| Message ID | 20250325172727.600716-3-stewart.hildebrand@amd.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | PCI devices passthrough on Arm, part 3 | expand |
Hi Steward, On 25/03/2025 17:27, Stewart Hildebrand wrote: > We expect mmio read handlers to leave the bits above the access size > zeroed. Add an ASSERT to check this aspect of read handler behavior. > > Suggested-by: Roger Pau Monné <roger.pau@citrix.com> > Signed-off-by: Stewart Hildebrand <stewart.hildebrand@amd.com> With one question below: Acked-by: Julien Grall <jgrall@amazon.com> > --- > v17->v18: > * no change > > v16->v17: > * new patch > > See https://lore.kernel.org/xen-devel/bc6660ef-59f1-4514-9792-067d987e3fbc@xen.org/ > > Also see 7db7bd0f319f ("arm/vpci: honor access size when returning an error") > > Also see xen/arch/arm/ioreq.c:handle_ioserv() > --- > xen/arch/arm/io.c | 2 ++ > 1 file changed, 2 insertions(+) > > diff --git a/xen/arch/arm/io.c b/xen/arch/arm/io.c > index 653428e16c1f..68b5dca70026 100644 > --- a/xen/arch/arm/io.c > +++ b/xen/arch/arm/io.c > @@ -37,6 +37,8 @@ static enum io_state handle_read(const struct mmio_handler *handler, > if ( !handler->ops->read(v, info, &r, handler->priv) ) > return IO_ABORT; > > + ASSERT((r & ~GENMASK_ULL((1U << info->dabt.size) * 8 - 1, 0)) == 0); OOI, I was expecing GENMASK to be sufficient because "r" is effectively an "unsigned long". So any reason to use GENMASK_ULL? Cheers,
diff --git a/xen/arch/arm/io.c b/xen/arch/arm/io.c index 653428e16c1f..68b5dca70026 100644 --- a/xen/arch/arm/io.c +++ b/xen/arch/arm/io.c @@ -37,6 +37,8 @@ static enum io_state handle_read(const struct mmio_handler *handler, if ( !handler->ops->read(v, info, &r, handler->priv) ) return IO_ABORT; + ASSERT((r & ~GENMASK_ULL((1U << info->dabt.size) * 8 - 1, 0)) == 0); + r = sign_extend(dabt, r); set_user_reg(regs, dabt.reg, r);
We expect mmio read handlers to leave the bits above the access size zeroed. Add an ASSERT to check this aspect of read handler behavior. Suggested-by: Roger Pau Monné <roger.pau@citrix.com> Signed-off-by: Stewart Hildebrand <stewart.hildebrand@amd.com> --- v17->v18: * no change v16->v17: * new patch See https://lore.kernel.org/xen-devel/bc6660ef-59f1-4514-9792-067d987e3fbc@xen.org/ Also see 7db7bd0f319f ("arm/vpci: honor access size when returning an error") Also see xen/arch/arm/ioreq.c:handle_ioserv() --- xen/arch/arm/io.c | 2 ++ 1 file changed, 2 insertions(+)