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Allow PM reset on multi-function PCI devices

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It turns out that a PCI Power Management reset only affects individual
functions, and not the whole device.

The PCI Power Management spec talks about resetting the 'device' rather
than the 'function', but Intel's Dexuan Cui informs me that it is
actually a per-function reset.

Also, Yu Zhao has added pci_pm_reset() to the kernel, and it doesn't
reject multi-function devices, so it must be true! :-)

(A side issue is that we could defer the PM reset to the kernel if we
could detect that the kernel has PM reset support, but barring version
number checks we don't have a way to detect that support)

* src/pci.c: remove the pciDeviceContainsOtherFunctions() check from
  pciTryPowerManagementReset() and prefer PM reset over bus reset
  where both are available

Cc: Cui, Dexuan <dexuan.cui@intel.com>
Cc: Yu Zhao <yu.zhao@intel.com>
This commit is contained in:
Mark McLoughlin 2009-08-14 08:31:11 +01:00
parent d4528d9ac2
commit 64a6682b93
1 changed files with 10 additions and 40 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

50
src/pci.c
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@ -402,29 +402,6 @@ pciBusContainsOtherDevices(virConnectPtr conn, pciDevice *dev)
return 1;
}
/* Any other functions on this device ? */
static int
pciSharesDevice(pciDevice *a, pciDevice *b)
{
return
a->domain == b->domain &&
a->bus == b->bus &&
a->slot == b->slot &&
a->function != b->function;
}
static int
pciDeviceContainsOtherFunctions(virConnectPtr conn, pciDevice *dev)
{
pciDevice *matched = NULL;
if (pciIterDevices(conn, pciSharesDevice, dev, &matched) < 0)
return 1;
if (!matched)
return 0;
pciFreeDevice(conn, matched);
return 1;
}
/* Is @a the parent of @b ? */
static int
pciIsParent(pciDevice *a, pciDevice *b)
@ -529,7 +506,7 @@ out:
* above we require the device supports a full internal reset.
*/
static int
pciTryPowerManagementReset(virConnectPtr conn, pciDevice *dev)
pciTryPowerManagementReset(virConnectPtr conn ATTRIBUTE_UNUSED, pciDevice *dev)
{
uint8_t config_space[PCI_CONF_LEN];
uint32_t ctl;
@ -537,16 +514,6 @@ pciTryPowerManagementReset(virConnectPtr conn, pciDevice *dev)
if (!dev->pci_pm_cap_pos)
return -1;
/* For now, we just refuse to do a power management reset
* if there are other functions on this device.
* In future, we could allow it so long as those functions
* are not in use by the host or other guests.
*/
if (pciDeviceContainsOtherFunctions(conn, dev)) {
VIR_WARN("%s contains other functions, not resetting", dev->name);
return -1;
}
/* Save and restore the device's config space. */
if (pciRead(dev, 0, &config_space[0], PCI_CONF_LEN) < 0) {
VIR_WARN("Failed to save PCI config space for %s", dev->name);
@ -604,14 +571,17 @@ pciResetDevice(virConnectPtr conn, pciDevice *dev)
if (dev->has_flr)
return 0;
/* Bus reset is not an option with the root bus */
if (dev->bus != 0)
ret = pciTrySecondaryBusReset(conn, dev);
/* Next best option is a PCI power management reset */
if (ret < 0 && dev->has_pm_reset)
/* If the device supports PCI power management reset,
* that's the next best thing because it only resets
* the function, not the whole device.
*/
if (dev->has_pm_reset)
ret = pciTryPowerManagementReset(conn, dev);
/* Bus reset is not an option with the root bus */
if (ret < 0 && dev->bus != 0)
ret = pciTrySecondaryBusReset(conn, dev);
if (ret < 0)
pciReportError(conn, VIR_ERR_NO_SUPPORT,
_("No PCI reset capability available for %s"),