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Re: [PATCH V1 03/16] xen/ioreq: Make x86's hvm_ioreq_needs_completion() common




On 14.09.20 17:59, Jan Beulich wrote:

Hi Jan

On 10.09.2020 22:21, Oleksandr Tyshchenko wrote:
--- a/xen/include/xen/ioreq.h
+++ b/xen/include/xen/ioreq.h
@@ -35,6 +35,13 @@ static inline struct hvm_ioreq_server 
*get_ioreq_server(const struct domain *d,
      return GET_IOREQ_SERVER(d, id);
  }
+static inline bool hvm_ioreq_needs_completion(const ioreq_t *ioreq)
+{
+    return ioreq->state == STATE_IOREQ_READY &&
+           !ioreq->data_is_ptr &&
+           (ioreq->type != IOREQ_TYPE_PIO || ioreq->dir != IOREQ_WRITE);
+}
While the PIO aspect has been discussed to some length, what about
the data_is_ptr concept? I didn't think there were Arm insns fitting
this? Instead I thought some other Arm-specific adjustments to the
protocol might be needed. At which point the question of course would
be in how far ioreq_t as a whole really fits Arm in its current shape.
I may mistake here but I don't think the "data_is_ptr" is supported.
It worth mentioning that on Arm, all the accesses to MMIO region will do a single memory access.
So we set "df" to 0 and "count" to 1. Other ioreq_t fields are in use.

--
Regards,

Oleksandr Tyshchenko




 


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