On 12/09/11 07:50, Jan Beulich wrote:
>>>> On 09.09.11 at 18:47, Andrew Cooper <andrew.cooper3@xxxxxxxxxx> wrote:
>> On 09/09/11 17:22, Andrew Cooper wrote:
>>> ---SNIP---
>>>
>>> Version 3. Applied Jan's suggestions, and extended some of the comments.
>>>
>> V4 - get the BUG_ON logic correct (oops).
>>
>> I have now done a few reboot tests and a kexec test with this patch.
>>
>> Are there any other tests you would suggest, or shall I formally submit
>> the patch for unstable and backporting?
>
> Looks technically good now, but there are a few cosmetic comments still:
>
>> --- a/xen/arch/x86/io_apic.c Mon Sep 05 15:10:28 2011 +0100
>> +++ b/xen/arch/x86/io_apic.c Fri Sep 09 17:20:49 2011 +0100
>> @@ -68,6 +68,16 @@ int __read_mostly nr_ioapics;
>> #define MAX_PLUS_SHARED_IRQS nr_irqs_gsi
>> #define PIN_MAP_SIZE (MAX_PLUS_SHARED_IRQS + nr_irqs_gsi)
>>
>> +
>> +#define ioapic_has_eoi_reg(apic) (mp_ioapics[(apic)].mpc_apicver >= 0x20)
>> +
>> +static void __io_apic_eoi(unsigned int apic, unsigned int vector, unsigned
>> int pin);
>> +static void io_apic_eoi(unsigned int apic, unsigned int vector, unsigned
>> int pin);
> No need to declare these here if you move the definitions up before
> the first use (would fit well after ioapic_write_entry()).
Ok
>> +
>> +#define io_apic_eoi_vector(apic, vector) io_apic_eoi((apic), (vector), -1)
>> +#define io_apic_eoi_pin(apic, pin) io_apic_eoi((apic), -1, (pin))
>> +
>> +
>> /*
>> * This is performance-critical, we want to do it O(1)
>> *
>> ...
>> @@ -2622,3 +2621,124 @@ void __init init_ioapic_mappings(void)
>> printk(XENLOG_INFO "IRQ limits: %u GSI, %u MSI/MSI-X\n",
>> nr_irqs_gsi, nr_irqs - nr_irqs_gsi);
>> }
>> +
>> +/* EOI an IO-APIC entry. One of vector or pin may be -1, indicating that
>> + * it should be worked out using the other. This function disables
>> interrupts
>> + * and takes the ioapic_lock */
>> +static void io_apic_eoi(unsigned int apic, unsigned int vector, unsigned
>> int pin)
>> +{
>> + unsigned int flags;
>> + spin_lock_irqsave(&ioapic_lock, flags);
>> + __io_apic_eoi(apic, vector, pin);
>> + spin_unlock_irqrestore(&ioapic_lock, flags);
>> +}
>> +
>> +/* EOI an IO-APIC entry. One of vector or pin may be -1, indicating that
>> + * it should be worked out using the other. This function expect that the
>> + * ioapic_lock is taken, and interrupts are disabled (or there is a good
>> reason
>> + * not to), and that if both pin and vector are passed, that they refer to
>> the
>> + * same redirection entry in the IO-APIC. */
>> +static void __io_apic_eoi(unsigned int apic, unsigned int vector, unsigned
>> int pin)
>> +{
>> + /* Ensure some useful information is passed in */
>> + BUG_ON( !(vector == -1 && pin != -1) );
>> +
>> + /* Prefer the use of the EOI register if available */
>> + if ( ioapic_has_eoi_reg(apic) )
>> + {
>> + /* If vector is unknown, read it from the IO-APIC */
>> + if ( vector == -1 )
>> + vector = __ioapic_read_entry(apic, pin, TRUE).vector;
>> +
>> + *(IO_APIC_BASE(apic)+16) = vector;
>> + }
>> + else
>> + {
>> + /* Else fake an EOI by switching to edge triggered mode
>> + * and back */
>> + struct IO_APIC_route_entry entry;
>> + bool_t need_to_unmask = 0;
>> +
>> + /* If pin is unknown, search for it */
>> + if ( pin == -1 )
>> + {
>> + unsigned int p;
>> + for ( p = 0; p < nr_ioapic_registers[apic]; ++p )
>> + {
>> + entry = __ioapic_read_entry(apic, p, TRUE);
>> + if ( entry.vector == vector )
>> + {
>> + pin = p;
>> + /* break; */
>> +
>> + /* Here should be a break out of the loop, but at the
> ... moment ...
>
>> + * 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. */
>> +
> Why don't you just call __io_apic_eoi() recursively here?
>
> Jan
If I call the function recursively, it will loop forever. Anyway, the
need to clear multiple pins is only temorary until George finishes his
per-device AMD interrupt remap patch which will enforce vector
uniqueness in each IO-APIC. My expectation is that this issue will be
fixed in the next few weeks.
>> + if ( ! entry.mask )
>> + {
>> + /* If entry is not currently masked, mask it and
>> make
>> + * a note to unmask it later */
>> + entry.mask = 1;
>> + __ioapic_write_entry(apic, pin, TRUE, entry);
>> + need_to_unmask = 1;
>> + }
>> +
>> + /* Flip the trigger mode to edge and back */
>> + entry.trigger = 0;
>> + __ioapic_write_entry(apic, pin, TRUE, entry);
>> + entry.trigger = 1;
>> + __ioapic_write_entry(apic, pin, TRUE, entry);
>> +
>> + if ( need_to_unmask )
>> + {
>> + /* Unmask if neccesary */
>> + entry.mask = 0;
>> + __ioapic_write_entry(apic, pin, TRUE, entry);
>> + }
>> +
>> + }
>> + }
>> +
>> + /* 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;
>> + }
>> +
>> + entry = __ioapic_read_entry(apic, pin, TRUE);
>> +
>> + if ( ! entry.mask )
>> + {
>> + /* If entry is not currently masked, mask it and make
>> + * a note to unmask it later */
>> + entry.mask = 1;
>> + __ioapic_write_entry(apic, pin, TRUE, entry);
>> + need_to_unmask = 1;
>> + }
>> +
>> + /* Flip the trigger mode to edge and back */
>> + entry.trigger = 0;
>> + __ioapic_write_entry(apic, pin, TRUE, entry);
>> + entry.trigger = 1;
>> + __ioapic_write_entry(apic, pin, TRUE, entry);
>> +
>> + if ( need_to_unmask )
>> + {
>> + /* Unmask if neccesary */
>> + entry.mask = 0;
>> + __ioapic_write_entry(apic, pin, TRUE, entry);
>> + }
>> + }
>> +}
>> ...
I will formally submit the patch for inclusion now.
--
Andrew Cooper - Dom0 Kernel Engineer, Citrix XenServer
T: +44 (0)1223 225 900, http://www.citrix.com
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