[libvirt] [PATCH 1/2] virpci: Introduce virPCIDeviceIsPCIExpress and friends

[Michal Privoznik]

These functions will handle PCIe devices and their link capabilities
to query some info about it.

Signed-off-by: Michal Privoznik <mprivozn at redhat.com>
---
 src/libvirt_private.syms |  3 ++
 src/util/virpci.c        | 81 +++++++++++++++++++++++++++++++++++++++++++++++-
 src/util/virpci.h        |  8 +++++
 3 files changed, 91 insertions(+), 1 deletion(-)

diff --git a/src/libvirt_private.syms b/src/libvirt_private.syms
index d73a9f5..f72a3ad 100644
--- a/src/libvirt_private.syms
+++ b/src/libvirt_private.syms
@@ -1690,6 +1690,8 @@ virPCIDeviceFree;
 virPCIDeviceGetDriverPathAndName;
 virPCIDeviceGetIOMMUGroupDev;
 virPCIDeviceGetIOMMUGroupList;
+virPCIDeviceGetLinkCap;
+virPCIDeviceGetLinkSta;
 virPCIDeviceGetManaged;
 virPCIDeviceGetName;
 virPCIDeviceGetRemoveSlot;
@@ -1698,6 +1700,7 @@ virPCIDeviceGetStubDriver;
 virPCIDeviceGetUnbindFromStub;
 virPCIDeviceGetUsedBy;
 virPCIDeviceIsAssignable;
+virPCIDeviceIsPCIExpress;
 virPCIDeviceListAdd;
 virPCIDeviceListAddCopy;
 virPCIDeviceListCount;
diff --git a/src/util/virpci.c b/src/util/virpci.c
index e0f2344..8ad28b8 100644
--- a/src/util/virpci.c
+++ b/src/util/virpci.c
@@ -130,7 +130,13 @@ struct _virPCIDeviceList {
 
 /* PCIe20 7.8.3  Device Capabilities Register (Offset 04h) */
 #define PCI_EXP_DEVCAP          0x4     /* Device capabilities */
-#define PCI_EXP_DEVCAP_FLR     (1<<28) /* Function Level Reset */
+#define PCI_EXP_LNKCAP          0xc     /* Link Capabilities */
+#define PCI_EXP_LNKSTA          0x12    /* Link Status */
+#define PCI_EXP_DEVCAP_FLR     (1<<28)  /* Function Level Reset */
+#define PCI_EXP_LNKCAP_SPEED    0x0000f /* Maximum Link Speed */
+#define PCI_EXP_LNKCAP_WIDTH    0x003f0 /* Maximum Link Width */
+#define PCI_EXP_LNKSTA_SPEED    0x000f  /* Negotiated Link Speed */
+#define PCI_EXP_LNKSTA_WIDTH    0x03f0  /* Negotiated Link Width */
 
 /* Header type 1 BR12 3.2 PCI-to-PCI Bridge Configuration Space Header Format */
 #define PCI_PRIMARY_BUS         0x18    /* BR12 3.2.5.2 Primary bus number */
@@ -2750,3 +2756,76 @@ virPCIGetVirtualFunctionInfo(const char *vf_sysfs_device_path ATTRIBUTE_UNUSED,
     return -1;
 }
 #endif /* __linux__ */
+
+int
+virPCIDeviceIsPCIExpress(virPCIDevicePtr dev)
+{
+    int fd;
+    int ret = -1;
+
+    if ((fd = virPCIDeviceConfigOpen(dev, true)) < 0)
+        return ret;
+
+    if (virPCIDeviceInit(dev, fd) < 0)
+        goto cleanup;
+
+    ret = dev->pcie_cap_pos != 0;
+
+ cleanup:
+    virPCIDeviceConfigClose(dev, fd);
+    return ret;
+}
+
+int
+virPCIDeviceGetLinkCap(virPCIDevicePtr dev,
+                       int *port,
+                       unsigned int *speed,
+                       unsigned int *width)
+{
+    uint32_t t;
+    int fd;
+    int ret = -1;
+
+    if ((fd = virPCIDeviceConfigOpen(dev, true) < 0))
+        return ret;
+
+    if (virPCIDeviceInit(dev, fd) < 0)
+        goto cleanup;
+
+    t = virPCIDeviceRead32(dev, fd, dev->pcie_cap_pos + PCI_EXP_LNKCAP);
+
+    *port = t >> 0x18;
+    *speed = t & PCI_EXP_LNKCAP_SPEED;
+    *width = (t & PCI_EXP_LNKCAP_WIDTH) >> 4;
+    ret = 0;
+
+ cleanup:
+    virPCIDeviceConfigClose(dev, fd);
+    return ret;
+}
+
+int
+virPCIDeviceGetLinkSta(virPCIDevicePtr dev,
+                       unsigned int *speed,
+                       unsigned int *width)
+{
+    uint32_t t;
+    int fd;
+    int ret = -1;
+
+    if ((fd = virPCIDeviceConfigOpen(dev, true) < 0))
+        return ret;
+
+    if (virPCIDeviceInit(dev, fd) < 0)
+        goto cleanup;
+
+    t = virPCIDeviceRead32(dev, fd, dev->pcie_cap_pos + PCI_EXP_LNKSTA);
+
+    *speed = t & PCI_EXP_LNKSTA_SPEED;
+    *width = (t & PCI_EXP_LNKSTA_WIDTH) >> 4;
+    ret = 0;
+
+ cleanup:
+    virPCIDeviceConfigClose(dev, fd);
+    return ret;
+}
diff --git a/src/util/virpci.h b/src/util/virpci.h
index 20ffe54..0a608c2 100644
--- a/src/util/virpci.h
+++ b/src/util/virpci.h
@@ -176,4 +176,12 @@ int virPCIDeviceGetDriverPathAndName(virPCIDevicePtr dev,
                                      char **path,
                                      char **name);
 
+int virPCIDeviceIsPCIExpress(virPCIDevicePtr dev);
+int virPCIDeviceGetLinkCap(virPCIDevicePtr dev,
+                           int *port,
+                           unsigned int *speed,
+                           unsigned int *width);
+int virPCIDeviceGetLinkSta(virPCIDevicePtr dev,
+                           unsigned int *speed,
+                           unsigned int *width);
 #endif /* __VIR_PCI_H__ */
-- 
2.0.0