| Message ID | 1461841492-29277-1-git-send-email-aik@ozlabs.ru (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Thu, 28 Apr 2016 21:04:52 +1000 Alexey Kardashevskiy <aik@ozlabs.ru> wrote: > VFIO reads a dword beyond the standard PCI config space (256 bytes) to > know if there are extended config space (4096 bytes). It relies on > the platform to return zero if there is no extended space. > > However at least on PPC64/POWERNV platform, the system firmware (OPAL) > returns 0xffffffff in this case. VFIO treats it as a proof that there is > extended config space and calls vfio_ecap_init() which fails to parse > capabilities (which is expected) but right before the exit, it writes > zero at offset of 256 which is beyond the buffer allocated for > vdev->vconfig - it is 256 bytes for a device without extended config > space. > > This adds an additional check that config space read returned non-zero > and non-ffffffff value. > > Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru> > --- > drivers/vfio/pci/vfio_pci_config.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/drivers/vfio/pci/vfio_pci_config.c b/drivers/vfio/pci/vfio_pci_config.c > index 142c533..8a53421 100644 > --- a/drivers/vfio/pci/vfio_pci_config.c > +++ b/drivers/vfio/pci/vfio_pci_config.c > @@ -1140,7 +1140,7 @@ static int vfio_cap_len(struct vfio_pci_device *vdev, u8 cap, u8 pos) > case PCI_CAP_ID_EXP: > /* Test for extended capabilities */ > pci_read_config_dword(pdev, PCI_CFG_SPACE_SIZE, &dword); > - vdev->extended_caps = (dword != 0); > + vdev->extended_caps = (dword != 0) && (dword != 0xffffffff); > > /* length based on version */ > if ((pcie_caps_reg(pdev) & PCI_EXP_FLAGS_VERS) == 1) If the device is already telling us that cfg_size is less, why use heuristics to figure out what the return value might be, just put the whole thing in a 'if (pdev->cfg_size > PCI_CFG_SPACE_SIZE)' test. Looks like the same should be done for PCI-X. Thanks, Alex -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/drivers/vfio/pci/vfio_pci_config.c b/drivers/vfio/pci/vfio_pci_config.c index 142c533..8a53421 100644 --- a/drivers/vfio/pci/vfio_pci_config.c +++ b/drivers/vfio/pci/vfio_pci_config.c @@ -1140,7 +1140,7 @@ static int vfio_cap_len(struct vfio_pci_device *vdev, u8 cap, u8 pos) case PCI_CAP_ID_EXP: /* Test for extended capabilities */ pci_read_config_dword(pdev, PCI_CFG_SPACE_SIZE, &dword); - vdev->extended_caps = (dword != 0); + vdev->extended_caps = (dword != 0) && (dword != 0xffffffff); /* length based on version */ if ((pcie_caps_reg(pdev) & PCI_EXP_FLAGS_VERS) == 1)
VFIO reads a dword beyond the standard PCI config space (256 bytes) to know if there are extended config space (4096 bytes). It relies on the platform to return zero if there is no extended space. However at least on PPC64/POWERNV platform, the system firmware (OPAL) returns 0xffffffff in this case. VFIO treats it as a proof that there is extended config space and calls vfio_ecap_init() which fails to parse capabilities (which is expected) but right before the exit, it writes zero at offset of 256 which is beyond the buffer allocated for vdev->vconfig - it is 256 bytes for a device without extended config space. This adds an additional check that config space read returned non-zero and non-ffffffff value. Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru> --- drivers/vfio/pci/vfio_pci_config.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)