KVM: SVM: Don't save/restore host cr2

The host never reads cr2 in process context, so are free to clobber it.  The
vmx code does this, so we can safely remove the save/restore code.

Signed-off-by: Avi Kivity <avi@redhat.com>

diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index 060aa9f..132be0c 100644 (file)
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -81,7 +81,6 @@ struct vcpu_svm {
 
        u64 host_user_msrs[NR_HOST_SAVE_USER_MSRS];
        u64 host_gs_base;
-       unsigned long host_cr2;
 
        u32 *msrpm;
        struct vmcb *hsave;
@@ -186,19 +185,6 @@ static inline void invlpga(unsigned long addr, u32 asid)
        asm volatile (__ex(SVM_INVLPGA) :: "a"(addr), "c"(asid));
 }
 
-static inline unsigned long kvm_read_cr2(void)
-{
-       unsigned long cr2;
-
-       asm volatile ("mov %%cr2, %0" : "=r" (cr2));
-       return cr2;
-}
-
-static inline void kvm_write_cr2(unsigned long val)
-{
-       asm volatile ("mov %0, %%cr2" :: "r" (val));
-}
-
 static inline void force_new_asid(struct kvm_vcpu *vcpu)
 {
        to_svm(vcpu)->asid_generation--;
@@ -2527,7 +2513,6 @@ static void svm_vcpu_run(struct kvm_vcpu *vcpu, struct kvm_run *kvm_run)
        fs_selector = kvm_read_fs();
        gs_selector = kvm_read_gs();
        ldt_selector = kvm_read_ldt();
-       svm->host_cr2 = kvm_read_cr2();
        if (!is_nested(svm))
                svm->vmcb->save.cr2 = vcpu->arch.cr2;
        /* required for live migration with NPT */
@@ -2614,8 +2599,6 @@ static void svm_vcpu_run(struct kvm_vcpu *vcpu, struct kvm_run *kvm_run)
        vcpu->arch.regs[VCPU_REGS_RSP] = svm->vmcb->save.rsp;
        vcpu->arch.regs[VCPU_REGS_RIP] = svm->vmcb->save.rip;
 
-       kvm_write_cr2(svm->host_cr2);
-
        kvm_load_fs(fs_selector);
        kvm_load_gs(gs_selector);
        kvm_load_ldt(ldt_selector);