On Thu, Mar 25, 2010 at 3:15 AM, Michael S. Tsirkin <mst@xxxxxxxxxx> wrote:
> On Thu, Mar 25, 2010 at 12:09:36AM -0600, Cam Macdonell wrote:
>> This patch adds a driver for my shared memory PCI device using the uio_pci
>> interface. The driver has three memory regions. The first memory region is for
>> device registers for sending interrupts. The second BAR is for receiving MSI-X
>> interrupts and the third memory region maps the shared memory. The device only
>> exports the first and third memory regions to userspace.
>>
>> This driver supports MSI-X and regular pin interrupts. Currently, the number of
>> MSI vectors is set to 4 which could be increased, but the driver will work with
>> fewer vectors. If MSI is not available, then regular interrupts will be used.
>
> Some high level questions, sorry if they have been raised in the past:
> - Can this device use virtio framework?
> This gives us some standards to work off, with feature negotiation,
> ability to detect config changes, support for non-PCI
> platforms, decent documentation that is easy to extend,
> legal id range to use.
> You would thus have your driver in uio/uio_virtio_shmem.c
There has been previous discussion of virtio, however while virtio is
good for exporting guest memory, it's not ideal for importing memory
into a guest.
>
> - Why are you using 32 bit long memory accesses for interrupts?
> 16 bit IO eould be enough and it's faster. This what virtio-pci does.
>
> - How was the driver tested?
I have some test programs in the git repo I linked to. I've been
using some simple producer/consumer tests to test the interrupt
framework.
>
>> ---
>> drivers/uio/Kconfig | 8 ++
>> drivers/uio/Makefile | 1 +
>> drivers/uio/uio_ivshmem.c | 235 +++++++++++++++++++++++++++++++++++++++++++++
>> 3 files changed, 244 insertions(+), 0 deletions(-)
>> create mode 100644 drivers/uio/uio_ivshmem.c
>>
>> diff --git a/drivers/uio/Kconfig b/drivers/uio/Kconfig
>> index 1da73ec..b92cded 100644
>> --- a/drivers/uio/Kconfig
>> +++ b/drivers/uio/Kconfig
>> @@ -74,6 +74,14 @@ config UIO_SERCOS3
>>
>> If you compile this as a module, it will be called uio_sercos3.
>>
>> +config UIO_IVSHMEM
>> + tristate "KVM shared memory PCI driver"
>> + default n
>> + help
>> + Userspace I/O interface for the KVM shared memory device. This
>> + driver will make available two memory regions, the first is
>> + registers and the second is a region for sharing between VMs.
>> +
>> config UIO_PCI_GENERIC
>> tristate "Generic driver for PCI 2.3 and PCI Express cards"
>> depends on PCI
>> diff --git a/drivers/uio/Makefile b/drivers/uio/Makefile
>> index 18fd818..25c1ca5 100644
>> --- a/drivers/uio/Makefile
>> +++ b/drivers/uio/Makefile
>> @@ -6,3 +6,4 @@ obj-$(CONFIG_UIO_AEC) += uio_aec.o
>> obj-$(CONFIG_UIO_SERCOS3) += uio_sercos3.o
>> obj-$(CONFIG_UIO_PCI_GENERIC) += uio_pci_generic.o
>> obj-$(CONFIG_UIO_NETX) += uio_netx.o
>> +obj-$(CONFIG_UIO_IVSHMEM) += uio_ivshmem.o
>> diff --git a/drivers/uio/uio_ivshmem.c b/drivers/uio/uio_ivshmem.c
>> new file mode 100644
>> index 0000000..607435b
>> --- /dev/null
>> +++ b/drivers/uio/uio_ivshmem.c
>> @@ -0,0 +1,235 @@
>> +/*
>> + * UIO IVShmem Driver
>> + *
>> + * (C) 2009 Cam Macdonell
>> + * based on Hilscher CIF card driver (C) 2007 Hans J. Koch <hjk@xxxxxxxxxxxxx>
>> + *
>> + * Licensed under GPL version 2 only.
>> + *
>> + */
>> +
>> +#include <linux/device.h>
>> +#include <linux/module.h>
>> +#include <linux/pci.h>
>> +#include <linux/uio_driver.h>
>> +
>> +#include <asm/io.h>
>> +
>> +#define IntrStatus 0x04
>> +#define IntrMask 0x00
>> +
>> +struct ivshmem_info {
>> + struct uio_info *uio;
>> + struct pci_dev *dev;
>> + char (*msix_names)[256];
>> + struct msix_entry *msix_entries;
>> + int nvectors;
>> +};
>> +
>> +static irqreturn_t ivshmem_handler(int irq, struct uio_info *dev_info)
>> +{
>> +
>> + void __iomem *plx_intscr = dev_info->mem[0].internal_addr
>> + + IntrStatus;
>> + u32 val;
>> +
>> + val = readl(plx_intscr);
>> + if (val == 0)
>> + return IRQ_NONE;
>> +
>> + printk(KERN_INFO "Regular interrupt (val = %d)\n", val);
>> + return IRQ_HANDLED;
>> +}
>> +
>> +static irqreturn_t ivshmem_msix_handler(int irq, void *opaque)
>> +{
>> +
>> + struct uio_info * dev_info = (struct uio_info *) opaque;
>> +
>> + /* we have to do this explicitly when using MSI-X */
>> + uio_event_notify(dev_info);
>> + printk(KERN_INFO "MSI-X interrupt (%d)\n", irq);
>> + return IRQ_HANDLED;
>> +
>> +}
>> +
>> +static int request_msix_vectors(struct ivshmem_info *ivs_info, int nvectors)
>> +{
>> + int i, err;
>> + const char *name = "ivshmem";
>> +
>> + printk(KERN_INFO "devname is %s\n", name);
>> + ivs_info->nvectors = nvectors;
>> +
>> +
>> + ivs_info->msix_entries = kmalloc(nvectors * sizeof *ivs_info->msix_entries,
>> + GFP_KERNEL);
>> + ivs_info->msix_names = kmalloc(nvectors * sizeof *ivs_info->msix_names,
>> + GFP_KERNEL);
>> +
>> + for (i = 0; i < nvectors; ++i)
>> + ivs_info->msix_entries[i].entry = i;
>> +
>> + err = pci_enable_msix(ivs_info->dev, ivs_info->msix_entries,
>> + ivs_info->nvectors);
>> + if (err > 0) {
>> + ivs_info->nvectors = err; /* msi-x positive error code
>> + returns the number available*/
>> + err = pci_enable_msix(ivs_info->dev, ivs_info->msix_entries,
>> + ivs_info->nvectors);
>> + if (err > 0) {
>> + printk(KERN_INFO "no MSI (%d). Back to INTx.\n", err);
>> + return -ENOSPC;
>> + }
>> + }
>> +
>> + printk(KERN_INFO "err is %d\n", err);
>> + if (err) return err;
>> +
>> + for (i = 0; i < ivs_info->nvectors; i++) {
>> +
>> + snprintf(ivs_info->msix_names[i], sizeof *ivs_info->msix_names,
>> + "%s-config", name);
>> +
>> + ivs_info->msix_entries[i].entry = i;
>> + err = request_irq(ivs_info->msix_entries[i].vector,
>> + ivshmem_msix_handler, 0,
>> + ivs_info->msix_names[i], ivs_info->uio);
>> +
>> + if (err) {
>> + return -ENOSPC;
>> + }
>> + }
>> +
>> + return 0;
>> +}
>> +
>> +static int __devinit ivshmem_pci_probe(struct pci_dev *dev,
>> + const struct pci_device_id *id)
>> +{
>> + struct uio_info *info;
>> + struct ivshmem_info * ivshmem_info;
>> + int nvectors = 4;
>> +
>> + info = kzalloc(sizeof(struct uio_info), GFP_KERNEL);
>> + if (!info)
>> + return -ENOMEM;
>> +
>> + ivshmem_info = kzalloc(sizeof(struct ivshmem_info), GFP_KERNEL);
>> + if (!ivshmem_info) {
>> + kfree(info);
>> + return -ENOMEM;
>> + }
>> +
>> + if (pci_enable_device(dev))
>> + goto out_free;
>> +
>> + if (pci_request_regions(dev, "ivshmem"))
>> + goto out_disable;
>> +
>> + info->mem[0].addr = pci_resource_start(dev, 0);
>> + if (!info->mem[0].addr)
>> + goto out_release;
>> +
>> + info->mem[0].size = pci_resource_len(dev, 0);
>> + info->mem[0].internal_addr = pci_ioremap_bar(dev, 0);
>> + if (!info->mem[0].internal_addr) {
>> + printk(KERN_INFO "got a null");
>> + goto out_release;
>> + }
>> +
>> + info->mem[0].memtype = UIO_MEM_PHYS;
>> +
>> + info->mem[1].addr = pci_resource_start(dev, 2);
>> + if (!info->mem[1].addr)
>> + goto out_unmap;
>> + info->mem[1].internal_addr = pci_ioremap_bar(dev, 2);
>> + if (!info->mem[1].internal_addr)
>> + goto out_unmap;
>> +
>> + info->mem[1].size = pci_resource_len(dev, 2);
>> + info->mem[1].memtype = UIO_MEM_PHYS;
>> +
>> + ivshmem_info->uio = info;
>> + ivshmem_info->dev = dev;
>> +
>> + if (request_msix_vectors(ivshmem_info, nvectors) != 0) {
>> + printk(KERN_INFO "regular IRQs\n");
>> + info->irq = dev->irq;
>> + info->irq_flags = IRQF_SHARED;
>> + info->handler = ivshmem_handler;
>> + writel(0xffffffff, info->mem[0].internal_addr + IntrMask);
>> + } else {
>> + printk(KERN_INFO "MSI-X enabled\n");
>> + info->irq = -1;
>> + }
>> +
>> + info->name = "ivshmem";
>> + info->version = "0.0.1";
>> +
>> + if (uio_register_device(&dev->dev, info))
>> + goto out_unmap2;
>> +
>> + pci_set_drvdata(dev, info);
>> +
>> +
>> + return 0;
>> +out_unmap2:
>> + iounmap(info->mem[2].internal_addr);
>> +out_unmap:
>> + iounmap(info->mem[0].internal_addr);
>> +out_release:
>> + pci_release_regions(dev);
>> +out_disable:
>> + pci_disable_device(dev);
>> +out_free:
>> + kfree (info);
>> + return -ENODEV;
>> +}
>> +
>> +static void ivshmem_pci_remove(struct pci_dev *dev)
>> +{
>> + struct uio_info *info = pci_get_drvdata(dev);
>> +
>> + uio_unregister_device(info);
>> + pci_release_regions(dev);
>> + pci_disable_device(dev);
>> + pci_set_drvdata(dev, NULL);
>> + iounmap(info->mem[0].internal_addr);
>> +
>> + kfree (info);
>> +}
>> +
>> +static struct pci_device_id ivshmem_pci_ids[] __devinitdata = {
>> + {
>> + .vendor = 0x1af4,
>> + .device = 0x1110,
>> + .subvendor = PCI_ANY_ID,
>> + .subdevice = PCI_ANY_ID,
>> + },
>> + { 0, }
>> +};
>> +
>> +static struct pci_driver ivshmem_pci_driver = {
>> + .name = "uio_ivshmem",
>> + .id_table = ivshmem_pci_ids,
>> + .probe = ivshmem_pci_probe,
>> + .remove = ivshmem_pci_remove,
>> +};
>> +
>> +static int __init ivshmem_init_module(void)
>> +{
>> + return pci_register_driver(&ivshmem_pci_driver);
>> +}
>> +
>> +static void __exit ivshmem_exit_module(void)
>> +{
>> + pci_unregister_driver(&ivshmem_pci_driver);
>> +}
>> +
>> +module_init(ivshmem_init_module);
>> +module_exit(ivshmem_exit_module);
>> +
>> +MODULE_DEVICE_TABLE(pci, ivshmem_pci_ids);
>> +MODULE_LICENSE("GPL v2");
>> +MODULE_AUTHOR("Cam Macdonell");
>> --
>> 1.6.6.1
>>
>> --
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>
>
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