Commit c2077e2c authored by Alex Williamson's avatar Alex Williamson Committed by Michael S. Tsirkin
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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: default avatarAlex Williamson <alex.williamson@redhat.com>
Reviewed-by: default avatarMarcel Apfelbaum <marcel@redhat.com>
Reviewed-by: default avatarMichael S. Tsirkin <mst@redhat.com>
Signed-off-by: default avatarMichael S. Tsirkin <mst@redhat.com>
parent 27c1da51

hw/pci/pci_host.c

+26 −0
Original line number Diff line number Diff line
@@ -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.