From c169e2c287c16d6cdef6f073d12fa02cbd80086c Mon Sep 17 00:00:00 2001
From: Stefano Stabellini <stefano.stabellini@xxxxxxxxxx>
Date: Mon, 20 Sep 2021 18:33:45 -0700
Subject: [PATCH] xen/arm: introduce PHYSDEV_sgi_send

Introduce a simple hypercall to inject an SGI interrupt into a target
domain/vcpu. Please note that the implementation doesn't come with any
rate limiting.

Signed-off-by: Stefano Stabellini <stefano.stabellini@xxxxxxxxxx>
---
 xen/arch/arm/physdev.c          | 34 ++++++++++++++++++++++++++++++---
 xen/arch/arm/traps.c            |  2 +-
 xen/include/asm-arm/hypercall.h |  3 ++-
 xen/include/public/physdev.h    | 19 ++++++++++++++++++
 4 files changed, 53 insertions(+), 5 deletions(-)

diff --git a/xen/arch/arm/physdev.c b/xen/arch/arm/physdev.c
index e91355fe22..2ee29939d2 100644
--- a/xen/arch/arm/physdev.c
+++ b/xen/arch/arm/physdev.c
@@ -11,10 +11,38 @@
 #include <asm/hypercall.h>
 
 
-int do_physdev_op(int cmd, XEN_GUEST_HANDLE_PARAM(void) arg)
+int do_physdev_op(int cmd, uint8_t sgi, uint16_t domid, uint32_t vcpuid)
 {
-    gdprintk(XENLOG_DEBUG, "PHYSDEVOP cmd=%d: not implemented\n", cmd);
-    return -ENOSYS;
+    int rc = 0;
+    struct domain *d;
+
+    if ( cmd != PHYSDEV_sgi_send )
+    {
+        gdprintk(XENLOG_DEBUG, "PHYSDEVOP cmd=%d: not implemented\n", cmd);
+        return -ENOSYS;
+    }
+
+    if ( sgi >= 16 )
+    {
+        gdprintk(XENLOG_DEBUG, "PHYSDEVOP_sgi_send invalid sgi=%u\n", sgi);
+        return -EINVAL;
+    }
+
+
+    d = rcu_lock_domain_by_any_id(domid);
+    if ( d == NULL )
+        return -ESRCH;
+    if ( vcpuid >= d->max_vcpus )
+    {
+        rc = -EINVAL;
+        goto out;
+    }
+
+    vgic_inject_irq(d, d->vcpu[vcpuid], sgi, true);
+
+out:
+    rcu_unlock_domain(d);
+    return rc;
 }
 
 /*
diff --git a/xen/arch/arm/traps.c b/xen/arch/arm/traps.c
index 219ab3c3fb..374ed490a2 100644
--- a/xen/arch/arm/traps.c
+++ b/xen/arch/arm/traps.c
@@ -1377,7 +1377,7 @@ static arm_hypercall_t arm_hypercall_table[] = {
     HYPERCALL(xsm_op, 1),
     HYPERCALL(event_channel_op, 2),
     HYPERCALL_DEPRECATED(event_channel_op_compat, 1),
-    HYPERCALL(physdev_op, 2),
+    HYPERCALL(physdev_op, 4),
     HYPERCALL_DEPRECATED(physdev_op_compat, 1),
     HYPERCALL(sysctl, 2),
     HYPERCALL(hvm_op, 2),
diff --git a/xen/include/asm-arm/hypercall.h b/xen/include/asm-arm/hypercall.h
index a0c5a31a2f..4299548907 100644
--- a/xen/include/asm-arm/hypercall.h
+++ b/xen/include/asm-arm/hypercall.h
@@ -2,7 +2,8 @@
 #define __ASM_ARM_HYPERCALL_H__
 
 #include <public/domctl.h> /* for arch_do_domctl */
-int do_physdev_op(int cmd, XEN_GUEST_HANDLE_PARAM(void) arg);
+
+int do_physdev_op(int cmd, uint8_t sgi, uint16_t domid, uint32_t vcpuid);
 
 long do_arm_vcpu_op(int cmd, unsigned int vcpuid, XEN_GUEST_HANDLE_PARAM(void) arg);
 
diff --git a/xen/include/public/physdev.h b/xen/include/public/physdev.h
index d271766ad0..64458fe7a1 100644
--- a/xen/include/public/physdev.h
+++ b/xen/include/public/physdev.h
@@ -340,6 +340,25 @@ struct physdev_dbgp_op {
 typedef struct physdev_dbgp_op physdev_dbgp_op_t;
 DEFINE_XEN_GUEST_HANDLE(physdev_dbgp_op_t);
 
+/*
+ * ARM only hypercall to send an SGI to another VM
+ *
+ * int physdev_op(int cmd, uint8_t sgi, uint16_t domid, uint32_t vcpuid)
+ *
+ * sgi: SGI number of the interrupt to inject
+ * domid: target domid
+ * vcpuid: target vcpusid
+ *
+ * example:
+ *     mov x0, #30  // PHYSDEV_sgi_send command
+ *     mov x1, #5   // SGI number 5, can chose any in the range 0-15
+ *     mov x2, #1   // destination domain id (e.g. 0 for dom0, 1 for first domU)
+ *     mov x3, #0   // destination vcpu id (not physical cpu), typically 0
+ *     mov x16, #33 // hypercall physdev_op number 33
+ *     hvc 0xEA1    // hypercall command
+ */
+#define PHYSDEV_sgi_send 30
+
 /*
  * Notify that some PIRQ-bound event channels have been unmasked.
  * ** This command is obsolete since interface version 0x00030202 and is **
-- 
2.17.1