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Re: [Qemu-devel] [PATCH v3 3/7] s390x: improve error handling for SSCH a
From: |
Thomas Huth |
Subject: |
Re: [Qemu-devel] [PATCH v3 3/7] s390x: improve error handling for SSCH and RSCH |
Date: |
Wed, 18 Oct 2017 11:30:47 +0200 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.4.0 |
On 17.10.2017 16:04, Halil Pasic wrote:
> Simplify the error handling of the SSCH and RSCH handler avoiding
> arbitrary and cryptic error codes being used to tell how the instruction
> is supposed to end. Let the code detecting the condition tell how it's
> to be handled in a less ambiguous way. It's best to handle SSCH and RSCH
> in one go as the emulation of the two shares a lot of code.
>
> For passthrough this change isn't pure refactoring, but changes the way
> kernel reported EFAULT is handled. After clarifying the kernel interface
> we decided that EFAULT shall be mapped to unit exception. Same goes for
> unexpected error codes and absence of required ORB flags.
>
> Signed-off-by: Halil Pasic <address@hidden>
> ---
> hw/s390x/css.c | 84
> +++++++++++++--------------------------------
> hw/s390x/s390-ccw.c | 11 +++---
> hw/vfio/ccw.c | 28 +++++++++++----
> include/hw/s390x/css.h | 23 +++++++++----
> include/hw/s390x/s390-ccw.h | 2 +-
> target/s390x/ioinst.c | 53 ++++------------------------
> 6 files changed, 75 insertions(+), 126 deletions(-)
>
> diff --git a/hw/s390x/css.c b/hw/s390x/css.c
> index aa233d5f8a..ff5a05c34b 100644
> --- a/hw/s390x/css.c
> +++ b/hw/s390x/css.c
> @@ -1181,12 +1181,11 @@ static void sch_handle_start_func_virtual(SubchDev
> *sch)
>
> }
>
> -static int sch_handle_start_func_passthrough(SubchDev *sch)
> +static IOInstEnding sch_handle_start_func_passthrough(SubchDev *sch)
> {
>
> PMCW *p = &sch->curr_status.pmcw;
> SCSW *s = &sch->curr_status.scsw;
> - int ret;
>
> ORB *orb = &sch->orb;
> if (!(s->ctrl & SCSW_ACTL_SUSP)) {
> @@ -1200,31 +1199,12 @@ static int sch_handle_start_func_passthrough(SubchDev
> *sch)
> */
> if (!(orb->ctrl0 & ORB_CTRL0_MASK_PFCH) ||
> !(orb->ctrl0 & ORB_CTRL0_MASK_C64)) {
> - return -EINVAL;
> + warn_report("vfio-ccw requires PFCH and C64 flags set...");
Not sure, but should this maybe rather be a
"qemu_log_mask(LOG_GUEST_ERROR, ...)" instead?
Anyway, as Cornelia already mentioned it: Please drop the trailing dots.
> + sch_gen_unit_exception(sch);
> + css_inject_io_interrupt(sch);
> + return IOINST_CC_EXPECTED;
> }
[...]
> @@ -1844,27 +1816,23 @@ void css_do_schm(uint8_t mbk, int update, int dct,
> uint64_t mbo)
> }
> }
>
> -int css_do_rsch(SubchDev *sch)
> +IOInstEnding css_do_rsch(SubchDev *sch)
> {
> SCSW *s = &sch->curr_status.scsw;
> PMCW *p = &sch->curr_status.pmcw;
> - int ret;
>
> if (~(p->flags) & (PMCW_FLAGS_MASK_DNV | PMCW_FLAGS_MASK_ENA)) {
> - ret = -ENODEV;
> - goto out;
> + return IOINST_CC_NOT_OPERATIONAL;
> }
>
> if (s->ctrl & SCSW_STCTL_STATUS_PEND) {
> - ret = -EINPROGRESS;
> - goto out;
> + return IOINST_CC_STATUS_PRESENT;
> }
>
> if (((s->ctrl & SCSW_CTRL_MASK_FCTL) != SCSW_FCTL_START_FUNC) ||
> (s->ctrl & SCSW_ACTL_RESUME_PEND) ||
> (!(s->ctrl & SCSW_ACTL_SUSP))) {
> - ret = -EINVAL;
> - goto out;
> + return IOINST_CC_BUSY;
Why is EINVAL now mapped to IOINST_CC_BUSY? Shouldn't that be
IOINST_CC_STATUS_PRESENT instead?
> }
[...]
> diff --git a/hw/vfio/ccw.c b/hw/vfio/ccw.c
> index 76323c6bde..1cc2e5d873 100644
> --- a/hw/vfio/ccw.c
> +++ b/hw/vfio/ccw.c
> @@ -47,9 +47,9 @@ struct VFIODeviceOps vfio_ccw_ops = {
> .vfio_compute_needs_reset = vfio_ccw_compute_needs_reset,
> };
>
> -static int vfio_ccw_handle_request(ORB *orb, SCSW *scsw, void *data)
> +static IOInstEnding vfio_ccw_handle_request(SubchDev *sch)
> {
> - S390CCWDevice *cdev = data;
> + S390CCWDevice *cdev = sch->driver_data;
> VFIOCCWDevice *vcdev = DO_UPCAST(VFIOCCWDevice, cdev, cdev);
> struct ccw_io_region *region = vcdev->io_region;
> int ret;
> @@ -60,8 +60,8 @@ static int vfio_ccw_handle_request(ORB *orb, SCSW *scsw,
> void *data)
>
> memset(region, 0, sizeof(*region));
>
> - memcpy(region->orb_area, orb, sizeof(ORB));
> - memcpy(region->scsw_area, scsw, sizeof(SCSW));
> + memcpy(region->orb_area, &sch->orb, sizeof(ORB));
> + memcpy(region->scsw_area, &sch->curr_status.scsw, sizeof(SCSW));
>
> again:
> ret = pwrite(vcdev->vdev.fd, region,
> @@ -71,10 +71,24 @@ again:
> goto again;
> }
> error_report("vfio-ccw: wirte I/O region failed with errno=%d",
> errno);
> - return -errno;
> + ret = -errno;
> + } else {
> + ret = region->ret_code;
> + }
> + switch (-ret) {
> + case 0:
> + return IOINST_CC_EXPECTED;
> + case EBUSY:
> + return IOINST_CC_BUSY;
> + case ENODEV:
> + case EACCES:
> + return IOINST_CC_NOT_OPERATIONAL;
> + case EFAULT:
> + default:
> + sch_gen_unit_exception(sch);
> + css_inject_io_interrupt(sch);
> + return IOINST_CC_EXPECTED;
Do we feel really confident that it is OK to do the setcc() in case of
an exception here later? ... otherwise it might be necessery to
introduce something like IOINST_EXCEPTION to the enum to signal the
ioinst_handle_xxx() callers that they should not do the setcc() anymore...
Thomas
- Re: [Qemu-devel] [PATCH v3 4/7] s390x: refactor error handling for XSCH handler, (continued)
- [Qemu-devel] [PATCH v3 3/7] s390x: improve error handling for SSCH and RSCH, Halil Pasic, 2017/10/17
- Re: [Qemu-devel] [PATCH v3 3/7] s390x: improve error handling for SSCH and RSCH, Cornelia Huck, 2017/10/18
- Re: [Qemu-devel] [PATCH v3 3/7] s390x: improve error handling for SSCH and RSCH, Thomas Huth, 2017/10/18
- Re: [Qemu-devel] [PATCH v3 3/7] s390x: improve error handling for SSCH and RSCH, Halil Pasic, 2017/10/18
- Re: [Qemu-devel] [PATCH v3 3/7] s390x: improve error handling for SSCH and RSCH, Thomas Huth, 2017/10/18
- Re: [Qemu-devel] [PATCH v3 3/7] s390x: improve error handling for SSCH and RSCH, Halil Pasic, 2017/10/18
Re: [Qemu-devel] [PATCH v3 3/7] s390x: improve error handling for SSCH and RSCH, Dong Jia Shi, 2017/10/19
[Qemu-devel] [PATCH v3 2/7] s390x/css: IO instr handler ending control, Halil Pasic, 2017/10/17