On 9/1/26 5:36 PM, Baptiste Le Duc wrote:
RISC-V guests can expose several virtual interrupt controllers at
distinct GPA ranges: vPLIC (hasn't been introduced yet) for legacy machines,
vAPLIC and vIMSIC for AIA-compliant ones (are being introduced in the follow
up patches).
As Jan said here [1], we shouldn't use "as later in this series" in
commit message...
I will reword this paragraph to:
```
A RISC-V guest can be given several emulated devices at distinct GPA
ranges; the virtual interrupt controllers alone account for vPLIC on
legacy machines and vAPLIC together with vIMSIC on AIA-compliant ones.
Routing MMIO faults via a per-device is_access() check in the trap
handler would couple that handler to every device it must serve,
requiring a new conditional branch in the fault path for each emulated
device added.
```
[1]:
https://lore.kernel.org/xen-devel/[email protected]/T/#m56fbac1ceb0642d5d868e9dcb2b5ed93ecbe5058
Routing MMIO faults via a per-device is_access() check in the
trap handler would couple it to every device it must serve, requiring a
new conditional branch in the fault path each time a new emulated device is
added.
Introduce a per-domain MMIO handler registration table, modeled
after the equivalent ARM framework, so that virtual devices
self-register their GPA ranges and read/write callbacks at domain
creation time. The MMIO fault path delegates to a single
try_handle_mmio() entry point and remains agnostic of which device
owns a particular address.
A subsequent patch wires this into the MMIO fault path in traps.c.
...same here
I'll reword this to:
```
Nothing registers a handler and try_handle_mmio() has no callers yet,
so this patch is a no-op; the trap handler is left untouched.
```
+
I will add after Signed-off-by:
```
---
Wiring this into the MMIO fault path in traps.c is done in this patch
series later.
```
[...]
+
+int register_mmio_handler(struct domain *d,
+ const struct mmio_handler_ops *ops,
+ paddr_t addr, paddr_t size)
+{
+ struct vmmio *vmmio = &d->arch.vmmio;
+ struct mmio_handler *handlers = vmmio->handlers;
+ paddr_t end = addr + size;
+ unsigned int i;
+ int rc = 0;
+ bool overlap;
+
+ if ( !ops || !ops->read || !ops->write || !size || end < addr )
+ return -EINVAL;
Just a question: is the aim of end < addr check to handle possible overflow of
end?
Yes, your understanding is correct.
Thanks.
~ Oleksii
