KVM: x86: DR6/7.RTM cannot be written
Haswell and newer Intel CPUs have support for RTM, and in that case DR6.RTM is
not fixed to 1 and DR7.RTM is not fixed to zero. That is not the case in the
current KVM implementation. This bug is apparent only if the MOV-DR instruction
is emulated or the host also debugs the guest.
This patch is a partial fix which enables DR6.RTM and DR7.RTM to be cleared and
set respectively. It also sets DR6.RTM upon every debug exception. Obviously,
it is not a complete fix, as debugging of RTM is still unsupported.
Signed-off-by: Nadav Amit <namit@cs.technion.ac.il>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index b8a4480..a84eaf7 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -152,14 +152,16 @@
#define DR6_BD (1 << 13)
#define DR6_BS (1 << 14)
-#define DR6_FIXED_1 0xffff0ff0
-#define DR6_VOLATILE 0x0000e00f
+#define DR6_RTM (1 << 16)
+#define DR6_FIXED_1 0xfffe0ff0
+#define DR6_INIT 0xffff0ff0
+#define DR6_VOLATILE 0x0001e00f
#define DR7_BP_EN_MASK 0x000000ff
#define DR7_GE (1 << 9)
#define DR7_GD (1 << 13)
#define DR7_FIXED_1 0x00000400
-#define DR7_VOLATILE 0xffff23ff
+#define DR7_VOLATILE 0xffff2bff
/* apic attention bits */
#define KVM_APIC_CHECK_VAPIC 0