Hi Andre,

I think you forgot to change the way the address is generated in
serial8250_generate_fdt_node, it's still KVM_IOPORT_AREA + dev->iobase. It's
technically correct, as KVM_IOPORT_AREA == ARM_IOPORT_AREA == 0x0, but very
confusing (and prone to breakage is something changes in the memory layout).

One more comment below.

On 2/25/21 12:59 AM, Andre Przywara wrote:
> Using the UART devices at their legacy I/O addresses as set by IBM in
> 1981 was a kludge we used for simplicity on ARM platforms as well.
> However this imposes problems due to their missing alignment and overlap
> with the PCI I/O address space.
>
> Now that we can switch a device easily between using ioports and MMIO,
> let's move the UARTs out of the first 4K of memory on ARM platforms.
>
> That should be transparent for well behaved guests, since the change is
> naturally reflected in the device tree. Even "earlycon" keeps working,
> as the stdout-path property is adjusted automatically.
>
> People providing direct earlycon parameters via the command line need to
> adjust it to: "earlycon=uart,mmio,0x1000000".
>
> Signed-off-by: Andre Przywara <[email protected]>
> ---
>  arm/include/arm-common/kvm-arch.h |  3 +++
>  hw/serial.c                       | 45 ++++++++++++++++++++-----------
>  2 files changed, 32 insertions(+), 16 deletions(-)
>
> diff --git a/arm/include/arm-common/kvm-arch.h 
> b/arm/include/arm-common/kvm-arch.h
> index b12255b0..633ea8fa 100644
> --- a/arm/include/arm-common/kvm-arch.h
> +++ b/arm/include/arm-common/kvm-arch.h
> @@ -28,6 +28,9 @@
>  #define ARM_IOPORT_SIZE              (1U << 16)
>  
>  
> +#define ARM_UART_MMIO_BASE   ARM_MMIO_AREA
> +#define ARM_UART_MMIO_SIZE   0x10000
> +
>  #define KVM_FLASH_MMIO_BASE  (ARM_MMIO_AREA + 0x1000000)
>  #define KVM_FLASH_MAX_SIZE   0x1000000
>  
> diff --git a/hw/serial.c b/hw/serial.c
> index 4be188a1..1854add2 100644
> --- a/hw/serial.c
> +++ b/hw/serial.c
> @@ -13,6 +13,17 @@
>  
>  #include <pthread.h>
>  
> +#if defined(CONFIG_ARM) || defined(CONFIG_ARM64)
> +#define serial_iobase(nr)    (ARM_UART_MMIO_BASE + (nr) * 0x1000)
> +#define serial_irq(nr)               (32 + (nr))
> +#define SERIAL8250_BUS_TYPE  DEVICE_BUS_MMIO
> +#else
> +#define serial_iobase(nr)    ((((nr) & 1) ? 0x200 : 0x300) + \
> +                              ((nr) >= 2 ? 0xe8 : 0xf8))
> +#define serial_irq(nr)               (((nr) & 1) ? 3 : 4)

Those two defines are hard to read, is there a reason for changing them from v1?
They looked a lot more readable in v1.

Thanks,

Alex

> +#define SERIAL8250_BUS_TYPE  DEVICE_BUS_IOPORT
> +#endif
> +
>  /*
>   * This fakes a U6_16550A. The fifo len needs to be 64 as the kernel
>   * expects that for autodetection.
> @@ -27,7 +38,7 @@ struct serial8250_device {
>       struct mutex            mutex;
>       u8                      id;
>  
> -     u16                     iobase;
> +     u32                     iobase;
>       u8                      irq;
>       u8                      irq_state;
>       int                     txcnt;
> @@ -65,56 +76,56 @@ static struct serial8250_device devices[] = {
>       /* ttyS0 */
>       [0]     = {
>               .dev_hdr = {
> -                     .bus_type       = DEVICE_BUS_IOPORT,
> +                     .bus_type       = SERIAL8250_BUS_TYPE,
>                       .data           = serial8250_generate_fdt_node,
>               },
>               .mutex                  = MUTEX_INITIALIZER,
>  
>               .id                     = 0,
> -             .iobase                 = 0x3f8,
> -             .irq                    = 4,
> +             .iobase                 = serial_iobase(0),
> +             .irq                    = serial_irq(0),
>  
>               SERIAL_REGS_SETTING
>       },
>       /* ttyS1 */
>       [1]     = {
>               .dev_hdr = {
> -                     .bus_type       = DEVICE_BUS_IOPORT,
> +                     .bus_type       = SERIAL8250_BUS_TYPE,
>                       .data           = serial8250_generate_fdt_node,
>               },
>               .mutex                  = MUTEX_INITIALIZER,
>  
>               .id                     = 1,
> -             .iobase                 = 0x2f8,
> -             .irq                    = 3,
> +             .iobase                 = serial_iobase(1),
> +             .irq                    = serial_irq(1),
>  
>               SERIAL_REGS_SETTING
>       },
>       /* ttyS2 */
>       [2]     = {
>               .dev_hdr = {
> -                     .bus_type       = DEVICE_BUS_IOPORT,
> +                     .bus_type       = SERIAL8250_BUS_TYPE,
>                       .data           = serial8250_generate_fdt_node,
>               },
>               .mutex                  = MUTEX_INITIALIZER,
>  
>               .id                     = 2,
> -             .iobase                 = 0x3e8,
> -             .irq                    = 4,
> +             .iobase                 = serial_iobase(2),
> +             .irq                    = serial_irq(2),
>  
>               SERIAL_REGS_SETTING
>       },
>       /* ttyS3 */
>       [3]     = {
>               .dev_hdr = {
> -                     .bus_type       = DEVICE_BUS_IOPORT,
> +                     .bus_type       = SERIAL8250_BUS_TYPE,
>                       .data           = serial8250_generate_fdt_node,
>               },
>               .mutex                  = MUTEX_INITIALIZER,
>  
>               .id                     = 3,
> -             .iobase                 = 0x2e8,
> -             .irq                    = 3,
> +             .iobase                 = serial_iobase(3),
> +             .irq                    = serial_irq(3),
>  
>               SERIAL_REGS_SETTING
>       },
> @@ -439,7 +450,8 @@ static int serial8250__device_init(struct kvm *kvm,
>               return r;
>  
>       ioport__map_irq(&dev->irq);
> -     r = kvm__register_pio(kvm, dev->iobase, 8, serial8250_mmio, dev);
> +     r = kvm__register_iotrap(kvm, dev->iobase, 8, serial8250_mmio, dev,
> +                              SERIAL8250_BUS_TYPE);
>  
>       return r;
>  }
> @@ -462,7 +474,7 @@ cleanup:
>       for (j = 0; j <= i; j++) {
>               struct serial8250_device *dev = &devices[j];
>  
> -             kvm__deregister_pio(kvm, dev->iobase);
> +             kvm__deregister_iotrap(kvm, dev->iobase, SERIAL8250_BUS_TYPE);
>               device__unregister(&dev->dev_hdr);
>       }
>  
> @@ -478,7 +490,8 @@ int serial8250__exit(struct kvm *kvm)
>       for (i = 0; i < ARRAY_SIZE(devices); i++) {
>               struct serial8250_device *dev = &devices[i];
>  
> -             r = kvm__deregister_pio(kvm, dev->iobase);
> +             r = kvm__deregister_iotrap(kvm, dev->iobase,
> +                                        SERIAL8250_BUS_TYPE);
>               if (r < 0)
>                       return r;
>               device__unregister(&dev->dev_hdr);
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