[PATCH v2 8/9] arm: KVM: Make unexpected register accesses inject an undef

Marc Zyngier
2017-03-27T16:02:16Z

Reads from write-only system registers are generally confined to
EL1 and not propagated to EL2 (that's what the architecture
mantates). In order to be sure that we have a sane behaviour
even in the unlikely event that we have a broken system, we still
handle it in KVM. Same goes for write to RO registers.

In that case, let's inject an undef into the guest.

Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
---
arch/arm/kvm/coproc.c | 18 ++++++++++++++++++
arch/arm/kvm/coproc.h | 18 ------------------
2 files changed, 18 insertions(+), 18 deletions(-)

diff --git a/arch/arm/kvm/coproc.c b/arch/arm/kvm/coproc.c
index 3e5e4194ef86..519aac12b365 100644
--- a/arch/arm/kvm/coproc.c
+++ b/arch/arm/kvm/coproc.c
@@ -40,6 +40,24 @@
* Co-processor emulation
*****************************************************************************/

+static bool write_to_read_only(struct kvm_vcpu *vcpu,
+ const struct coproc_params *params)
+{
+ WARN_ONCE(1, "CP15 write to read-only register\n");
+ print_cp_instr(params);
+ kvm_inject_undefined(vcpu);
+ return false;
+}
+
+static bool read_from_write_only(struct kvm_vcpu *vcpu,
+ const struct coproc_params *params)
+{
+ WARN_ONCE(1, "CP15 read to write-only register\n");
+ print_cp_instr(params);
+ kvm_inject_undefined(vcpu);
+ return false;
+}
+
/* 3 bits per cache level, as per CLIDR, but non-existent caches always 0 */
static u32 cache_levels;

diff --git a/arch/arm/kvm/coproc.h b/arch/arm/kvm/coproc.h
index eef1759c2b65..3a41b7d1eb86 100644
--- a/arch/arm/kvm/coproc.h
+++ b/arch/arm/kvm/coproc.h
@@ -81,24 +81,6 @@ static inline bool read_zero(struct kvm_vcpu *vcpu,
return true;
}

-static inline bool write_to_read_only(struct kvm_vcpu *vcpu,
- const struct coproc_params *params)
-{
- kvm_debug("CP15 write to read-only register at: %08lx\n",
- *vcpu_pc(vcpu));
- print_cp_instr(params);
- return false;
-}
-
-static inline bool read_from_write_only(struct kvm_vcpu *vcpu,
- const struct coproc_params *params)
-{
- kvm_debug("CP15 read to write-only register at: %08lx\n",
- *vcpu_pc(vcpu));
- print_cp_instr(params);
- return false;
-}
-
/* Reset functions */
static inline void reset_unknown(struct kvm_vcpu *vcpu,
const struct coproc_reg *r)
--
2.11.0