Re: [Xen-devel] Commit 1aeb1156fa43fe2cd2b5003995b20466cd19a622: "x86 don't change affinity with interrupt unmasked", APCI errors and assorted pci trouble

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 14.04.15 at 14:46, <linux@xxxxxxxxxxxxxx> wrote:
> I just had a hunch .. could it be related to the kernel apci/irq refactoring
> series of Jiang Liu, that already caused a lot of trouble in 3.17, 3.18 and 
> 3.19
> with Xen.  And yes that seems to be the case:
> 
> On Xen without "x86 don't change affinity with interrupt unmasked"
> - 3.16 && 3.19 && 4.0 all work fine 
> 
> On Xen with "x86 don't change affinity with interrupt unmasked" 
> - 3.16 (which is before that kernel refactoring series) works fine.
> - 3.19, 4.0 both give the dom0 kernel hangs and the :
>         (XEN) [2015-03-26 20:35:42.205] APIC error on CPU0: 00(40)
>         (XEN) [2015-03-26 20:35:42.372] APIC error on CPU0: 40(40)
> 
> (haven't tested 3.17 and 3.18 because these have asorted problems due that 
>  series that weren't fixed in time before stable updates ended.)
> 
> So it seems Jan's patch seems to interfere with that patch series.

That's rather odd a finding - the patch in question in fact uncovered
a bug introduced in 2ca9fbd739 ("AMD IOMMU: allocate IRTE entries
instead of using a static mapping") in that IO-APIC RTE reads would
unconditionally translate the data (i.e. regardless of whether the
entry was already in translated format). The patch below fixes this
for me - can you please give this a try too?

Thanks, Jan

--- unstable.orig/xen/drivers/passthrough/amd/iommu_intr.c
+++ unstable/xen/drivers/passthrough/amd/iommu_intr.c
@@ -365,15 +365,17 @@ unsigned int amd_iommu_read_ioapic_from_
     unsigned int apic, unsigned int reg)
 {
     unsigned int val = __io_apic_read(apic, reg);
+    unsigned int pin = (reg - 0x10) / 2;
+    unsigned int offset = ioapic_sbdf[IO_APIC_ID(apic)].pin_2_idx[pin];
 
-    if ( !(reg & 1) )
+    if ( !(reg & 1) && offset < INTREMAP_ENTRIES )
     {
-        unsigned int offset = val & (INTREMAP_ENTRIES - 1);
         u16 bdf = ioapic_sbdf[IO_APIC_ID(apic)].bdf;
         u16 seg = ioapic_sbdf[IO_APIC_ID(apic)].seg;
         u16 req_id = get_intremap_requestor_id(seg, bdf);
         const u32 *entry = get_intremap_entry(seg, req_id, offset);
 
+        ASSERT(offset == (val & (INTREMAP_ENTRIES - 1)));
         val &= ~(INTREMAP_ENTRIES - 1);
         val |= get_field_from_reg_u32(*entry,
                                       INT_REMAP_ENTRY_INTTYPE_MASK,



_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxx
http://lists.xen.org/xen-devel