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Re: [Qemu-devel] [PACTH v4 5/6] target-arm: add emulation of PSCI calls
From: |
Paolo Bonzini |
Subject: |
Re: [Qemu-devel] [PACTH v4 5/6] target-arm: add emulation of PSCI calls for system emulation |
Date: |
Fri, 26 Sep 2014 17:34:05 +0200 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.1.1 |
Il 26/09/2014 11:10, Peter Maydell ha scritto:
> On 10 September 2014 08:02, Ard Biesheuvel <address@hidden> wrote:
>> From: Rob Herring <address@hidden>
>>
>> Add support for handling PSCI calls in system emulation. Both version
>> 0.1 and 0.2 of the PSCI spec are supported. Platforms can enable support
>> by setting the "psci-conduit" QOM property on the cpus to SMC or HVC
>> emulation and having a PSCI binding in their dtb.
>>
>> Signed-off-by: Rob Herring <address@hidden>
>> Signed-off-by: Ard Biesheuvel <address@hidden>
>
>> + case QEMU_PSCI_0_2_FN_SYSTEM_RESET:
>> + qemu_system_reset_request();
>> + break;
>> + case QEMU_PSCI_0_2_FN_SYSTEM_OFF:
>> + qemu_system_shutdown_request();
>> + break;
>
> I just realised that this isn't quite right: PSCI
> mandates that the SYSTEM_RESET and SYSTEM_OFF
> functions never return to the caller, but the QEMU
> qemu_system_*_request() functions are just requests
> which the main loop will later handle asynchronously.
> So we should put the calling CPU into power off
> (and rely on CPU reset to power it up again if it's
> CPU 0; we don't care if we're shutting down, obviously).
>
> I propose to apply the following fixup patch to
> deal with this (since this patchset is very nearly
> ready and I know Ard's not going to be back to
> deal with it for a few weeks):
FWIW, looks good.
Thanks,
Paolo
> diff --git a/target-arm/psci.c b/target-arm/psci.c
> index 7347cbd..1cda7d3 100644
> --- a/target-arm/psci.c
> +++ b/target-arm/psci.c
> @@ -85,10 +85,15 @@ bool arm_handle_psci(CPUState *cs)
> break;
> case QEMU_PSCI_0_2_FN_SYSTEM_RESET:
> qemu_system_reset_request();
> - break;
> + /* QEMU reset and shutdown are async requests, but PSCI
> + * mandates that we never return from the reset/shutdown
> + * call, so power the CPU off now so it doesn't execute
> + * anything further.
> + */
> + goto cpu_off;
> case QEMU_PSCI_0_2_FN_SYSTEM_OFF:
> qemu_system_shutdown_request();
> - break;
> + goto cpu_off;
> case QEMU_PSCI_0_1_FN_CPU_ON:
> case QEMU_PSCI_0_2_FN_CPU_ON:
> case QEMU_PSCI_0_2_FN64_CPU_ON:
> @@ -144,11 +149,7 @@ bool arm_handle_psci(CPUState *cs)
> break;
> case QEMU_PSCI_0_1_FN_CPU_OFF:
> case QEMU_PSCI_0_2_FN_CPU_OFF:
> - cpu->powered_off = true;
> - cs->halted = 1;
> - cs->exception_index = EXCP_HLT;
> - cpu_loop_exit(cs);
> - /* notreached */
> + goto cpu_off;
> case QEMU_PSCI_0_1_FN_CPU_SUSPEND:
> case QEMU_PSCI_0_2_FN_CPU_SUSPEND:
> case QEMU_PSCI_0_2_FN64_CPU_SUSPEND:
> @@ -180,4 +181,11 @@ err:
> env->regs[0] = ret;
> }
> return true;
> +
> +cpu_off:
> + cpu->powered_off = true;
> + cs->halted = 1;
> + cs->exception_index = EXCP_HLT;
> + cpu_loop_exit(cs);
> + /* notreached */
> }
>
> thanks
> -- PMM
>
>
- [Qemu-devel] [PACTH v4 0/6] ARM: add PSCI 0.2 support in TCG mode, Ard Biesheuvel, 2014/09/10
- [Qemu-devel] [PACTH v4 2/6] target-arm: do not set do_interrupt handlers for ARM and AArch64 user modes, Ard Biesheuvel, 2014/09/10
- [Qemu-devel] [PACTH v4 1/6] target-arm: add powered off cpu state, Ard Biesheuvel, 2014/09/10
- [Qemu-devel] [PACTH v4 3/6] target-arm: add hvc and smc exception emulation handling infrastructure, Ard Biesheuvel, 2014/09/10
- [Qemu-devel] [PACTH v4 4/6] target-arm: add missing PSCI constants needed for PSCI emulation, Ard Biesheuvel, 2014/09/10
- [Qemu-devel] [PACTH v4 5/6] target-arm: add emulation of PSCI calls for system emulation, Ard Biesheuvel, 2014/09/10
- [Qemu-devel] [PACTH v4 6/6] arm/virt: enable PSCI emulation support for system emulation, Ard Biesheuvel, 2014/09/10