On 11/11/11 16:07, Jan Beulich wrote:
> Irrespective of the IO-APIC vector sharing suppression patch just sent
> the logic in this function needs to iterate over all RTEs, since
> multiple pins within an IO-APIC may still use the same vector.
Why? The whole point of preventing vector sharing for IO-APICs is to
prevent two or more RTEs referencing the same vector.
~Andrew
> This is
> due to the irq_2_pin[] mapping not necessarily being 1:1.
>
> Consequently we should remove the commented out code as well as the
> respective comments provisioned for the point in time when vector
> sharing between unrelated RTEs would be disabled.
>
> Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
>
> --- a/xen/arch/x86/io_apic.c
> +++ b/xen/arch/x86/io_apic.c
> @@ -281,36 +281,15 @@ static void __io_apic_eoi(unsigned int a
> /* If pin is unknown, search for it */
> if ( pin == -1 )
> {
> - unsigned int p;
> - for ( p = 0; p < nr_ioapic_entries[apic]; ++p )
> + for ( pin = 0; pin < nr_ioapic_entries[apic]; ++pin )
> {
> - entry = __ioapic_read_entry(apic, p, TRUE);
> + entry = __ioapic_read_entry(apic, pin, TRUE);
> if ( entry.vector == vector )
> - {
> - pin = p;
> - /* break; */
> -
> - /* Here should be a break out of the loop, but at the
> - * Xen code doesn't actually prevent multiple IO-APIC
> - * entries being assigned the same vector, so EOI all
> - * pins which have the correct vector.
> - *
> - * Remove the following code when the above assertion
> - * is fulfilled. */
> - __io_apic_eoi(apic, vector, p);
> - }
> + __io_apic_eoi(apic, vector, pin);
> }
>
> /* If search fails, nothing to do */
>
> - /* if ( pin == -1 ) */
> -
> - /* Because the loop wasn't broken out of (see comment above),
> - * all relevant pins have been EOI, so we can always return.
> - *
> - * Re-instate the if statement above when the Xen logic has been
> - * fixed.*/
> -
> return;
> }
>
>
>
>
--
Andrew Cooper - Dom0 Kernel Engineer, Citrix XenServer
T: +44 (0)1223 225 900, http://www.citrix.com
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