i386/xen: handle Xen hypercall page

Firstly create the blob and set up the vmmcall. Afterwards
we update number of hypercall pages to 1, and then make the
vm ioctl to set XEN_HVM_CONFIG. This allows the guest to
make hypercalls

Signed-off-by: Joao Martins <joao.m.martins@oracle.com>

diff --git a/target/i386/Makefile.objs b/target/i386/Makefile.objs
index cb9c2655259afc729cb0ed84bc1a2404168ff7fc..8496f1444ea10f3fa4c549879ba7b1cdbae8bf03 100644 (file)
--- a/target/i386/Makefile.objs
+++ b/target/i386/Makefile.objs
@@ -9,6 +9,7 @@ obj-$(CONFIG_KVM) += kvm.o
 obj-$(call lnot,$(CONFIG_KVM)) += kvm-stub.o
 obj-$(CONFIG_HYPERV) += hyperv.o
 obj-$(call lnot,$(CONFIG_HYPERV)) += hyperv-stub.o
+obj-$(CONFIG_XEN) += xen.o
 ifeq ($(CONFIG_WIN32),y)
 obj-$(CONFIG_HAX) += hax-all.o hax-mem.o hax-windows.o
 endif

diff --git a/target/i386/kvm.c b/target/i386/kvm.c
index 8bb5d2d2e9a23496bebd478e8508edcc5711c042..4eb0629db577b90f77125a24a8d5ddfbdc1525f1 100644 (file)
--- a/target/i386/kvm.c
+++ b/target/i386/kvm.c
@@ -29,6 +29,7 @@
 #include "kvm_i386.h"
 #include "hyperv.h"
 #include "hyperv-proto.h"
+#include "xen.h"
 
 #include "exec/gdbstub.h"
 #include "qemu/host-utils.h"
@@ -651,12 +652,6 @@ static bool hyperv_enabled(X86CPU *cpu)
             cpu->hyperv_ipi);
 }
 
-#define XEN_CPUID_SIGNATURE        0x40000000
-#define XEN_CPUID_VENDOR           0x40000001
-#define XEN_CPUID_HVM_MSR          0x40000002
-#define XEN_CPUID_TIME             0x40000003
-#define XEN_CPUID_HVM              0x40000004
-
 static bool xen_enabled_on_kvm(X86CPU *cpu)
 {
     return cpu->xen;
@@ -1058,7 +1053,7 @@ int kvm_arch_init_vcpu(CPUState *cs)
         c = &cpuid_data.entries[cpuid_i++];
         c->function = XEN_CPUID_HVM_MSR;
         /* Number of hypercall-transfer pages */
-        c->eax = 0;
+        c->eax = 1;
         /* Hypercall MSR base address */
         c->ebx = XEN_CPUID_SIGNATURE;
         c->ecx = 0;
@@ -1094,6 +1089,14 @@ int kvm_arch_init_vcpu(CPUState *cs)
             }
         }
 
+        if (kvm_check_extension(cs->kvm_state, KVM_CAP_XEN_HVM)) {
+            r = kvm_xen_set_hypercall_page(cs);
+            if (r) {
+                error_report("Failed to initialize Xen hypercall page %d", r);
+                abort();
+            }
+        }
+
         kvm_base = KVM_CPUID_SIGNATURE_NEXT;
     }
 

diff --git a/target/i386/xen.c b/target/i386/xen.c
new file mode 100644 (file)
index 0000000..efd5b91
--- /dev/null
+++ b/target/i386/xen.c
@@ -0,0 +1,63 @@
+/*
+ * Xen HVM emulation support in KVM
+ *
+ * Copyright (c) 2019 Oracle and/or its affiliates. All rights reserved.
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2 or later.
+ * See the COPYING file in the top-level directory.
+ *
+ */
+
+#include "qemu/osdep.h"
+#include "qemu/main-loop.h"
+#include "linux/kvm.h"
+#include "cpu.h"
+#include "xen.h"
+
+static void arch_init_hypercall_page(CPUState *cs, void *addr)
+{
+    CPUX86State *env = cs->env_ptr;
+    char *p;
+    int i;
+
+    for (i = 0; i < (TARGET_PAGE_SIZE / 32); i++) {
+        p = (char *)(addr + (i * 32));
+        *(uint8_t  *)(p + 0) = 0xb8; /* mov imm32, %eax */
+        *(uint32_t *)(p + 1) = i;
+        *(uint8_t  *)(p + 5) = 0x0f; /* vmcall */
+        *(uint8_t  *)(p + 6) = 0x01;
+
+        if (env->cpuid_vendor1 == CPUID_VENDOR_INTEL_1 &&
+            env->cpuid_vendor2 == CPUID_VENDOR_INTEL_2 &&
+            env->cpuid_vendor3 == CPUID_VENDOR_INTEL_3)
+            *(uint8_t  *)(p + 7) = 0xc1;
+        else
+            *(uint8_t  *)(p + 7) = 0xd9;
+
+        *(uint8_t  *)(p + 8) = 0xc3; /* ret */
+    }
+}
+
+int kvm_xen_set_hypercall_page(CPUState *env)
+{
+    struct kvm_xen_hvm_config cfg;
+    void *page;
+
+    page = g_malloc(TARGET_PAGE_SIZE);
+    if (!page) {
+        return -ENOMEM;
+    }
+
+    memset(page, 0xCC, TARGET_PAGE_SIZE);
+
+    arch_init_hypercall_page(env, page);
+
+    cfg.msr = XEN_CPUID_SIGNATURE;
+    cfg.flags = 0;
+    cfg.blob_addr_32 = (uint64_t) page;
+    cfg.blob_size_32 = 1;
+    cfg.blob_addr_64 = (uint64_t) page;
+    cfg.blob_size_64 = 1;
+
+    return kvm_vm_ioctl(env->kvm_state, KVM_XEN_HVM_CONFIG, &cfg);
+}

diff --git a/target/i386/xen.h b/target/i386/xen.h
new file mode 100644 (file)
index 0000000..4512e12
--- /dev/null
+++ b/target/i386/xen.h
@@ -0,0 +1,26 @@
+/*
+ * Xen HVM emulation support in KVM
+ *
+ * Copyright (c) 2019 Oracle and/or its affiliates. All rights reserved.
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2 or later.
+ * See the COPYING file in the top-level directory.
+ *
+ */
+
+#ifndef TARGET_I386_XEN_H
+#define TARGET_I386_XEN_H
+
+#include "cpu.h"
+#include "sysemu/kvm.h"
+#include "qemu/event_notifier.h"
+
+#define XEN_CPUID_SIGNATURE        0x40000000
+#define XEN_CPUID_VENDOR           0x40000001
+#define XEN_CPUID_HVM_MSR          0x40000002
+#define XEN_CPUID_TIME             0x40000003
+#define XEN_CPUID_HVM              0x40000004
+
+int kvm_xen_set_hypercall_page(CPUState *env);
+
+#endif