From: Andrew Jones <drjones@redhat.com>
Date: Wed, 7 Oct 2009 13:43:48 +0200
Subject: [xen] mask out xsave for hvm guests
Message-id: f45d2faa689c4b76282060583cdbd64972d91463.1254915619.git.drjones@redhat.com
O-Subject: [RHEL5.5 PATCH v2] [xen] mask out xsave for hvm guests
Bugzilla: 524052
RH-Acked-by: Chris Lalancette <clalance@redhat.com>
RH-Acked-by: Miroslav Rezanina <mrezanin@redhat.com>
RH-Acked-by: Paolo Bonzini <pbonzini@redhat.com>

This patch insures that the XSAVE cpu feature is not advertised to an
HVM guest. Without this patch the guest may attempt to use XSAVE, but
since it is not supported by the hypervisor the guest will fail to boot.
As an added precaution OSXSAVE is also masked. With the patch, tested by
me, the guest boots. Resolves BZ 524052.

diff --git a/arch/x86/hvm/vmx/vmx.c b/arch/x86/hvm/vmx/vmx.c
index 1e60e4d..ce8da33 100644
--- a/arch/x86/hvm/vmx/vmx.c
+++ b/arch/x86/hvm/vmx/vmx.c
@@ -1610,7 +1610,9 @@ static void vmx_do_cpuid(struct cpu_user_regs *regs)
             ecx &= ~(bitmaskof(X86_FEATURE_VMXE) |
                      bitmaskof(X86_FEATURE_EST)  |
                      bitmaskof(X86_FEATURE_TM2)  |
-                     bitmaskof(X86_FEATURE_CID));
+                     bitmaskof(X86_FEATURE_CID)  |
+                     bitmaskof(X86_FEATURE_XSAVE)|
+                     bitmaskof(X86_FEATURE_OSXSAVE));
 
             edx &= ~(bitmaskof(X86_FEATURE_HT)   |
                      bitmaskof(X86_FEATURE_ACPI) |
diff --git a/include/asm-x86/cpufeature.h b/include/asm-x86/cpufeature.h
index ec86f05..f5b4c34 100644
--- a/include/asm-x86/cpufeature.h
+++ b/include/asm-x86/cpufeature.h
@@ -89,6 +89,7 @@
 #define X86_FEATURE_PDCM	(4*32+15) /* Perf/Debug Capability MSR */
 #define X86_FEATURE_DCA		(4*32+18) /* Direct Cache Access */
 #define X86_FEATURE_XSAVE	(4*32+26) /* XSAVE/XRSTOR/XSETBV/XGETBV */
+#define X86_FEATURE_OSXSAVE	(4*32+27) /* "" XSAVE enabled in the OS */
 
 /* VIA/Cyrix/Centaur-defined CPU features, CPUID level 0xC0000001, word 5 */
 #define X86_FEATURE_XSTORE	(5*32+ 2) /* on-CPU RNG present (xstore insn) */