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Re: [Xen-devel] [PATCH v11 2/3] Differentiate IO/mem resources tracked by ioreq server

On 1/26/2016 7:24 PM, Jan Beulich wrote:
On 26.01.16 at 08:59, <yu.c.zhang@xxxxxxxxxxxxxxx> wrote:

On 1/22/2016 7:43 PM, Jan Beulich wrote:
On 22.01.16 at 04:20, <yu.c.zhang@xxxxxxxxxxxxxxx> wrote:
@@ -2601,6 +2605,16 @@ struct hvm_ioreq_server
*hvm_select_ioreq_server(struct domain *d,
           type = (p->type == IOREQ_TYPE_PIO) ?
           addr = p->addr;
+        if ( type == HVMOP_IO_RANGE_MEMORY )
+        {
+             ram_page = get_page_from_gfn(d, p->addr >> PAGE_SHIFT,
+                                          &p2mt, P2M_UNSHARE);

It seems to me like I had asked before: Why P2M_UNSHARE instead
of just P2M_QUERY? (This could surely be fixed up while committing,
the more that I've already done some cleanup here, but I'd like to
understand this before it goes in.)

Hah, sorry for my bad memory. :)
I did not found P2M_QUERY; only P2M_UNSHARE and P2M_ALLOC are
defined. But after reading the code in ept_get_entry(), I guess the
P2M_UNSHARE is not accurate, maybe I should use 0 here for the
p2m_query_t parameter in get_page_from_gfn()?

Ah, sorry for the misnamed suggestion. I'm not sure whether using
zero here actually matches your needs; P2M_UNSHARE though
seems odd in any case, so at least switching to P2M_ALLOC (to
populate PoD pages) would seem to be necessary.

Thanks, Jan.  :)
And now I believe we should use zero here. By now XenGT does not
support PoD and here all we care about is whether the p2m type of this
gfn is p2m_mmio_write_dm.

@@ -2642,6 +2656,11 @@ struct hvm_ioreq_server *hvm_select_ioreq_server(struct 
domain *d,

+        case HVMOP_IO_RANGE_WP_MEM:
+            if ( rangeset_contains_singleton(r, PFN_DOWN(addr)) )
+                return s;

Considering you've got p2m_mmio_write_dm above - can this
validly return false here?

Well, if we have multiple ioreq servers defined, it will...

Ah, right. That's fine then.



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