RISC-V: KVM: Add more arch-specific tracepoints

Add RISC-V KVM tracepoints for events that are useful when debugging
guest exits and in-kernel emulation paths. The existing kvm_entry and
kvm_exit tracepoints are kept, with the kvm_entry PC format fixed to use
zero-padded hexadecimal output.

The newly added tracepoints cover:

- kvm_vcpu_exit for synchronous guest traps
- kvm_vcpu_irq for VS-mode interrupt set/clear
- kvm_mmio_emulate for MMIO load/store emulation

kvm_vcpu_exit reports the full trap context (sepc/scause/stval/htval/
htinst) so userspace can filter by scause, and is placed after the
interrupt early-return so it fires only for synchronous traps.
kvm_vcpu_irq covers every set/unset_interrupt() caller from a single
place.

Example trace output:

kvm_vcpu_exit:
VCPU: 0, SEPC: 0x80200000, SCAUSE: 0x17,
STVAL: 0x10000000, HTVAL: 0x4000000, HTINST: 0x2023

kvm_mmio_emulate:
VCPU: 0, Store MMIO at 0x10000000, len 4, insn 0x2023, sepc 0x80200000

kvm_vcpu_irq:
VCPU: 0, IRQ: 10, level: 1

Testing:

A QEMU-based test program was used to exercise:

- Guest page faults
- MMIO emulation
- IRQ injection

Verified trace output generation for:

- kvm_vcpu_exit
- kvm_vcpu_irq
- kvm_mmio_emulate

Assisted-by: YuanSheng:deepseek-v4-pro
Co-developed-by: Quan Zhou <zhouquan@iscas.ac.cn>
Signed-off-by: Quan Zhou <zhouquan@iscas.ac.cn>
Signed-off-by: Yuhang.Chen <yhchen312@gmail.com>
Reviewed-by: Anup Patel <anup@brainfault.org>
Link: https://lore.kernel.org/r/20260730065711.3721489-1-yhchen312@gmail.com
Signed-off-by: Anup Patel <anup@brainfault.org>

0 files changed, 0 insertions, 0 deletions