Have is_hvm_pv_evtchn_vcpu() return true for vector callbacks for
evtchn delivery set up on a per-vCPU basis via
HVMOP_set_evtchn_upcall_vector.

is_hvm_pv_evtchn_vcpu() returning true is a condition for setting up
physical IRQ to event channel mappings.

The naming of the CPUID bit is quite generic about upcall support
being available. That's done so that the define name doesn't become
overly long like XEN_HVM_CPUID_UPCALL_VECTOR_SUPPORTS_PIRQ or some
such.

A guest that doesn't care about physical interrupts routed over event
channels can just test for the availability of the hypercall directly
(HVMOP_set_evtchn_upcall_vector) without checking the CPUID bit.

Signed-off-by: Jane Malalane <jane.malalane@citrix.com>
---
CC: Jan Beulich <jbeulich@suse.com>
CC: Andrew Cooper <andrew.cooper3@citrix.com>
CC: "Roger Pau Monné" <roger.pau@citrix.com>
CC: Wei Liu <wl@xen.org>

v2:
 * Since the naming of the CPUID bit is quite generic, better explain
   when it should be checked for, in code comments and commit message.
---
 xen/arch/x86/include/asm/domain.h   | 8 +++++++-
 xen/arch/x86/traps.c                | 6 ++++++
 xen/include/public/arch-x86/cpuid.h | 5 +++++
 3 files changed, 18 insertions(+), 1 deletion(-)

diff --git a/xen/arch/x86/include/asm/domain.h b/xen/arch/x86/include/asm/domain.h
index 35898d725f..f044e0a492 100644
--- a/xen/arch/x86/include/asm/domain.h
+++ b/xen/arch/x86/include/asm/domain.h
@@ -14,8 +14,14 @@
 
 #define has_32bit_shinfo(d)    ((d)->arch.has_32bit_shinfo)
 
+/*
+ * Set to true if either the global vector-type callback or per-vCPU
+ * LAPIC vectors are used. Assume all vCPUs will use
+ * HVMOP_set_evtchn_upcall_vector as long as the initial vCPU does.
+ */
 #define is_hvm_pv_evtchn_domain(d) (is_hvm_domain(d) && \
-        (d)->arch.hvm.irq->callback_via_type == HVMIRQ_callback_vector)
+        ((d)->arch.hvm.irq->callback_via_type == HVMIRQ_callback_vector || \
+         (d)->vcpu[0]->arch.hvm.evtchn_upcall_vector))
 #define is_hvm_pv_evtchn_vcpu(v) (is_hvm_pv_evtchn_domain(v->domain))
 #define is_domain_direct_mapped(d) ((void)(d), 0)
 
diff --git a/xen/arch/x86/traps.c b/xen/arch/x86/traps.c
index 25bffe47d7..1a7f9df067 100644
--- a/xen/arch/x86/traps.c
+++ b/xen/arch/x86/traps.c
@@ -1152,6 +1152,12 @@ void cpuid_hypervisor_leaves(const struct vcpu *v, uint32_t leaf,
         res->a |= XEN_HVM_CPUID_DOMID_PRESENT;
         res->c = d->domain_id;
 
+        /*
+         * Per-vCPU event channel upcalls are implemented and work
+         * correctly with PIRQs routed over event channels.
+         */
+        res->a |= XEN_HVM_CPUID_UPCALL_VECTOR;
+
         break;
 
     case 5: /* PV-specific parameters */
diff --git a/xen/include/public/arch-x86/cpuid.h b/xen/include/public/arch-x86/cpuid.h
index f2b2b3632c..c49eefeaf8 100644
--- a/xen/include/public/arch-x86/cpuid.h
+++ b/xen/include/public/arch-x86/cpuid.h
@@ -109,6 +109,11 @@
  * field from 8 to 15 bits, allowing to target APIC IDs up 32768.
  */
 #define XEN_HVM_CPUID_EXT_DEST_ID      (1u << 5)
+/*
+ * Per-vCPU event channel upcalls work correctly with physical IRQs
+ * bound to event channels.
+ */
+#define XEN_HVM_CPUID_UPCALL_VECTOR    (1u << 6)
 
 /*
  * Leaf 6 (0x40000x05)
-- 
2.11.0