[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] Status of FLR in Xen 4.4
On 26/09/13 17:05, Matthias wrote: > Hi everyone, > > I would like to ask what the current status of FLR, or better of FLR > emulation is in latest Xen and if we can expect better support in the > future. What are these cards, are they multi-function and do they actually support FLR? Many graphics cards do not. I have the following hack to pciback to fallback to a bus reset for multi-function devices without FLR. Does it help for your use case? You will need to ensure that all functions are co-assigned to the same domain. David 8<--------------------------------------- diff --git a/drivers/xen/xen-pciback/pci_stub.c b/drivers/xen/xen-pciback/pci_stub.c index 4e8ba38..5a03e63 100644 --- a/drivers/xen/xen-pciback/pci_stub.c +++ b/drivers/xen/xen-pciback/pci_stub.c @@ -14,6 +14,7 @@ #include <linux/wait.h> #include <linux/sched.h> #include <linux/atomic.h> +#include <linux/delay.h> #include <xen/events.h> #include <asm/xen/pci.h> #include <asm/xen/hypervisor.h> @@ -43,6 +44,7 @@ struct pcistub_device { struct kref kref; struct list_head dev_list; spinlock_t lock; + bool created_reset_file; struct pci_dev *dev; struct xen_pcibk_device *pdev;/* non-NULL if struct pci_dev is in use */ @@ -60,6 +62,114 @@ static LIST_HEAD(pcistub_devices); static int initialize_devices; static LIST_HEAD(seized_devices); +/* + * pci_reset_function() will only work if there is a mechanism to + * reset that single function (e.g., FLR or a D-state transition). + * For PCI hardware that has two or more functions but no per-function + * reset, we can do a bus reset iff all the functions are co-assigned + * to the same domain. + * + * If a function has no per-function reset mechanism the 'reset' sysfs + * file that the toolstack uses to reset a function prior to assigning + * the device will be missing. In this case, pciback adds its own + * which will try a bus reset. + * + * Note: pciback does not check for co-assigment before doing a bus + * reset, only that the devices are bound to pciback. The toolstack + * is assumed to have done the right thing. + */ +static int __pcistub_reset_function(struct pci_dev *dev) +{ + struct pci_dev *pdev; + u16 ctrl; + int ret; + + ret = __pci_reset_function_locked(dev); + if (ret == 0) + return 0; + + if (pci_is_root_bus(dev->bus) || dev->subordinate || !dev->bus->self) + return -ENOTTY; + + list_for_each_entry(pdev, &dev->bus->devices, bus_list) { + if (pdev != dev && (!pdev->driver + || strcmp(pdev->driver->name, "pciback"))) + return -ENOTTY; + pci_save_state(pdev); + } + + pci_read_config_word(dev->bus->self, PCI_BRIDGE_CONTROL, &ctrl); + ctrl |= PCI_BRIDGE_CTL_BUS_RESET; + pci_write_config_word(dev->bus->self, PCI_BRIDGE_CONTROL, ctrl); + msleep(200); + + ctrl &= ~PCI_BRIDGE_CTL_BUS_RESET; + pci_write_config_word(dev->bus->self, PCI_BRIDGE_CONTROL, ctrl); + msleep(200); + + list_for_each_entry(pdev, &dev->bus->devices, bus_list) + pci_restore_state(pdev); + + return 0; +} + +static int pcistub_reset_function(struct pci_dev *dev) +{ + int ret; + + device_lock(&dev->dev); + ret = __pcistub_reset_function(dev); + device_unlock(&dev->dev); + + return ret; +} + +static ssize_t pcistub_reset_store(struct device *dev, + struct device_attribute *attr, + const char *buf, size_t count) +{ + struct pci_dev *pdev = to_pci_dev(dev); + unsigned long val; + ssize_t result = strict_strtoul(buf, 0, &val); + + if (result < 0) + return result; + + if (val != 1) + return -EINVAL; + + result = pcistub_reset_function(pdev); + if (result < 0) + return result; + return count; +} +static DEVICE_ATTR(reset, 0200, NULL, pcistub_reset_store); + +static int pcistub_try_create_reset_file(struct pcistub_device *psdev) +{ + struct device *dev = &psdev->dev->dev; + struct sysfs_dirent *reset_dirent; + int ret; + + reset_dirent = sysfs_get_dirent(dev->kobj.sd, NULL, "reset"); + if (reset_dirent) { + sysfs_put(reset_dirent); + return 0; + } + + ret = device_create_file(dev, &dev_attr_reset); + if (ret < 0) + return ret; + psdev->created_reset_file = true; + return 0; +} + +static void pcistub_remove_reset_file(struct pcistub_device *psdev) +{ + if (psdev && psdev->created_reset_file) + device_remove_file(&psdev->dev->dev, &dev_attr_reset); +} + static struct pcistub_device *pcistub_device_alloc(struct pci_dev *dev) { struct pcistub_device *psdev; @@ -95,12 +205,15 @@ static void pcistub_device_release(struct kref *kref) dev_dbg(&dev->dev, "pcistub_device_release\n"); + pcistub_remove_reset_file(psdev); + xen_unregister_device_domain_owner(dev); /* Call the reset function which does not take lock as this * is called from "unbind" which takes a device_lock mutex. */ - __pci_reset_function_locked(dev); + __pcistub_reset_function(psdev->dev); + if (pci_load_and_free_saved_state(dev, &dev_data->pci_saved_state)) dev_dbg(&dev->dev, "Could not reload PCI state\n"); else @@ -268,7 +381,7 @@ void pcistub_put_pci_dev(struct pci_dev *dev) /* This is OK - we are running from workqueue context * and want to inhibit the user from fiddling with 'reset' */ - pci_reset_function(dev); + pcistub_reset_function(psdev->dev); pci_restore_state(psdev->dev); /* This disables the device. */ @@ -392,7 +505,7 @@ static int pcistub_init_device(struct pci_dev *dev) dev_err(&dev->dev, "Could not store PCI conf saved state!\n"); else { dev_dbg(&dev->dev, "resetting (FLR, D3, etc) the device\n"); - __pci_reset_function_locked(dev); + __pcistub_reset_function(dev); pci_restore_state(dev); } /* Now disable the device (this also ensures some private device @@ -467,6 +580,10 @@ static int pcistub_seize(struct pci_dev *dev) if (!psdev) return -ENOMEM; + err = pcistub_try_create_reset_file(psdev); + if (err < 0) + goto out; + spin_lock_irqsave(&pcistub_devices_lock, flags); if (initialize_devices) { @@ -485,10 +602,9 @@ static int pcistub_seize(struct pci_dev *dev) } spin_unlock_irqrestore(&pcistub_devices_lock, flags); - +out: if (err) pcistub_device_put(psdev); - return err; } _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxx http://lists.xen.org/xen-devel
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