[RFC PATCH v2 19/22] i386/xen: implement HVMOP_set_evtchn_upcall_vector

[David Woodhouse <dwmw2@infradead.org>]

From: Ankur Arora <ankur.a.arora@oracle.com>

The HVMOP_set_evtchn_upcall_vector hypercall sets the per-vCPU upcall
vector, to be delivered to the local APIC just like an MSI (with an EOI).

This takes precedence over the system-wide delivery method set by the
HVMOP_set_param hypercall with HVM_PARAM_CALLBACK_IRQ. It's used by
Windows and Xen (PV shim) guests but normally not by Linux.

Signed-off-by: Ankur Arora <ankur.a.arora@oracle.com>
Signed-off-by: Joao Martins <joao.m.martins@oracle.com>
[dwmw2: Rework for upstream kernel changes and split from HVMOP_set_param]
Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
---
 target/i386/cpu.h        |  1 +
 target/i386/kvm/kvm.c    |  7 ++++
 target/i386/machine.c    |  4 ++-
 target/i386/trace-events |  1 +
 target/i386/xen.c        | 69 +++++++++++++++++++++++++++++++++++++---
 target/i386/xen.h        |  1 +
 6 files changed, 77 insertions(+), 6 deletions(-)

diff --git a/target/i386/cpu.h b/target/i386/cpu.h
index bf44a87ddb..938a1b9c8b 100644
--- a/target/i386/cpu.h
+++ b/target/i386/cpu.h
@@ -1792,6 +1792,7 @@ typedef struct CPUArchState {
     uint64_t xen_vcpu_info_default_gpa;
     uint64_t xen_vcpu_time_info_gpa;
     uint64_t xen_vcpu_runstate_gpa;
+    uint8_t xen_vcpu_callback_vector;
 #endif
 #if defined(CONFIG_HVF)
     HVFX86LazyFlags hvf_lflags;
diff --git a/target/i386/kvm/kvm.c b/target/i386/kvm/kvm.c
index a5e67a3119..dc1b3fc502 100644
--- a/target/i386/kvm/kvm.c
+++ b/target/i386/kvm/kvm.c
@@ -4762,6 +4762,13 @@ int kvm_arch_put_registers(CPUState *cpu, int level)
                 return ret;
             }
         }
+
+        if (x86_cpu->env.xen_vcpu_callback_vector) {
+            ret = kvm_xen_set_vcpu_callback_vector(cpu);
+            if (ret < 0) {
+                return ret;
+            }
+        }
     }
 #endif
 
diff --git a/target/i386/machine.c b/target/i386/machine.c
index 6a510e5cbd..09e13cf716 100644
--- a/target/i386/machine.c
+++ b/target/i386/machine.c
@@ -1265,7 +1265,8 @@ static bool xen_vcpu_needed(void *opaque)
     return (env->xen_vcpu_info_gpa != UINT64_MAX ||
             env->xen_vcpu_info_default_gpa != UINT64_MAX ||
             env->xen_vcpu_time_info_gpa != UINT64_MAX ||
-            env->xen_vcpu_runstate_gpa != UINT64_MAX);
+            env->xen_vcpu_runstate_gpa != UINT64_MAX ||
+            env->xen_vcpu_callback_vector != 0);
 }
 
 static const VMStateDescription vmstate_xen_vcpu = {
@@ -1278,6 +1279,7 @@ static const VMStateDescription vmstate_xen_vcpu = {
         VMSTATE_UINT64(env.xen_vcpu_info_default_gpa, X86CPU),
         VMSTATE_UINT64(env.xen_vcpu_time_info_gpa, X86CPU),
         VMSTATE_UINT64(env.xen_vcpu_runstate_gpa, X86CPU),
+        VMSTATE_UINT8(env.xen_vcpu_callback_vector, X86CPU),
         VMSTATE_END_OF_LIST()
     }
 };
diff --git a/target/i386/trace-events b/target/i386/trace-events
index 7118640697..58e28f1a19 100644
--- a/target/i386/trace-events
+++ b/target/i386/trace-events
@@ -16,3 +16,4 @@ kvm_sev_attestation_report(const char *mnonce, const char *data) "mnonce %s data
 kvm_xen_hypercall(int cpu, uint8_t cpl, uint64_t input, uint64_t a0, uint64_t a1, uint64_t a2, uint64_t ret) "xen_hypercall: cpu %d cpl %d input %" PRIu64 " a0 0x%" PRIx64 " a1 0x%" PRIx64 " a2 0x%" PRIx64" ret 0x%" PRIx64
 kvm_xen_set_shared_info(uint64_t gfn) "shared info at gfn 0x%" PRIx64
 kvm_xen_set_vcpu_attr(int cpu, int type, uint64_t gpa) "vcpu attr cpu %d type %d gpa 0x%" PRIx64
+kvm_xen_set_vcpu_callback(int cpu, int vector) "callback vcpu %d vector %d"
diff --git a/target/i386/xen.c b/target/i386/xen.c
index 97032049e6..2583c00a6b 100644
--- a/target/i386/xen.c
+++ b/target/i386/xen.c
@@ -19,6 +19,7 @@
 #include "standard-headers/xen/version.h"
 #include "standard-headers/xen/memory.h"
 #include "standard-headers/xen/hvm/hvm_op.h"
+#include "standard-headers/xen/hvm/params.h"
 #include "standard-headers/xen/vcpu.h"
 
 static bool kvm_gva_to_gpa(CPUState *cs, uint64_t gva, uint64_t *gpa,
@@ -127,7 +128,8 @@ static bool kvm_xen_hcall_xen_version(struct kvm_xen_exit *exit, X86CPU *cpu,
             fi.submap |= 1 << XENFEAT_writable_page_tables |
                          1 << XENFEAT_writable_descriptor_tables |
                          1 << XENFEAT_auto_translated_physmap |
-                         1 << XENFEAT_supervisor_mode_kernel;
+                         1 << XENFEAT_supervisor_mode_kernel |
+                         1 << XENFEAT_hvm_callback_vector;
         }
 
         err = kvm_copy_to_gva(CPU(cpu), arg, &fi, sizeof(fi));
@@ -154,6 +156,29 @@ int kvm_xen_set_vcpu_attr(CPUState *cs, uint16_t type, uint64_t gpa)
     return kvm_vcpu_ioctl(cs, KVM_XEN_VCPU_SET_ATTR, &xhsi);
 }
 
+int kvm_xen_set_vcpu_callback_vector(CPUState *cs)
+{
+    uint8_t vector = X86_CPU(cs)->env.xen_vcpu_callback_vector;
+    struct kvm_xen_vcpu_attr xva;
+
+    xva.type = KVM_XEN_VCPU_ATTR_TYPE_UPCALL_VECTOR;
+    xva.u.vector = vector;
+
+    trace_kvm_xen_set_vcpu_callback(cs->cpu_index, vector);
+
+    return kvm_vcpu_ioctl(cs, KVM_XEN_HVM_SET_ATTR, &xva);
+}
+
+static void do_set_vcpu_callback_vector(CPUState *cs, run_on_cpu_data data)
+{
+    X86CPU *cpu = X86_CPU(cs);
+    CPUX86State *env = &cpu->env;
+
+    env->xen_vcpu_callback_vector = data.host_int;
+
+    kvm_xen_set_vcpu_callback_vector(cs);
+}
+
 static void do_set_vcpu_info_default_gpa(CPUState *cs, run_on_cpu_data data)
 {
     X86CPU *cpu = X86_CPU(cs);
@@ -262,17 +287,51 @@ static bool kvm_xen_hcall_memory_op(struct kvm_xen_exit *exit,
     return true;
 }
 
-static bool kvm_xen_hcall_hvm_op(struct kvm_xen_exit *exit,
+static int kvm_xen_hcall_evtchn_upcall_vector(struct kvm_xen_exit *exit,
+                                              X86CPU *cpu, uint64_t arg)
+{
+    struct xen_hvm_evtchn_upcall_vector *up;
+    CPUState *target_cs;
+    int vector;
+
+    up = gva_to_hva(CPU(cpu), arg);
+    if (!up) {
+        return -EFAULT;
+    }
+
+    vector = up->vector;
+    if (vector < 0x10) {
+        return -EINVAL;
+    }
+
+    target_cs = qemu_get_cpu(up->vcpu);
+    if (!target_cs) {
+        return -EINVAL;
+    }
+
+    async_run_on_cpu(target_cs, do_set_vcpu_callback_vector, RUN_ON_CPU_HOST_INT(vector));
+    return 0;
+}
+
+static bool kvm_xen_hcall_hvm_op(struct kvm_xen_exit *exit, X86CPU *cpu,
                                  int cmd, uint64_t arg)
 {
+    int ret = -ENOSYS;
     switch (cmd) {
+    case HVMOP_set_evtchn_upcall_vector:
+            ret = kvm_xen_hcall_evtchn_upcall_vector(exit, cpu,
+                                                     exit->u.hcall.params[0]);
+            break;
     case HVMOP_pagetable_dying:
-            exit->u.hcall.result = -ENOSYS;
-            return true;
+            ret = -ENOSYS;
+            break;
 
     default:
             return false;
     }
+
+    exit->u.hcall.result = ret;
+    return true;
 }
 
 static int vcpuop_register_vcpu_info(CPUState *cs, CPUState *target,
@@ -377,7 +436,7 @@ static bool __kvm_xen_handle_exit(X86CPU *cpu, struct kvm_xen_exit *exit)
                                      exit->u.hcall.params[1],
                                      exit->u.hcall.params[2]);
     case __HYPERVISOR_hvm_op:
-        return kvm_xen_hcall_hvm_op(exit, exit->u.hcall.params[0],
+        return kvm_xen_hcall_hvm_op(exit, cpu, exit->u.hcall.params[0],
                                     exit->u.hcall.params[1]);
     case __HYPERVISOR_memory_op:
         return kvm_xen_hcall_memory_op(exit, exit->u.hcall.params[0],
diff --git a/target/i386/xen.h b/target/i386/xen.h
index 53573e07f8..07b133ae29 100644
--- a/target/i386/xen.h
+++ b/target/i386/xen.h
@@ -25,5 +25,6 @@
 int kvm_xen_init(KVMState *s, uint32_t xen_version);
 int kvm_xen_handle_exit(X86CPU *cpu, struct kvm_xen_exit *exit);
 int kvm_xen_set_vcpu_attr(CPUState *cs, uint16_t type, uint64_t gpa);
+int kvm_xen_set_vcpu_callback_vector(CPUState *cs);
 
 #endif /* QEMU_I386_XEN_H */
-- 
2.35.3