[RFC 19/55] KVM: arm64: Trap CPACR_EL1 access in virtual EL2

[Jintack Lim]

For the same reason we trap virtual memory register accesses in virtual
EL2, we trap CPACR_EL1 access too. Basically, we don't want the guest
hypervisor to access the real CPACR_EL1, which is used to emulate
virtual EL2. Instead, we want it to access virtual CPACR_EL1 which is
used to run software in EL0/EL1 from the guest hypervisor's perspective.

Signed-off-by: Jintack Lim <jint...@cs.columbia.edu>
---
 arch/arm64/kvm/hyp/switch.c | 10 +++++++---
 arch/arm64/kvm/sys_regs.c   | 10 +++++++++-
 2 files changed, 16 insertions(+), 4 deletions(-)

diff --git a/arch/arm64/kvm/hyp/switch.c b/arch/arm64/kvm/hyp/switch.c
index c05c48f..b7c8c30 100644
--- a/arch/arm64/kvm/hyp/switch.c
+++ b/arch/arm64/kvm/hyp/switch.c
@@ -41,7 +41,8 @@ bool __hyp_text __fpsimd_enabled(void)
        return __fpsimd_is_enabled()();
 }
 
-static void __hyp_text __activate_traps_vhe(void)
+static void __hyp_text __activate_traps_vhe(struct kvm_vcpu *vcpu)
+
 {
        u64 val;
 
@@ -53,12 +54,15 @@ static void __hyp_text __activate_traps_vhe(void)
        write_sysreg(__kvm_hyp_vector, vbar_el1);
 }
 
-static void __hyp_text __activate_traps_nvhe(void)
+static void __hyp_text __activate_traps_nvhe(struct kvm_vcpu *vcpu)
+
 {
        u64 val;
 
        val = CPTR_EL2_DEFAULT;
        val |= CPTR_EL2_TTA | CPTR_EL2_TFP;
+       if (vcpu_mode_el2(vcpu))
+               val |= CPTR_EL2_TCPAC;
        write_sysreg(val, cptr_el2);
 }
 
@@ -90,7 +94,7 @@ static void __hyp_text __activate_traps(struct kvm_vcpu *vcpu)
        /* Make sure we trap PMU access from EL0 to EL2 */
        write_sysreg(ARMV8_PMU_USERENR_MASK, pmuserenr_el0);
        write_sysreg(vcpu->arch.mdcr_el2, mdcr_el2);
-       __activate_traps_arch()();
+       __activate_traps_arch()(vcpu);
 }
 
 static void __hyp_text __deactivate_traps_vhe(void)
diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c
index 59f9cc6..321ecbc 100644
--- a/arch/arm64/kvm/sys_regs.c
+++ b/arch/arm64/kvm/sys_regs.c
@@ -947,6 +947,14 @@ static bool access_vbar(struct kvm_vcpu *vcpu,
        return true;
 }
 
+static bool access_cpacr(struct kvm_vcpu *vcpu,
+               struct sys_reg_params *p,
+               const struct sys_reg_desc *r)
+{
+       access_rw(p, &vcpu_sys_reg(vcpu, r->reg));
+       return true;
+}
+
 static bool trap_el2_reg(struct kvm_vcpu *vcpu,
                         struct sys_reg_params *p,
                         const struct sys_reg_desc *r)
@@ -1051,7 +1059,7 @@ static bool trap_el2_reg(struct kvm_vcpu *vcpu,
          access_vm_reg, reset_val, SCTLR_EL1, 0x00C50078 },
        /* CPACR_EL1 */
        { Op0(0b11), Op1(0b000), CRn(0b0001), CRm(0b0000), Op2(0b010),
-         NULL, reset_val, CPACR_EL1, 0 },
+         access_cpacr, reset_val, CPACR_EL1, 0 },
        /* TTBR0_EL1 */
        { Op0(0b11), Op1(0b000), CRn(0b0010), CRm(0b0000), Op2(0b000),
          access_vm_reg, reset_unknown, TTBR0_EL1 },
-- 
1.9.1