Re: [PATCH v3 19/25] xen/arm: generate vpl011 node on device tree for domU

[Julien Grall <julien.grall@arm.com>]

Hi Stefano,

On 01/08/18 00:28, Stefano Stabellini wrote:
> Introduce vpl011 support to guests started from Xen: it provides a
> simple way to print output from a guest, as most guests come with a
> pl011 driver. It is also able to provide a working console with
> interrupt support.
> 
> The UART exposed to the guest is a SBSA compatible UART and not a PL011.
> SBSA UART is a subset of PL011 r1p5. A full PL011 implementation in Xen
> would just be too difficult, so guests may require some drivers changes.
> 
> Enable vpl011 conditionally if the user requested it.
> 
> Make set_interrupt_ppi able to handle non-PPI and rename it
> set_interrupt.

It would have been better to have this change in a separate patch.

> 
> Signed-off-by: Stefano Stabellini <stefanos@xilinx.com>
> ---
> Changes in v3:
> - use bool
> - retain BUG_ON(irq < 16)
> - add vpl011 bool to kinfo
> - return error of vpl011 is required but CONFIG_SBSA_VUART_CONSOLE is
>    missing
> 
> Changes in v2:
> - code style fixes
> - make set_interrupt_ppi generic
> - rename set_interrupt_ppi to set_interrupt
> - only make the vpl011 node if the option was enabled
> ---
>   xen/arch/arm/domain_build.c | 95 ++++++++++++++++++++++++++++++++++++++-------
>   xen/arch/arm/kernel.h       |  3 ++
>   2 files changed, 83 insertions(+), 15 deletions(-)
> 
> diff --git a/xen/arch/arm/domain_build.c b/xen/arch/arm/domain_build.c
> index 167a56e..f9fa484 100644
> --- a/xen/arch/arm/domain_build.c
> +++ b/xen/arch/arm/domain_build.c
> @@ -619,19 +619,20 @@ static int __init write_properties(struct domain *d, struct kernel_info *kinfo,
>   
>   typedef __be32 gic_interrupt_t[3];
>   
> -static void __init set_interrupt_ppi(gic_interrupt_t interrupt,
> -                                     unsigned int irq,
> -                                     unsigned int cpumask,
> -                                     unsigned int level)
> +static void __init set_interrupt(gic_interrupt_t interrupt,
> +                                 unsigned int irq,
> +                                 unsigned int cpumask,
> +                                 unsigned int level)
>   {
>       __be32 *cells = interrupt;
> +    bool is_ppi = !!(irq < 32);
>   
>       BUG_ON(irq < 16);
> -    BUG_ON(irq >= 32);
> +    irq -= (is_ppi) ? 16: 32; /* PPIs start at 16, SPIs at 32 */
>   
>       /* See linux Documentation/devicetree/bindings/interrupt-controller/arm,gic.txt */
> -    dt_set_cell(&cells, 1, 1); /* is a PPI */
> -    dt_set_cell(&cells, 1, irq - 16); /* PPIs start at 16 */
> +    dt_set_cell(&cells, 1, is_ppi); /* is a PPI? */
> +    dt_set_cell(&cells, 1, irq);
>       dt_set_cell(&cells, 1, (cpumask << 8) | level);
>   }
>   
> @@ -752,7 +753,7 @@ static int __init make_hypervisor_node(struct domain *d,
>        *  - All CPUs
>        *  TODO: Handle properly the cpumask;
>        */
> -    set_interrupt_ppi(intr, d->arch.evtchn_irq, 0xf, DT_IRQ_TYPE_LEVEL_LOW);
> +    set_interrupt(intr, d->arch.evtchn_irq, 0xf, DT_IRQ_TYPE_LEVEL_LOW);
>       res = fdt_property_interrupts(fdt, &intr, 1);
>       if ( res )
>           return res;
> @@ -1029,15 +1030,15 @@ static int __init make_timer_node(const struct domain *d, void *fdt,
>   
>       irq = timer_get_irq(TIMER_PHYS_SECURE_PPI);
>       dt_dprintk("  Secure interrupt %u\n", irq);
> -    set_interrupt_ppi(intrs[0], irq, 0xf, DT_IRQ_TYPE_LEVEL_LOW);
> +    set_interrupt(intrs[0], irq, 0xf, DT_IRQ_TYPE_LEVEL_LOW);
>   
>       irq = timer_get_irq(TIMER_PHYS_NONSECURE_PPI);
>       dt_dprintk("  Non secure interrupt %u\n", irq);
> -    set_interrupt_ppi(intrs[1], irq, 0xf, DT_IRQ_TYPE_LEVEL_LOW);
> +    set_interrupt(intrs[1], irq, 0xf, DT_IRQ_TYPE_LEVEL_LOW);
>   
>       irq = timer_get_irq(TIMER_VIRT_PPI);
>       dt_dprintk("  Virt interrupt %u\n", irq);
> -    set_interrupt_ppi(intrs[2], irq, 0xf, DT_IRQ_TYPE_LEVEL_LOW);
> +    set_interrupt(intrs[2], irq, 0xf, DT_IRQ_TYPE_LEVEL_LOW);
>   
>       res = fdt_property_interrupts(fdt, intrs, 3);
>       if ( res )
> @@ -1605,9 +1606,9 @@ static int __init make_timer_domU_node(const struct domain *d, void *fdt)
>               return res;
>       }
>   
> -    set_interrupt_ppi(intrs[0], GUEST_TIMER_PHYS_S_PPI, 0xf, DT_IRQ_TYPE_LEVEL_LOW);
> -    set_interrupt_ppi(intrs[1], GUEST_TIMER_PHYS_NS_PPI, 0xf, DT_IRQ_TYPE_LEVEL_LOW);
> -    set_interrupt_ppi(intrs[2], GUEST_TIMER_VIRT_PPI, 0xf, DT_IRQ_TYPE_LEVEL_LOW);
> +    set_interrupt(intrs[0], GUEST_TIMER_PHYS_S_PPI, 0xf, DT_IRQ_TYPE_LEVEL_LOW);
> +    set_interrupt(intrs[1], GUEST_TIMER_PHYS_NS_PPI, 0xf, DT_IRQ_TYPE_LEVEL_LOW);
> +    set_interrupt(intrs[2], GUEST_TIMER_VIRT_PPI, 0xf, DT_IRQ_TYPE_LEVEL_LOW);
>   
>       res = fdt_property(fdt, "interrupts", intrs, sizeof (intrs[0]) * 3);
>       if ( res )
> @@ -1622,6 +1623,56 @@ static int __init make_timer_domU_node(const struct domain *d, void *fdt)
>       return res;
>   }
>   
> +#ifdef CONFIG_SBSA_VUART_CONSOLE
> +static int __init make_vpl011_uart_node(const struct domain *d, void *fdt,
> +                                 int addrcells, int sizecells)
> +{
> +    int res;
> +    gic_interrupt_t intr;
> +    int reg_size = addrcells + sizecells;
> +    int nr_cells = reg_size;
> +    __be32 reg[nr_cells];
> +    __be32 *cells;
> +
> +    res = fdt_begin_node(fdt, "sbsa-pl011");

Node should contain the address in the name. Also, the name should be 
SBSA UART (which happens to be based on PL011 :)).

> +    if ( res )
> +        return res;
> +
> +    res = fdt_property_string(fdt, "compatible", "arm,sbsa-uart");
> +    if ( res )
> +        return res;
> +
> +    cells = &reg[0];
> +    dt_child_set_range(&cells, addrcells, sizecells, GUEST_PL011_BASE,
> +                       GUEST_PL011_SIZE);
> +    if ( res )
> +        return res;
> +    res = fdt_property(fdt, "reg", reg, sizeof(reg));
> +    if ( res )
> +        return res;
> +
> +    set_interrupt(intr, GUEST_VPL011_SPI, 0xf, DT_IRQ_TYPE_LEVEL_HIGH);
> +
> +    res = fdt_property(fdt, "interrupts", intr, sizeof (intr));
> +    if ( res )
> +        return res;
> +
> +    res = fdt_property_cell(fdt, "interrupt-parent",
> +                            GUEST_PHANDLE_GIC);
> +    if ( res )
> +        return res;
> +
> +    /* Use a default baud rate of 115200. */
> +    fdt_property_u32(fdt, "current-speed", 115200);
> +
> +    res = fdt_end_node(fdt);
> +    if ( res )
> +        return res;
> +
> +    return 0;
> +}
> +#endif
> +
>   /*
>    * The max size for DT is 2MB. However, the generated DT is small, 4KB
>    * are enough for now, but we might have to increase it in the feature.
> @@ -1683,6 +1734,18 @@ static int __init prepare_dtb_domU(struct domain *d, struct kernel_info *kinfo)
>       if ( ret )
>           goto err;
>   
> +    if ( kinfo->vpl011 )
> +    {
> +#ifdef CONFIG_SBSA_VUART_CONSOLE
> +        ret = make_vpl011_uart_node(d, kinfo->fdt, addrcells, sizecells);
> +        if ( ret )
> +            goto err;
> +#else
> +        ret = -EINVAL;
> +        goto err;
> +#endif

I would prefer:


ret = -EINVAL
#ifdef CONFIG_SBSA...
	ret = make...
#endif
	if ( ret )
	  goto err;

> +    }
> +
>       ret = fdt_end_node(kinfo->fdt);
>       if ( ret < 0 )
>           goto err;
> @@ -2537,7 +2600,7 @@ static int __init construct_domU(struct domain *d, struct dt_device_node *node)
>   {
>       struct kernel_info kinfo = {};
>       int rc;
> -    u32 mem;
> +    u32 mem, len;
>   
>       printk("*** LOADING DOMU ***\n");
>   
> @@ -2550,6 +2613,8 @@ static int __init construct_domU(struct domain *d, struct dt_device_node *node)
>           return -EINVAL;
>       kinfo.unassigned_mem = (paddr_t)mem << 10;
>   
> +    kinfo.vpl011 = dt_get_property(node, "vpl011", &len) != NULL;
> +
>       d->vcpu = xzalloc_array(struct vcpu *, d->max_vcpus);
>       if ( !d->vcpu )
>           return -ENOMEM;;
> diff --git a/xen/arch/arm/kernel.h b/xen/arch/arm/kernel.h
> index 4a65289..9c9e568 100644
> --- a/xen/arch/arm/kernel.h
> +++ b/xen/arch/arm/kernel.h
> @@ -33,6 +33,9 @@ struct kernel_info {
>       paddr_t dtb_paddr;
>       paddr_t initrd_paddr;
>   
> +    /* Enable pl011 emulation */
> +    bool vpl011;
> +
>       /* loader to use for this kernel */
>       void (*load)(struct kernel_info *info);
>       /* loader specific state */
> 

Cheers,

-- 
Julien Grall

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