[libvirt] [PATCH v2 1/2] Tests for ACS in PCIe switches
Jiri Denemark
jdenemar at redhat.com
Tue Dec 22 17:21:15 UTC 2009
New pciDeviceIsAssignable() function for checking whether a given PCI
device can be assigned to a guest was added. Currently it only checks
for ACS being enabled on all PCIe switches between root and the PCI
device. In the future, it could be the right place to check whether a
device is unbound or bound to a stub driver.
Signed-off-by: Jiri Denemark <jdenemar at redhat.com>
---
src/libvirt_private.syms | 1 +
src/util/pci.c | 151 ++++++++++++++++++++++++++++++++++++++++++++++
src/util/pci.h | 4 +
3 files changed, 156 insertions(+), 0 deletions(-)
diff --git a/src/libvirt_private.syms b/src/libvirt_private.syms
index f90f269..0f97e79 100644
--- a/src/libvirt_private.syms
+++ b/src/libvirt_private.syms
@@ -438,6 +438,7 @@ pciDeviceListGet;
pciDeviceListLock;
pciDeviceListUnlock;
pciDeviceListSteal;
+pciDeviceIsAssignable;
# processinfo.h
diff --git a/src/util/pci.c b/src/util/pci.c
index 1e003c2..8cf66a2 100644
--- a/src/util/pci.c
+++ b/src/util/pci.c
@@ -140,6 +140,28 @@ struct _pciDeviceList {
#define PCI_AF_CAP 0x3 /* Advanced features capabilities */
#define PCI_AF_CAP_FLR 0x2 /* Function Level Reset */
+#define PCI_EXP_FLAGS 0x2
+#define PCI_EXP_FLAGS_TYPE 0x00f0
+#define PCI_EXP_TYPE_DOWNSTREAM 0x6
+
+#define PCI_EXT_CAP_BASE 0x100
+#define PCI_EXT_CAP_LIMIT 0x1000
+#define PCI_EXT_CAP_ID_MASK 0x0000ffff
+#define PCI_EXT_CAP_OFFSET_SHIFT 20
+#define PCI_EXT_CAP_OFFSET_MASK 0x00000ffc
+
+#define PCI_EXT_CAP_ID_ACS 0x000d
+#define PCI_EXT_ACS_CTRL 0x06
+
+#define PCI_EXT_CAP_ACS_SV 0x01
+#define PCI_EXT_CAP_ACS_RR 0x04
+#define PCI_EXT_CAP_ACS_CR 0x08
+#define PCI_EXT_CAP_ACS_UF 0x10
+#define PCI_EXT_CAP_ACS_ENABLED (PCI_EXT_CAP_ACS_SV | \
+ PCI_EXT_CAP_ACS_RR | \
+ PCI_EXT_CAP_ACS_CR | \
+ PCI_EXT_CAP_ACS_UF)
+
static int
pciOpenConfig(pciDevice *dev)
{
@@ -326,6 +348,30 @@ pciFindCapabilityOffset(pciDevice *dev, unsigned capability)
return 0;
}
+static unsigned int
+pciFindExtendedCapabilityOffset(pciDevice *dev, unsigned capability)
+{
+ int ttl;
+ unsigned int pos;
+ uint32_t header;
+
+ /* minimum 8 bytes per capability */
+ ttl = (PCI_EXT_CAP_LIMIT - PCI_EXT_CAP_BASE) / 8;
+ pos = PCI_EXT_CAP_BASE;
+
+ while (ttl > 0 && pos >= PCI_EXT_CAP_BASE) {
+ header = pciRead32(dev, pos);
+
+ if ((header & PCI_EXT_CAP_ID_MASK) == capability)
+ return pos;
+
+ pos = (header >> PCI_EXT_CAP_OFFSET_SHIFT) & PCI_EXT_CAP_OFFSET_MASK;
+ ttl--;
+ }
+
+ return 0;
+}
+
static unsigned
pciDetectFunctionLevelReset(pciDevice *dev)
{
@@ -1110,3 +1156,108 @@ cleanup:
VIR_FREE(pcidir);
return ret;
}
+
+static int
+pciDeviceDownstreamLacksACS(virConnectPtr conn,
+ pciDevice *dev)
+{
+ uint16_t flags;
+ uint16_t ctrl;
+ unsigned int pos;
+
+ if (!dev->initted && pciInitDevice(conn, dev) < 0)
+ return -1;
+
+ pos = dev->pcie_cap_pos;
+ if (!pos || !pciRead16(dev, PCI_CLASS_DEVICE) == PCI_CLASS_BRIDGE_PCI)
+ return 0;
+
+ flags = pciRead16(dev, pos + PCI_EXP_FLAGS);
+ if (((flags & PCI_EXP_FLAGS_TYPE) >> 4) != PCI_EXP_TYPE_DOWNSTREAM)
+ return 0;
+
+ pos = pciFindExtendedCapabilityOffset(dev, PCI_EXT_CAP_ID_ACS);
+ if (!pos) {
+ VIR_DEBUG("%s %s: downstream port lacks ACS", dev->id, dev->name);
+ return 1;
+ }
+
+ ctrl = pciRead16(dev, pos + PCI_EXT_ACS_CTRL);
+ if ((ctrl & PCI_EXT_CAP_ACS_ENABLED) != PCI_EXT_CAP_ACS_ENABLED) {
+ VIR_DEBUG("%s %s: downstream port has ACS disabled",
+ dev->id, dev->name);
+ return 1;
+ }
+
+ return 0;
+}
+
+static int
+pciDeviceIsBehindSwitchLackingACS(virConnectPtr conn,
+ pciDevice *dev)
+{
+ pciDevice *parent;
+
+ if (!(parent = pciGetParentDevice(conn, dev))) {
+ pciReportError(conn, VIR_ERR_NO_SUPPORT,
+ _("Failed to find parent device for %s"),
+ dev->name);
+ return -1;
+ }
+
+ /* XXX we should rather fail when we can't find device's parent and
+ * stop the loop when we get to root instead of just stopping when no
+ * parent can be found
+ */
+ do {
+ pciDevice *tmp;
+ int acs;
+
+ acs = pciDeviceDownstreamLacksACS(conn, parent);
+
+ if (acs) {
+ pciFreeDevice(conn, parent);
+ if (acs < 0)
+ return -1;
+ else
+ return 1;
+ }
+
+ tmp = parent;
+ parent = pciGetParentDevice(conn, parent);
+ pciFreeDevice(conn, tmp);
+ } while (parent);
+
+ return 0;
+}
+
+int pciDeviceIsAssignable(virConnectPtr conn,
+ pciDevice *dev,
+ int strict_acs_check)
+{
+ int ret;
+
+ /* XXX This could be a great place to actually check that a non-managed
+ * device isn't in use, e.g. by checking that device is either un-bound
+ * or bound to a stub driver.
+ */
+
+ ret = pciDeviceIsBehindSwitchLackingACS(conn, dev);
+ if (ret < 0)
+ return 0;
+
+ if (ret) {
+ if (!strict_acs_check) {
+ VIR_DEBUG("%s %s: strict ACS check disabled; device assignment allowed",
+ dev->id, dev->name);
+ } else {
+ pciReportError(conn, VIR_ERR_NO_SUPPORT,
+ _("Device %s is behind a switch lacking ACS and "
+ "cannot be assigned"),
+ dev->name);
+ return 0;
+ }
+ }
+
+ return 1;
+}
diff --git a/src/util/pci.h b/src/util/pci.h
index 1f0b9d2..a1a19e7 100644
--- a/src/util/pci.h
+++ b/src/util/pci.h
@@ -78,4 +78,8 @@ int pciDeviceFileIterate(virConnectPtr conn,
pciDeviceFileActor actor,
void *opaque);
+int pciDeviceIsAssignable(virConnectPtr conn,
+ pciDevice *dev,
+ int strict_acs_check);
+
#endif /* __VIR_PCI_H__ */
--
1.6.6.rc4
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