Re: [PATCH v9 23/27] virt: gunyah: Add IO handlers

[Elliot Berman]

On 2/6/2023 2:46 AM, Srivatsa Vaddagiri wrote:
> * Elliot Berman <quic_eberman@xxxxxxxxxxx> [2023-01-20 14:46:22]:
>
> > +static inline bool gh_vm_io_handler_matches(struct gunyah_vm_io_handler *io_hdlr, u64 addr,
> > +						u64 len, u64 data)
> > +{
> > +	u64 mask = BIT_ULL(io_hdlr->len * BITS_PER_BYTE) - 1;
> > +
> > +	if (io_hdlr->addr != addr)
>
> Isn't this test redundant (given that caller would have performed same test)?

Done.

> > +		return false;
> > +
> > +	if (!io_hdlr->datamatch)
> > +		return true;
> > +
> > +	if (io_hdlr->len != len)
> > +		return false;
> > +
> > +	return (data & mask) == (io_hdlr->data & mask);
> > +}
> > +
> > +static struct gunyah_vm_io_handler *gh_vm_mgr_find_io_hdlr(struct gunyah_vm *ghvm, u64 addr,
> > +								u64 len, u64 data)
> > +{
> > +	struct gunyah_vm_io_handler *io_hdlr = NULL;
> > +	struct rb_node *root = NULL;
> > +
> > +	root = ghvm->mmio_handler_root.rb_node;
> > +	while (root) {
> > +		io_hdlr = rb_entry(root, struct gunyah_vm_io_handler, node);
> > +		if (addr < io_hdlr->addr)
> > +			root = root->rb_left;
> > +		else if (addr > io_hdlr->addr)
> > +			root = root->rb_right;
> > +		else if (gh_vm_io_handler_matches(io_hdlr, addr, len, data))
>
> In case of handler not matching, don't we need to modify root?
> Otherwise we can be stuck in infinite loop here AFAICS.

Done.

> > +			return io_hdlr;
> > +	}
> > +	return NULL;
> > +}
>
> // snip
>
> > +int gh_vm_mgr_add_io_handler(struct gunyah_vm *ghvm, struct gunyah_vm_io_handler *io_hdlr)
> > +{
> > +	struct rb_node **root, *parent = NULL;
> > +
> > +	if (io_hdlr->datamatch &&
> > +		(!io_hdlr->len || io_hdlr->len > (sizeof(io_hdlr->data) * BITS_PER_BYTE)))
> > +		return -EINVAL;
> > +
> > +	root = &ghvm->mmio_handler_root.rb_node;
> > +	while (*root) {
> > +		struct gunyah_vm_io_handler *curr = rb_entry(*root, struct gunyah_vm_io_handler,
> > +								node);
> > +
> > +		parent = *root;
> > +		if (io_hdlr->addr < curr->addr)
> > +			root = &((*root)->rb_left);
> > +		else if (io_hdlr->addr > curr->addr)
> > +			root = &((*root)->rb_right);
> > +		else
>
> We should allow two io_handlers on the same addr, but with different data
> matches I think.

Done.

> > +			return -EEXIST;
> > +	}
> > +
> > +	rb_link_node(&io_hdlr->node, parent, root);
> > +	rb_insert_color(&io_hdlr->node, &ghvm->mmio_handler_root);
> > +	return 0;
> > +}
> > +EXPORT_SYMBOL_GPL(gh_vm_mgr_add_io_handler);