[xen staging] xen/riscv: introduce vcpu_kick() implementation

[patchbot@xxxxxxx]

commit d81a91b0e4dde994c5ebb0e4d199f7bc44358aec
Author:     Oleksii Kurochko <oleksii.kurochko@xxxxxxxxx>
AuthorDate: Fri Mar 6 17:33:23 2026 +0100
Commit:     Jan Beulich <jbeulich@xxxxxxxx>
CommitDate: Tue Mar 10 09:26:13 2026 +0100

    xen/riscv: introduce vcpu_kick() implementation
    
    Add a RISC-V implementation of vcpu_kick(), which unblocks the target
    vCPU and sends an event check IPI if the vCPU was running on another
    processor. This mirrors the behavior of Arm and enables proper vCPU
    wakeup handling on RISC-V.
    
    Remove the stub implementation from stubs.c, as it is now provided by
    arch/riscv/domain.c.
    
    Since vcpu_kick() calls perfc_incr(vcpu_kick), add perfcounter for
    vcpu_kick to handle the case when CONFIG_PERF_COUNTERS=y. Although
    CONFIG_PERF_COUNTERS is not enabled by default, it can be enabled,
    for example, by randconfig what will lead to CI build issues.
    
    Signed-off-by: Oleksii Kurochko <oleksii.kurochko@xxxxxxxxx>
    Acked-by: Jan Beulich <jbeulich@xxxxxxxx>
---
 xen/arch/riscv/domain.c                 | 14 ++++++++++++++
 xen/arch/riscv/include/asm/Makefile     |  1 -
 xen/arch/riscv/include/asm/perfc_defn.h |  3 +++
 xen/arch/riscv/stubs.c                  |  5 -----
 4 files changed, 17 insertions(+), 6 deletions(-)

diff --git a/xen/arch/riscv/domain.c b/xen/arch/riscv/domain.c
index d25938200f..470eca3ad7 100644
--- a/xen/arch/riscv/domain.c
+++ b/xen/arch/riscv/domain.c
@@ -1,9 +1,11 @@
 /* SPDX-License-Identifier: GPL-2.0-only */
 
+#include <xen/cpumask.h>
 #include <xen/init.h>
 #include <xen/mm.h>
 #include <xen/sections.h>
 #include <xen/sched.h>
+#include <xen/smp.h>
 #include <xen/vmap.h>
 
 #include <asm/bitops.h>
@@ -264,6 +266,18 @@ void vcpu_flush_interrupts(struct vcpu *curr)
 #endif
 }
 
+void vcpu_kick(struct vcpu *v)
+{
+    bool running = v->is_running;
+
+    vcpu_unblock(v);
+    if ( running && v != current )
+    {
+        perfc_incr(vcpu_kick);
+        smp_send_event_check_mask(cpumask_of(v->processor));
+    }
+}
+
 static void __init __maybe_unused build_assertions(void)
 {
     /*
diff --git a/xen/arch/riscv/include/asm/Makefile 
b/xen/arch/riscv/include/asm/Makefile
index 3824f31c39..86c56251d5 100644
--- a/xen/arch/riscv/include/asm/Makefile
+++ b/xen/arch/riscv/include/asm/Makefile
@@ -7,7 +7,6 @@ generic-y += hypercall.h
 generic-y += iocap.h
 generic-y += irq-dt.h
 generic-y += percpu.h
-generic-y += perfc_defn.h
 generic-y += random.h
 generic-y += softirq.h
 generic-y += vm_event.h
diff --git a/xen/arch/riscv/include/asm/perfc_defn.h 
b/xen/arch/riscv/include/asm/perfc_defn.h
new file mode 100644
index 0000000000..8a4b945df6
--- /dev/null
+++ b/xen/arch/riscv/include/asm/perfc_defn.h
@@ -0,0 +1,3 @@
+/* This file is intended to be included multiple times. */
+
+PERFCOUNTER(vcpu_kick, "vcpu: notify other vcpu")
diff --git a/xen/arch/riscv/stubs.c b/xen/arch/riscv/stubs.c
index daadff0138..eedf8bf935 100644
--- a/xen/arch/riscv/stubs.c
+++ b/xen/arch/riscv/stubs.c
@@ -203,11 +203,6 @@ void vcpu_block_unless_event_pending(struct vcpu *v)
     BUG_ON("unimplemented");
 }
 
-void vcpu_kick(struct vcpu *v)
-{
-    BUG_ON("unimplemented");
-}
-
 unsigned long
 hypercall_create_continuation(unsigned int op, const char *format, ...)
 {
--
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