target/i386: Added Intercept CR0 writes check
When the selective CR0 write intercept is set, all writes to bits in
CR0 other than CR0.TS or CR0.MP cause a VMEXIT.
Signed-off-by: Lara Lazier <laramglazier@gmail.com>
Message-Id: <20210616123907.17765-5-laramglazier@gmail.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
diff --git a/target/i386/tcg/sysemu/misc_helper.c b/target/i386/tcg/sysemu/misc_helper.c
index 0cef2f1..db0d8a9 100644
--- a/target/i386/tcg/sysemu/misc_helper.c
+++ b/target/i386/tcg/sysemu/misc_helper.c
@@ -84,6 +84,15 @@
{
switch (reg) {
case 0:
+ /*
+ * If we reach this point, the CR0 write intercept is disabled.
+ * But we could still exit if the hypervisor has requested the selective
+ * intercept for bits other than TS and MP
+ */
+ if (cpu_svm_has_intercept(env, SVM_EXIT_CR0_SEL_WRITE) &&
+ ((env->cr[0] ^ t0) & ~(CR0_TS_MASK | CR0_MP_MASK))) {
+ cpu_vmexit(env, SVM_EXIT_CR0_SEL_WRITE, 0, GETPC());
+ }
cpu_x86_update_cr0(env, t0);
break;
case 3:
