On Fri, Mar 13, 2015 at 02:28:09PM -0600, Alex Williamson wrote: >On Thu, 2015-03-12 at 15:21 +1100, David Gibson wrote: >> On Thu, Mar 12, 2015 at 02:16:42PM +1100, Gavin Shan wrote: >> > On Thu, Mar 12, 2015 at 11:57:21AM +1100, David Gibson wrote: >> > >On Wed, Mar 11, 2015 at 05:34:11PM +1100, Gavin Shan wrote: >> > >> The patch adds one more EEH sub-command (VFIO_EEH_PE_INJECT_ERR) >> > >> to inject the specified EEH error, which is represented by >> > >> (struct vfio_eeh_pe_err), to the indicated PE for testing purpose. >> > >> >> > >> Signed-off-by: Gavin Shan <gwshan@xxxxxxxxxxxxxxxxxx> >> > >> --- >> > >> Documentation/vfio.txt | 47 ++++++++++++++++++++++++++++++------------- >> > >> drivers/vfio/vfio_spapr_eeh.c | 14 +++++++++++++ >> > >> include/uapi/linux/vfio.h | 34 ++++++++++++++++++++++++++++++- >> > >> 3 files changed, 80 insertions(+), 15 deletions(-) >> > >> >> > >> diff --git a/Documentation/vfio.txt b/Documentation/vfio.txt >> > >> index 96978ec..2e7f736 100644 >> > >> --- a/Documentation/vfio.txt >> > >> +++ b/Documentation/vfio.txt >> > >> @@ -328,7 +328,13 @@ So 4 additional ioctls have been added: >> > >> >> > >> The code flow from the example above should be slightly changed: >> > >> >> > >> - struct vfio_eeh_pe_op pe_op = { .argsz = sizeof(pe_op), .flags = 0 }; >> > >> + struct vfio_eeh_pe_op *pe_op; >> > >> + struct vfio_eeh_pe_err *pe_err; >> > >> + >> > >> + pe_op = malloc(sizeof(*pe_op) + sizeof(*pe_err)); >> > >> + pe_err = (void *)pe_op + sizeof(*pe_op); >> > >> + pe_op->argsz = sizeof(*pe_op) + sizeof(*pe_err); >> > > >> > >Surely that argsz can't be correct for most of the operations. The >> > >extended structure should only be there for the error inject ioctl, >> > >yes? >> > > >> > >> > argsz isn't appropriate for most cases because kernel has the check >> > "expected_argsz < passed_argsz", not "expected_argsz == >> > passed_argsz". >> >> It works for now, but if any of those calls was extended with more >> data, it would break horribly. By setting the argsz greater than >> necessary, you're effectively passing uninitialized data to the >> ioctl(). At the moment, the ioctl() ignores it, but the whole point >> of the argsz value is that in the future, it might not. > >argsz tells us how much data the user is passing, we're always going to >need to figure out what the extra data is, so I don't really see the >point of this objection. In fact, it might make use of this interface >quite a bit easier if vfio_eeh_pe_op ended with a union including >vfio_eeh_pe_err. op == VFIO_EEH_PE_INJECT_ERR defines that the user has >passed vfio_eeh_pe_err in the union, other ops may add new unions later. >Thanks, > Ok. I'll have following data struct in next revision: struct vfio_eeh_pe_err { __u32 type; __u32 func; __u64 addr; __u64 mask; }; struct vfio_eeh_pe_op { __u32 argsz; __u32 flags; __u32 op; union { struct vfio_eeh_pe_err err; }; }; Thanks, Gavin >Alex > >> > However, I'll fix it as follows to avoid confusion after collecting >> > more comments: >> > >> > struct vfio_eeh_pe_op *pe_op; >> > struct vfio_eeh_pe_err *pe_err; >> > >> > /* For all cases except error injection */ >> > pe_op = malloc(sizeof(*pe_op)); >> > pe_op->argsz = sizeof(*pe_op); >> > >> > /* For error injection case here */ >> > pe_op = realloc(sizeof(*pe_op) + sizeof(*pe_err)); >> > pe_op->argsz = sizeof(*pe_op) + sizeof(*pe_err); >> > pe_err = (void *)pe_op + sizeof(*pe_op); >> > >> > Thanks, >> > Gavin >> > >> > >> > >> > > > -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html