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    Subject[PATCH 3.13.y-ckt 51/86] KVM: Disable SMAP for guests in EPT realmode and EPT unpaging mode
    Date
    3.13.11-ckt31 -stable review patch.  If anyone has any objections, please let me know.

    ------------------

    From: Feng Wu <feng.wu@intel.com>

    commit e1e746b3c55d1d1e0841a2e600a154d8f6747232 upstream.

    SMAP is disabled if CPU is in non-paging mode in hardware.
    However KVM always uses paging mode to emulate guest non-paging
    mode with TDP. To emulate this behavior, SMAP needs to be
    manually disabled when guest switches to non-paging mode.

    Signed-off-by: Feng Wu <feng.wu@intel.com>
    Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
    [ kamal: 3.13-stable prereq for
    656ec4a KVM: VMX: fix SMEP and SMAP without EPT ]
    Signed-off-by: Kamal Mostafa <kamal@canonical.com>
    ---
    arch/x86/kvm/vmx.c | 11 ++++++-----
    1 file changed, 6 insertions(+), 5 deletions(-)

    diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
    index 9c2c662..45019f0 100644
    --- a/arch/x86/kvm/vmx.c
    +++ b/arch/x86/kvm/vmx.c
    @@ -3429,13 +3429,14 @@ static int vmx_set_cr4(struct kvm_vcpu *vcpu, unsigned long cr4)
    hw_cr4 &= ~X86_CR4_PAE;
    hw_cr4 |= X86_CR4_PSE;
    /*
    - * SMEP is disabled if CPU is in non-paging mode in
    - * hardware. However KVM always uses paging mode to
    + * SMEP/SMAP is disabled if CPU is in non-paging mode
    + * in hardware. However KVM always uses paging mode to
    * emulate guest non-paging mode with TDP.
    - * To emulate this behavior, SMEP needs to be manually
    - * disabled when guest switches to non-paging mode.
    + * To emulate this behavior, SMEP/SMAP needs to be
    + * manually disabled when guest switches to non-paging
    + * mode.
    */
    - hw_cr4 &= ~X86_CR4_SMEP;
    + hw_cr4 &= ~(X86_CR4_SMEP | X86_CR4_SMAP);
    } else if (!(cr4 & X86_CR4_PAE)) {
    hw_cr4 &= ~X86_CR4_PAE;
    }
    --
    1.9.1


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