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Violators will be prosecuted for from ; Tue, 25 Jul 2017 23:31:27 -0400 Date: Wed, 26 Jul 2017 11:31:21 +0800 From: Dong Jia Shi References: <20170725224442.13383-1-pasic@linux.vnet.ibm.com> <20170725224442.13383-2-pasic@linux.vnet.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20170725224442.13383-2-pasic@linux.vnet.ibm.com> Message-Id: <20170726033121.GP7483@bjsdjshi@linux.vnet.ibm.com> Subject: Re: [Qemu-devel] [PATCH 1/2] s390x/css: check ccw address validity List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Halil Pasic Cc: Christian Borntraeger , Cornelia Huck , Dong Jia Shi , qemu-devel@nongnu.org * Halil Pasic [2017-07-26 00:44:41 +0200]: > According to the PoP channel command words (CCW) must be doubleword > aligned and 31 bit addressable for format 1 and 24 bit addressable for > format 0 CCWs. > > If the channel subsystem encounters ccw address which does not satisfy > this alignment requirement a program-check condition is recognised. > > The situation with 31 bit addressable is a bit more complicated: both the > ORB and a format 1 CCW TIC hold the address of the (rest of) the channel ^^^^^^^^^^^^^^^^^^^^ Meant to be (?): of the (rest of the) Maybe just saying: the address of a channel probram > program, that is the address of the next CCW in a word, and the PoP > mandates that bit 0 of that word shall be zero -- or a program-check > condition is to be recognized -- and does not belong to the field holding > the ccw address. > > Since in code the corresponding fields span across the whole word (unlike > in PoP where these are defined as 31 bit wide) we can check this by > applying a mask. The 24 addressable case isn't affecting TIC because the > address is composed of a halfword and a byte portion (no additional zero > bit requirements) and just slightly complicates the ORB case where also > bits 1-7 need to be zero. > > Let's make our CSS implementation follow the AR more closely. > > Signed-off-by: Halil Pasic > --- > Note: Checking for 31 bit addressable ain't strictly necessary: > According to the AR the all zero fields of the ORB may or may not be > checked during the execution of SSCH. We do check the corresponding > single bit field of the ORB and respond to it accordingly. Using > the same mask for TIC and for ORB does not hurt. > --- > hw/s390x/css.c | 18 ++++++++++++++++++ > 1 file changed, 18 insertions(+) > > diff --git a/hw/s390x/css.c b/hw/s390x/css.c > index 6a42b95cee..d17e21b7af 100644 > --- a/hw/s390x/css.c > +++ b/hw/s390x/css.c > @@ -24,6 +24,9 @@ > #include "hw/s390x/s390_flic.h" > #include "hw/s390x/s390-virtio-ccw.h" > > +/* CCWs are doubleword aligned and addressable by 31 bit */ > +#define CCW1_ADDR_MASK 0x80000007 > + Move this hunk to ioinst.h? > typedef struct CrwContainer { > CRW crw; > QTAILQ_ENTRY(CrwContainer) sibling; > @@ -885,6 +888,10 @@ static int css_interpret_ccw(SubchDev *sch, hwaddr ccw_addr, > ret = -EINVAL; > break; > } > + if (ccw.cda & CCW1_ADDR_MASK) { > + ret = -EINVAL; > + break; > + } > sch->channel_prog = ccw.cda; > ret = -EAGAIN; > break; > @@ -946,6 +953,17 @@ static void sch_handle_start_func_virtual(SubchDev *sch) > suspend_allowed = true; > } > sch->last_cmd_valid = false; > + if (sch->channel_prog & (CCW1_ADDR_MASK | > + sch->ccw_fmt_1 ? 0 : 0xff000000)) { I have problem in recognizing the operator precedence here: (CCW1_ADDR_MASK | sch->ccw_fmt_1 ? 0 : 0xff000000) Bitwise '|' has higher precedence than '?:', so the above equals to: (CCW1_ADDR_MASK | sch->ccw_fmt_1) ? 0 : 0xff000000 So you will always get a '0', no? > + /* generate channel program check */ > + s->ctrl &= ~SCSW_ACTL_START_PEND; > + s->cstat = SCSW_CSTAT_PROG_CHECK; > + s->ctrl &= ~SCSW_CTRL_MASK_STCTL; > + s->ctrl |= SCSW_STCTL_PRIMARY | SCSW_STCTL_SECONDARY | > + SCSW_STCTL_ALERT | SCSW_STCTL_STATUS_PEND; > + s->cpa = sch->channel_prog + 8; > + return; > + } I think you could let css_interpret_ccw() do the sanity check on its @ccw_addr parameter when (sch->last_cmd_valid == false), to reuse the code of generating channel program check. > do { > ret = css_interpret_ccw(sch, sch->channel_prog, suspend_allowed); > switch (ret) { > -- > 2.11.2 > -- Dong Jia Shi