[PATCH] VT-d: return full destination ID for IO-APIC reads

[PATCH] VT-d: return full destination ID for IO-APIC reads

[Jan Beulich]

In x2APIC mode it is 32 bits wide. Not having returned the full value
was mostly benign: We never modify the ID based on its original value;
full new values get written at all times. It was "just" debug logging
which ended up wrong this way (and which will need adjustment itself as
well, to also consume the full value).

Signed-off-by: Jan Beulich <jbeulich@suse.com>

--- a/xen/drivers/passthrough/vtd/intremap.c
+++ b/xen/drivers/passthrough/vtd/intremap.c
@@ -314,8 +314,13 @@ static int remap_entry_to_ioapic_rte(
     old_rte->dest_mode = iremap_entry->remap.dm;
     old_rte->trigger = iremap_entry->remap.tm;
     old_rte->__reserved_2 = 0;
-    old_rte->dest.logical.__reserved_1 = 0;
-    old_rte->dest.logical.logical_dest = iremap_entry->remap.dst >> 8;
+    if ( x2apic_enabled )
+        old_rte->dest.dest32 = iremap_entry->remap.dst;
+    else
+    {
+        old_rte->dest.logical.__reserved_1 = 0;
+        old_rte->dest.logical.logical_dest = iremap_entry->remap.dst >> 8;
+    }
 
     unmap_vtd_domain_page(iremap_entries);
     spin_unlock_irqrestore(&ir_ctrl->iremap_lock, flags);



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Re: [PATCH] VT-d: return full destination ID for IO-APIC reads

[Andrew Cooper]

On 02/04/2019 13:56, Jan Beulich wrote:
> In x2APIC mode it is 32 bits wide. Not having returned the full value
> was mostly benign: We never modify the ID based on its original value;
> full new values get written at all times. It was "just" debug logging
> which ended up wrong this way (and which will need adjustment itself as
> well, to also consume the full value).
>
> Signed-off-by: Jan Beulich <jbeulich@suse.com>

Acked-by: Andrew Cooper <andrew.cooper3@citrix.com>

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Re: [PATCH] VT-d: return full destination ID for IO-APIC reads

[Tian, Kevin]

> From: Jan Beulich [mailto:JBeulich@suse.com]
> Sent: Tuesday, April 2, 2019 8:57 PM
> 
> In x2APIC mode it is 32 bits wide. Not having returned the full value
> was mostly benign: We never modify the ID based on its original value;
> full new values get written at all times. It was "just" debug logging
> which ended up wrong this way (and which will need adjustment itself as
> well, to also consume the full value).
> 
> Signed-off-by: Jan Beulich <jbeulich@suse.com>

Acked-by: Kevin Tian <kevin.tian@intel.com>

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