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Re: [Qemu-ppc] [RFC PATCH v3 6/7] target/ppc: Refactor kvm_handle_debug
From: |
Alexey Kardashevskiy |
Subject: |
Re: [Qemu-ppc] [RFC PATCH v3 6/7] target/ppc: Refactor kvm_handle_debug |
Date: |
Fri, 25 Jan 2019 12:37:23 +1100 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.4.0 |
On 19/01/2019 01:07, Fabiano Rosas wrote:
> There are four scenarios being handled in this function:
>
> - single stepping
> - hardware breakpoints
> - software breakpoints
> - fallback (no debug supported)
>
> A future patch will add code to handle specific single step and
> software breakpoints cases so let's split each scenario into its own
> function now to avoid hurting readability.
>
> Signed-off-by: Fabiano Rosas <address@hidden>
Reviewed-by: Alexey Kardashevskiy <address@hidden>
> ---
> target/ppc/kvm.c | 86 ++++++++++++++++++++++++++++--------------------
> 1 file changed, 50 insertions(+), 36 deletions(-)
>
> diff --git a/target/ppc/kvm.c b/target/ppc/kvm.c
> index 96a5895792..c27190d7fb 100644
> --- a/target/ppc/kvm.c
> +++ b/target/ppc/kvm.c
> @@ -1621,52 +1621,66 @@ static int kvm_handle_hw_breakpoint(CPUState *cs,
> return handle;
> }
>
> +static int kvm_handle_singlestep(void)
> +{
> + return 1;
> +}
> +
> +static int kvm_handle_sw_breakpoint(void)
> +{
> + return 1;
> +}
> +
> 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 (cs->singlestep_enabled) {
> - handle = 1;
> - } else if (arch_info->status) {
> - handle = kvm_handle_hw_breakpoint(cs, arch_info);
> - } else 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 !!
> - * When QEMU is using debug resources then debug exception must
> - * be always set. To achieve this we set MSR_DE and also set
> - * MSRP_DEP so guest cannot change MSR_DE.
> - * When emulating debug resource for guest we want guest
> - * to control MSR_DE (enable/disable debug interrupt on need).
> - * Supporting both configurations are NOT possible.
> - * So the result is that we cannot share debug resources
> - * between QEMU and Guest on BOOKE architecture.
> - * In the current design QEMU gets the priority over guest,
> - * this means that if QEMU is using debug resources then guest
> - * cannot use them;
> - * For software breakpoint QEMU uses a privileged instruction;
> - * So there cannot be any reason that we are here for guest
> - * set debug exception, only possibility is guest executed a
> - * privileged / illegal instruction and that's why we are
> - * injecting a program interrupt.
> - */
> + return kvm_handle_singlestep();
> + }
> +
> + if (arch_info->status) {
> + return kvm_handle_hw_breakpoint(cs, arch_info);
> + }
>
> - 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);
> + if (kvm_find_sw_breakpoint(cs, arch_info->address)) {
> + return kvm_handle_sw_breakpoint();
> }
>
> - return handle;
> + /*
> + * QEMU is not able to handle debug exception, so inject
> + * program exception to guest;
> + * Yes program exception NOT debug exception !!
> + * When QEMU is using debug resources then debug exception must
> + * be always set. To achieve this we set MSR_DE and also set
> + * MSRP_DEP so guest cannot change MSR_DE.
> + * When emulating debug resource for guest we want guest
> + * to control MSR_DE (enable/disable debug interrupt on need).
> + * Supporting both configurations are NOT possible.
> + * So the result is that we cannot share debug resources
> + * between QEMU and Guest on BOOKE architecture.
> + * In the current design QEMU gets the priority over guest,
> + * this means that if QEMU is using debug resources then guest
> + * cannot use them;
> + * For software breakpoint QEMU uses a privileged instruction;
> + * So there cannot be any reason that we are here for guest
> + * set debug exception, only possibility is guest executed a
> + * privileged / illegal instruction and that's why we are
> + * injecting a program interrupt.
> + */
> + 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 0;
> }
>
> int kvm_arch_handle_exit(CPUState *cs, struct kvm_run *run)
>
--
Alexey
- [Qemu-ppc] [RFC PATCH v3 0/7] target/ppc: single step for KVM HV, Fabiano Rosas, 2019/01/18
- [Qemu-ppc] [RFC PATCH v3 2/7] target/ppc: Add ppc_get_trace_int_handler_addr, Fabiano Rosas, 2019/01/18
- [Qemu-ppc] [RFC PATCH v3 1/7] target/ppc: Move exception vector offset computation into a function, Fabiano Rosas, 2019/01/18
- [Qemu-ppc] [RFC PATCH v3 3/7] kvm: support checking for single step capability, Fabiano Rosas, 2019/01/18
- [Qemu-ppc] [RFC PATCH v3 5/7] target/ppc: Move handling of hardware breakpoints to a separate function, Fabiano Rosas, 2019/01/18
- [Qemu-ppc] [RFC PATCH v3 4/7] kvm-all: Introduce kvm_set_singlestep, Fabiano Rosas, 2019/01/18
- [Qemu-ppc] [RFC PATCH v3 6/7] target/ppc: Refactor kvm_handle_debug, Fabiano Rosas, 2019/01/18
- Re: [Qemu-ppc] [RFC PATCH v3 6/7] target/ppc: Refactor kvm_handle_debug,
Alexey Kardashevskiy <=
- [Qemu-ppc] [RFC PATCH v3 7/7] target/ppc: support single stepping with KVM HV, Fabiano Rosas, 2019/01/18