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Date: Thu, 15 Apr 2010 13:51:34 -0700
From: "Tom Lyon" <pugs@...co.com>
To: mst@...hat.com, hjk@...utronix.de, gregkh@...e.de,
chrisw@...s-sol.org, joro@...tes.org, avi@...hat.com,
kvm@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH V2] drivers/uio/uio_pci_generic.c: allow access for
non-privileged processes
This is the firt of 2 related, but independent, patches. This is for
uio_pci_generic.c, the next is for uio.c.
The 2 patches were previously one large patch. Changes for this version:
- uio_pci_generic.c just gets extensions so that a single fd can be used
by non-privileged processes for interrupt control and mmaps
- All of the DMA and IOMMU related stuff move to uio.c; no longer a need
to pass ioctls to individual uio drivers. It turns out that the code
is not PCI specific anyways.
- A new ioctl to pin DMA buffers to certain IO virtual addresses for KVM.
- New eventfd based interrupt notifications, including support for PCI
specific MSI and MSI-X interrupts.
- PCI specific code to reset PCI functions before and after use
--- linux-2.6.33/drivers/uio/uio_pci_generic.c 2010-02-24 10:52:17.000000000 -0800
+++ uio-2.6.33/drivers/uio/uio_pci_generic.c 2010-04-15 13:44:25.000000000 -0700
@@ -14,9 +14,9 @@
* # ls -l /sys/bus/pci/devices/0000:00:19.0/driver
* .../0000:00:19.0/driver -> ../../../bus/pci/drivers/uio_pci_generic
*
- * Driver won't bind to devices which do not support the Interrupt Disable Bit
+ * Driver won't bind to devices which do not support MSI, MSI-x, or the Interrupt Disable Bit
* in the command register. All devices compliant to PCI 2.3 (circa 2002) and
- * all compliant PCI Express devices should support this bit.
+ * all compliant PCI Express devices should support one of these.
*/
#include <linux/device.h>
@@ -41,6 +41,39 @@
return container_of(info, struct uio_pci_generic_dev, info);
}
+/* Read/modify/write command register to disable interrupts.
+ * Note: we could cache the value and optimize the read if there was a way to
+ * get notified of user changes to command register through sysfs.
+ * */
+static void irqtoggle(struct uio_pci_generic_dev *gdev, int irq_on)
+{
+ struct pci_dev *pdev = gdev->pdev;
+ unsigned long flags;
+ u16 orig, new;
+
+ spin_lock_irqsave(&gdev->lock, flags);
+ pci_block_user_cfg_access(pdev);
+ pci_read_config_word(pdev, PCI_COMMAND, &orig);
+ new = irq_on ? (orig & ~PCI_COMMAND_INTX_DISABLE)
+ : (orig | PCI_COMMAND_INTX_DISABLE);
+ if (new != orig)
+ pci_write_config_word(gdev->pdev, PCI_COMMAND, new);
+ pci_unblock_user_cfg_access(pdev);
+ spin_unlock_irqrestore(&gdev->lock, flags);
+}
+
+/* irqcontrol is use by userspace to enable/disable interrupts. */
+/* A privileged app can write the PCI_COMMAND register directly,
+ * but we need this for normal apps
+ */
+static int irqcontrol(struct uio_info *info, s32 irq_on)
+{
+ struct uio_pci_generic_dev *gdev = to_uio_pci_generic_dev(info);
+
+ irqtoggle(gdev, irq_on);
+ return 0;
+}
+
/* Interrupt handler. Read/modify/write the command register to disable
* the interrupt. */
static irqreturn_t irqhandler(int irq, struct uio_info *info)
@@ -89,7 +122,7 @@
/* Verify that the device supports Interrupt Disable bit in command register,
* per PCI 2.3, by flipping this bit and reading it back: this bit was readonly
* in PCI 2.2. */
-static int __devinit verify_pci_2_3(struct pci_dev *pdev)
+static int verify_pci_2_3(struct pci_dev *pdev)
{
u16 orig, new;
int err = 0;
@@ -121,17 +154,51 @@
return err;
}
-static int __devinit probe(struct pci_dev *pdev,
+/* we could've used the generic pci sysfs stuff for mmap,
+ * but this way we can allow non-privileged users as long
+ * as /dev/uio* has the right permissions
+ */
+static void uio_do_maps(struct uio_pci_generic_dev *gdev)
+{
+ struct pci_dev *pdev = gdev->pdev;
+ struct uio_info *info = &gdev->info;
+ int i, j;
+ char *name;
+
+ for (i=0, j=0; i<PCI_STD_RESOURCE_END && j<MAX_UIO_MAPS; i++) {
+ if (pci_resource_flags(pdev, i) & IORESOURCE_MEM) {
+ name = kmalloc(8, GFP_KERNEL);
+ if (name == NULL)
+ break;
+ sprintf(name, "membar%d", i);
+ info->mem[j].name = name;
+ info->mem[j].addr = pci_resource_start(pdev, i);
+ info->mem[j].size = pci_resource_len(pdev, i);
+ info->mem[j].memtype = UIO_MEM_PHYS;
+ j++;
+ }
+ }
+ for (i=0, j=0; i<PCI_STD_RESOURCE_END && j<MAX_UIO_PORT_REGIONS; i++) {
+ if (pci_resource_flags(pdev, i) & IORESOURCE_IO) {
+ name = kmalloc(8, GFP_KERNEL);
+ if (name == NULL)
+ break;
+ sprintf(name, "iobar%d", i);
+ info->port[j].name = name;
+ info->port[j].start = pci_resource_start(pdev, i);
+ info->port[j].size = pci_resource_len(pdev, i);
+ info->port[j].porttype = UIO_PORT_X86;
+ j++;
+ }
+ }
+}
+
+static int probe(struct pci_dev *pdev,
const struct pci_device_id *id)
{
struct uio_pci_generic_dev *gdev;
int err;
-
- if (!pdev->irq) {
- dev_warn(&pdev->dev, "No IRQ assigned to device: "
- "no support for interrupts?\n");
- return -ENODEV;
- }
+ int msi=0;
err = pci_enable_device(pdev);
if (err) {
@@ -140,9 +207,26 @@
return err;
}
- err = verify_pci_2_3(pdev);
- if (err)
- goto err_verify;
+ if (pci_find_capability(pdev, PCI_CAP_ID_MSI)) {
+ msi++;
+ pci_disable_msi(pdev);
+ }
+ if (pci_find_capability(pdev, PCI_CAP_ID_MSIX)) {
+ msi++;
+ pci_disable_msix(pdev);
+ }
+
+ if (!msi && !pdev->irq) {
+ dev_warn(&pdev->dev, "No MSI, MSIX, or IRQ assigned to device: "
+ "no support for interrupts?\n");
+ return -ENODEV;
+ }
+
+ if (pdev->irq) {
+ err = verify_pci_2_3(pdev);
+ if (err)
+ goto err_verify;
+ }
gdev = kzalloc(sizeof(struct uio_pci_generic_dev), GFP_KERNEL);
if (!gdev) {
@@ -152,10 +236,15 @@
gdev->info.name = "uio_pci_generic";
gdev->info.version = DRIVER_VERSION;
- gdev->info.irq = pdev->irq;
- gdev->info.irq_flags = IRQF_SHARED;
- gdev->info.handler = irqhandler;
+ if (pdev->irq) {
+ gdev->info.irq = pdev->irq;
+ gdev->info.irq_flags = IRQF_SHARED;
+ gdev->info.handler = irqhandler;
+ gdev->info.irqcontrol = irqcontrol;
+ } else
+ gdev->info.irq = -1;
gdev->pdev = pdev;
+ uio_do_maps(gdev);
spin_lock_init(&gdev->lock);
if (uio_register_device(&pdev->dev, &gdev->info))
--
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