[PATCH v4 9/9] arm64: KVM: enable trapping of all debug registers

[Marc Zyngier]

Enable trapping of the debug registers, preventing the guests to
mess with the host state (and allowing guests to use the debug
infrastructure as well).

Reviewed-by: Anup Patel <anup.patel at linaro.org>
Reviewed-by: Christoffer Dall <christoffer.dall at linaro.org>
Signed-off-by: Marc Zyngier <marc.zyngier at arm.com>
---
 arch/arm64/kvm/hyp.S | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/arch/arm64/kvm/hyp.S b/arch/arm64/kvm/hyp.S
index 100494b..b72aa9f 100644
--- a/arch/arm64/kvm/hyp.S
+++ b/arch/arm64/kvm/hyp.S
@@ -770,6 +770,14 @@
 	mrs	x2, mdcr_el2
 	and	x2, x2, #MDCR_EL2_HPMN_MASK
 	orr	x2, x2, #(MDCR_EL2_TPM | MDCR_EL2_TPMCR)
+	orr	x2, x2, #(MDCR_EL2_TDRA | MDCR_EL2_TDOSA)
+
+	// Check for KVM_ARM64_DEBUG_DIRTY, and set debug to trap
+	// if not dirty.
+	ldr	x3, [x0, #VCPU_DEBUG_FLAGS]
+	tbnz	x3, #KVM_ARM64_DEBUG_DIRTY_SHIFT, 1f
+	orr	x2, x2,  #MDCR_EL2_TDA
+1:
 	msr	mdcr_el2, x2
 .endm
 
-- 
2.0.0