[PATCH v7 48/51] i386/xen: handle HVMOP_get_param

[David Woodhouse <dwmw2@infradead.org>]

From: Joao Martins <joao.m.martins@oracle.com>

Which is used to fetch xenstore PFN and port to be used
by the guest. This is preallocated by the toolstack when
guest will just read those and use it straight away.

Signed-off-by: Joao Martins <joao.m.martins@oracle.com>
Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
---
 target/i386/kvm/xen-emu.c | 39 +++++++++++++++++++++++++++++++++++++++
 1 file changed, 39 insertions(+)

diff --git a/target/i386/kvm/xen-emu.c b/target/i386/kvm/xen-emu.c
index 0110ef55c7..c55d2e16a3 100644
--- a/target/i386/kvm/xen-emu.c
+++ b/target/i386/kvm/xen-emu.c
@@ -744,6 +744,42 @@ out:
     return true;
 }
 
+static bool handle_get_param(struct kvm_xen_exit *exit, X86CPU *cpu,
+                             uint64_t arg)
+{
+    CPUState *cs = CPU(cpu);
+    struct xen_hvm_param hp;
+    int err = 0;
+
+    /* No need for 32/64 compat handling */
+    qemu_build_assert(sizeof(hp) == 16);
+
+    if (kvm_copy_from_gva(cs, arg, &hp, sizeof(hp))) {
+        err = -EFAULT;
+        goto out;
+    }
+
+    if (hp.domid != DOMID_SELF && hp.domid != xen_domid) {
+        err = -ESRCH;
+        goto out;
+    }
+
+    switch (hp.index) {
+    case HVM_PARAM_STORE_PFN:
+        hp.value = XEN_SPECIAL_PFN(XENSTORE);
+        break;
+    default:
+        return false;
+    }
+
+    if (kvm_copy_to_gva(cs, arg, &hp, sizeof(hp))) {
+        err = -EFAULT;
+    }
+out:
+    exit->u.hcall.result = err;
+    return true;
+}
+
 static int kvm_xen_hcall_evtchn_upcall_vector(struct kvm_xen_exit *exit,
                                               X86CPU *cpu, uint64_t arg)
 {
@@ -788,6 +824,9 @@ static bool kvm_xen_hcall_hvm_op(struct kvm_xen_exit *exit, X86CPU *cpu,
     case HVMOP_set_param:
         return handle_set_param(exit, cpu, arg);
 
+    case HVMOP_get_param:
+        return handle_get_param(exit, cpu, arg);
+
     default:
         return false;
     }
-- 
2.39.0