From: Keir Fraser <keir@xensource.com>
Date: Thu, 4 Oct 2007 08:36:18 +0000 (+0100)
Subject: svm: Enable nested paging only on x86/64.
X-Git-Tag: archive/raspbian/4.8.0-1+rpi1~1^2~14922
X-Git-Url: https://dgit.raspbian.org/?a=commitdiff_plain;h=84daf5fe4f55e78b2bbc44ea81998ae749b02a0b;p=xen.git

svm: Enable nested paging only on x86/64.
Signed-off-by: Keir Fraser <keir@xensource.com>
---

diff --git a/xen/arch/x86/hvm/svm/svm.c b/xen/arch/x86/hvm/svm/svm.c
index d6dd66192f..a679593d0d 100644
--- a/xen/arch/x86/hvm/svm/svm.c
+++ b/xen/arch/x86/hvm/svm/svm.c
@@ -885,16 +885,6 @@ static struct hvm_function_table svm_function_table = {
     .event_pending        = svm_event_pending
 };
 
-static int svm_npt_detect(void)
-{
-    u32 eax, ebx, ecx, edx;
-
-    /* Check CPUID for nested paging support. */
-    cpuid(0x8000000A, &eax, &ebx, &ecx, &edx);
-
-    return (edx & 1);
-}
-
 int start_svm(struct cpuinfo_x86 *c)
 {
     u32 eax, ecx, edx;
@@ -937,7 +927,14 @@ int start_svm(struct cpuinfo_x86 *c)
 
     setup_vmcb_dump();
 
-    svm_function_table.hap_supported = svm_npt_detect();
+#ifdef __x86_64__
+    /*
+     * Check CPUID for nested paging support. We support NPT only on 64-bit
+     * hosts since the phys-to-machine table is in host format. Hence 32-bit
+     * Xen could only support guests using NPT with up to a 4GB memory map.
+     */
+    svm_function_table.hap_supported = (cpuid_edx(0x8000000A) & 1);
+#endif
 
     hvm_enable(&svm_function_table);