@@ -1867,6 +1867,89 @@ struct pci_device *pci_find_dev(struct phb *phb, uint16_t bdfn)
return pci_walk_dev(phb, NULL, __pci_find_dev, &bdfn);
}
+static struct pci_device *__pci_find_parent(struct pci_device *pd, uint8_t bus)
+{
+ struct pci_device *child;
+
+ if (!pd)
+ return NULL;
+
+ if (pd->secondary_bus == bus)
+ return pd;
+
+ if (bus < pd->secondary_bus || bus > pd->subordinate_bus)
+ return NULL;
+
+ list_for_each(&pd->children, child, link) {
+ if (child->secondary_bus == bus)
+ return child;
+ }
+
+ list_for_each(&pd->children, child, link) {
+ struct pci_device *found = __pci_find_parent(child, bus);
+
+ if (found)
+ return found;
+ }
+
+ return NULL;
+}
+
+struct pci_device *pci_find_parent_dev(struct phb *phb, uint16_t bdfn)
+{
+ struct pci_device *pd;
+ uint8_t bus = (bdfn >> 8);
+
+ if (!phb)
+ return NULL;
+
+ list_for_each(&phb->devices, pd, link) {
+ struct pci_device *found = __pci_find_parent(pd, bus);
+
+ if (found)
+ return found;
+ }
+
+ return NULL;
+}
+
+struct pci_device *pci_find_dev_safe(struct phb *phb, uint16_t bdfn)
+{
+ struct pci_device *parent;
+ struct pci_device *child;
+
+ if (!phb)
+ return NULL;
+
+ if (!bdfn) {
+ struct pci_device *pd;
+
+ list_for_each(&phb->devices, pd, link) {
+ if (pd->bdfn == bdfn)
+ return pd;
+ }
+ }
+
+ parent = pci_find_parent_dev(phb, bdfn);
+ if (!parent)
+ return NULL;
+
+ list_for_each(&parent->children, child, link) {
+ if ((child->bdfn & 0xff) == (bdfn & 0xff)) {
+ if (child->bdfn != bdfn) {
+ PCIERR(phb, bdfn, "pci_device has invalid bdfn field %04x:%02x:%02x.%d\n",
+ phb->opal_id,
+ child->bdfn >> 8,
+ (child->bdfn >> 3) & 0x1f,
+ child->bdfn & 0x7);
+ }
+ return child;
+ }
+ }
+
+ return NULL;
+}
+
static int __pci_restore_bridge_buses(struct phb *phb,
struct pci_device *pd,
void *data __unused)
@@ -473,6 +473,8 @@ extern struct pci_device *pci_walk_dev(struct phb *phb,
void *),
void *userdata);
extern struct pci_device *pci_find_dev(struct phb *phb, uint16_t bdfn);
+extern struct pci_device *pci_find_dev_safe(struct phb *phb, uint16_t bdfn);
+extern struct pci_device *pci_find_parent_dev(struct phb *phb, uint16_t bdfn);
extern void pci_restore_bridge_buses(struct phb *phb, struct pci_device *pd);
extern struct pci_cfg_reg_filter *pci_find_cfg_reg_filter(struct pci_device *pd,
uint32_t start, uint32_t len);
During the PCIe re-enumeration by an OS the .bdfn field of the struct pci_device may not correspond to its device's actual address for a while, so the pci_find_dev() will return an invalid descriptor in this case. Some code may rely on this behavior, so this patch introduces a new function to return a descriptor for addressable devices only. This new function will help in discovering hotplugged devices. Here's a synthetic (but possible) scenario where pci_find_dev_safe() is different from pci_find_dev(): I. Before the re-enumeration: +-[0021:00]---00.0-[01-04]--+-00.0-[02]-- +-01.0-[03]----00.0 Device Z1 +-02.0-[04]-- - pci_find_dev(0021:03:00.0) returns correct struct pci_device *pd for Device Z1; - pci_find_dev_safe(0021:03:00.0) returns the same pd. II. Re-enumeration, step 1: _____ Dropped the bus numbers by writing zeros / +-[0021:00]---00.0-[00-00]--+-00.0-[02]-- +-01.0-[03]----00.0 Device Z1 +-02.0-[04]-- - Device Z1 is unreachable (bus 1 is not assigned), but pci_find_dev(0021:03:00.0) returns its pd; - pci_find_dev_safe(0021:03:00.0) returns NULL. III. Re-enumeration, step 2: __ Update the bus numbers: primary <- 0, / secondary <- 1, subordinate <- ff / +-[0021:00]---00.0-[01-ff]--+-00.0-[02]-- +-01.0-[03]----00.0 Device Z1 +-02.0-[04]-- - By coincidence, pci_find_dev(0021:03:00.0) returns pd for Device Z1; - pci_find_dev_safe(0021:03:00.0) returns pd for Device Z1, which is correct by coincidence. IV. Re-enumeration, step 3: ___ Drop the bus numbers / +-[0021:00]---00.0-[01-ff]--+-00.0-[00-00]-- +-01.0-[00-00]----00.0 Device Z1 +-02.0-[00-00]-- - Device Z1 is unreachable (downstream 0021:01:01.0 has no bus numbers assigned), but pci_find_dev(0021:03:00.0) returns its uncorrected pd; - pci_find_dev_safe(0021:03:00.0) returns NULL. V. Re-enumeration, step 4: Set the bus numbers __ _ A phantom of Device Z1 \ / from pci_find_dev(03:00.0) +-[0021:00]---00.0-[01-ff]--+-00.0-[02-06]-- - +-01.0-[00-00]----00.0 Device Z1 +-02.0-[00-00]-- - pci_find_dev(0021:03:00.0) returns a phantom of the Device Z1 for wrong address; - pci_find_dev_safe(0021:03:00.0) returns NULL. VI. Re-enumeration, step 5: +-[0021:00]---00.0-[01-ff]--+-00.0-[02-06]-- -+-01.0-[07-0b]----00.0 Device Z1 / +-02.0-[00-00]-- Set the bus numbers -- - pci_find_dev(0021:03:00.0) returns a phantom of the Device Z1; - pci_find_dev_safe(0021:03:00.0) returns NULL; - pci_find_dev_safe(0021:07:00.0) returns pd for the Device Z1, but its .bdfn field needs to be corrected (by the following patch). VI. After the re-enumeration: +-[0021:00]---00.0-[01-10]--+-00.0-[02-06]-- +-01.0-[07-0b]----00.0 Device Z1 +-02.0-[0c-10]-- Even though the .bdfn field is not correct at the moment, it is clear that this is a previously known device, not a hotplugged one. Signed-off-by: Sergey Miroshnichenko <s.miroshnichenko@yadro.com> --- core/pci.c | 83 +++++++++++++++++++++++++++++++++++++++++++++++++++ include/pci.h | 2 ++ 2 files changed, 85 insertions(+)