x86: Check for XENFEAT_mmu_pt_update_preserve_ad before attempting to

use new mmu_update() hypercall. Older Xen versions are noisy if the
unsupported hypercall is attempted.
Signed-off-by: Keir Fraser <keir.fraser@citrix.com>

diff --git a/arch/i386/mm/hypervisor.c b/arch/i386/mm/hypervisor.c
index 1516776eafe2e2f1b3713e3bbdd01dbbb4bff5e1..1234320de2aa3abf372aa16080cb06a013877f54 100644 (file)
--- a/arch/i386/mm/hypervisor.c
+++ b/arch/i386/mm/hypervisor.c
@@ -559,6 +559,9 @@ int xen_change_pte_range(struct mm_struct *mm, pmd_t *pmd,
        pte_t *pte;
        spinlock_t *ptl;
 
+       if (!xen_feature(XENFEAT_mmu_pt_update_preserve_ad))
+               return 0;
+
        pte = pte_offset_map_lock(mm, pmd, addr, &ptl);
        do {
                if (pte_present(*pte)) {

diff --git a/include/xen/interface/arch-x86/cpuid.h b/include/xen/interface/arch-x86/cpuid.h
new file mode 100644 (file)
index 0000000..34fd72d
--- /dev/null
+++ b/include/xen/interface/arch-x86/cpuid.h
@@ -0,0 +1,68 @@
+/******************************************************************************
+ * arch-x86/cpuid.h
+ * 
+ * CPUID interface to Xen.
+ * 
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to
+ * deal in the Software without restriction, including without limitation the
+ * rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
+ * sell copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+ * DEALINGS IN THE SOFTWARE.
+ * 
+ * Copyright (c) 2007 Citrix Systems, Inc.
+ * 
+ * Authors:
+ *    Keir Fraser <keir.fraser@citrix.com>
+ */
+
+#ifndef __XEN_PUBLIC_ARCH_X86_CPUID_H__
+#define __XEN_PUBLIC_ARCH_X86_CPUID_H__
+
+/* Xen identification leaves start at 0x40000000. */
+#define XEN_CPUID_FIRST_LEAF 0x40000000
+#define XEN_CPUID_LEAF(i)    (XEN_CPUID_FIRST_LEAF + (i))
+
+/*
+ * Leaf 1 (0x40000000)
+ * EAX: Largest Xen-information leaf. All leaves up to an including @EAX
+ *      are supported by the Xen host.
+ * EBX-EDX: "XenVMMXenVMM" signature, allowing positive identification
+ *      of a Xen host.
+ */
+#define XEN_CPUID_SIGNATURE_EBX 0x566e6558 /* "XenV" */
+#define XEN_CPUID_SIGNATURE_ECX 0x65584d4d /* "MMXe" */
+#define XEN_CPUID_SIGNATURE_EDX 0x4d4d566e /* "nVMM" */
+
+/*
+ * Leaf 2 (0x40000001)
+ * EAX[31:16]: Xen major version.
+ * EAX[15: 0]: Xen minor version.
+ * EBX-EDX: Reserved (currently all zeroes).
+ */
+
+/*
+ * Leaf 3 (0x40000002)
+ * EAX: Number of hypercall transfer pages. This register is always guaranteed
+ *      to specify one hypercall page.
+ * EBX: Base address of Xen-specific MSRs.
+ * ECX: Features 1. Unused bits are set to zero.
+ * EDX: Features 2. Unused bits are set to zero.
+ */
+
+/* Does the host support MMU_PT_UPDATE_PRESERVE_AD for this guest? */
+#define _XEN_CPUID_FEAT1_MMU_PT_UPDATE_PRESERVE_AD 0
+#define XEN_CPUID_FEAT1_MMU_PT_UPDATE_PRESERVE_AD  (1u<<0)
+
+#endif /* __XEN_PUBLIC_ARCH_X86_CPUID_H__ */

diff --git a/include/xen/interface/features.h b/include/xen/interface/features.h
index d4b373ff17ac7820e646601c0b556e0a193e2df0..05fc5dc4644273c74aae21aac68a86e0bdefd399 100644 (file)
--- a/include/xen/interface/features.h
+++ b/include/xen/interface/features.h
@@ -56,6 +56,9 @@
  */
 #define XENFEAT_pae_pgdir_above_4gb        4
 
+/* x86: Does this Xen host support the MMU_PT_UPDATE_PRESERVE_AD hypercall? */
+#define XENFEAT_mmu_pt_update_preserve_ad  5
+
 #define XENFEAT_NR_SUBMAPS 1
 
 #endif /* __XEN_PUBLIC_FEATURES_H__ */