From: Alexandru Elisei <alexandru.elisei@arm.com>
To: Andre Przywara <andre.przywara@arm.com>,
Will Deacon <will@kernel.org>,
Julien Thierry <julien.thierry.kdev@gmail.com>
Cc: linux-arm-kernel@lists.infradead.org,
Marc Zyngier <maz@kernel.org>,
kvmarm@lists.cs.columbia.edu, kvm@vger.kernel.org
Subject: Re: [PATCH kvmtool 20/21] hw/serial: ARM/arm64: Use MMIO at higher addresses
Date: Thu, 18 Feb 2021 12:18:38 +0000 [thread overview]
Message-ID: <f16f89dc-78fd-1046-eefc-1dccd468fba8@arm.com> (raw)
In-Reply-To: <bce317a9-2c8e-2254-57c3-e0bea9a13760@arm.com>
Hi Andre,
On 2/17/21 4:48 PM, Alexandru Elisei wrote:
> Hi Andre,
>
> On 12/10/20 2:29 PM, 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 <andre.przywara@arm.com>
>> ---
>> hw/serial.c | 52 ++++++++++++++++++++++++++++++++++++----------------
>> 1 file changed, 36 insertions(+), 16 deletions(-)
>>
>> diff --git a/hw/serial.c b/hw/serial.c
>> index d840eebc..00fb3aa8 100644
>> --- a/hw/serial.c
>> +++ b/hw/serial.c
>> @@ -13,6 +13,24 @@
>>
>> #include <pthread.h>
>>
>> +#if defined(CONFIG_ARM) || defined(CONFIG_ARM64)
>> +#define serial_iobase(nr) (0x1000000 + (nr) * 0x1000)
>> +#define serial_irq(nr) (32 + (nr))
>> +#define SERIAL8250_BUS_TYPE DEVICE_BUS_MMIO
>> +#else
>> +#define serial_iobase_0 0x3f8
>> +#define serial_iobase_1 0x2f8
>> +#define serial_iobase_2 0x3e8
>> +#define serial_iobase_3 0x2e8
>> +#define serial_irq_0 4
>> +#define serial_irq_1 3
>> +#define serial_irq_2 4
>> +#define serial_irq_3 3
> Nitpick: serial_iobase_* and serial_irq_* could be changed to have two leading
> underscores, to stress the fact that they are helpers for serial_iobase() and
> serial_irq() and are not meant to be used by themselves. But that's just personal
> preference, otherwise the patch looks really nice and clean:
>
> Reviewed-by: Alexandru Elisei <alexandru.elisei@arm.com>
I gave it more thought and I think I spoke too soon. I think it would be good to
document in the commit message how you came to the base MMIO address and size
(even if it was just a nice looking number). Also, the CFI flash device has its
memory range described in the memory layout for the architecture, in
arm/include/arm-common/kvm-arch.h. I think it would be a good idea to put the
serial region there, to prevent regressions in the future.
I did the math to make sure there's no overlap with the ioport region (16M >> 16K)
or the flash region (16M + 0x4000 < 32M). I also tested the changes with a kernel
with 4K and 64K pages (I can't access any hardware with 16K pages at the moment),
and everything worked as expected.
Thanks,
Alex
> Thanks,
>
> Alex
>
>> +#define serial_iobase(nr) serial_iobase_##nr
>> +#define serial_irq(nr) serial_irq_##nr
>> +#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 +45,7 @@ struct serial8250_device {
>> struct mutex mutex;
>> u8 id;
>>
>> - u16 iobase;
>> + u32 iobase;
>> u8 irq;
>> u8 irq_state;
>> int txcnt;
>> @@ -65,56 +83,56 @@ 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
>> },
>> @@ -444,7 +462,8 @@ 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;
>> }
>> @@ -467,7 +486,7 @@ 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);
>> }
>>
>> @@ -483,7 +502,8 @@ 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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next prev parent reply other threads:[~2021-02-18 12:37 UTC|newest]
Thread overview: 72+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-12-10 14:28 [PATCH kvmtool 00/21] Unify I/O port and MMIO trap handling Andre Przywara
2020-12-10 14:28 ` [PATCH kvmtool 01/21] ioport: Remove ioport__setup_arch() Andre Przywara
2021-02-10 17:44 ` Alexandru Elisei
2021-02-11 17:16 ` Andre Przywara
2021-02-11 17:32 ` Alexandru Elisei
2021-02-17 16:46 ` Andre Przywara
2021-02-22 10:23 ` Andre Przywara
2021-02-22 15:01 ` Alexandru Elisei
2020-12-10 14:28 ` [PATCH kvmtool 02/21] hw/serial: Use device abstraction for FDT generator function Andre Przywara
2021-02-11 12:05 ` Alexandru Elisei
2021-02-11 17:45 ` Andre Przywara
2020-12-10 14:28 ` [PATCH kvmtool 03/21] ioport: Retire .generate_fdt_node functionality Andre Przywara
2021-02-11 14:05 ` Alexandru Elisei
2021-02-17 15:54 ` Andre Przywara
2021-02-17 16:06 ` Alexandru Elisei
2020-12-10 14:28 ` [PATCH kvmtool 04/21] mmio: Extend handling to include ioport emulation Andre Przywara
2021-02-11 16:10 ` Alexandru Elisei
2021-02-17 17:43 ` Andre Przywara
2021-02-22 15:50 ` Alexandru Elisei
2020-12-10 14:28 ` [PATCH kvmtool 05/21] hw/i8042: Clean up data types Andre Przywara
2021-02-11 16:55 ` Alexandru Elisei
2021-02-17 17:46 ` Andre Przywara
2020-12-10 14:28 ` [PATCH kvmtool 06/21] hw/i8042: Refactor trap handler Andre Przywara
2021-02-11 17:23 ` Alexandru Elisei
2021-02-18 10:34 ` Andre Przywara
2021-02-18 11:17 ` Alexandru Elisei
2021-02-18 11:48 ` Andre Przywara
2021-02-22 16:03 ` Alexandru Elisei
2020-12-10 14:28 ` [PATCH kvmtool 07/21] hw/i8042: Switch to new trap handlers Andre Przywara
2021-02-12 10:41 ` Alexandru Elisei
2021-02-18 12:09 ` Andre Przywara
2021-02-22 16:19 ` Alexandru Elisei
2020-12-10 14:28 ` [PATCH kvmtool 08/21] x86/ioport: Refactor " Andre Przywara
2021-02-12 11:14 ` Alexandru Elisei
2020-12-10 14:28 ` [PATCH kvmtool 09/21] x86/ioport: Switch to new " Andre Przywara
2021-02-12 11:27 ` Alexandru Elisei
2021-02-18 14:05 ` Andre Przywara
2020-12-10 14:28 ` [PATCH kvmtool 10/21] hw/rtc: Refactor " Andre Przywara
2021-02-12 11:56 ` Alexandru Elisei
2020-12-10 14:28 ` [PATCH kvmtool 11/21] hw/rtc: Switch to new trap handler Andre Przywara
2021-02-12 12:02 ` Alexandru Elisei
2020-12-10 14:28 ` [PATCH kvmtool 12/21] hw/vesa: Switch trap handling to use MMIO handler Andre Przywara
2021-02-12 17:50 ` Alexandru Elisei
2020-12-10 14:29 ` [PATCH kvmtool 13/21] hw/serial: Refactor trap handler Andre Przywara
2021-02-16 14:22 ` Alexandru Elisei
2021-02-18 14:41 ` Andre Przywara
2021-02-22 17:40 ` Alexandru Elisei
2021-02-24 14:54 ` Andre Przywara
2020-12-10 14:29 ` [PATCH kvmtool 14/21] hw/serial: Switch to new trap handlers Andre Przywara
2021-02-16 14:31 ` Alexandru Elisei
2020-12-10 14:29 ` [PATCH kvmtool 15/21] vfio: Refactor ioport trap handler Andre Przywara
2021-02-16 14:47 ` Alexandru Elisei
2021-02-18 15:51 ` Andre Przywara
2020-12-10 14:29 ` [PATCH kvmtool 16/21] vfio: Switch to new ioport trap handlers Andre Przywara
2021-02-16 14:52 ` Alexandru Elisei
2020-12-10 14:29 ` [PATCH kvmtool 17/21] virtio: Switch trap handling to use MMIO handler Andre Przywara
2021-02-16 17:03 ` Alexandru Elisei
2021-02-18 16:13 ` Andre Przywara
2020-12-10 14:29 ` [PATCH kvmtool 18/21] pci: " Andre Przywara
2021-02-17 15:14 ` Alexandru Elisei
2020-12-10 14:29 ` [PATCH kvmtool 19/21] Remove ioport specific routines Andre Przywara
2021-02-17 15:49 ` Alexandru Elisei
2021-02-17 16:11 ` Alexandru Elisei
2021-02-18 16:34 ` Andre Przywara
2020-12-10 14:29 ` [PATCH kvmtool 20/21] hw/serial: ARM/arm64: Use MMIO at higher addresses Andre Przywara
2021-02-17 16:48 ` Alexandru Elisei
2021-02-18 12:18 ` Alexandru Elisei [this message]
2021-02-18 16:38 ` Andre Przywara
2020-12-10 14:29 ` [PATCH kvmtool 21/21] hw/rtc: " Andre Przywara
2021-02-18 13:33 ` Alexandru Elisei
2021-02-18 16:41 ` Andre Przywara
2021-02-10 17:44 ` [PATCH kvmtool 00/21] Unify I/O port and MMIO trap handling Alexandru Elisei
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