xen: add PV/PVH kernel entry point

Add the PV/PVH entry point and the low level functions for PVH
early initialization.

Approved by: gibbs
Sponsored by: Citrix Systems R&D

amd64/amd64/genassym.c:
 - Add __FreeBSD_version define to assym.s so it can be used for the
   Xen notes.

amd64/amd64/locore.S:
 - Make bootstack global so it can be used from Xen kernel entry
   point.

amd64/amd64/xen-locore.S:
 - Add Xen notes to the kernel.
 - Add the Xen PV entry point, that is going to call hammer_time_xen.

amd64/include/asmacros.h:
 - Add ELFNOTE macros.

i386/xen/xen_machdep.c:
 - Define HYPERVISOR_start_info for the XEN i386 PV port, which is
   going to be used in some shared code between PV and PVH.

x86/xen/hvm.c:
 - Define HYPERVISOR_start_info for the PVH port.

x86/xen/pv.c:
 - Introduce hammer_time_xen which is going to perform early setup for
   Xen PVH:
    - Setup shared Xen variables start_info, shared_info and
      xen_store.
    - Set guest type.
    - Create initial page tables as FreeBSD expects to find them.
    - Call into native init function (hammer_time).

xen/xen-os.h:
 - Declare HYPERVISOR_start_info.

conf/files.amd64:
 - Add amd64/amd64/locore.S and x86/xen/pv.c to the list of files.

2 files changed, 120 insertions, 0 deletions

diff --git a/sys/x86/xen/hvm.c b/sys/x86/xen/hvm.c
index 9f4c6be..6977d56 100644
--- a/sys/x86/xen/hvm.c
+++ b/sys/x86/xen/hvm.c
@@ -149,6 +149,7 @@ DPCPU_DEFINE(xen_intr_handle_t, ipi_handle[nitems(xen_ipis)]);
 /** Hypercall table accessed via HYPERVISOR_*_op() methods. */
 char *hypercall_stubs;
 shared_info_t *HYPERVISOR_shared_info;
+start_info_t *HYPERVISOR_start_info;
 
 #ifdef SMP
 /*---------------------------- XEN PV IPI Handlers ---------------------------*/
diff --git a/sys/x86/xen/pv.c b/sys/x86/xen/pv.c
new file mode 100644
index 0000000..6805baa
--- /dev/null
+++ b/sys/x86/xen/pv.c
@@ -0,0 +1,119 @@
+/*
+ * Copyright (c) 2004 Christian Limpach.
+ * Copyright (c) 2004-2006,2008 Kip Macy
+ * Copyright (c) 2013 Roger Pau Monné <roger.pau@citrix.com>
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+#include <sys/cdefs.h>
+__FBSDID("$FreeBSD$");
+
+#include <sys/param.h>
+#include <sys/bus.h>
+#include <sys/kernel.h>
+#include <sys/reboot.h>
+#include <sys/systm.h>
+#include <sys/lock.h>
+#include <sys/rwlock.h>
+
+#include <vm/vm.h>
+#include <vm/vm_extern.h>
+#include <vm/vm_kern.h>
+#include <vm/vm_page.h>
+#include <vm/vm_map.h>
+#include <vm/vm_object.h>
+#include <vm/vm_pager.h>
+#include <vm/vm_param.h>
+
+#include <xen/xen-os.h>
+#include <xen/hypervisor.h>
+
+/* Native initial function */
+extern u_int64_t hammer_time(u_int64_t, u_int64_t);
+/* Xen initial function */
+uint64_t hammer_time_xen(start_info_t *, uint64_t);
+
+/*
+ * First function called by the Xen PVH boot sequence.
+ *
+ * Set some Xen global variables and prepare the environment so it is
+ * as similar as possible to what native FreeBSD init function expects.
+ */
+uint64_t
+hammer_time_xen(start_info_t *si, uint64_t xenstack)
+{
+	uint64_t physfree;
+	uint64_t *PT4 = (u_int64_t *)xenstack;
+	uint64_t *PT3 = (u_int64_t *)(xenstack + PAGE_SIZE);
+	uint64_t *PT2 = (u_int64_t *)(xenstack + 2 * PAGE_SIZE);
+	int i;
+
+	xen_domain_type = XEN_PV_DOMAIN;
+	vm_guest = VM_GUEST_XEN;
+
+	if ((si == NULL) || (xenstack == 0)) {
+		HYPERVISOR_shutdown(SHUTDOWN_crash);
+	}
+
+	/* We use 3 pages of xen stack for the boot pagetables */
+	physfree = xenstack + 3 * PAGE_SIZE - KERNBASE;
+
+	/* Setup Xen global variables */
+	HYPERVISOR_start_info = si;
+	HYPERVISOR_shared_info =
+	    (shared_info_t *)(si->shared_info + KERNBASE);
+
+	/*
+	 * Setup some misc global variables for Xen devices
+	 *
+	 * XXX: Devices that need these specific variables should
+	 *      be rewritten to fetch this info by themselves from the
+	 *      start_info page.
+	 */
+	xen_store = (struct xenstore_domain_interface *)
+	    (ptoa(si->store_mfn) + KERNBASE);
+
+	/*
+	 * Use the stack Xen gives us to build the page tables
+	 * as native FreeBSD expects to find them (created
+	 * by the boot trampoline).
+	 */
+	for (i = 0; i < (PAGE_SIZE / sizeof(uint64_t)); i++) {
+		/* Each slot of the level 4 pages points to the same level 3 page */
+		PT4[i] = ((uint64_t)&PT3[0]) - KERNBASE;
+		PT4[i] |= PG_V | PG_RW | PG_U;
+
+		/* Each slot of the level 3 pages points to the same level 2 page */
+		PT3[i] = ((uint64_t)&PT2[0]) - KERNBASE;
+		PT3[i] |= PG_V | PG_RW | PG_U;
+
+		/* The level 2 page slots are mapped with 2MB pages for 1GB. */
+		PT2[i] = i * (2 * 1024 * 1024);
+		PT2[i] |= PG_V | PG_RW | PG_PS | PG_U;
+	}
+	load_cr3(((uint64_t)&PT4[0]) - KERNBASE);
+
+	/* Now we can jump into the native init function */
+	return (hammer_time(0, physfree));
+}