Messages in this thread | | | Date | Fri, 31 Mar 2023 09:27:23 -0500 | From | Alex Elder <> | Subject | Re: [PATCH v11 21/26] virt: gunyah: Add IO handlers |
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On 3/3/23 7:06 PM, Elliot Berman wrote: > Add framework for VM functions to handle stage-2 write faults from Gunyah > guest virtual machines. IO handlers have a range of addresses which they > apply to. Optionally, they may apply to only when the value written > matches the IO handler's value. > > Co-developed-by: Prakruthi Deepak Heragu <quic_pheragu@quicinc.com> > Signed-off-by: Prakruthi Deepak Heragu <quic_pheragu@quicinc.com> > Signed-off-by: Elliot Berman <quic_eberman@quicinc.com>
Two (related) bugs and a suggestion that might help avoid adding the same problem in the future. (Or maybe I made that suggestion elsewhere? Anyway, you'll see.)
-Alex
> --- > drivers/virt/gunyah/vm_mgr.c | 94 +++++++++++++++++++++++++++++++++++ > drivers/virt/gunyah/vm_mgr.h | 4 ++ > include/linux/gunyah_vm_mgr.h | 25 ++++++++++ > 3 files changed, 123 insertions(+) > > diff --git a/drivers/virt/gunyah/vm_mgr.c b/drivers/virt/gunyah/vm_mgr.c > index 0269bcdaf692..b31fac15ff45 100644 > --- a/drivers/virt/gunyah/vm_mgr.c > +++ b/drivers/virt/gunyah/vm_mgr.c > @@ -233,6 +233,100 @@ static void gh_vm_add_resource(struct gh_vm *ghvm, struct gh_resource *ghrsc) > mutex_unlock(&ghvm->resources_lock); > } > > +static int _gh_vm_io_handler_compare(const struct rb_node *node, const struct rb_node *parent) > +{ > + struct gh_vm_io_handler *n = container_of(node, struct gh_vm_io_handler, node); > + struct gh_vm_io_handler *p = container_of(parent, struct gh_vm_io_handler, node); > + > + if (n->addr < p->addr) > + return -1; > + if (n->addr > p->addr) > + return 1; > + if ((n->len && !p->len) || (!n->len && p->len)) > + return 0; > + if (n->len < p->len) > + return -1; > + if (n->len > p->len) > + return 1;
The datamatch field in a gh_vm_io_handler structure is Boolean. If this is what you intend, it would be better to not treat them as integer values (i.e., don't use < and >).
However I *think* what you want is to be comparing the data fields here. If so, this is a BUG.
I think you should maybe use "data" in the gh_fn_ioeventfd_arg structure rather than "datamatch". And then use "datamatch" consistently as a Boolean indicating whether to do matching, and "data" to be the value used in matching.
> + if (n->datamatch < p->datamatch) > + return -1; > + if (n->datamatch > p->datamatch) > + return 1; > + return 0; > +} > + > +static int gh_vm_io_handler_compare(struct rb_node *node, const struct rb_node *parent) > +{ > + return _gh_vm_io_handler_compare(node, parent); > +} > + > +static int gh_vm_io_handler_find(const void *key, const struct rb_node *node) > +{ > + const struct gh_vm_io_handler *k = key; > + > + return _gh_vm_io_handler_compare(&k->node, node); > +} > + > +static struct gh_vm_io_handler *gh_vm_mgr_find_io_hdlr(struct gh_vm *ghvm, u64 addr, > + u64 len, u64 data) > +{ > + struct gh_vm_io_handler key = { > + .addr = addr, > + .len = len, > + .datamatch = data,
The datamatch field here is Boolean. I'm pretty sure you want to assign the data field instead, in which case, this is a BUG.
If you *do* intend to treat the data assigned as Boolean, please use !!data to make this obvious.
> + }; > + struct rb_node *node; > + > + node = rb_find(&key, &ghvm->mmio_handler_root, gh_vm_io_handler_find); > + if (!node) > + return NULL; > + > + return container_of(node, struct gh_vm_io_handler, node); > +} > + > +int gh_vm_mmio_write(struct gh_vm *ghvm, u64 addr, u32 len, u64 data) > +{ > + struct gh_vm_io_handler *io_hdlr = NULL; > + int ret; > + > + down_read(&ghvm->mmio_handler_lock); > + io_hdlr = gh_vm_mgr_find_io_hdlr(ghvm, addr, len, data); > + if (!io_hdlr || !io_hdlr->ops || !io_hdlr->ops->write) { > + ret = -ENODEV; > + goto out; > + } > + > + ret = io_hdlr->ops->write(io_hdlr, addr, len, data); > + > +out: > + up_read(&ghvm->mmio_handler_lock); > + return ret; > +} > +EXPORT_SYMBOL_GPL(gh_vm_mmio_write);
. . .
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