Subject: Re: [PATCH v3 2/2] drivers/vfio: Support EEH error injection

From: Alex Williamson <[email-masked]>
Date: Mon, 23 Mar 2015 10:14:59 -0600

On Mon, 2015-03-23 at 16:20 +1100, Gavin Shan wrote:
> On Mon, Mar 23, 2015 at 04:10:20PM +1100, David Gibson wrote:
> >On Mon, Mar 23, 2015 at 04:03:59PM +1100, Gavin Shan wrote:
> >> On Mon, Mar 23, 2015 at 02:43:03PM +1100, David Gibson wrote:
> >> >On Mon, Mar 23, 2015 at 12:56:36PM +1100, Gavin Shan wrote:
> >> >> On Mon, Mar 23, 2015 at 12:39:45PM +1100, David Gibson wrote:
> >> >> >On Sat, Mar 21, 2015 at 06:58:45AM +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 <[email-masked]>
> >> >> >
> >> >> >Reviewed-by: David Gibson <[email-masked]>
> >> >> >
> >> >> >> ---
> >> >> >>  Documentation/vfio.txt        | 12 ++++++++++++
> >> >> >>  drivers/vfio/vfio_spapr_eeh.c | 10 ++++++++++
> >> >> >>  include/uapi/linux/vfio.h     | 36 +++++++++++++++++++++++++++++++++++-
> >> >> >>  3 files changed, 57 insertions(+), 1 deletion(-)
> >> >> >> 
> >> >> >> diff --git a/Documentation/vfio.txt b/Documentation/vfio.txt
> >> >> >> index 96978ec..c6e11a3 100644
> >> >> >> --- a/Documentation/vfio.txt
> >> >> >> +++ b/Documentation/vfio.txt
> >> >> >> @@ -385,6 +385,18 @@ The code flow from the example above should be slightly changed:
> >> >> >>  
> >> >> >>  	....
> >> >> >>  
> >> >> >> +	/* Inject EEH error, which is expected to be caused by 32-bits
> >> >> >> +	 * config load.
> >> >> >> +	 */
> >> >> >> +	pe_op.op = VFIO_EEH_PE_INJECT_ERR;
> >> >> >> +	pe_op.err.type = VFIO_EEH_ERR_TYPE_32;
> >> >> >> +	pe_op.err.func = VFIO_EEH_ERR_FUNC_LD_CFG_ADDR;
> >> >> >> +	pe_op.err.addr = 0ul;
> >> >> >> +	pe_op.err.mask = 0ul;
> >> >> >> +	ioctl(container, VFIO_EEH_PE_OP, &pe_op);
> >> >> >> +
> >> >> >> +	....
> >> >> >> +
> >> >> >>  	/* When 0xFF's returned from reading PCI config space or IO BARs
> >> >> >>  	 * of the PCI device. Check the PE's state to see if that has been
> >> >> >>  	 * frozen.
> >> >> >> diff --git a/drivers/vfio/vfio_spapr_eeh.c b/drivers/vfio/vfio_spapr_eeh.c
> >> >> >> index 5fa42db..38edeb4 100644
> >> >> >> --- a/drivers/vfio/vfio_spapr_eeh.c
> >> >> >> +++ b/drivers/vfio/vfio_spapr_eeh.c
> >> >> >> @@ -85,6 +85,16 @@ long vfio_spapr_iommu_eeh_ioctl(struct iommu_group *group,
> >> >> >>  		case VFIO_EEH_PE_CONFIGURE:
> >> >> >>  			ret = eeh_pe_configure(pe);
> >> >> >>  			break;
> >> >> >> +		case VFIO_EEH_PE_INJECT_ERR:
> >> >> >> +			minsz = offsetofend(struct vfio_eeh_pe_op, err.mask);
> >> >> >> +			if (op.argsz < minsz)
> >> >> >> +				return -EINVAL;
> >> >> >> +			if (copy_from_user(&op, (void __user *)arg, minsz))
> >> >> >> +				return -EFAULT;
> >> >> >> +
> >> >> >> +			ret = eeh_pe_inject_err(pe, op.err.type, op.err.func,
> >> >> >> +						op.err.addr, op.err.mask);
> >> >> >> +			break;
> >> >> >>  		default:
> >> >> >>  			ret = -EINVAL;
> >> >> >>  		}
> >> >> >> diff --git a/include/uapi/linux/vfio.h b/include/uapi/linux/vfio.h
> >> >> >> index 82889c3..f68e962 100644
> >> >> >> --- a/include/uapi/linux/vfio.h
> >> >> >> +++ b/include/uapi/linux/vfio.h
> >> >> >> @@ -468,12 +468,23 @@ struct vfio_iommu_spapr_tce_info {
> >> >> >>   * - unfreeze IO/DMA for frozen PE;
> >> >> >>   * - read PE state;
> >> >> >>   * - reset PE;
> >> >> >> - * - configure PE.
> >> >> >> + * - configure PE;
> >> >> >> + * - inject EEH error.
> >> >> >>   */
> >> >> >> +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;
> >> >> >> +	};
> >> >> >>  };
> >> >> >>  
> >> >> >>  #define VFIO_EEH_PE_DISABLE		0	/* Disable EEH functionality */
> >> >> >> @@ -490,6 +501,29 @@ struct vfio_eeh_pe_op {
> >> >> >>  #define VFIO_EEH_PE_RESET_HOT		6	/* Assert hot reset          */
> >> >> >>  #define VFIO_EEH_PE_RESET_FUNDAMENTAL	7	/* Assert fundamental reset  */
> >> >> >>  #define VFIO_EEH_PE_CONFIGURE		8	/* PE configuration          */
> >> >> >> +#define VFIO_EEH_PE_INJECT_ERR		9	/* Inject EEH error          */
> >> >> >> +#define  VFIO_EEH_ERR_TYPE_32		0	/* 32-bits EEH error type    */
> >> >> >> +#define  VFIO_EEH_ERR_TYPE_64		1	/* 64-bits EEH error type    */
> >> >> >> +#define  VFIO_EEH_ERR_FUNC_LD_MEM_ADDR		0	/* Memory load  */
> >> >> >> +#define  VFIO_EEH_ERR_FUNC_LD_MEM_DATA		1
> >> >> >> +#define  VFIO_EEH_ERR_FUNC_LD_IO_ADDR		2	/* IO load      */
> >> >> >> +#define  VFIO_EEH_ERR_FUNC_LD_IO_DATA		3
> >> >> >> +#define  VFIO_EEH_ERR_FUNC_LD_CFG_ADDR		4	/* Config load  */
> >> >> >> +#define  VFIO_EEH_ERR_FUNC_LD_CFG_DATA		5
> >> >> >> +#define  VFIO_EEH_ERR_FUNC_ST_MEM_ADDR		6	/* Memory store */
> >> >> >> +#define  VFIO_EEH_ERR_FUNC_ST_MEM_DATA		7
> >> >> >> +#define  VFIO_EEH_ERR_FUNC_ST_IO_ADDR		8	/* IO store     */
> >> >> >> +#define  VFIO_EEH_ERR_FUNC_ST_IO_DATA		9
> >> >> >> +#define  VFIO_EEH_ERR_FUNC_ST_CFG_ADDR		10	/* Config store */
> >> >> >> +#define  VFIO_EEH_ERR_FUNC_ST_CFG_DATA		11
> >> >> >> +#define  VFIO_EEH_ERR_FUNC_DMA_RD_ADDR		12	/* DMA read     */
> >> >> >> +#define  VFIO_EEH_ERR_FUNC_DMA_RD_DATA		13
> >> >> >> +#define  VFIO_EEH_ERR_FUNC_DMA_RD_MASTER	14
> >> >> >> +#define  VFIO_EEH_ERR_FUNC_DMA_RD_TARGET	15
> >> >> >> +#define  VFIO_EEH_ERR_FUNC_DMA_WR_ADDR		16	/* DMA write    */
> >> >> >> +#define  VFIO_EEH_ERR_FUNC_DMA_WR_DATA		17
> >> >> >> +#define  VFIO_EEH_ERR_FUNC_DMA_WR_MASTER	18
> >> >> >> +#define  VFIO_EEH_ERR_FUNC_DMA_WR_TARGET	19
> >> >> >
> >> >> >These all seem to duplicate (under slightly different names) the
> >> >> >defines you just added in arch/powerpc/include/asm/eeh.h.  It would
> >> >> >make more sense to only have the uapi copy, surely.
> >> >> >
> >> >> 
> >> >> David, Thanks for your time. The defines in eeh.h is used not only
> >> >> for mapping those constants defined in vfio.h, but also for validating
> >> >> arguments from debugfs entry "err_injct". So it'd better to keep
> >> >> them separate: one set is used by userspace, another set is used
> >> >> by host kernel.
> >> >
> >> >I don't understand why this is an argument for duplicating them.  They
> >> >have the same meanings and values, why can't you use the uapi versions
> >> >everywhere?
> >> >
> >> 
> >> We can drop the constants defined in eeh.h and just use those defines
> >> in vfio.h. But I prefer separate constants for some ovbious reasons
> >> except the one I mentioned above :)
> >> 
> >> - We already had separate sets of constants for EEH and VFIO. For example,
> >>   VFIO_EEH_PE_STATE_* in include/uapi/vfio.h always have counter part in
> >>   arch/powerpc/asm/include/eeh.h
> >
> >Oh.. I see your point.
> >
> >Yes, the EEH internal code shouldn't need to use the VFIO defined
> >constants.
> >
> >But it's still silly to duplicate, I think the correct think would be
> >to expose the EEH constants in uapi, and use those for VFIO as well.
> >
> 
> I'm not sure. If Alex.W agree on this, I can have one patch to address
> it in future :-)

I agree with David, there should be a uapi eeh header and the vfio
documentation should define that as the valid set of functions.

> >> - The UAPI interface is expected to be stable, or back-compatible when
> >>   introducing changes to it. The defines (at least their names) in eeh.h
> >>   doesn't have to be stable.
> >
> >But is there any reason not to make them stable.  The VFIO case shows
> >that we need to lock down an interface somewhere.  I don't see that
> >there's an advantage to having a not locked down interface in addition
> >to a locked down one.
> >
> 
> I was saying that the UAPI interace should be stable. I don't see
> there're any reasons the UAPI interface will be changed in near
> future :)

When I asked previously whether a translation layer was needed between
the vfio uapi and kernel internal eeh api I was told that the values
were defined by the spapr spec and therefore not changeable.  If that's
true, we shouldn't need to worry about exporting them via uapi.  Thanks,

Alex

> >> - I would like keep the code between EEH/VFIO independent to each other
> >>   enough.
> >> 
> >> Thanks,
> >> Gavin
> >> 
> >> >> By the way, Alex Williamson, could you please ACK this if you don't
> >> >> find obvious errors in the patch. I really want this to be merged
> >> >> to 4.1.
> >> >> 
> >> >> Thanks,
> >> >> Gavin 
> >> >> 
> >> >> 
> >> >> 
> >> >
> >> 
> >> 
> >
> >-- 
> >David Gibson			| I'll have my music baroque, and my code
> >david AT gibson.dropbear.id.au	| minimalist, thank you.  NOT _the_ _other_
> >				| _way_ _around_!
> >http://www.ozlabs.org/~dgibson
> 
>