Re: [PATCH V2] device-assignment pci: correct pci config size default for cap version 2 endpoints

[Don Dutile <ddutile@redhat.com>]

On 07/21/2011 01:02 PM, Alex Williamson wrote:
> On Thu, 2011-07-21 at 12:39 -0400, Donald Dutile wrote:
>> v2: do local boundary check with respect to legacy PCI header length,
>>      and don't depend on it in pci_add_capability().
>>    : fix compilation, and change else>2 to simple else for all other cases.
>>
>> Doing device assignement using a PCIe device with it's
>> PCI Cap structure at offset 0xcc showed a problem in
>> the default size mapped for this cap-id.
>>
>> The failure caused a corruption which might have gone unnoticed
>> otherwise.
>>
>> Fix assigned_device_pci_cap_init() to set the default
>> size of PCIe Cap structure (cap-id 0x10) to 0x34 instead of 0x3c.
>> 0x34 is default, min, for endpoint device with a cap version of 2.
>>
>> Add check in assigned_devic_pci_cap_init() to ensure
>> size of Cap structure doesn't exceed legacy PCI header space,
>> which is where it must fit.
>>
>> Signed-off-by: Donald Dutile<ddutile@redhat.com>
>> cc: Alex Williamson<alex.williamson@redhat.com>
>> cc: Michael S. Tsirkin<mst@redhat.com>
>> ---
>>
>>   hw/device-assignment.c |   19 ++++++++++++++++---
>>   1 files changed, 16 insertions(+), 3 deletions(-)
>>
>> diff --git a/hw/device-assignment.c b/hw/device-assignment.c
>> index 36ad6b0..6bb8af7 100644
>> --- a/hw/device-assignment.c
>> +++ b/hw/device-assignment.c
>> @@ -1419,21 +1419,34 @@ static int assigned_device_pci_cap_init(PCIDevice *pci_dev)
>>       }
>>
>>       if ((pos = pci_find_cap_offset(pci_dev, PCI_CAP_ID_EXP, 0))) {
>> -        uint8_t version;
>> +        uint8_t version, size;
>>           uint16_t type, devctl, lnkcap, lnksta;
>>           uint32_t devcap;
>> -        int size = 0x3c; /* version 2 size */
>>
>>           version = pci_get_byte(pci_dev->config + pos + PCI_EXP_FLAGS);
>>           version&= PCI_EXP_FLAGS_VERS;
>>           if (version == 1) {
>>               size = 0x14;
>> -        } else if (version>  2) {
>> +        } else if (version == 2) {
>> +            /* don't include slot cap/stat/ctrl 2 regs; only support endpoints */
>> +            size = 0x34;
>> +        } else {
>>               fprintf(stderr, "Unsupported PCI express capability version %d\n",
>>                       version);
>>               return -EINVAL;
>>           }
>>
>> +	/* make sure cap struct resides in legacy hdr space */
>> +	if (size>  PCI_CONFIG_SPACE_SIZE - pos) {
>> +            fprintf(stderr, "ERROR: %04x:%02x:%02x.%x "
>> +                    "Attempt to add PCI Cap Structure 0x%x at offset 0x%x,"
>> +                    "size 0x%x, which exceeds legacy PCI config space 0x%x\n",
>> +                    pci_find_domain(pci_dev->bus), pci_bus_num(pci_dev->bus),
>> +                    PCI_SLOT(pci_dev->devfn), PCI_FUNC(pci_dev->devfn),
>> +                    PCI_CAP_ID_EXP, pos, size, PCI_CONFIG_SPACE_SIZE);
>> +            return -EINVAL;
>> +        }
>> +
>
> This is crazy, why would we only test this for PCI_CAP_ID_EXP?  If the
> test is going to go in device-assignment, we need to wrap
> pci_add_capability and do it for all callers.  However, maybe we can get
> MST to take it in pci_add_capability() if we make the test more
> complete...  something like:
>
> if ((pos<  256&&  size>  256 - pos) ||
>      (pci_config_size()>  256&&  pos>  256&&
>       size>  pci_config_size() - pos)) {
>     ... badness
>
> Thanks,
>
> Alex
>
+1

>>           if ((ret = pci_add_capability(pci_dev, PCI_CAP_ID_EXP,
>>                                         pos, size))<  0) {
>>               return ret;
>>
>
>
>