Hi, On Wed, 26 Jan 2022, 16:58 Ayan Kumar Halder, <ayan.kumar.hal...@xilinx.com> wrote:
> Refer to Armv8 ARM DDI 0487G.b, Page D13-3219 "ISS encoding for an > exception > from a Data Abort" :- > ISV - ISS[23:14] holds a valid instruction syndrome > > When the ISV is 0, the instruction could not be decoded by the hardware > (ie ISS > is invalid). One should immediately return an error to the caller with an > appropriate error message. That's going to be very spammy because we have use-case where it could trap without a valid ISV (e.g. when break-before-make happens). So please don't had a message. That makes me think that the same will be valid for your other patch. There is no use of the MMIO handler. This is the > reason why one should check for ISV before attempting to find a MMIO > handler. > > Signed-off-by: Ayan Kumar Halder <ayank...@xilinx.com> > --- > > Suggested by Julien Grall in > https://lists.xenproject.org/archives/html/xen-devel/2022-01/msg01245.html > > xen/arch/arm/io.c | 11 +++++++---- > 1 file changed, 7 insertions(+), 4 deletions(-) > > diff --git a/xen/arch/arm/io.c b/xen/arch/arm/io.c > index 729287e37c..14d39222f2 100644 > --- a/xen/arch/arm/io.c > +++ b/xen/arch/arm/io.c > @@ -109,6 +109,13 @@ enum io_state try_handle_mmio(struct cpu_user_regs > *regs, > > ASSERT(hsr.ec == HSR_EC_DATA_ABORT_LOWER_EL); > > + /* All the instructions used on emulated MMIO region should be valid > */ > + if ( !dabt.valid ) > + { > + gprintk(XENLOG_DEBUG, "No valid instruction syndrome for data > abort\n"); > + return IO_ABORT; > + } > + > handler = find_mmio_handler(v->domain, info.gpa); > if ( !handler ) > { > @@ -121,10 +128,6 @@ enum io_state try_handle_mmio(struct cpu_user_regs > *regs, > return rc; > } > > - /* All the instructions used on emulated MMIO region should be valid > */ > - if ( !dabt.valid ) > - return IO_ABORT; > - > /* > * Erratum 766422: Thumb store translation fault to Hypervisor may > * not have correct HSR Rt value. > -- > 2.17 >
