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pci: Adjust PCI config limit based on bus topology 

A conventional PCI bus does not support config space accesses above
the standard 256 byte configuration space.  PCIe-to-PCI bridges are
not permitted to forward transactions if the extended register address
field is non-zero and must handle it as an unsupported request (PCIe
bridge spec rev 1.0, 4.1.3, 4.1.4).  Therefore, we should not support
extended config space if there is a conventional bus anywhere on the
path to a device.

Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
Reviewed-by: Marcel Apfelbaum <marcel@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
This commit is contained in:
Alex Williamson 2016-01-18 16:06:03 -07:00 committed by Michael S. Tsirkin
parent 27c1da5129
commit c2077e2ca0
1 changed files with 26 additions and 0 deletions
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26
hw/pci/pci_host.c
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@ -20,6 +20,7 @@
#include "qemu/osdep.h"
#include "hw/pci/pci.h"
#include "hw/pci/pci_bridge.h"
#include "hw/pci/pci_host.h"
#include "hw/pci/pci_bus.h"
#include "trace.h"
@ -50,9 +51,29 @@ static inline PCIDevice *pci_dev_find_by_addr(PCIBus *bus, uint32_t addr)
return pci_find_device(bus, bus_num, devfn);
}
static void pci_adjust_config_limit(PCIBus *bus, uint32_t *limit)
{
if (*limit > PCI_CONFIG_SPACE_SIZE) {
if (!pci_bus_is_express(bus)) {
*limit = PCI_CONFIG_SPACE_SIZE;
return;
}
if (!pci_bus_is_root(bus)) {
PCIDevice *bridge = pci_bridge_get_device(bus);
pci_adjust_config_limit(pci_get_bus(bridge), limit);
}
}
}
void pci_host_config_write_common(PCIDevice *pci_dev, uint32_t addr,
uint32_t limit, uint32_t val, uint32_t len)
{
pci_adjust_config_limit(pci_get_bus(pci_dev), &limit);
if (limit <= addr) {
return;
}
assert(len <= 4);
/* non-zero functions are only exposed when function 0 is present,
* allowing direct removal of unexposed functions.
@ -71,6 +92,11 @@ uint32_t pci_host_config_read_common(PCIDevice *pci_dev, uint32_t addr,
{
uint32_t ret;
pci_adjust_config_limit(pci_get_bus(pci_dev), &limit);
if (limit <= addr) {
return ~0x0;
}
assert(len <= 4);
/* non-zero functions are only exposed when function 0 is present,
* allowing direct removal of unexposed functions.