Re: [Qemu-devel] [PULL, 22/30] hw/arm: Move virt's PSCI DT fixup code to arm/boot.c

[Marc Zyngier <marc.zyngier@arm.com>]

On Fri, 09 Feb 2018 11:03:06 +0000,
Peter Maydell wrote:

Hi Peter, Andrey,

> 
> From: Andrey Smirnov <andrew.smirnov@gmail.com>
> 
> Move virt's PSCI DT fixup code to arm/boot.c and set this fixup to
> happen automatically for every board that doesn't mark "psci-conduit"
> as disabled. This way emulated boards other than "virt" that rely on
> PSIC for SMP could benefit from that code.
> 
> Cc: Peter Maydell <peter.maydell@linaro.org>
> Cc: Jason Wang <jasowang@redhat.com>
> Cc: Philippe Mathieu-Daudé <f4bug@amsat.org>
> Cc: Marcel Apfelbaum <marcel.apfelbaum@zoho.com>
> Cc: Michael S. Tsirkin <mst@redhat.com>
> Cc: qemu-devel@nongnu.org
> Cc: qemu-arm@nongnu.org
> Cc: yurovsky@gmail.com
> Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
> Signed-off-by: Andrey Smirnov <andrew.smirnov@gmail.com>
> Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
> Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
> ---
>  hw/arm/boot.c | 65 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
>  hw/arm/virt.c | 61 -------------------------------------------------------
>  2 files changed, 65 insertions(+), 61 deletions(-)
> 
> diff --git a/hw/arm/boot.c b/hw/arm/boot.c
> index bb244ec359..9b174b982c 100644
> --- a/hw/arm/boot.c
> +++ b/hw/arm/boot.c
> @@ -385,6 +385,69 @@ static void set_kernel_args_old(const struct arm_boot_info *info)
>      }
>  }
>  
> +static void fdt_add_psci_node(void *fdt)
> +{
> +    uint32_t cpu_suspend_fn;
> +    uint32_t cpu_off_fn;
> +    uint32_t cpu_on_fn;
> +    uint32_t migrate_fn;
> +    ARMCPU *armcpu = ARM_CPU(qemu_get_cpu(0));
> +    const char *psci_method;
> +    int64_t psci_conduit;
> +
> +    psci_conduit = object_property_get_int(OBJECT(armcpu),
> +                                           "psci-conduit",
> +                                           &error_abort);
> +    switch (psci_conduit) {
> +    case QEMU_PSCI_CONDUIT_DISABLED:
> +        return;
> +    case QEMU_PSCI_CONDUIT_HVC:
> +        psci_method = "hvc";
> +        break;
> +    case QEMU_PSCI_CONDUIT_SMC:
> +        psci_method = "smc";
> +        break;
> +    default:
> +        g_assert_not_reached();
> +    }
> +
> +    qemu_fdt_add_subnode(fdt, "/psci");
> +    if (armcpu->psci_version == 2) {
> +        const char comp[] = "arm,psci-0.2\0arm,psci";
> +        qemu_fdt_setprop(fdt, "/psci", "compatible", comp, sizeof(comp));
> +
> +        cpu_off_fn = QEMU_PSCI_0_2_FN_CPU_OFF;
> +        if (arm_feature(&armcpu->env, ARM_FEATURE_AARCH64)) {
> +            cpu_suspend_fn = QEMU_PSCI_0_2_FN64_CPU_SUSPEND;
> +            cpu_on_fn = QEMU_PSCI_0_2_FN64_CPU_ON;
> +            migrate_fn = QEMU_PSCI_0_2_FN64_MIGRATE;
> +        } else {
> +            cpu_suspend_fn = QEMU_PSCI_0_2_FN_CPU_SUSPEND;
> +            cpu_on_fn = QEMU_PSCI_0_2_FN_CPU_ON;
> +            migrate_fn = QEMU_PSCI_0_2_FN_MIGRATE;
> +        }
> +    } else {
> +        qemu_fdt_setprop_string(fdt, "/psci", "compatible", "arm,psci");
> +
> +        cpu_suspend_fn = QEMU_PSCI_0_1_FN_CPU_SUSPEND;
> +        cpu_off_fn = QEMU_PSCI_0_1_FN_CPU_OFF;
> +        cpu_on_fn = QEMU_PSCI_0_1_FN_CPU_ON;
> +        migrate_fn = QEMU_PSCI_0_1_FN_MIGRATE;
> +    }
> +
> +    /* We adopt the PSCI spec's nomenclature, and use 'conduit' to refer
> +     * to the instruction that should be used to invoke PSCI functions.
> +     * However, the device tree binding uses 'method' instead, so that is
> +     * what we should use here.
> +     */
> +    qemu_fdt_setprop_string(fdt, "/psci", "method", psci_method);
> +
> +    qemu_fdt_setprop_cell(fdt, "/psci", "cpu_suspend", cpu_suspend_fn);
> +    qemu_fdt_setprop_cell(fdt, "/psci", "cpu_off", cpu_off_fn);
> +    qemu_fdt_setprop_cell(fdt, "/psci", "cpu_on", cpu_on_fn);
> +    qemu_fdt_setprop_cell(fdt, "/psci", "migrate", migrate_fn);
> +}
> +
>  /**
>   * load_dtb() - load a device tree binary image into memory
>   * @addr:       the address to load the image at
> @@ -541,6 +604,8 @@ static int load_dtb(hwaddr addr, const struct arm_boot_info *binfo,
>          }
>      }
>  
> +    fdt_add_psci_node(fdt);
> +

This particular change broke one of my favourite use cases, which is
to feed the guest with a hand-crafted DTB, and expect QEMU to just
take it as granted, and not touch it.

I now get an error:

qemu-system-aarch64: FDT: Failed to create subnode /psci: FDT_ERR_EXISTS

The obvious workaround would be to test the presence of the /psci node
before generating it (such as done for the /chosen node, for example).

Thanks,

	M.

-- 
Jazz is not dead, it just smell funny.