On Monday 14 July 2014 02:45 PM, Bharat Bhushan wrote:
> This patch allow insert/remove software breakpoint.
>
> When QEMU is not able to handle debug exception then we inject
> program exception to guest because for software breakpoint QEMU
> uses a ehpriv-1 instruction;
> So there cannot be any reason that we are in qemu with exit reason
> KVM_EXIT_DEBUG for guest set debug exception, only possibility is
> guest executed ehpriv-1 privilege instruction and that's why we are
> injecting program exception.
>
> Signed-off-by: Bharat Bhushan <bharat.bhus...@freescale.com>
> ---
> v7->v8
> - Decrement nip by 4 before calling ppc_cpu_do_interrupt()
> as pointed by "Madhavan Srinivasan"
Just a minor change. We increment the nip.
> - Also added missing cpu_sync()
>
> target-ppc/kvm.c | 93
> +++++++++++++++++++++++++++++++++++++++++++++++---------
> 1 file changed, 79 insertions(+), 14 deletions(-)
>
> diff --git a/target-ppc/kvm.c b/target-ppc/kvm.c
> index e00a20f..0f2e8e4 100644
> --- a/target-ppc/kvm.c
> +++ b/target-ppc/kvm.c
> @@ -1275,6 +1275,75 @@ static int kvmppc_handle_dcr_write(CPUPPCState *env,
> uint32_t dcrn, uint32_t dat
> return 0;
> }
>
> +int kvm_arch_insert_sw_breakpoint(CPUState *cs, struct kvm_sw_breakpoint *bp)
> +{
> + /* Mixed endian case is not handled */
> + uint32_t sc = debug_inst_opcode;
> +
> + if (cpu_memory_rw_debug(cs, bp->pc, (uint8_t *)&bp->saved_insn,
> + sizeof(sc), 0) ||
> + cpu_memory_rw_debug(cs, bp->pc, (uint8_t *)&sc, sizeof(sc), 1)) {
> + return -EINVAL;
> + }
> +
> + return 0;
> +}
> +
> +int kvm_arch_remove_sw_breakpoint(CPUState *cs, struct kvm_sw_breakpoint *bp)
> +{
> + uint32_t sc;
> +
> + if (cpu_memory_rw_debug(cs, bp->pc, (uint8_t *)&sc, sizeof(sc), 0) ||
> + sc != debug_inst_opcode ||
> + cpu_memory_rw_debug(cs, bp->pc, (uint8_t *)&bp->saved_insn,
> + sizeof(sc), 1)) {
> + return -EINVAL;
> + }
> +
> + return 0;
> +}
> +
> +void kvm_arch_update_guest_debug(CPUState *cs, struct kvm_guest_debug *dbg)
> +{
> + /* Software Breakpoint updates */
> + if (kvm_sw_breakpoints_active(cs)) {
> + dbg->control |= KVM_GUESTDBG_ENABLE | KVM_GUESTDBG_USE_SW_BP;
> + }
> +}
> +
> +static int kvm_handle_debug(PowerPCCPU *cpu, struct kvm_run *run)
> +{
> + CPUState *cs = CPU(cpu);
> + CPUPPCState *env = &cpu->env;
> + struct kvm_debug_exit_arch *arch_info = &run->debug.arch;
> + int handle = 0;
> +
> + if (kvm_find_sw_breakpoint(cs, arch_info->address)) {
> + handle = 1;
> + } else {
> + /* QEMU is not able to handle debug exception, so inject
> + * program exception to guest;
> + * Yes program exception NOT debug exception !!
> + * For software breakpoint QEMU uses a ehpriv-1 instruction;
Instead, can you say "QEMU uses a SW breakpoint instruction". In server
side, we use illegal instruction to trap to hypervisor ("0x00dddd00")
> + * So there cannot be any reason that we are here for guest
> + * set debug exception, only possibility is guest executed a
> + * privilege instruction and that's why we are injecting
^^^^privilege or illegal instruction
My Bad. I should have read just last time. But just minor and I am ok as is.
Reviewed By: Madhavan Srinivasan <ma...@linux.vnet.ibm.com>
> + * program exception.
> + */
> +
> + cpu_synchronize_state(cs);
> + /* env->nip is PC, so increment this by 4 to use
> + * ppc_cpu_do_interrupt(), which set srr0 = env->nip - 4.
> + */
> + env->nip += 4;
> + cs->exception_index = POWERPC_EXCP_PROGRAM;
> + env->error_code = POWERPC_EXCP_INVAL;
> + ppc_cpu_do_interrupt(cs);
> + }
> +
> + return handle;
> +}
> +
> int kvm_arch_handle_exit(CPUState *cs, struct kvm_run *run)
> {
> PowerPCCPU *cpu = POWERPC_CPU(cs);
> @@ -1315,6 +1384,16 @@ int kvm_arch_handle_exit(CPUState *cs, struct kvm_run
> *run)
> ret = 0;
> break;
>
> + case KVM_EXIT_DEBUG:
> + DPRINTF("handle debug exception\n");
> + if (kvm_handle_debug(cpu, run)) {
> + ret = EXCP_DEBUG;
> + break;
> + }
> + /* re-enter, this exception was guest-internal */
> + ret = 0;
> + break;
> +
> default:
> fprintf(stderr, "KVM: unknown exit reason %d\n", run->exit_reason);
> ret = -1;
> @@ -2003,16 +2082,6 @@ void kvm_arch_init_irq_routing(KVMState *s)
> {
> }
>
> -int kvm_arch_insert_sw_breakpoint(CPUState *cpu, struct kvm_sw_breakpoint
> *bp)
> -{
> - return -EINVAL;
> -}
> -
> -int kvm_arch_remove_sw_breakpoint(CPUState *cpu, struct kvm_sw_breakpoint
> *bp)
> -{
> - return -EINVAL;
> -}
> -
> int kvm_arch_insert_hw_breakpoint(target_ulong addr, target_ulong len, int
> type)
> {
> return -EINVAL;
> @@ -2027,10 +2096,6 @@ void kvm_arch_remove_all_hw_breakpoints(void)
> {
> }
>
> -void kvm_arch_update_guest_debug(CPUState *cpu, struct kvm_guest_debug *dbg)
> -{
> -}
> -
> struct kvm_get_htab_buf {
> struct kvm_get_htab_header header;
> /*
>
