Have is_hvm_pv_evtchn_domain() 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_domain() returning true is a condition for setting up
physical IRQ to event channel mappings.
Therefore, a CPUID bit is added so that guests know whether the check
in is_hvm_pv_evtchn_domain() will fail when using
HVMOP_set_evtchn_upcall_vector. This matters for guests that route
PIRQs over event channels since is_hvm_pv_evtchn_domain() is a
condition in physdev_map_pirq().
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.malal...@citrix.com>
---
CC: Jan Beulich <jbeul...@suse.com>
CC: Andrew Cooper <andrew.coop...@citrix.com>
CC: "Roger Pau Monné" <roger....@citrix.com>
CC: Wei Liu <w...@xen.org>
v3:
* Improve commit message and title.
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
