1 | /* |
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2 | * PCI Backend Operations - respond to PCI requests from Frontend |
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3 | * |
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4 | * Author: Ryan Wilson <hap9@epoch.ncsc.mil> |
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5 | */ |
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6 | #include <linux/module.h> |
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7 | #include <asm/bitops.h> |
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8 | #include <xen/evtchn.h> |
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9 | #include "pciback.h" |
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10 | |
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11 | int verbose_request = 0; |
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12 | module_param(verbose_request, int, 0644); |
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13 | |
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14 | /* Ensure a device is "turned off" and ready to be exported. |
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15 | * (Also see pciback_config_reset to ensure virtual configuration space is |
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16 | * ready to be re-exported) |
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17 | */ |
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18 | void pciback_reset_device(struct pci_dev *dev) |
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19 | { |
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20 | u16 cmd; |
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21 | |
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22 | /* Disable devices (but not bridges) */ |
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23 | if (dev->hdr_type == PCI_HEADER_TYPE_NORMAL) { |
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24 | pci_disable_device(dev); |
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25 | |
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26 | pci_write_config_word(dev, PCI_COMMAND, 0); |
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27 | |
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28 | dev->is_enabled = 0; |
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29 | dev->is_busmaster = 0; |
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30 | } else { |
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31 | pci_read_config_word(dev, PCI_COMMAND, &cmd); |
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32 | if (cmd & (PCI_COMMAND_INVALIDATE)) { |
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33 | cmd &= ~(PCI_COMMAND_INVALIDATE); |
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34 | pci_write_config_word(dev, PCI_COMMAND, cmd); |
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35 | |
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36 | dev->is_busmaster = 0; |
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37 | } |
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38 | } |
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39 | } |
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40 | |
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41 | static inline void test_and_schedule_op(struct pciback_device *pdev) |
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42 | { |
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43 | /* Check that frontend is requesting an operation and that we are not |
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44 | * already processing a request */ |
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45 | if (test_bit(_XEN_PCIF_active, (unsigned long *)&pdev->sh_info->flags) |
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46 | && !test_and_set_bit(_PDEVF_op_active, &pdev->flags)) |
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47 | schedule_work(&pdev->op_work); |
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48 | } |
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49 | |
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50 | /* Performing the configuration space reads/writes must not be done in atomic |
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51 | * context because some of the pci_* functions can sleep (mostly due to ACPI |
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52 | * use of semaphores). This function is intended to be called from a work |
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53 | * queue in process context taking a struct pciback_device as a parameter */ |
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54 | void pciback_do_op(void *data) |
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55 | { |
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56 | struct pciback_device *pdev = data; |
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57 | struct pci_dev *dev; |
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58 | struct xen_pci_op *op = &pdev->sh_info->op; |
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59 | |
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60 | dev = pciback_get_pci_dev(pdev, op->domain, op->bus, op->devfn); |
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61 | |
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62 | if (dev == NULL) |
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63 | op->err = XEN_PCI_ERR_dev_not_found; |
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64 | else if (op->cmd == XEN_PCI_OP_conf_read) |
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65 | op->err = pciback_config_read(dev, op->offset, op->size, |
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66 | &op->value); |
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67 | else if (op->cmd == XEN_PCI_OP_conf_write) |
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68 | op->err = pciback_config_write(dev, op->offset, op->size, |
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69 | op->value); |
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70 | else |
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71 | op->err = XEN_PCI_ERR_not_implemented; |
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72 | |
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73 | /* Tell the driver domain that we're done. */ |
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74 | wmb(); |
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75 | clear_bit(_XEN_PCIF_active, (unsigned long *)&pdev->sh_info->flags); |
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76 | notify_remote_via_irq(pdev->evtchn_irq); |
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77 | |
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78 | /* Mark that we're done. */ |
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79 | smp_mb__before_clear_bit(); /* /after/ clearing PCIF_active */ |
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80 | clear_bit(_PDEVF_op_active, &pdev->flags); |
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81 | smp_mb__after_clear_bit(); /* /before/ final check for work */ |
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82 | |
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83 | /* Check to see if the driver domain tried to start another request in |
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84 | * between clearing _XEN_PCIF_active and clearing _PDEVF_op_active. */ |
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85 | test_and_schedule_op(pdev); |
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86 | } |
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87 | |
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88 | irqreturn_t pciback_handle_event(int irq, void *dev_id, struct pt_regs *regs) |
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89 | { |
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90 | struct pciback_device *pdev = dev_id; |
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91 | |
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92 | test_and_schedule_op(pdev); |
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93 | |
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94 | return IRQ_HANDLED; |
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95 | } |
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