File 5aaa9878-x86-vlapic-clear-TMR-bit-for-edge-triggered-intr.patch of Package xen.7673

# Commit 12a50030a81a14a3c7be672ddfde707b961479ec
# Date 2018-03-15 16:59:52 +0100
# Author Liran Alon <liran.alon@oracle.com>
# Committer Jan Beulich <jbeulich@suse.com>
x86/vlapic: clear TMR bit upon acceptance of edge-triggered interrupt to IRR

According to Intel SDM section "Interrupt Acceptance for Fixed Interrupts":
"The trigger mode register (TMR) indicates the trigger mode of the
interrupt (see Figure 10-20). Upon acceptance of an interrupt
into the IRR, the corresponding TMR bit is cleared for
edge-triggered interrupts and set for level-triggered interrupts.
If a TMR bit is set when an EOI cycle for its corresponding
interrupt vector is generated, an EOI message is sent to
all I/O APICs."

Before this patch TMR-bit was cleared on LAPIC EOI which is not what
real hardware does. This was also confirmed in KVM upstream commit
a0c9a822bf37 ("KVM: dont clear TMR on EOI").

Behavior after this patch is aligned with both Intel SDM and KVM
implementation.

Signed-off-by: Liran Alon <liran.alon@oracle.com>
Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>

--- a/xen/arch/x86/hvm/vlapic.c
+++ b/xen/arch/x86/hvm/vlapic.c
@@ -153,6 +153,8 @@ void vlapic_set_irq(struct vlapic *vlapi
 
     if ( trig )
         vlapic_set_vector(vec, &vlapic->regs->data[APIC_TMR]);
+    else
+        vlapic_clear_vector(vec, &vlapic->regs->data[APIC_TMR]);
 
     if ( hvm_funcs.update_eoi_exit_bitmap )
         hvm_funcs.update_eoi_exit_bitmap(target, vec, trig);
@@ -419,7 +421,7 @@ void vlapic_EOI_set(struct vlapic *vlapi
     if ( hvm_funcs.handle_eoi )
         hvm_funcs.handle_eoi(vector);
 
-    if ( vlapic_test_and_clear_vector(vector, &vlapic->regs->data[APIC_TMR]) )
+    if ( vlapic_test_vector(vector, &vlapic->regs->data[APIC_TMR]) )
         vioapic_update_EOI(vlapic_domain(vlapic), vector);
 
     hvm_dpci_msi_eoi(current->domain, vector);
@@ -427,7 +429,7 @@ void vlapic_EOI_set(struct vlapic *vlapi
 
 void vlapic_handle_EOI_induced_exit(struct vlapic *vlapic, int vector)
 {
-    if ( vlapic_test_and_clear_vector(vector, &vlapic->regs->data[APIC_TMR]) )
+    if ( vlapic_test_vector(vector, &vlapic->regs->data[APIC_TMR]) )
         vioapic_update_EOI(vlapic_domain(vlapic), vector);
 
     hvm_dpci_msi_eoi(current->domain, vector);