On Tue, 12 Nov 2024 22:02:12 +0000
Juan Pablo Ruiz <jprui...@gmail.com> wrote:
> Some platform devices have large MMIO regions (e.g., GPU reserved memory). For
> certain devices, it's preferable to have a 1:1 address translation in the VM
> to
> avoid modifying driver source code.
Why do we need 1:1 mappings? Shouldn't the device tree describe where
the device lives in the VM address space and the driver should adapt
rather than use hard coded addresses?
How does a user know which devices need fixed base addresses and what
those addresses should be?
> This patch:
... should be split into at least 3 patches.
>
> 1. Increases the VFIO platform bus size from 32MB to 130GB.
That's a very strange and specific size.
> 2. Changes the mmio_size property from 32 to 64 bits.
> 3. Adds an mmio-base property to define the starting MMIO address for mapping
> the VFIO device.
>
> Signed-off-by: Juan Pablo Ruiz juanpablo.r...@unikie.com
> ---
> hw/arm/virt.c | 6 +++---
> hw/core/platform-bus.c | 28 ++++++++++++++++++++++++++--
> hw/vfio/platform.c | 1 +
> include/hw/platform-bus.h | 2 +-
> include/hw/vfio/vfio-platform.h | 1 +
> 5 files changed, 32 insertions(+), 6 deletions(-)
>
> diff --git a/hw/arm/virt.c b/hw/arm/virt.c
> index 1a381e9a2b..9fc8f4425a 100644
> --- a/hw/arm/virt.c
> +++ b/hw/arm/virt.c
> @@ -183,13 +183,13 @@ static const MemMapEntry base_memmap[] = {
> [VIRT_SECURE_GPIO] = { 0x090b0000, 0x00001000 },
> [VIRT_MMIO] = { 0x0a000000, 0x00000200 },
> /* ...repeating for a total of NUM_VIRTIO_TRANSPORTS, each of that size
> */
> - [VIRT_PLATFORM_BUS] = { 0x0c000000, 0x02000000 },
> + [VIRT_PLATFORM_BUS] = { 0x60000000, 0x1FC0000000 }, //
> 130048MB
> [VIRT_SECURE_MEM] = { 0x0e000000, 0x01000000 },
> [VIRT_PCIE_MMIO] = { 0x10000000, 0x2eff0000 },
> [VIRT_PCIE_PIO] = { 0x3eff0000, 0x00010000 },
> [VIRT_PCIE_ECAM] = { 0x3f000000, 0x01000000 },
> /* Actual RAM size depends on initial RAM and device memory settings */
> - [VIRT_MEM] = { GiB, LEGACY_RAMLIMIT_BYTES },
> + [VIRT_MEM] = { 0x2000000000, LEGACY_RAMLIMIT_BYTES },
> };
>
> /*
> @@ -1625,7 +1625,7 @@ static void create_platform_bus(VirtMachineState *vms)
> dev = qdev_new(TYPE_PLATFORM_BUS_DEVICE);
> dev->id = g_strdup(TYPE_PLATFORM_BUS_DEVICE);
> qdev_prop_set_uint32(dev, "num_irqs", PLATFORM_BUS_NUM_IRQS);
> - qdev_prop_set_uint32(dev, "mmio_size",
> vms->memmap[VIRT_PLATFORM_BUS].size);
> + qdev_prop_set_uint64(dev, "mmio_size",
> vms->memmap[VIRT_PLATFORM_BUS].size);
> sysbus_realize_and_unref(SYS_BUS_DEVICE(dev), &error_fatal);
> vms->platform_bus_dev = dev;
>
> diff --git a/hw/core/platform-bus.c b/hw/core/platform-bus.c
> index dc58bf505a..f545fab6e5 100644
> --- a/hw/core/platform-bus.c
> +++ b/hw/core/platform-bus.c
> @@ -22,6 +22,7 @@
> #include "qemu/osdep.h"
> #include "hw/platform-bus.h"
> #include "hw/qdev-properties.h"
> +#include "hw/vfio/vfio-platform.h"
> #include "qapi/error.h"
> #include "qemu/error-report.h"
> #include "qemu/module.h"
> @@ -130,11 +131,29 @@ static void platform_bus_map_mmio(PlatformBusDevice
> *pbus, SysBusDevice *sbdev,
> int n)
> {
> MemoryRegion *sbdev_mr = sysbus_mmio_get_region(sbdev, n);
> + VFIOPlatformDevice *vdev = VFIO_PLATFORM_DEVICE(sbdev);
How do you know it's a vfio-platform device? This completely breaks
device abstraction. Thanks,
Alex
> uint64_t size = memory_region_size(sbdev_mr);
> uint64_t alignment = (1ULL << (63 - clz64(size + size - 1)));
> uint64_t off;
> + uint64_t mmio_base_off;
> bool found_region = false;
>
> + if (vdev->mmio_base) {
> + if(vdev->mmio_base < pbus->mmio.addr ||
> + vdev->mmio_base >= pbus->mmio.addr + pbus->mmio_size){
> + error_report("Platform Bus: MMIO base 0x%"PRIx64
> + " outside platform bus region [0x%"PRIx64",0x%"PRIx64"]",
> + vdev->mmio_base,
> + pbus->mmio.addr,
> + pbus->mmio.addr + pbus->mmio_size);
> + exit(1);
> + }
> +
> + mmio_base_off = vdev->mmio_base - pbus->mmio.addr;
> + } else {
> + mmio_base_off = 0;
> + }
> +
> if (memory_region_is_mapped(sbdev_mr)) {
> /* Region is already mapped, nothing to do */
> return;
> @@ -144,7 +163,7 @@ static void platform_bus_map_mmio(PlatformBusDevice
> *pbus, SysBusDevice *sbdev,
> * Look for empty space in the MMIO space that is naturally aligned with
> * the target device's memory region
> */
> - for (off = 0; off < pbus->mmio_size; off += alignment) {
> + for (off = mmio_base_off; off < pbus->mmio_size; off += alignment) {
> MemoryRegion *mr = memory_region_find(&pbus->mmio, off, size).mr;
> if (!mr) {
> found_region = true;
> @@ -154,6 +173,11 @@ static void platform_bus_map_mmio(PlatformBusDevice
> *pbus, SysBusDevice *sbdev,
> }
> }
>
> + if (vdev->mmio_base && vdev->mmio_base != off + pbus->mmio.addr) {
> + warn_report("Platform Bus: Not able to map in mmio base: 0x%"PRIx64,
> + vdev->mmio_base);
> + }
> +
> if (!found_region) {
> error_report("Platform Bus: Can not fit MMIO region of size %"PRIx64,
> size);
> @@ -206,7 +230,7 @@ static void platform_bus_realize(DeviceState *dev, Error
> **errp)
>
> static Property platform_bus_properties[] = {
> DEFINE_PROP_UINT32("num_irqs", PlatformBusDevice, num_irqs, 0),
> - DEFINE_PROP_UINT32("mmio_size", PlatformBusDevice, mmio_size, 0),
> + DEFINE_PROP_UINT64("mmio_size", PlatformBusDevice, mmio_size, 0),
> DEFINE_PROP_END_OF_LIST()
> };
>
> diff --git a/hw/vfio/platform.c b/hw/vfio/platform.c
> index a85c199c76..cfac564093 100644
> --- a/hw/vfio/platform.c
> +++ b/hw/vfio/platform.c
> @@ -640,6 +640,7 @@ static Property vfio_platform_dev_properties[] = {
> DEFINE_PROP_LINK("iommufd", VFIOPlatformDevice, vbasedev.iommufd,
> TYPE_IOMMUFD_BACKEND, IOMMUFDBackend *),
> #endif
> + DEFINE_PROP_UINT64("mmio-base", VFIOPlatformDevice, mmio_base, 0),
> DEFINE_PROP_END_OF_LIST(),
> };
>
> diff --git a/include/hw/platform-bus.h b/include/hw/platform-bus.h
> index 44f30c5353..4e9913a5d7 100644
> --- a/include/hw/platform-bus.h
> +++ b/include/hw/platform-bus.h
> @@ -34,7 +34,7 @@ struct PlatformBusDevice {
> SysBusDevice parent_obj;
>
> /*< public >*/
> - uint32_t mmio_size;
> + uint64_t mmio_size;
> MemoryRegion mmio;
>
> uint32_t num_irqs;
> diff --git a/include/hw/vfio/vfio-platform.h b/include/hw/vfio/vfio-platform.h
> index c414c3dffc..90575b5852 100644
> --- a/include/hw/vfio/vfio-platform.h
> +++ b/include/hw/vfio/vfio-platform.h
> @@ -59,6 +59,7 @@ struct VFIOPlatformDevice {
> uint32_t mmap_timeout; /* delay to re-enable mmaps after interrupt */
> QEMUTimer *mmap_timer; /* allows fast-path resume after IRQ hit */
> QemuMutex intp_mutex; /* protect the intp_list IRQ state */
> + uint64_t mmio_base; /* base address to start looking for mmio */
> bool irqfd_allowed; /* debug option to force irqfd on/off */
> };
> typedef struct VFIOPlatformDevice VFIOPlatformDevice;
