| Message ID | 20190514234248.36203-8-farman@linux.ibm.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | s390: vfio-ccw fixes | expand |
On Wed, 15 May 2019 01:42:48 +0200 Eric Farman <farman@linux.ibm.com> wrote: > If the CCW being processed is a No-Operation, then by definition no > data is being transferred. Let's fold those checks into the normal > CCW processors, rather than skipping out early. > > Likewise, if the CCW being processed is a "test" (an invented > definition to simply mean it ends in a zero), let's permit that to go > through to the hardware. There's nothing inherently unique about > those command codes versus one that ends in an eight [1], or any other > otherwise valid command codes that are undefined for the device type > in question. Hm... let's tweak that a bit? It's not that "test" is an invented category; it's just that this has not been a valid command for post-s/370 and therefore should not get any special treatment and just be sent to the hardware? > > [1] POPS states that a x08 is a TIC CCW, and that having any high-order > bits enabled is invalid for format-1 CCWs. For format-0 CCWs, the > high-order bits are ignored. > > Signed-off-by: Eric Farman <farman@linux.ibm.com> > --- > drivers/s390/cio/vfio_ccw_cp.c | 11 +++++------ > 1 file changed, 5 insertions(+), 6 deletions(-)
On 5/15/19 8:43 AM, Cornelia Huck wrote: > On Wed, 15 May 2019 01:42:48 +0200 > Eric Farman <farman@linux.ibm.com> wrote: > >> If the CCW being processed is a No-Operation, then by definition no >> data is being transferred. Let's fold those checks into the normal >> CCW processors, rather than skipping out early. >> >> Likewise, if the CCW being processed is a "test" (an invented >> definition to simply mean it ends in a zero), let's permit that to go >> through to the hardware. There's nothing inherently unique about >> those command codes versus one that ends in an eight [1], or any other >> otherwise valid command codes that are undefined for the device type >> in question. > > Hm... let's tweak that a bit? It's not that "test" is an invented > category; it's just that this has not been a valid command for > post-s/370 and therefore should not get any special treatment and just > be sent to the hardware? Agreed, I should've re-read that one before I sent it... How about: Likewise, if the CCW being processed is a "test" (a category defined here as an opcode that contains zero in the lowest four bits) then no special processing is necessary as far as vfio-ccw is concerned. These command codes have not been valid since the S/370 days, meaning they are invalid in the same way as one that ends in an eight [1] or an otherwise valid command code that is undefined for the device type in question. Considering that, let's just process "test" CCWs like any other CCW, and send everything to the hardware. > >> >> [1] POPS states that a x08 is a TIC CCW, and that having any high-order >> bits enabled is invalid for format-1 CCWs. For format-0 CCWs, the >> high-order bits are ignored. >> >> Signed-off-by: Eric Farman <farman@linux.ibm.com> >> --- >> drivers/s390/cio/vfio_ccw_cp.c | 11 +++++------ >> 1 file changed, 5 insertions(+), 6 deletions(-) >
On Wed, 15 May 2019 09:36:01 -0400 Eric Farman <farman@linux.ibm.com> wrote: > On 5/15/19 8:43 AM, Cornelia Huck wrote: > > On Wed, 15 May 2019 01:42:48 +0200 > > Eric Farman <farman@linux.ibm.com> wrote: > > > >> If the CCW being processed is a No-Operation, then by definition no > >> data is being transferred. Let's fold those checks into the normal > >> CCW processors, rather than skipping out early. > >> > >> Likewise, if the CCW being processed is a "test" (an invented > >> definition to simply mean it ends in a zero), let's permit that to go > >> through to the hardware. There's nothing inherently unique about > >> those command codes versus one that ends in an eight [1], or any other > >> otherwise valid command codes that are undefined for the device type > >> in question. > > > > Hm... let's tweak that a bit? It's not that "test" is an invented > > category; it's just that this has not been a valid command for > > post-s/370 and therefore should not get any special treatment and just > > be sent to the hardware? > > Agreed, I should've re-read that one before I sent it... How about: > > Likewise, if the CCW being processed is a "test" (a category defined > here as an opcode that contains zero in the lowest four bits) then no > special processing is necessary as far as vfio-ccw is concerned. > These command codes have not been valid since the S/370 days, meaning > they are invalid in the same way as one that ends in an eight [1] or > an otherwise valid command code that is undefined for the device type > in question. Considering that, let's just process "test" CCWs like > any other CCW, and send everything to the hardware. Sounds good to me! > > > > >> > >> [1] POPS states that a x08 is a TIC CCW, and that having any high-order > >> bits enabled is invalid for format-1 CCWs. For format-0 CCWs, the > >> high-order bits are ignored. > >> > >> Signed-off-by: Eric Farman <farman@linux.ibm.com> > >> --- > >> drivers/s390/cio/vfio_ccw_cp.c | 11 +++++------ > >> 1 file changed, 5 insertions(+), 6 deletions(-) > > >
diff --git a/drivers/s390/cio/vfio_ccw_cp.c b/drivers/s390/cio/vfio_ccw_cp.c index 94888094ed2c..abe0f501a963 100644 --- a/drivers/s390/cio/vfio_ccw_cp.c +++ b/drivers/s390/cio/vfio_ccw_cp.c @@ -295,8 +295,6 @@ static long copy_ccw_from_iova(struct channel_program *cp, #define ccw_is_read_backward(_ccw) (((_ccw)->cmd_code & 0x0F) == 0x0C) #define ccw_is_sense(_ccw) (((_ccw)->cmd_code & 0x0F) == CCW_CMD_BASIC_SENSE) -#define ccw_is_test(_ccw) (((_ccw)->cmd_code & 0x0F) == 0) - #define ccw_is_noop(_ccw) ((_ccw)->cmd_code == CCW_CMD_NOOP) #define ccw_is_tic(_ccw) ((_ccw)->cmd_code == CCW_CMD_TIC) @@ -320,6 +318,10 @@ static inline int ccw_does_data_transfer(struct ccw1 *ccw) if (ccw->count == 0) return 0; + /* If the command is a NOP, then no data will be transferred */ + if (ccw_is_noop(ccw)) + return 0; + /* If the skip flag is off, then data will be transferred */ if (!ccw_is_skip(ccw)) return 1; @@ -404,7 +406,7 @@ static void ccwchain_cda_free(struct ccwchain *chain, int idx) { struct ccw1 *ccw = chain->ch_ccw + idx; - if (ccw_is_test(ccw) || ccw_is_noop(ccw) || ccw_is_tic(ccw)) + if (ccw_is_tic(ccw)) return; kfree((void *)(u64)ccw->cda); @@ -729,9 +731,6 @@ static int ccwchain_fetch_one(struct ccwchain *chain, { struct ccw1 *ccw = chain->ch_ccw + idx; - if (ccw_is_test(ccw) || ccw_is_noop(ccw)) - return 0; - if (ccw_is_tic(ccw)) return ccwchain_fetch_tic(chain, idx, cp);
If the CCW being processed is a No-Operation, then by definition no data is being transferred. Let's fold those checks into the normal CCW processors, rather than skipping out early. Likewise, if the CCW being processed is a "test" (an invented definition to simply mean it ends in a zero), let's permit that to go through to the hardware. There's nothing inherently unique about those command codes versus one that ends in an eight [1], or any other otherwise valid command codes that are undefined for the device type in question. [1] POPS states that a x08 is a TIC CCW, and that having any high-order bits enabled is invalid for format-1 CCWs. For format-0 CCWs, the high-order bits are ignored. Signed-off-by: Eric Farman <farman@linux.ibm.com> --- drivers/s390/cio/vfio_ccw_cp.c | 11 +++++------ 1 file changed, 5 insertions(+), 6 deletions(-)