xen: use the same hypercall mechanism for XEN and XENHVM

Currently XEN (PV) and XENHVM (PVHVM) ports use different ways to
issue hypercalls, unify this by filling the hypercall_page under HVM
also.

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

amd64/include/xen/hypercall.h:
 - Unify Xen hypercall code by always using the PV way.

i386/i386/locore.s:
 - Define hypercall_page on i386 XENHVM.

x86/xen/hvm.c:
 - Fill hypercall_page on XENHVM kernels using the HVM method (only
   when running as an HVM guest).

4 files changed, 19 insertions, 29 deletions

diff --git a/sys/amd64/include/xen/hypercall.h b/sys/amd64/include/xen/hypercall.h
index a1b2a5c..499fb4d 100644
--- a/sys/amd64/include/xen/hypercall.h
+++ b/sys/amd64/include/xen/hypercall.h
@@ -51,15 +51,8 @@
 #define CONFIG_XEN_COMPAT	0x030002
 #define __must_check
 
-#ifdef XEN
 #define HYPERCALL_STR(name)					\
 	"call hypercall_page + ("STR(__HYPERVISOR_##name)" * 32)"
-#else
-#define HYPERCALL_STR(name)					\
-	"mov $("STR(__HYPERVISOR_##name)" * 32),%%eax; "\
-	"add hypercall_stubs(%%rip),%%rax; "			\
-	"call *%%rax"
-#endif
 
 #define _hypercall0(type, name)			\
 ({						\
diff --git a/sys/i386/i386/locore.s b/sys/i386/i386/locore.s
index 68cb430..bd136b1 100644
--- a/sys/i386/i386/locore.s
+++ b/sys/i386/i386/locore.s
@@ -898,3 +898,12 @@ done_pde:
 #endif
 
 	ret
+
+#ifdef XENHVM
+/* Xen Hypercall page */
+	.text
+.p2align PAGE_SHIFT, 0x90	/* Hypercall_page needs to be PAGE aligned */
+
+NON_GPROF_ENTRY(hypercall_page)
+	.skip	0x1000, 0x90	/* Fill with "nop"s */
+#endif
diff --git a/sys/i386/include/xen/hypercall.h b/sys/i386/include/xen/hypercall.h
index edc13f4..16b5ee2 100644
--- a/sys/i386/include/xen/hypercall.h
+++ b/sys/i386/include/xen/hypercall.h
@@ -39,16 +39,8 @@
 #define	ENOXENSYS	38
 #define CONFIG_XEN_COMPAT	0x030002
 
-
-#if defined(XEN)
 #define HYPERCALL_STR(name)                                     \
         "call hypercall_page + ("STR(__HYPERVISOR_##name)" * 32)"
-#else
-#define HYPERCALL_STR(name)                                     \
-        "mov hypercall_stubs,%%eax; "                           \
-        "add $("STR(__HYPERVISOR_##name)" * 32),%%eax; "        \
-        "call *%%eax"
-#endif
 
 #define _hypercall0(type, name)                 \
 ({                                              \
diff --git a/sys/x86/xen/hvm.c b/sys/x86/xen/hvm.c
index 6977d56..cb895e5 100644
--- a/sys/x86/xen/hvm.c
+++ b/sys/x86/xen/hvm.c
@@ -147,7 +147,7 @@ DPCPU_DEFINE(xen_intr_handle_t, ipi_handle[nitems(xen_ipis)]);
 
 /*------------------ Hypervisor Access Shared Memory Regions -----------------*/
 /** Hypercall table accessed via HYPERVISOR_*_op() methods. */
-char *hypercall_stubs;
+extern char *hypercall_page;
 shared_info_t *HYPERVISOR_shared_info;
 start_info_t *HYPERVISOR_start_info;
 
@@ -386,16 +386,21 @@ xen_hvm_cpuid_base(void)
  * Allocate and fill in the hypcall page.
  */
 static int
-xen_hvm_init_hypercall_stubs(void)
+xen_hvm_init_hypercall_stubs(enum xen_hvm_init_type init_type)
 {
 	uint32_t base, regs[4];
 	int i;
 
+	if (xen_pv_domain()) {
+		/* hypercall page is already set in the PV case */
+		return (0);
+	}
+
 	base = xen_hvm_cpuid_base();
 	if (base == 0)
 		return (ENXIO);
 
-	if (hypercall_stubs == NULL) {
+	if (init_type == XEN_HVM_INIT_COLD) {
 		do_cpuid(base + 1, regs);
 		printf("XEN: Hypervisor version %d.%d detected.\n",
 		    regs[0] >> 16, regs[0] & 0xffff);
@@ -405,18 +410,9 @@ xen_hvm_init_hypercall_stubs(void)
 	 * Find the hypercall pages.
 	 */
 	do_cpuid(base + 2, regs);
-	
-	if (hypercall_stubs == NULL) {
-		size_t call_region_size;
-
-		call_region_size = regs[0] * PAGE_SIZE;
-		hypercall_stubs = malloc(call_region_size, M_XENHVM, M_NOWAIT);
-		if (hypercall_stubs == NULL)
-			panic("Unable to allocate Xen hypercall region");
-	}
 
 	for (i = 0; i < regs[0]; i++)
-		wrmsr(regs[1], vtophys(hypercall_stubs + i * PAGE_SIZE) + i);
+		wrmsr(regs[1], vtophys(&hypercall_page + i * PAGE_SIZE) + i);
 
 	return (0);
 }
@@ -519,7 +515,7 @@ xen_hvm_init(enum xen_hvm_init_type init_type)
 	if (init_type == XEN_HVM_INIT_CANCELLED_SUSPEND)
 		return;
 
-	error = xen_hvm_init_hypercall_stubs();
+	error = xen_hvm_init_hypercall_stubs(init_type);
 
 	switch (init_type) {
 	case XEN_HVM_INIT_COLD: