[PATCH v2 03/15] KVM: arm64: nv: Handle CPACR_EL1 traps

Oliver Upton
2024-06-13T20:18:36Z

From: Marc Zyngier <maz@kernel.org>

Handle CPACR_EL1 accesses when running a VHE guest. In order to
limit the cost of the emulation, implement it ass a shallow exit.

In the other cases:

- this is a nVHE L1 which will write to memory, and we don't trap

- this is a L2 guest:

* the L1 has CPTR_EL2.TCPAC==0, and the L2 has direct register
access

* the L1 has CPTR_EL2.TCPAC==1, and the L2 will trap, but the
handling is defered to the general handling for forwarding

Signed-off-by: Marc Zyngier <maz@kernel.org>
Signed-off-by: Oliver Upton <oliver.upton@linux.dev>
---
arch/arm64/kvm/hyp/vhe/switch.c | 32 +++++++++++++++++++++++++++++++-
1 file changed, 31 insertions(+), 1 deletion(-)

diff --git a/arch/arm64/kvm/hyp/vhe/switch.c b/arch/arm64/kvm/hyp/vhe/switch.c
index d7af5f46f22a..fed36457fef9 100644
--- a/arch/arm64/kvm/hyp/vhe/switch.c
+++ b/arch/arm64/kvm/hyp/vhe/switch.c
@@ -262,10 +262,40 @@ static bool kvm_hyp_handle_eret(struct kvm_vcpu *vcpu, u64 *exit_code)
return true;
}

+static bool kvm_hyp_handle_cpacr_el1(struct kvm_vcpu *vcpu, u64 *exit_code)
+{
+ u64 esr = kvm_vcpu_get_esr(vcpu);
+ int rt;
+
+ if (!is_hyp_ctxt(vcpu) || esr_sys64_to_sysreg(esr) != SYS_CPACR_EL1)
+ return false;
+
+ rt = kvm_vcpu_sys_get_rt(vcpu);
+
+ if ((esr & ESR_ELx_SYS64_ISS_DIR_MASK) == ESR_ELx_SYS64_ISS_DIR_READ) {
+ vcpu_set_reg(vcpu, rt, __vcpu_sys_reg(vcpu, CPTR_EL2));
+ } else {
+ vcpu_write_sys_reg(vcpu, vcpu_get_reg(vcpu, rt), CPTR_EL2);
+ __activate_cptr_traps(vcpu);
+ }
+
+ __kvm_skip_instr(vcpu);
+
+ return true;
+}
+
+static bool kvm_hyp_handle_sysreg_vhe(struct kvm_vcpu *vcpu, u64 *exit_code)
+{
+ if (kvm_hyp_handle_cpacr_el1(vcpu, exit_code))
+ return true;
+
+ return kvm_hyp_handle_sysreg(vcpu, exit_code);
+}
+
static const exit_handler_fn hyp_exit_handlers[] = {
[0 ... ESR_ELx_EC_MAX] = NULL,
[ESR_ELx_EC_CP15_32] = kvm_hyp_handle_cp15_32,
- [ESR_ELx_EC_SYS64] = kvm_hyp_handle_sysreg,
+ [ESR_ELx_EC_SYS64] = kvm_hyp_handle_sysreg_vhe,
[ESR_ELx_EC_SVE] = kvm_hyp_handle_fpsimd,
[ESR_ELx_EC_FP_ASIMD] = kvm_hyp_handle_fpsimd,
[ESR_ELx_EC_IABT_LOW] = kvm_hyp_handle_iabt_low,
--
2.45.2.627.g7a2c4fd464-goog