[Xen-changelog] [xen master] VMX: disable SMAP feature when guest is in non-paging mode

[patchbot@xxxxxxx]

commit 67fa47753f55cbfdada11f8f517ddd07bc9f6be8
Author:     Feng Wu <feng.wu@xxxxxxxxx>
AuthorDate: Mon May 12 17:03:09 2014 +0200
Commit:     Jan Beulich <jbeulich@xxxxxxxx>
CommitDate: Mon May 12 17:03:09 2014 +0200

    VMX: disable SMAP feature when guest is in non-paging mode
    
    SMAP is disabled if CPU is in non-paging mode in hardware.
    However Xen always uses paging mode to emulate guest non-paging
    mode with HAP. To emulate this behavior, SMAP needs to be manually
    disabled when guest switches to non-paging mode.
    
    This logic is similiar with SMEP.
    
    Signed-off-by: Feng Wu <feng.wu@xxxxxxxxx>
    Reviewed-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
    Acked-by: Kevin Tian <kevin.tian@xxxxxxxxx>
---
 xen/arch/x86/hvm/vmx/vmx.c |    6 +++---
 1 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/xen/arch/x86/hvm/vmx/vmx.c b/xen/arch/x86/hvm/vmx/vmx.c
index 00cab8a..b6c022b 100644
--- a/xen/arch/x86/hvm/vmx/vmx.c
+++ b/xen/arch/x86/hvm/vmx/vmx.c
@@ -1320,12 +1320,12 @@ static void vmx_update_guest_cr(struct vcpu *v, 
unsigned int cr)
         if ( !hvm_paging_enabled(v) )
         {
             /*
-             * SMEP is disabled if CPU is in non-paging mode in hardware.
+             * SMEP/SMAP is disabled if CPU is in non-paging mode in hardware.
              * However Xen always uses paging mode to emulate guest non-paging
-             * mode. To emulate this behavior, SMEP needs to be manually
+             * mode. To emulate this behavior, SMEP/SMAP needs to be manually
              * disabled when guest VCPU is in non-paging mode.
              */
-            v->arch.hvm_vcpu.hw_cr[4] &= ~X86_CR4_SMEP;
+            v->arch.hvm_vcpu.hw_cr[4] &= ~(X86_CR4_SMEP | X86_CR4_SMAP);
         }
         __vmwrite(GUEST_CR4, v->arch.hvm_vcpu.hw_cr[4]);
         break;
--
generated by git-patchbot for /home/xen/git/xen.git#master

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