Re: [Xen-devel] [PATCH v2] x86/passthrough: fix migration of MSI when using posted interrupts

[Roger Pau Monné <roger.pau@xxxxxxxxxx>]

On Tue, Oct 29, 2019 at 05:20:18PM -0700, Joe Jin wrote:
> Hi Roger & Jan,
> 
> I got my test env back, and back the patch to stable-4.12, run same
> test, I still seen original issue, guest kernel printed error:
> 
>  kernel:do_IRQ: 20.114 No irq handler for vector (irq -1)
> 
> After that, pass through infiniband VF stopped to work.

Thanks for the testing, TBH I'm not sure what's wrong here, since I
intended my proposed patch to be functionally equivalent to your first
proposed fix.

> My patch as below, please check:

The patch LGTM.

Can you try to add the following debug patch on top of the existing
one and report the output that you get on the Xen console?

---8<---
diff --git a/xen/drivers/passthrough/vtd/intremap.c 
b/xen/drivers/passthrough/vtd/intremap.c
index 07c1c1627a..91a1dde131 100644
--- a/xen/drivers/passthrough/vtd/intremap.c
+++ b/xen/drivers/passthrough/vtd/intremap.c
@@ -977,7 +977,13 @@ int pi_update_irte(const struct pi_desc *pi_desc, const 
struct pirq *pirq,
 
     rc = msi_msg_write_remap_rte(msi_desc, &msi_desc->msg);
     if ( !rc && prev )
+{
+         printk("sync PIRR on vcpu#%u\n", prev->vcpu_id);
          vlapic_sync_pir_to_irr(prev);
+}
+else
+         printk("not syncing PIRR rc: %d vcpu#%u\n",
+                rc, prev ? prev->vcpu_id : -1);
 
     return rc;
 }

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