Re: [Qemu-devel] vfio: blacklist loading of unstable roms

[Alex Williamson <alex.williamson@redhat.com>]

On Wed, 2014-02-19 at 13:58 -0500, Bandan Das wrote:
> Alex Williamson <alex.williamson@redhat.com> writes:
> 
> > On Wed, 2014-02-19 at 11:12 -0500, Bandan Das wrote:
> >> Certain cards such as the Broadcom BCM57810 have rom quirks
> >> that exhibit unstable system behavior duing device assignment. In
> >> the particular case of 57810, rom execution hangs and if a FLR
> >> follows, the device becomes inoperable until a power cycle.
> >> 
> >> This is a simple change to disable rom loading for such cards.
> >> In terms of implementation change, rombar now has a default value
> >> of 2. Existing code shouldn't be affected by changing the default value
> >> of rombar since all relevant decisions only rely on whether rom_bar is
> >> zero or non-zero. The motivation behind this change is that in
> >> certain cases such as a firmware upgrade, the user might
> >> want to override this blacklisting behavior and can do so
> >> by running with rombar = 1. Same reasoning applies to running with
> >> romfile.
> >> 
> >> Signed-off-by: Bandan Das <bsd@redhat.com>
> >> ---
> >>  hw/misc/vfio.c | 63 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
> >>  hw/pci/pci.c   |  3 ++-
> >>  2 files changed, 65 insertions(+), 1 deletion(-)
> >> 
> >> diff --git a/hw/misc/vfio.c b/hw/misc/vfio.c
> >> index 8db182f..f5021f4 100644
> >> --- a/hw/misc/vfio.c
> >> +++ b/hw/misc/vfio.c
> >> @@ -209,6 +209,16 @@ typedef struct VFIOGroup {
> >>      QLIST_ENTRY(VFIOGroup) container_next;
> >>  } VFIOGroup;
> >>  
> >> +typedef struct VFIORomQList {
> >> +    unsigned int vendor_id;
> >> +    unsigned int device_id;
> >
> > uint16_t
> 
> Oops! yes, indeed.
> 
> >> +} VFIORomQList;
> >> +
> >> +static const VFIORomQList romqdevlist[] = {
> >> +    /* Broadcom BCM 57810 */
> >> +    { 0x14e4, 0x168e }
> >> +};
> >
> > Naming of these doesn't make sense, there's neither a QLIST nor are
> > these qdevs.  We're creating a blacklist, so I'd probably name the array
> > VFIORomBlacklist and the entry can simply be a VFIOBlacklistEntry.
> 
> The naming signified abbreviation of VFIORomQuirkList and romquirkdevicelist.
> Obviously, it ended up signifying something else altogether. Your suggestion
> sounds fine and I will change it in the next version.
> 
> >> +
> >>  #define MSIX_CAP_LENGTH 12
> >>  
> >>  static QLIST_HEAD(, VFIOContainer)
> >> @@ -1197,16 +1207,69 @@ static const MemoryRegionOps vfio_rom_ops = {
> >>      .endianness = DEVICE_LITTLE_ENDIAN,
> >>  };
> >>  
> >> +static bool vfio_blacklist_opt_rom(VFIODevice *vdev)
> >> +{
> >> +    PCIDevice *pdev = &vdev->pdev;
> >> +    unsigned int vendor_id, device_id;
> >
> > uint16_t
> >
> >> +    int count = 0;
> >> +
> >> +    vendor_id = pci_get_word(pdev->config + PCI_VENDOR_ID);
> >> +    device_id = pci_get_word(pdev->config + PCI_DEVICE_ID);
> >> +
> >> +    while (count < ARRAY_SIZE(romqdevlist)) {
> >> +        if (romqdevlist[count].vendor_id == vendor_id &&
> >> +            romqdevlist[count].device_id == device_id) {
> >> +                return true;
> >> +        }
> >> +        count++;
> >> +    }
> >> +
> >> +    return false;
> >> +}
> >> +
> >>  static void vfio_pci_size_rom(VFIODevice *vdev)
> >>  {
> >>      uint32_t orig, size = cpu_to_le32((uint32_t)PCI_ROM_ADDRESS_MASK);
> >>      off_t offset = vdev->config_offset + PCI_ROM_ADDRESS;
> >>      char name[32];
> >> +    int rom_quirk = 0;
> >
> > bool?  Actually, we don't even need this variable, just call the
> > blacklist test function inline.  There's not even a path that would call
> > it twice.
> 
> Yeah, it is actually used twice below - Once for the case 
> where romfile is set and once for when rombar is set. If you
> prefer, I can re-word this so that it's called once and displays
> a common message instead of different ones as in the current 
> version. 

It's used twice, but there's no path that calls it more than once.

> >> +
> >> +    if (vfio_blacklist_opt_rom(vdev)) {
> >> +        rom_quirk = 1;
> >> +    }
> >>  
> >>      if (vdev->pdev.romfile || !vdev->pdev.rom_bar) {
> >> +        /* Since pci handles romfile, just print a message and return */
> >> +        if (rom_quirk && vdev->pdev.romfile) {
> >> +            error_printf("Warning : Device at %04x:%02x:%02x.%x "
> >> +                         "is known to cause system instability issues during "
> >> +                         "option rom execution. "
> >> +                         "Proceeding anyway since user specified romfile\n",
> >> +                         vdev->host.domain, vdev->host.bus, vdev->host.slot,
> >> +                         vdev->host.function);
> >> +        }
> >>          return;
> >>      }
> >>  
> >> +    if (rom_quirk && vdev->pdev.rom_bar) {
> >> +        if (vdev->pdev.rom_bar == 1) {
> >> +            error_printf("Warning : Device at %04x:%02x:%02x.%x "
> >> +                         "is known to cause system instability issues during "
> >> +                         "option rom execution. "
> >> +                         "Proceeding anyway since user specified rombar=1\n",
> >> +                         vdev->host.domain, vdev->host.bus, vdev->host.slot,
> >> +                         vdev->host.function);
> >> +        } else {
> >> +            error_printf("Warning : Rom loading for device at "
> >> +                         "%04x:%02x:%02x.%x has been disabled due to "
> >> +                         "system instability issues. "
> >> +                         "Specify rombar=1 or romfile to force\n",
> >> +                         vdev->host.domain, vdev->host.bus, vdev->host.slot,
> >> +                         vdev->host.function);
> >> +            return;
> >> +        }
> >> +    }
> >> +
> >>      /*
> >>       * Use the same size ROM BAR as the physical device.  The contents
> >>       * will get filled in later when the guest tries to read it.
> >> diff --git a/hw/pci/pci.c b/hw/pci/pci.c
> >> index 4e0701d..65766d8 100644
> >> --- a/hw/pci/pci.c
> >> +++ b/hw/pci/pci.c
> >> @@ -53,7 +53,8 @@ static void pci_bus_finalize(Object *obj);
> >>  static Property pci_props[] = {
> >>      DEFINE_PROP_PCI_DEVFN("addr", PCIDevice, devfn, -1),
> >>      DEFINE_PROP_STRING("romfile", PCIDevice, romfile),
> >> -    DEFINE_PROP_UINT32("rombar",  PCIDevice, rom_bar, 1),
> >> +    /* 0 = disable, 1 = user requested (on), 2 = default (on) */
> >> +    DEFINE_PROP_UINT32("rombar",  PCIDevice, rom_bar, 2),
> >>      DEFINE_PROP_BIT("multifunction", PCIDevice, cap_present,
> >>                      QEMU_PCI_CAP_MULTIFUNCTION_BITNR, false),
> >>      DEFINE_PROP_BIT("command_serr_enable", PCIDevice, cap_present,
> >
> > This should be a separate patch.  Thanks,
> 
> Umm.. isn't this part of "one logical change" and be grouped together ?
> Or having it in a different patch makes maintainer's work easy ?

This latter bit is an infrastructure change and should be evaluated on
it's own.  The rest of it just depends on that change.  Thanks,

Alex