On 03/25/2011 11:29 AM, Joerg Roedel wrote:
This patch adds all necessary intercept checks for
instructions that access the crX registers.


@@ -3871,11 +3871,89 @@ static void svm_fpu_deactivate(struct kvm_vcpu *vcpu)
        update_cr0_intercept(svm);
  }

+#define POST_EX(exit) { .exit_code = (exit), \
+                       .stage = x86_icpt_post_except, \
+                       .valid = true }
+
+static struct __x86_intercept {
+       u32 exit_code;
+       enum x86_intercept_stage stage;
+       bool valid;

Isn't .valid always true, even in later patches?

+} x86_intercept_map[] = {

const?

+       [x86_intercept_cr_read]         = POST_EX(SVM_EXIT_READ_CR0),
+       [x86_intercept_cr_write]        = POST_EX(SVM_EXIT_WRITE_CR0),
+       [x86_intercept_clts]            = POST_EX(SVM_EXIT_WRITE_CR0),
+       [x86_intercept_lmsw]            = POST_EX(SVM_EXIT_WRITE_CR0),
+       [x86_intercept_smsw]            = POST_EX(SVM_EXIT_READ_CR0),
+};
+
+#undef POST_EX
+
  static int svm_check_intercept(struct kvm_vcpu *vcpu,
                               struct x86_instruction_info *info,
                               enum x86_intercept_stage stage)
  {
-       return X86EMUL_CONTINUE;
+       struct vcpu_svm *svm = to_svm(vcpu);
+       int vmexit, ret = X86EMUL_CONTINUE;
+       struct __x86_intercept icpt_info;
+       struct vmcb *vmcb = svm->vmcb;
+       int reg;
+
+       if (info->intercept>= ARRAY_SIZE(x86_intercept_map))
+               goto out;
+
+       icpt_info = x86_intercept_map[info->intercept];
+
+       if (!icpt_info.valid || stage != icpt_info.stage)
+               goto out;
+
+       reg = (info->modrm>>  3)&  7;

Doesn't work for r8-r15 or cr8-cr15; better to have the emulator put it into a separate variable.

+
+       switch (icpt_info.exit_code) {
+       case SVM_EXIT_READ_CR0:
+               if (info->intercept == x86_intercept_cr_read)
+                       icpt_info.exit_code += reg;

break; ?

(would work without it too, but we'll just get endless fixes for it)

+       case SVM_EXIT_WRITE_CR0: {
+               unsigned long cr0, val;
+               u64 intercept;
+
+               if (info->intercept == x86_intercept_cr_write)
+                       icpt_info.exit_code += reg;
+
+               if (icpt_info.exit_code != SVM_EXIT_WRITE_CR0)
+                       break;
+
+               intercept = svm->nested.intercept;
+
+               if (!(intercept&  (1ULL<<  INTERCEPT_SELECTIVE_CR0)))
+                       break;
+
+               cr0 = vcpu->arch.cr0&  ~SVM_CR0_SELECTIVE_MASK;
+               val = info->src_val&  ~SVM_CR0_SELECTIVE_MASK;
+
+               if (info->intercept == x86_intercept_lmsw) {
+                       cr0&= 0xfUL;
+                       val&= 0xfUL;

Probably, val |= X86_CR0_PE, since lmsw can't change that bit.

+               }
+
+               if (cr0 ^ val)
+                       icpt_info.exit_code = SVM_EXIT_CR0_SEL_WRITE;
+
+               break;
+       }
+       default:
+               break;
+       }
+
+       vmcb->control.next_rip  = info->next_rip;
+       vmcb->control.exit_code = icpt_info.exit_code;
+       vmexit = nested_svm_exit_handled(svm);
+
+       ret = (vmexit == NESTED_EXIT_DONE) ? X86EMUL_INTERCEPTED
+                                          : X86EMUL_CONTINUE;
+
+out:
+       return ret;
  }

  static struct kvm_x86_ops svm_x86_ops = {


--
I have a truly marvellous patch that fixes the bug which this
signature is too narrow to contain.

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