_sys_reg(vcpu, MDSCR_EL1) &= ~DBG_MDSCR_SS;
}

+ trace_kvm_arm_set_dreg32("SPSR_EL2", *vcpu_cpsr(vcpu));
+
/*
* HW Breakpoints and watchpoints
*
@@ -156,6 +169,14 @@ void kvm_arm_setup_debug(struct kvm_vcpu *vcpu)
vcpu->arch.debug_ptr = &vcpu->arch.external_debug_state;
vcpu->arch.debug_flags |= KVM_ARM64_DEBUG_DIRTY;
trap_debug = true;
+
+ trace_kvm_arm_set_regset("BKPTS", get_num_brps(),
+ &vcpu->arch.debug_ptr->dbg_bcr[0],
+ &vcpu->arch.debug_ptr->dbg_bvr[0]);
+
+ trace_kvm_arm_set_regset("WAPTS", get_num_wrps(),
+ &vcpu->arch.debug_ptr->dbg_wcr[0],
+ &vcpu->arch.debug_ptr->dbg_wvr[0]);
}
}

@@ -165,10 +186,15 @@ void kvm_arm_setup_debug(struct kvm_vcpu *vcpu)
/* Trap debug register access */
if (trap_debug)
vcpu->arch.mdcr_el2 |= MDCR_EL2_TDA;
+
+ trace_kvm_arm_set_dreg32("MDCR_EL2", vcpu->arch.mdcr_el2);
+ trace_kvm_arm_set_dreg32("MDSCR_EL1", vcpu_sys_reg(vcpu, MDSCR_EL1));
}

void kvm_arm_clear_debug(struct kvm_vcpu *vcpu)
{
+ trace_kvm_arm_clear_debug(vcpu->guest_debug);
+
if (vcpu->guest_debug) {
restore_guest_debug_regs(vcpu);

@@ -176,8 +202,16 @@ void kvm_arm_clear_debug(struct kvm_vcpu *vcpu)
* If we were using HW debug we need to restore the
* debug_ptr to the guest debug state.
*/
- if (vcpu->guest_debug & KVM_GUESTDBG_USE_HW)
+ if (vcpu->guest_debug & KVM_GUESTDBG_USE_HW) {
kvm_arm_reset_debug_ptr(vcpu);

+ trace_kvm_arm_set_regset("BKPTS", get_num_brps(),
+ &vcpu->arch.debug_ptr->dbg_bcr[0],
+ &vcpu->arch.debug_ptr->dbg_bvr[0]);
+
+ trace_kvm_arm_set_regset("WAPTS", get_num_wrps(),
+ &vcpu->arch.debug_ptr->dbg_wcr[0],
+ &vcpu->arch.debug_ptr->dbg_wvr[0]);
+ }
}
}
diff --git a/arch/arm64/kvm/guest.c b/arch/arm64/kvm/guest.c
index 6f1b249..48868d8 100644
--- a/arch/arm64/kvm/guest.c
+++ b/arch/arm64/kvm/guest.c
@@ -32,6 +32,8 @@
#include <asm/kvm_emulate.h>
#include <asm/kvm_coproc.h>

+#include "trace.h"
+
struct kvm_stats_debugfs_item debugfs_entries[] = {
{ NULL }
};
@@ -350,6 +352,8 @@ int kvm_arch_vcpu_ioctl_translate(struct kvm_vcpu *vcpu,
int kvm_arch_vcpu_ioctl_set_guest_debug(struct kvm_vcpu *vcpu,
struct kvm_guest_debug *dbg)
{
+ trace_kvm_set_guest_debug(vcpu, dbg->control);
+
if (dbg->control & ~KVM_GUESTDBG_VALID_MASK)
return -EINVAL;

diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c
index 158bae7..b41607d 100644
--- a/arch/arm64/kvm/sys_regs.c
+++ b/arch/arm64/kvm/sys_regs.c
@@ -38,6 +38,8 @@

#include "sys_regs.h"

+#include "trace.h"
+
/*
* All of this file is extremly similar to the ARM coproc.c, but the
* types are different. My gut feeling is that it should be pretty
@@ -208,6 +210,8 @@ static bool trap_debug_regs(struct kvm_vcpu *vcpu,
*vcpu_reg(vcpu, p->Rt) = vcpu_sys_reg(vcpu, r->reg);
}

+ trace_trap_reg(__func__, r->reg, p->is_write, *vcpu_reg(vcpu, p->Rt));
+
return true;
}

@@ -258,6 +262,8 @@ static inline bool trap_bvr(struct kvm_vcpu *vcpu,
else
dbg_to_reg(vcpu, p, dbg_reg);

+ trace_trap_reg(__func__, rd->reg, p->is_write, *dbg_reg);
+
return true;
}

@@ -298,6 +304,8 @@ static inline bool trap_bcr(struct kvm_vcpu *vcpu,
else
dbg_to_reg(vcpu, p, dbg_reg);

+ trace_trap_reg(__func__, rd->reg, p->is_write, *dbg_reg);
+
return true;
}

@@ -339,6 +347,9 @@ static inline bool trap_wvr(struct kvm_vcpu *vcpu,
else
dbg_to_reg(vcpu, p, dbg_reg);

+ trace_trap_reg(__func__, rd->reg, p->is_write,
+ vcpu->arch.vcpu_debug_state.dbg_wvr[rd->reg]);
+
return true;
}

@@ -379,6 +390,8 @@ static inline bool trap_wcr(struct kvm_vcpu *vcpu,
else
dbg_to_reg(vcpu, p, dbg_reg);

+ trace_trap_reg(__func__, rd->reg, p->is_write, *dbg_reg);
+
return true;
}

@@ -742,6 +755,8 @@ static inline bool trap_xvr(struct kvm_vcpu *vcpu,
*vcpu_reg(vcpu, p->Rt) = *dbg_reg >> 32;
}

+ trace_trap_reg(__func__, rd->reg, p->is_write, *dbg_reg);
+
return true;
}

@@ -1223,6 +1238,8 @@ int kvm_handle_sys_reg(struct kvm_vcpu *vcpu, struct kvm_run *run)
struct sys_reg_params params;
unsigned long esr = kvm_vcpu_get_hsr(vcpu);

+ trace_kvm_handle_sys_reg(esr);
+
params.is_aarch32 = false;
params.is_32bit = false;
params.Op0 = (esr >> 20) & 3;
diff --git a/arch/arm64/kvm/trace.h b/arch/arm64/kvm/trace.h
index 157416e9..7fb0008 100644
--- a/arch/arm64/kvm/trace.h
+++ b/arch/arm64/kvm/trace.h
@@ -44,6 +44,129 @@ TRACE_EVENT(kvm_hvc_arm64,
__entry->vcpu_pc, __entry->r0, __entry->imm)
);

+TRACE_EVENT(kvm_arm_setup_debug,
+ TP_PROTO(struct kvm_vcpu *vcpu, __u32 guest_debug),
+ TP_ARGS(vcpu, guest_debug),
+
+ TP_STRUCT__entry(
+ __field(struct kvm_vcpu *, vcpu)
+ __field(__u32, guest_debug)
+ ),
+
+ TP_fast_assign(
+ __entry->vcpu = vcpu;
+ __entry->guest_debug = guest_debug;
+ ),
+
+ TP_printk("vcpu: %p, flags: 0x%08x", __entry->vcpu, __entry->guest_debug)
+);
+
+TRACE_EVENT(kvm_arm_clear_debug,
+ TP_PROTO(__u32 guest_debug),
+ TP_ARGS(guest_debug),
+
+ TP_STRUCT__entry(
+ __field(__u32, guest_debug)
+ ),
+
+ TP_fast_assign(
+ __entry->guest_debug = guest_debug;
+ ),
+
+ TP_printk("flags: 0x%08x", __entry->guest_debug)
+);
+
+TRACE_EVENT(kvm_arm_set_dreg32,
+ TP_PROTO(const char *name, __u32 value),
+ TP_ARGS(name, value),
+
+ TP_STRUCT__entry(
+ __field(const char *, name)
+ __field(__u32, value)
+ ),
+
+ TP_fast_assign(
+ __entry->name = name;
+ __entry->value = value;
+ ),
+
+ TP_printk("%s: 0x%08x", __entry->name, __entry->value)
+);
+
+TRACE_EVENT(kvm_arm_set_regset,
+ TP_PROTO(const char *type, int len, __u64 *control, __u64 *value),
+ TP_ARGS(type, len, control, value),
+ TP_STRUCT__entry(
+ __field(const char *, name)
+ __field(int, len)
+ __array(u64, ctrls, 16)
+ __array(u64, values, 16)
+ ),
+ TP_fast_assign(
+ __entry->name = type;
+ __entry->len = len;
+ memcpy(__entry->ctrls, control, len << 3);
+ memcpy(__entry->values, value, len << 3);
+ ),
+ TP_printk("%d %s CTRL:%s VALUE:%s", __entry->len, __entry->name,
+ __print_array(__entry->ctrls, __entry->len, sizeof(__u64)),
+ __print_array(__entry->values, __entry->len, sizeof(__u64)))
+);
+
+TRACE_EVENT(trap_reg,
+ TP_PROTO(const char *fn, int reg, bool is_write, u64 write_value),
+ TP_ARGS(fn, reg, is_write, write_value),
+
+ TP_STRUCT__entry(
+ __field(const char *, fn)
+ __field(int, reg)
+ __field(bool, is_write)
+ __field(u64, write_value)
+ ),
+
+ TP_fast_assign(
+ __entry->fn = fn;
+ __entry->reg = reg;
+ __entry->is_write = is_write;
+ __entry->write_value = write_value;
+ ),
+
+ TP_printk("%s %s reg %d (0x%08llx)", __entry->fn, __entry->is_write?"write to":"read from", __entry->reg, __entry->write_value)
+);
+
+TRACE_EVENT(kvm_handle_sys_reg,
+ TP_PROTO(unsigned long hsr),
+ TP_ARGS(hsr),
+
+ TP_STRUCT__entry(
+ __field(unsigned long, hsr)
+ ),
+
+ TP_fast_assign(
+ __entry->hsr = hsr;
+ ),
+
+ TP_printk("HSR 0x%08lx", __entry->hsr)
+);
+
+TRACE_EVENT(kvm_set_guest_debug,
+ TP_PROTO(struct kvm_vcpu *vcpu, __u32 guest_debug),
+ TP_ARGS(vcpu, guest_debug),
+
+ TP_STRUCT__entry(
+ __field(struct kvm_vcpu *, vcpu)
+ __field(__u32, guest_debug)
+ ),
+
+ TP_fast_assign(
+ __entry->vcpu = vcpu;
+ __entry->guest_debug = guest_debug;
+ ),
+
+ TP_printk("vcpu: %p, flags: 0x%08x", __entry->vcpu, __entry->guest_debug)
+);
+
+
#endif /* _TRACE_ARM64_KVM_H */

#undef TRACE_INCLUDE_PATH