[v6,02/17] pci: Allow to omit errp for pci_add_capability

Commit Message

Akihiko Odaki Oct. 31, 2022, 12:33 p.m. UTC

pci_add_capability appears most PCI devices. Its error handling required
lots of code, and led to inconsistent behaviors such as:
- passing error_abort
- passing error_fatal
- asserting the returned value
- propagating the error to the caller
- skipping the rest of the function
- just ignoring

The code generating errors in pci_add_capability had a comment which
says:
> Verify that capabilities don't overlap.  Note: device assignment
> depends on this check to verify that the device is not broken.
> Should never trigger for emulated devices, but it's helpful for
> debugging these.

Indeed vfio has some code that passes capability offsets and sizes from
a physical device, but it explicitly pays attention so that the
capabilities never overlap. Therefore, we can always assert that
capabilities never overlap when pci_add_capability is called, resolving
these inconsistencies.

Such an implementation of pci_add_capability will not have errp
parameter. However, there are so many callers of pci_add_capability
that it does not make sense to amend all of them at once to match
with the new signature. Instead, this change will allow callers of
pci_add_capability to omit errp as the first step.

Signed-off-by: Akihiko Odaki <[e-mail]>
---
 hw/pci/pci.c         |  8 ++++----
 include/hw/pci/pci.h | 13 ++++++++++---
 2 files changed, 14 insertions(+), 7 deletions(-)

Patch

diff --git a/hw/pci/pci.c b/hw/pci/pci.c
index 2f450f6a72..8ee2171011 100644
--- a/hw/pci/pci.c
+++ b/hw/pci/pci.c
@@ -2513,14 +2513,14 @@  static void pci_del_option_rom(PCIDevice *pdev)
 }
 
 /*
- * On success, pci_add_capability() returns a positive value
+ * On success, pci_add_capability_legacy() returns a positive value
  * that the offset of the pci capability.
  * On failure, it sets an error and returns a negative error
  * code.
  */
-int pci_add_capability(PCIDevice *pdev, uint8_t cap_id,
-                       uint8_t offset, uint8_t size,
-                       Error **errp)
+int pci_add_capability_legacy(PCIDevice *pdev, uint8_t cap_id,
+                              uint8_t offset, uint8_t size,
+                              Error **errp)
 {
     uint8_t *config;
     int i, overlapping_cap;
diff --git a/include/hw/pci/pci.h b/include/hw/pci/pci.h
index b54b6ef88f..51fd106f16 100644
--- a/include/hw/pci/pci.h
+++ b/include/hw/pci/pci.h
@@ -2,6 +2,7 @@ 
 #define QEMU_PCI_H
 
 #include "exec/memory.h"
+#include "qapi/error.h"
 #include "sysemu/dma.h"
 
 /* PCI includes legacy ISA access.  */
@@ -390,9 +391,15 @@  void pci_register_vga(PCIDevice *pci_dev, MemoryRegion *mem,
 void pci_unregister_vga(PCIDevice *pci_dev);
 pcibus_t pci_get_bar_addr(PCIDevice *pci_dev, int region_num);
 
-int pci_add_capability(PCIDevice *pdev, uint8_t cap_id,
-                       uint8_t offset, uint8_t size,
-                       Error **errp);
+int pci_add_capability_legacy(PCIDevice *pdev, uint8_t cap_id,
+                              uint8_t offset, uint8_t size,
+                              Error **errp);
+
+#define PCI_ADD_CAPABILITY_VA(pdev, cap_id, offset, size, errp, ...) \
+    pci_add_capability_legacy(pdev, cap_id, offset, size, errp)
+
+#define pci_add_capability(...) \
+    PCI_ADD_CAPABILITY_VA(__VA_ARGS__, &error_abort)
 
 void pci_del_capability(PCIDevice *pci_dev, uint8_t cap_id, uint8_t cap_size);