[PATCH] x86/xen: Add support for HVMOP_set_evtchn_upcall_vector

[Jane Malalane <jane.malalane@xxxxxxxxxx>]

Implement support for the HVMOP_set_evtchn_upcall_vector hypercall in
order to set the per-vCPU event channel vector callback on Linux and
use it in preference of HVM_PARAM_CALLBACK_IRQ.

If the per-VCPU vector setup is successful on BSP, use this method
for the APs. If not, fallback to the global vector-type callback.

Also register callback_irq at per-vCPU event channel setup to trick
toolstack to think the domain is enlightened.

Suggested-by: "Roger Pau Monné" <roger.pau@xxxxxxxxxx>
Signed-off-by: Jane Malalane <jane.malalane@xxxxxxxxxx>
---
CC: Juergen Gross <jgross@xxxxxxxx>
CC: Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx>
CC: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
CC: Ingo Molnar <mingo@xxxxxxxxxx>
CC: Borislav Petkov <bp@xxxxxxxxx>
CC: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
CC: x86@xxxxxxxxxx
CC: "H. Peter Anvin" <hpa@xxxxxxxxx>
CC: Stefano Stabellini <sstabellini@xxxxxxxxxx>
CC: Oleksandr Tyshchenko <oleksandr_tyshchenko@xxxxxxxx>
CC: Jane Malalane <jane.malalane@xxxxxxxxxx>
CC: Maximilian Heyne <mheyne@xxxxxxxxx>
CC: Jan Beulich <jbeulich@xxxxxxxx>
CC: Colin Ian King <colin.king@xxxxxxxxx>
CC: xen-devel@xxxxxxxxxxxxxxxxxxxx
---
 arch/x86/include/asm/xen/cpuid.h   |  2 ++
 arch/x86/include/asm/xen/events.h  |  1 +
 arch/x86/xen/enlighten_hvm.c       | 19 +++++++++++++++++--
 arch/x86/xen/suspend_hvm.c         | 20 +++++++++++++++++++-
 drivers/xen/events/events_base.c   | 32 ++++++++++++++++++++++++++++----
 include/xen/interface/hvm/hvm_op.h | 15 +++++++++++++++
 6 files changed, 82 insertions(+), 7 deletions(-)

diff --git a/arch/x86/include/asm/xen/cpuid.h b/arch/x86/include/asm/xen/cpuid.h
index 78e667a31d6c..6daa9b0c8d11 100644
--- a/arch/x86/include/asm/xen/cpuid.h
+++ b/arch/x86/include/asm/xen/cpuid.h
@@ -107,6 +107,8 @@
  * ID 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 */
+#define XEN_HVM_CPUID_UPCALL_VECTOR    (1u << 6)
 
 /*
  * Leaf 6 (0x40000x05)
diff --git a/arch/x86/include/asm/xen/events.h 
b/arch/x86/include/asm/xen/events.h
index 068d9b067c83..b2d86c761bf8 100644
--- a/arch/x86/include/asm/xen/events.h
+++ b/arch/x86/include/asm/xen/events.h
@@ -34,4 +34,5 @@ static inline bool xen_support_evtchn_rebind(void)
        return (!xen_hvm_domain() || xen_have_vector_callback);
 }
 
+extern bool xen_ack_upcall;
 #endif /* _ASM_X86_XEN_EVENTS_H */
diff --git a/arch/x86/xen/enlighten_hvm.c b/arch/x86/xen/enlighten_hvm.c
index 8b71b1dd7639..847d1da46ff7 100644
--- a/arch/x86/xen/enlighten_hvm.c
+++ b/arch/x86/xen/enlighten_hvm.c
@@ -7,6 +7,7 @@
 
 #include <xen/features.h>
 #include <xen/events.h>
+#include <xen/interface/hvm/hvm_op.h>
 #include <xen/interface/memory.h>
 
 #include <asm/apic.h>
@@ -30,6 +31,9 @@
 
 static unsigned long shared_info_pfn;
 
+__ro_after_init bool xen_ack_upcall;
+EXPORT_SYMBOL_GPL(xen_ack_upcall);
+
 void xen_hvm_init_shared_info(void)
 {
        struct xen_add_to_physmap xatp;
@@ -125,6 +129,9 @@ DEFINE_IDTENTRY_SYSVEC(sysvec_xen_hvm_callback)
 {
        struct pt_regs *old_regs = set_irq_regs(regs);
 
+       if (xen_ack_upcall)
+               ack_APIC_irq();
+
        inc_irq_stat(irq_hv_callback_count);
 
        xen_hvm_evtchn_do_upcall();
@@ -168,6 +175,15 @@ static int xen_cpu_up_prepare_hvm(unsigned int cpu)
        if (!xen_have_vector_callback)
                return 0;
 
+       if (xen_ack_upcall) {
+               xen_hvm_evtchn_upcall_vector_t op = {
+                       .vector = HYPERVISOR_CALLBACK_VECTOR,
+                       .vcpu = per_cpu(xen_vcpu_id, cpu),
+               };
+
+               BUG_ON(HYPERVISOR_hvm_op(HVMOP_set_evtchn_upcall_vector, &op));
+       }
+
        if (xen_feature(XENFEAT_hvm_safe_pvclock))
                xen_setup_timer(cpu);
 
@@ -211,8 +227,7 @@ static void __init xen_hvm_guest_init(void)
 
        xen_panic_handler_init();
 
-       if (!no_vector_callback && xen_feature(XENFEAT_hvm_callback_vector))
-               xen_have_vector_callback = 1;
+       xen_have_vector_callback = !no_vector_callback;
 
        xen_hvm_smp_init();
        WARN_ON(xen_cpuhp_setup(xen_cpu_up_prepare_hvm, xen_cpu_dead_hvm));
diff --git a/arch/x86/xen/suspend_hvm.c b/arch/x86/xen/suspend_hvm.c
index 9d548b0c772f..be66e027ef28 100644
--- a/arch/x86/xen/suspend_hvm.c
+++ b/arch/x86/xen/suspend_hvm.c
@@ -5,6 +5,7 @@
 #include <xen/hvm.h>
 #include <xen/features.h>
 #include <xen/interface/features.h>
+#include <xen/events.h>
 
 #include "xen-ops.h"
 
@@ -14,6 +15,23 @@ void xen_hvm_post_suspend(int suspend_cancelled)
                xen_hvm_init_shared_info();
                xen_vcpu_restore();
        }
-       xen_setup_callback_vector();
+       if (xen_ack_upcall) {
+               unsigned int cpu;
+
+               for_each_online_cpu(cpu) {
+                       xen_hvm_evtchn_upcall_vector_t op = {
+                                       .vector = HYPERVISOR_CALLBACK_VECTOR,
+                                       .vcpu = per_cpu(xen_vcpu_id, cpu),
+                       };
+
+                       BUG_ON(HYPERVISOR_hvm_op(HVMOP_set_evtchn_upcall_vector,
+                                                &op));
+                       /* Trick toolstack to think we are enlightened. */
+                       if (!cpu)
+                               BUG_ON(xen_set_callback_via(1));
+               }
+       } else {
+               xen_setup_callback_vector();
+       }
        xen_unplug_emulated_devices();
 }
diff --git a/drivers/xen/events/events_base.c b/drivers/xen/events/events_base.c
index 46d9295d9a6e..a2420b66e735 100644
--- a/drivers/xen/events/events_base.c
+++ b/drivers/xen/events/events_base.c
@@ -48,6 +48,7 @@
 #include <asm/xen/pci.h>
 #endif
 #include <asm/sync_bitops.h>
+#include <asm/xen/cpuid.h>
 #include <asm/xen/hypercall.h>
 #include <asm/xen/hypervisor.h>
 #include <xen/page.h>
@@ -2200,6 +2201,29 @@ void xen_setup_callback_vector(void)
        }
 }
 
+/* Setup per-vCPU vector-type callbacks and trick toolstack to think
+ * we are enlightened. If this setup is unavailable, fallback to the
+ * global vector-type callback. */
+static __init void xen_setup_upcall_vector(void)
+{
+       xen_hvm_evtchn_upcall_vector_t op = {
+               .vector = HYPERVISOR_CALLBACK_VECTOR,
+               .vcpu = per_cpu(xen_vcpu_id, 0),
+       };
+
+       if (!xen_have_vector_callback)
+               return;
+
+       if ((cpuid_eax(xen_cpuid_base() + 4) & XEN_HVM_CPUID_UPCALL_VECTOR) &&
+           !HYPERVISOR_hvm_op(HVMOP_set_evtchn_upcall_vector, &op) &&
+           !xen_set_callback_via(1))
+               xen_ack_upcall = true;
+       else if (xen_feature(XENFEAT_hvm_callback_vector))
+               xen_setup_callback_vector();
+       else
+               xen_have_vector_callback = 0;
+}
+
 static __init void xen_alloc_callback_vector(void)
 {
        if (!xen_have_vector_callback)
@@ -2210,6 +2234,7 @@ static __init void xen_alloc_callback_vector(void)
 }
 #else
 void xen_setup_callback_vector(void) {}
+static inline void xen_setup_upcall_vector(void) {}
 static inline void xen_alloc_callback_vector(void) {}
 #endif
 
@@ -2271,10 +2296,9 @@ void __init xen_init_IRQ(void)
                if (xen_initial_domain())
                        pci_xen_initial_domain();
        }
-       if (xen_feature(XENFEAT_hvm_callback_vector)) {
-               xen_setup_callback_vector();
-               xen_alloc_callback_vector();
-       }
+       xen_setup_upcall_vector();
+       xen_alloc_callback_vector();
+
 
        if (xen_hvm_domain()) {
                native_init_IRQ();
diff --git a/include/xen/interface/hvm/hvm_op.h 
b/include/xen/interface/hvm/hvm_op.h
index f3097e79bb03..e714d8b6ef89 100644
--- a/include/xen/interface/hvm/hvm_op.h
+++ b/include/xen/interface/hvm/hvm_op.h
@@ -46,4 +46,19 @@ struct xen_hvm_get_mem_type {
 };
 DEFINE_GUEST_HANDLE_STRUCT(xen_hvm_get_mem_type);
 
+/*
+ * HVMOP_set_evtchn_upcall_vector: Set a <vector> that should be used for event
+ *                                 channel upcalls on the specified <vcpu>. If 
set,
+ *                                 this vector will be used in preference to 
the
+ *                                 domain global callback via (see
+ *                                 HVM_PARAM_CALLBACK_IRQ).
+ */
+#define HVMOP_set_evtchn_upcall_vector 23
+struct xen_hvm_evtchn_upcall_vector {
+    uint32_t vcpu;
+    uint8_t vector;
+};
+typedef struct xen_hvm_evtchn_upcall_vector xen_hvm_evtchn_upcall_vector_t;
+DEFINE_GUEST_HANDLE_STRUCT(xen_hvm_evtchn_upcall_vector_t);
+
 #endif /* __XEN_PUBLIC_HVM_HVM_OP_H__ */
-- 
2.11.0