From b1fa10f0c1ffddfa7a0b44924c8bf8ac55f800cd Mon Sep 17 00:00:00 2001
From: Joao Martins <joao.m.martins@oracle.com>
Date: Wed, 13 Jun 2018 10:14:31 -0400
Subject: [PATCH] i386/xen: handle guest hypercalls

This means handling the new exit reason for Xen but still
crashing on purpose. As we implement each of the hypercalls
we will then return the right return code.

Signed-off-by: Joao Martins <joao.m.martins@oracle.com>
[dwmw2: Add CPL to hypercall tracing, disallow hypercalls from CPL > 0]
Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
---
 target/i386/kvm/kvm.c    |  5 +++++
 target/i386/trace-events |  3 +++
 target/i386/xen.c        | 39 +++++++++++++++++++++++++++++++++++++++
 target/i386/xen.h        |  1 +
 4 files changed, 48 insertions(+)

diff --git a/target/i386/kvm/kvm.c b/target/i386/kvm/kvm.c
index 0d3eddf9de..ebde6bc204 100644
--- a/target/i386/kvm/kvm.c
+++ b/target/i386/kvm/kvm.c
@@ -5471,6 +5471,11 @@ int kvm_arch_handle_exit(CPUState *cs, struct kvm_run *run)
         assert(run->msr.reason == KVM_MSR_EXIT_REASON_FILTER);
         ret = kvm_handle_wrmsr(cpu, run);
         break;
+#ifdef CONFIG_XEN_EMU
+    case KVM_EXIT_XEN:
+        ret = kvm_xen_handle_exit(cpu, &run->xen);
+        break;
+#endif
     default:
         fprintf(stderr, "KVM: unknown exit reason %d\n", run->exit_reason);
         ret = -1;
diff --git a/target/i386/trace-events b/target/i386/trace-events
index 2cd8726eeb..1bf9558811 100644
--- a/target/i386/trace-events
+++ b/target/i386/trace-events
@@ -11,3 +11,6 @@ kvm_sev_launch_measurement(const char *value) "data %s"
 kvm_sev_launch_finish(void) ""
 kvm_sev_launch_secret(uint64_t hpa, uint64_t hva, uint64_t secret, int len) "hpa 0x%" PRIx64 " hva 0x%" PRIx64 " data 0x%" PRIx64 " len %d"
 kvm_sev_attestation_report(const char *mnonce, const char *data) "mnonce %s data %s"
+
+# target/i386/xen.c
+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
diff --git a/target/i386/xen.c b/target/i386/xen.c
index bc183dce4e..708ab908a0 100644
--- a/target/i386/xen.c
+++ b/target/i386/xen.c
@@ -10,8 +10,10 @@
  */
 
 #include "qemu/osdep.h"
+#include "qemu/log.h"
 #include "kvm/kvm_i386.h"
 #include "xen.h"
+#include "trace.h"
 
 int kvm_xen_init(KVMState *s, uint32_t xen_version)
 {
@@ -47,3 +49,40 @@ int kvm_xen_init(KVMState *s, uint32_t xen_version)
 
     return 0;
 }
+
+static bool __kvm_xen_handle_exit(X86CPU *cpu, struct kvm_xen_exit *exit)
+{
+    uint16_t code = exit->u.hcall.input;
+
+    if (exit->u.hcall.cpl > 0) {
+        exit->u.hcall.result = -EPERM;
+        return true;
+    }
+
+    switch (code) {
+    default:
+        return false;
+    }
+}
+
+int kvm_xen_handle_exit(X86CPU *cpu, struct kvm_xen_exit *exit)
+{
+    if (exit->type != KVM_EXIT_XEN_HCALL)
+        return -1;
+
+    if (!__kvm_xen_handle_exit(cpu, exit)) {
+        /* Some hypercalls will be deliberately "implemented" by returning
+         * -ENOSYS. This case is for hypercalls which are unexpected. */
+        exit->u.hcall.result = -ENOSYS;
+        qemu_log_mask(LOG_GUEST_ERROR, "Unimplemented Xen hypercall %"
+                      PRId64 " (0x%" PRIx64 " 0x%" PRIx64 " 0x%" PRIx64 ")\n",
+                      (uint64_t)exit->u.hcall.input, (uint64_t)exit->u.hcall.params[0],
+                      (uint64_t)exit->u.hcall.params[1], (uint64_t)exit->u.hcall.params[1]);
+    }
+
+    trace_kvm_xen_hypercall(CPU(cpu)->cpu_index, exit->u.hcall.cpl,
+                            exit->u.hcall.input, exit->u.hcall.params[0],
+                            exit->u.hcall.params[1], exit->u.hcall.params[2],
+                            exit->u.hcall.result);
+    return 0;
+}
diff --git a/target/i386/xen.h b/target/i386/xen.h
index ae880c47bc..9134d78685 100644
--- a/target/i386/xen.h
+++ b/target/i386/xen.h
@@ -23,5 +23,6 @@
 #define XEN_VERSION(maj, min) ((maj) << 16 | (min))
 
 int kvm_xen_init(KVMState *s, uint32_t xen_version);
+int kvm_xen_handle_exit(X86CPU *cpu, struct kvm_xen_exit *exit);
 
 #endif /* QEMU_I386_XEN_H */
-- 
2.50.1