| Message ID | 153747346143.7344.14634545723456004489.stgit@gimli.home (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [v2] vfio/pci: Mask buggy SR-IOV VF INTx support | expand |
Hi Alex, This patch passes testing with the 0x270c device, and (when I comment out its known_bogus_vf_intx_pin entry) the warning is triggered by QEMU. Thanks, Gage > -----Original Message----- > From: Alex Williamson [mailto:alex.williamson@redhat.com] > Sent: Thursday, September 20, 2018 3:03 PM > To: kvm@vger.kernel.org; Raj, Ashok <ashok.raj@intel.com>; Eads, Gage > <gage.eads@intel.com> > Cc: gnomes@lxorguk.ukuu.org.uk; linux-kernel@vger.kernel.org > Subject: [PATCH v2] vfio/pci: Mask buggy SR-IOV VF INTx support > > The SR-IOV spec requires that VFs must report zero for the INTx pin register as > VFs are precluded from INTx support. It's much easier for the host kernel to > understand whether a device is a VF and therefore whether a non-zero pin > register value is bogus than it is to do the same in userspace. Override the INTx > count for such devices and virtualize the pin register to provide a consistent view > of the device to the user. > > As this is clearly a spec violation, warn about it to support hardware validation, > but also provide a known whitelist as it doesn't do much good to continue > complaining if the hardware vendor doesn't plan to fix it. > > Known devices with this issue: 8086:270c > > Signed-off-by: Alex Williamson <alex.williamson@redhat.com> Tested-by: Gage Eads <gage.eads@intel.com>
On Thu, Sep 20, 2018 at 03:56:41PM -0700, Eads, Gage wrote: Thanks Gage. > Hi Alex, > > > > Known devices with this issue: 8086:270c > > > > Signed-off-by: Alex Williamson <alex.williamson@redhat.com> > > Tested-by: Gage Eads <gage.eads@intel.com> Reviewed-by: Ashok Raj <ashok.raj@intel.com>
> +/* > + * Nag about hardware bugs, hopefully to have vendors fix them, but at least > + * to collect a list of dependencies for the VF INTx pin quirk below. > + */ > +static const struct pci_device_id known_bogus_vf_intx_pin[] = { > + { PCI_DEVICE(PCI_VENDOR_ID_INTEL, 0x270c) }, > + {} > +}; What device is this? We don't have the device ID anywhere, so I guess it is something match by the class code?
On Thu, 20 Sep 2018 22:53:04 -0700 Christoph Hellwig <hch@infradead.org> wrote: > > +/* > > + * Nag about hardware bugs, hopefully to have vendors fix them, but at least > > + * to collect a list of dependencies for the VF INTx pin quirk below. > > + */ > > +static const struct pci_device_id known_bogus_vf_intx_pin[] = { > > + { PCI_DEVICE(PCI_VENDOR_ID_INTEL, 0x270c) }, > > + {} > > +}; > > What device is this? We don't have the device ID anywhere, so I guess > it is something match by the class code? Intel hasn't disclosed the device yet, so we don't know that there's an existing driver at all for it. Thanks, Alex
diff --git a/drivers/vfio/pci/vfio_pci.c b/drivers/vfio/pci/vfio_pci.c index cddb453a1ba5..50cdedfca9fe 100644 --- a/drivers/vfio/pci/vfio_pci.c +++ b/drivers/vfio/pci/vfio_pci.c @@ -434,10 +434,14 @@ static int vfio_pci_get_irq_count(struct vfio_pci_device *vdev, int irq_type) { if (irq_type == VFIO_PCI_INTX_IRQ_INDEX) { u8 pin; + + if (!IS_ENABLED(CONFIG_VFIO_PCI_INTX) || + vdev->nointx || vdev->pdev->is_virtfn) + return 0; + pci_read_config_byte(vdev->pdev, PCI_INTERRUPT_PIN, &pin); - if (IS_ENABLED(CONFIG_VFIO_PCI_INTX) && !vdev->nointx && pin) - return 1; + return pin ? 1 : 0; } else if (irq_type == VFIO_PCI_MSI_IRQ_INDEX) { u8 pos; u16 flags; diff --git a/drivers/vfio/pci/vfio_pci_config.c b/drivers/vfio/pci/vfio_pci_config.c index 62023b4a373b..423ea1f98441 100644 --- a/drivers/vfio/pci/vfio_pci_config.c +++ b/drivers/vfio/pci/vfio_pci_config.c @@ -1611,6 +1611,15 @@ static int vfio_ecap_init(struct vfio_pci_device *vdev) return 0; } +/* + * Nag about hardware bugs, hopefully to have vendors fix them, but at least + * to collect a list of dependencies for the VF INTx pin quirk below. + */ +static const struct pci_device_id known_bogus_vf_intx_pin[] = { + { PCI_DEVICE(PCI_VENDOR_ID_INTEL, 0x270c) }, + {} +}; + /* * For each device we allocate a pci_config_map that indicates the * capability occupying each dword and thus the struct perm_bits we @@ -1676,6 +1685,24 @@ int vfio_config_init(struct vfio_pci_device *vdev) if (pdev->is_virtfn) { *(__le16 *)&vconfig[PCI_VENDOR_ID] = cpu_to_le16(pdev->vendor); *(__le16 *)&vconfig[PCI_DEVICE_ID] = cpu_to_le16(pdev->device); + + /* + * Per SR-IOV spec rev 1.1, 3.4.1.18 the interrupt pin register + * does not apply to VFs and VFs must implement this register + * as read-only with value zero. Userspace is not readily able + * to identify whether a device is a VF and thus that the pin + * definition on the device is bogus should it violate this + * requirement. We already virtualize the pin register for + * other purposes, so we simply need to replace the bogus value + * and consider VFs when we determine INTx IRQ count. + */ + if (vconfig[PCI_INTERRUPT_PIN] && + !pci_match_id(known_bogus_vf_intx_pin, pdev)) + pci_warn(pdev, + "Hardware bug: VF reports bogus INTx pin %d\n", + vconfig[PCI_INTERRUPT_PIN]); + + vconfig[PCI_INTERRUPT_PIN] = 0; /* Gratuitous for good VFs */ } if (!IS_ENABLED(CONFIG_VFIO_PCI_INTX) || vdev->nointx)
The SR-IOV spec requires that VFs must report zero for the INTx pin register as VFs are precluded from INTx support. It's much easier for the host kernel to understand whether a device is a VF and therefore whether a non-zero pin register value is bogus than it is to do the same in userspace. Override the INTx count for such devices and virtualize the pin register to provide a consistent view of the device to the user. As this is clearly a spec violation, warn about it to support hardware validation, but also provide a known whitelist as it doesn't do much good to continue complaining if the hardware vendor doesn't plan to fix it. Known devices with this issue: 8086:270c Signed-off-by: Alex Williamson <alex.williamson@redhat.com> --- v2: Moved the warning to vfio_config_init(), so it triggers on device open and no longer depends on the user looking at the number of INTx IRQs available. Also changed from dev_warn_once() to pci_warn() as this new location seems sufficiently low frequency to nag repeatedly. Please test. Thanks, Alex drivers/vfio/pci/vfio_pci.c | 8 ++++++-- drivers/vfio/pci/vfio_pci_config.c | 27 +++++++++++++++++++++++++++ 2 files changed, 33 insertions(+), 2 deletions(-)