arm64: KVM: Make unexpected reads from WO registers inject an undef

BugLink: https://bugs.launchpad.net/bugs/1673564
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.

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

Let's also remove write_to_read_only which isn't used anywhere.

Reviewed-by: Christoffer Dall <cdall@linaro.org>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
(cherry picked from commit 7b5b4df1a79954e0b208630fc63b16ec0231a516)
Signed-off-by: dann frazier <dann.frazier@canonical.com>
Acked-by: Stefan Bader <stefan.bader@canonical.com>
Acked-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com>
Signed-off-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com>

diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c
index 7cee552ce0bf025759fb75a4c13850fa641878c8..5bc9ede609407d8459f755630512656784a25ac8 100644 (file)
--- a/arch/arm64/kvm/sys_regs.c
+++ b/arch/arm64/kvm/sys_regs.c
@@ -55,6 +55,15 @@
  * 64bit interface.
  */
 
+static bool read_from_write_only(struct kvm_vcpu *vcpu,
+                                const struct sys_reg_params *params)
+{
+       WARN_ONCE(1, "Unexpected sys_reg read to write-only register\n");
+       print_sys_reg_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/arm64/kvm/sys_regs.h b/arch/arm64/kvm/sys_regs.h
index dbbb01cfbee9c504980943921c841b61118837b8..bcc7527d266c8e8f26cbce22c00254cd6356acd5 100644 (file)
--- a/arch/arm64/kvm/sys_regs.h
+++ b/arch/arm64/kvm/sys_regs.h
@@ -83,24 +83,6 @@ static inline bool read_zero(struct kvm_vcpu *vcpu,
        return true;
 }
 
-static inline bool write_to_read_only(struct kvm_vcpu *vcpu,
-                                     const struct sys_reg_params *params)
-{
-       kvm_debug("sys_reg write to read-only register at: %lx\n",
-                 *vcpu_pc(vcpu));
-       print_sys_reg_instr(params);
-       return false;
-}
-
-static inline bool read_from_write_only(struct kvm_vcpu *vcpu,
-                                       const struct sys_reg_params *params)
-{
-       kvm_debug("sys_reg read to write-only register at: %lx\n",
-                 *vcpu_pc(vcpu));
-       print_sys_reg_instr(params);
-       return false;
-}
-
 /* Reset functions */
 static inline void reset_unknown(struct kvm_vcpu *vcpu,
                                 const struct sys_reg_desc *r)