Re: [Qemu-devel] [PATCH 3/3] s390x/pci: use the right pal and pba in reg_ioat()

[Cornelia Huck]

On Thu, 1 Feb 2018 12:33:01 +0100
Pierre Morel <address@hidden> wrote:

> On 31/01/2018 12:44, Cornelia Huck wrote:
> > On Tue, 30 Jan 2018 10:47:15 +0100
> > Yi Min Zhao <address@hidden> wrote:
> >  
> >> When registering ioat, pba should be comprised of leftmost 52 bits and
> >> rightmost 12 binary zeros, and pal should be comprised of leftmost 52
> >> bits and right most 12 binary ones. Let's fixup this.
> >>
> >> Reviewed-by: Pierre Morel <address@hidden>
> >> Signed-off-by: Yi Min Zhao <address@hidden>
> >> ---
> >>   hw/s390x/s390-pci-inst.c | 2 ++
> >>   1 file changed, 2 insertions(+)
> >>
> >> diff --git a/hw/s390x/s390-pci-inst.c b/hw/s390x/s390-pci-inst.c
> >> index 997a9cc2e9..3fcc330fe3 100644
> >> --- a/hw/s390x/s390-pci-inst.c
> >> +++ b/hw/s390x/s390-pci-inst.c
> >> @@ -865,6 +865,8 @@ static int reg_ioat(CPUS390XState *env, S390PCIIOMMU 
> >> *iommu, ZpciFib fib,
> >>       uint8_t dt = (g_iota >> 2) & 0x7;
> >>       uint8_t t = (g_iota >> 11) & 0x1;
> >>   
> >> +    pba &= ~0xfff;
> >> +    pal |= 0xfff;
> >>       if (pba > pal || pba < ZPCI_SDMA_ADDR || pal > ZPCI_EDMA_ADDR) {
> >>           s390_program_interrupt(env, PGM_OPERAND, 6, ra);
> >>           return -EINVAL;  
> > It seems like pba and pal are part of the fib, which in turn seems to
> > be provided by the caller. Is that correct? If yes, is it valid for
> > them to not have the rightmost 12 bits as 0s resp. 1s?
> >
> > (Probably answered in the architecture, I know. Might make sense to be
> > a tad more explicit in the description.)
> >  
> Yes it is, only word6 and the bits 0-19 of word 7 are used for PAL and
> the zPCI facility treats the right most 12 bits of the PAL as containing 
> ones.
> 
> For PBA words 4 and 0-19 bits of word 5 with 12 0 append on the right 
> provides the PBA.
> 
> The lower 12 bits of words 5 and 7 of the FIB are ignored by the facility.
> 
> @Yi Min: may be add the last sentence to the commit message.
> 
> @Conny: Is it clearer?

Yes, adding the last sentence makes it clearer. Thanks!