KVM: arm64: Disable guest access to trace filter controls

[ Upstream commit a354a64d91eec3e0f8ef0eed575b480fd75b999c ]

Disable guest access to the Trace Filter control registers.
We do not advertise the Trace filter feature to the guest
(ID_AA64DFR0_EL1: TRACE_FILT is cleared) already, but the guest
can still access the TRFCR_EL1 unless we trap it.

This will also make sure that the guest cannot fiddle with
the filtering controls set by a nvhe host.

Cc: Marc Zyngier <maz@kernel.org>
Cc: Will Deacon <will@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20210323120647.454211-3-suzuki.poulose@arm.com
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/arch/arm64/include/asm/kvm_arm.h b/arch/arm64/include/asm/kvm_arm.h
index a3b6f58..6d43f79 100644 (file)
--- a/arch/arm64/include/asm/kvm_arm.h
+++ b/arch/arm64/include/asm/kvm_arm.h
@@ -198,6 +198,7 @@
 #define CPTR_EL2_DEFAULT       CPTR_EL2_RES1
 
 /* Hyp Debug Configuration Register bits */
+#define MDCR_EL2_TTRF          (1 << 19)
 #define MDCR_EL2_TPMS          (1 << 14)
 #define MDCR_EL2_E2PB_MASK     (UL(0x3))
 #define MDCR_EL2_E2PB_SHIFT    (UL(12))

diff --git a/arch/arm64/kvm/debug.c b/arch/arm64/kvm/debug.c
index 4e722d7..3606f6b 100644 (file)
--- a/arch/arm64/kvm/debug.c
+++ b/arch/arm64/kvm/debug.c
@@ -100,6 +100,7 @@ void kvm_arm_reset_debug_ptr(struct kvm_vcpu *vcpu)
  *  - Debug ROM Address (MDCR_EL2_TDRA)
  *  - OS related registers (MDCR_EL2_TDOSA)
  *  - Statistical profiler (MDCR_EL2_TPMS/MDCR_EL2_E2PB)
+ *  - Self-hosted Trace Filter controls (MDCR_EL2_TTRF)
  *
  * Additionally, KVM only traps guest accesses to the debug registers if
  * the guest is not actively using them (see the KVM_ARM64_DEBUG_DIRTY
@@ -123,6 +124,7 @@ void kvm_arm_setup_debug(struct kvm_vcpu *vcpu)
        vcpu->arch.mdcr_el2 = __this_cpu_read(mdcr_el2) & MDCR_EL2_HPMN_MASK;
        vcpu->arch.mdcr_el2 |= (MDCR_EL2_TPM |
                                MDCR_EL2_TPMS |
+                               MDCR_EL2_TTRF |
                                MDCR_EL2_TPMCR |
                                MDCR_EL2_TDRA |
                                MDCR_EL2_TDOSA);