arm64: KVM: enable trapping of all debug registers

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@linaro.org>
Reviewed-by: Christoffer Dall <christoffer.dall@linaro.org>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>

diff --git a/arch/arm64/kvm/hyp.S b/arch/arm64/kvm/hyp.S
index 100494b..b72aa9f 100644 (file)
--- 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