[Xen-changelog] [xen master] x86/pt: mask MSI vectors on unbind

[patchbot@xxxxxxx]

commit 8c97eb6551f2942a634483ecefdf0e7978ae50e1
Author:     Roger Pau Monne <roger.pau@xxxxxxxxxx>
AuthorDate: Thu Mar 22 14:59:00 2018 +0100
Commit:     Jan Beulich <jbeulich@xxxxxxxx>
CommitDate: Fri Mar 23 10:24:09 2018 +0100

    x86/pt: mask MSI vectors on unbind
    
    When a MSI device with per-vector masking capabilities is detected or
    added to Xen all the vectors are masked when initializing it. This
    implies that the first time the interrupt is bound to a domain it's
    masked.
    
    This however only applies to the first time the interrupt is bound
    because neither the unbind nor the pirq unmap will mask the vector
    again. In order to fix this re-mask the interrupt when unbinding it
    from a guest. This makes sure that pairs of bind/unbind will always
    get the same masking state.
    
    Note that no issues have been reported regarding this behavior because
    QEMU always uses the newly introduced XEN_PT_GFLAGSSHIFT_UNMASKED when
    binding interrupts, so it's always unmasked.
    
    Signed-off-by: Roger Pau Monné <roger.pau@xxxxxxxxxx>
    Reviewed-by: Jan Beulich <jbeulich@xxxxxxxx>
---
 xen/drivers/passthrough/io.c | 15 +++++++++++++++
 1 file changed, 15 insertions(+)

diff --git a/xen/drivers/passthrough/io.c b/xen/drivers/passthrough/io.c
index 8f16e6c0a5..bab3aa349a 100644
--- a/xen/drivers/passthrough/io.c
+++ b/xen/drivers/passthrough/io.c
@@ -645,7 +645,22 @@ int pt_irq_destroy_bind(
         }
         break;
     case PT_IRQ_TYPE_MSI:
+    {
+        unsigned long flags;
+        struct irq_desc *desc = domain_spin_lock_irq_desc(d, machine_gsi,
+                                                          &flags);
+
+        if ( !desc )
+            return -EINVAL;
+        /*
+         * Leave the MSI masked, so that the state when calling
+         * pt_irq_create_bind is consistent across bind/unbinds.
+         */
+        guest_mask_msi_irq(desc, true);
+        spin_unlock_irqrestore(&desc->lock, flags);
         break;
+    }
+
     default:
         return -EOPNOTSUPP;
     }
--
generated by git-patchbot for /home/xen/git/xen.git#master

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