[xen staging] x86/passthrough: do not assert edge triggered GSIs for PVH dom0

[patchbot@xxxxxxx]

commit 6fa25d568f4e597b1940309d97cfd98f4f6eecd6
Author:     Roger Pau Monne <roger.pau@xxxxxxxxxx>
AuthorDate: Wed Jun 10 16:29:22 2020 +0200
Commit:     Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
CommitDate: Thu Jun 11 18:14:29 2020 +0100

    x86/passthrough: do not assert edge triggered GSIs for PVH dom0
    
    Edge triggered interrupts do not assert the line, so the handling done
    in Xen should also avoid asserting it. Asserting the line prevents
    further edge triggered interrupts on the same vIO-APIC pin from being
    delivered, since the line is not de-asserted.
    
    One case of such kind of interrupt is the RTC timer, which is edge
    triggered and available to a PVH dom0. Note this should not affect
    domUs, as it only modifies the behavior of IDENTITY_GSI kind of passed
    through interrupts.
    
    Signed-off-by: Roger Pau Monné <roger.pau@xxxxxxxxxx>
    Acked-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
    Reviewed-by: Paul Durrant <paul@xxxxxxx>
    Release-acked-by: Paul Durrant <paul@xxxxxxx>
---
 xen/arch/x86/hvm/irq.c | 13 ++++++++-----
 1 file changed, 8 insertions(+), 5 deletions(-)

diff --git a/xen/arch/x86/hvm/irq.c b/xen/arch/x86/hvm/irq.c
index 9c8adbc495..fd02cf2e8d 100644
--- a/xen/arch/x86/hvm/irq.c
+++ b/xen/arch/x86/hvm/irq.c
@@ -169,9 +169,10 @@ void hvm_pci_intx_deassert(
 
 void hvm_gsi_assert(struct domain *d, unsigned int gsi)
 {
+    int trig = vioapic_get_trigger_mode(d, gsi);
     struct hvm_irq *hvm_irq = hvm_domain_irq(d);
 
-    if ( gsi >= hvm_irq->nr_gsis )
+    if ( gsi >= hvm_irq->nr_gsis || trig < 0 )
     {
         ASSERT_UNREACHABLE();
         return;
@@ -186,9 +187,10 @@ void hvm_gsi_assert(struct domain *d, unsigned int gsi)
      * to know if the GSI is pending or not.
      */
     spin_lock(&d->arch.hvm.irq_lock);
-    if ( !hvm_irq->gsi_assert_count[gsi] )
+    if ( trig == VIOAPIC_EDGE_TRIG || !hvm_irq->gsi_assert_count[gsi] )
     {
-        hvm_irq->gsi_assert_count[gsi] = 1;
+        if ( trig == VIOAPIC_LEVEL_TRIG )
+            hvm_irq->gsi_assert_count[gsi] = 1;
         assert_gsi(d, gsi);
     }
     spin_unlock(&d->arch.hvm.irq_lock);
@@ -196,11 +198,12 @@ void hvm_gsi_assert(struct domain *d, unsigned int gsi)
 
 void hvm_gsi_deassert(struct domain *d, unsigned int gsi)
 {
+    int trig = vioapic_get_trigger_mode(d, gsi);
     struct hvm_irq *hvm_irq = hvm_domain_irq(d);
 
-    if ( gsi >= hvm_irq->nr_gsis )
+    if ( trig <= VIOAPIC_EDGE_TRIG || gsi >= hvm_irq->nr_gsis )
     {
-        ASSERT_UNREACHABLE();
+        ASSERT(trig == VIOAPIC_EDGE_TRIG && gsi < hvm_irq->nr_gsis);
         return;
     }
 
--
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